TGaxis Class Reference

The axis painter class.

Instances of this class are generated by the histograms and graphs painting classes when TAxis are drawn. TGaxis is the "painter class" of TAxis. Therefore it is mainly used via TAxis, even if is some occasion it can be used directly to draw an axis which is not part of a graph or an instance. For instance to draw an extra scale on a plot.

• Basic definition
• Definition with a function
• Logarithmic axis
• Blank axis
• Tick marks' orientation
• Tick marks' size
• Labels' positionning
• Labels' orientation
• Labels' position on tick marks
• Labels' format
• Alphanumeric labels
• Changing axis labels
• Number of divisions optimisation
• Maximum Number of Digits for the axis labels
• Optional grid
• Time axis

Basic definition

A TGaxis is defined the following way:

TGaxis::TGaxis(Double_t xmin, Double_t ymin, Double_t xmax, Double_t ymax,
               Double_t wmin, Double_t wmax, Int_t ndiv, Option_t *chopt,
               Double_t gridlength)

Where:

• xmin : X origin coordinate in user's coordinates space.
• xmax : X end axis coordinate in user's coordinates space.
• ymin : Y origin coordinate in user's coordinates space.
• ymax : Y end axis coordinate in user's coordinates space.
• wmin : Lowest value for the tick mark labels written on the axis.
• wmax : Highest value for the tick mark labels written on the axis.
• ndiv : Number of divisions.
  • ndiv=N1 + 100*N2 + 10000*N3
  • N1=number of 1st divisions.
  • N2=number of 2nd divisions.
  • N3=number of 3rd divisions. e.g.:
    • ndiv=0 --> no tick marks.
    • ndiv=2 --> 2 divisions, one tick mark in the middle of the axis.
• chopt : Drawing options (see below).
• gridlength: grid length on main tick marks.

The example below generates various kind of axis.

{
   TCanvas *c1 = new TCanvas("c1","Examples of TGaxis",10,10,700,500);
 
   c1->Range(-10,-1,10,1);
 
   TGaxis *axis1 = new TGaxis(-4.5,-0.2,5.5,-0.2,-6,8,510,"");
   axis1->SetName("axis1");
   axis1->Draw();
 
   TGaxis *axis2 = new TGaxis(-4.5,0.2,5.5,0.2,0.001,10000,510,"G");
   axis2->SetName("axis2");
   axis2->Draw();
 
   TGaxis *axis3 = new TGaxis(-9,-0.8,-9,0.8,-8,8,50510,"");
   axis3->SetName("axis3");
   axis3->Draw();
 
   TGaxis *axis4 = new TGaxis(-7,-0.8,-7,0.8,1,10000,50510,"G");
   axis4->SetName("axis4");
   axis4->Draw();
 
   TGaxis *axis5 = new TGaxis(-4.5,-0.6,5.5,-0.6,1.2,1.32,80506,"-+");
   axis5->SetName("axis5");
   axis5->SetLabelSize(0.03);
   axis5->SetTextFont(72);
   axis5->SetLabelOffset(0.025);
 
   axis5->Draw();
 
   TGaxis *axis6 = new TGaxis(-4.5,0.6,5.5,0.6,100,900,50510,"-");
   axis6->SetName("axis6");
   axis6->Draw();
 
   TGaxis *axis7 = new TGaxis(8,-0.8,8,0.8,0,9000,50510,"+L");
   axis7->SetName("axis7");
   axis7->SetLabelOffset(0.01);
   axis7->Draw();
 
   //one can make axis going top->bottom. However because of a long standing
   //problem, the two x values should not be equal
   TGaxis *axis8 = new TGaxis(6.5,0.8,6.499,-0.8,0,90,50510,"-");
   axis8->SetName("axis8");
   axis8->Draw();
}

Definition with a function

Instead of the wmin,wmax arguments of the normal definition, the name of a TF1 function can be specified. This function will be used to map the user coordinates to the axis values and ticks.

A TGaxis is defined the following way:

TGaxis::TGaxis(Double_t xmin, Double_t ymin, Double_t xmax, Double_t ymax,
               const char *func, Int_t ndiv,   Option_t *chopt,
               Double_t gridlength)

Where:

• xmin : X origin coordinate in user's coordinates space.
• xmax : X end axis coordinate in user's coordinates space.
• ymin : Y origin coordinate in user's coordinates space.
• ymax : Y end axis coordinate in user's coordinates space.
• func : function defining axis labels and tick marks.
• ndiv : Number of divisions.
  • ndiv=N1 + 100*N2 + 10000*N3
  • N1=number of 1st divisions.
  • N2=number of 2nd divisions.
  • N3=number of 3rd divisions. e.g.:
    • ndiv=0 --> no tick marks.
    • ndiv=2 --> 2 divisions, one tick mark in the middle of the axis.
• chopt : Drawing options (see below).
• gridlength: grid length on main tick marks.

Examples:

{
   TCanvas *c2 = new TCanvas("c2","c2",10,10,700,500);
 
   gPad->DrawFrame(0.,-2.,10.,2);
 
   TF1 *f1=new TF1("f1","-x",-10,10);
   TGaxis *A1 = new TGaxis(0,2,10,2,"f1",510,"-");
   A1->SetTitle("axis with decreasing values");
   A1->Draw();
 
   TF1 *f2=new TF1("f2","exp(x)",0,2);
   TGaxis *A2 = new TGaxis(1,1,9,1,"f2");
   A2->SetTitle("exponential axis");
   A2->SetLabelSize(0.03);
   A2->SetTitleSize(0.03);
   A2->SetTitleOffset(1.2);
   A2->Draw();
 
   TF1 *f3=new TF1("f3","log10(x)",1,1000);
   TGaxis *A3 = new TGaxis(2,-2,2,0,"f3",505,"");
   A3->SetTitle("logarithmic axis");
   A3->SetLabelSize(0.02);
   A3->SetTitleSize(0.03);
   A3->SetTitleOffset(0.); // Axis title automatically placed
   A3->Draw();
}

Logarithmic axis

By default axis are linear. To define a TGaxis as logarithmic, it is enough to create it with the option "G".

When plotting an histogram or a graph the logarithmic scale can be set using:

• gPad->SetLogx(1); set the logarithmic scale on the X axis
• gPad->SetLogy(1); set the logarithmic scale on the Y axis

When the SetMoreLogLabels() method is called more labels are drawn when in logarithmic scale and there is a small number of decades (less than 3).

Blank axis

To draw only the axis tick marks without the axis body, it is enough to specify the option "B". It useful to superpose axis.

Tick marks' orientation

By default tick marks are drawn on the positive side of the axis, except for vertical axis for which the default is negative. The chop parameter allows to control the tick marks orientation:

• chopt = "+": tick marks are drawn on Positive side. (default)
• chopt ="-": tick mark are drawn on the negative side.
• chopt = "+-": tick marks are drawn on both sides of the axis.
• chopt = "U": Unlabelled axis, default is labeled.

Tick marks' size

By default, tick marks have a length equal to 3 per cent of the axis length. When the option "S" is specified, the length of the tick marks is equal to fTickSize*axis_length, where fTickSize may be set via TGaxis::SetTickSize.

When plotting an histogram h the tick marks size can be changed using:

• h->GetXaxis()->SetTickLength(0.02); set the tick length for the X axis
• gStyle->SetTickLength(0.02,"x"); set the tick length for the X axis of all histograms drawn after this instruction.

A good way to remove tick marks on an axis is to set the tick length to 0: h->GetXaxis()->SetTickLength(0.);

Labels' positionning

Labels are normally drawn on side opposite to tick marks. However the option "=" allows to draw them on the same side. The distance between the labels and the axis body can be changed with SetLabelOffset.

Labels' orientation

By default axis labels are drawn parallel to the axis. However if the axis is vertical then are drawn perpendicular to the axis.

Labels' position on tick marks

By default axis labels are centered on tick marks. However, for vertical axis, they are right adjusted. The chop parameter allows to control the labels' position on tick marks:

• chopt = "R": labels are Right adjusted on tick mark.(default is centered)
• chopt = "L": labels are Left adjusted on tick mark.
• chopt = "C": labels are Centered on tick mark.
• chopt = "M": In the Middle of the divisions.

Labels' format

Blank characters are stripped, and then the label is correctly aligned. the dot, if last character of the string, is also stripped, unless the option "." (a dot, or period) is specified. if SetDecimals(kTRUE) has been called all labels have the same number of decimals after the "." The same is true if gStyle->SetStripDecimals(kFALSE) has been called.

In the following, we have some parameters, like tick marks length and characters height (in percentage of the length of the axis (user's coordinates)) The default values are as follows:

• Primary tick marks: 3.0 %
• Secondary tick marks: 1.5 %
• Third order tick marks: .75 %
• Characters height for labels: 4%
• Labels offset: 1.0 %

By default, an exponent of the form 10^N is used when the label values are either all very small or very large. One can disable the exponent by calling axis.SetNoExponent(kTRUE).

TGaxis::SetExponentOffset(Float_t xoff, Float_t yoff, Option_t *axis) is static function to set X and Y offset of the axis 10^n notation. It is in % of the pad size. It can be negative. axis specifies which axis ("x" or/and "y"), default is "x" if axis = "xz" set the two axes

Alphanumeric labels

Axis labels can be any alphanumeric character strings. Such axis can be produced only with histograms because the labels'definition is stored in TAxis. The following example demonstrates how to create such labels.

 
TCanvas *hlabels2()
{
   const Int_t nx = 12;
   const Int_t ny = 20;
   const char *month[nx]  = {"January","February","March","April","May",
      "June","July","August","September","October","November",
      "December"};
   const char *people[ny] = {"Jean","Pierre","Marie","Odile","Sebastien",
      "Fons","Rene","Nicolas","Xavier","Greg","Bjarne","Anton",
      "Otto","Eddy","Peter","Pasha","Philippe","Suzanne","Jeff",
      "Valery"};
   TCanvas *c1 = new TCanvas("c1","demo bin labels",10,10,600,600);
   c1->SetGrid();
   c1->SetLeftMargin(0.15);
   c1->SetBottomMargin(0.15);
   TH2F *h = new TH2F("h","test",3,0,3,2,0,2);
   h->SetCanExtend(TH1::kAllAxes);
   h->SetStats(0);
   gRandom->SetSeed();
   for (Int_t i=0;i<15000;i++) {
      Int_t rx = gRandom->Rndm()*nx;
      Int_t ry = gRandom->Rndm()*ny;
      h->Fill(people[ry],month[rx],1);
   }
   h->LabelsDeflate("X");
   h->LabelsDeflate("Y");
   h->LabelsOption("v");
   h->Draw("text");
 
   TPaveText *pt = new TPaveText(0.6,0.85,0.98,0.98,"brNDC");
   pt->SetFillColor(18);
   pt->SetTextAlign(12);
   pt->AddText("Use the axis Context Menu LabelsOption");
   pt->AddText(" \"a\"   to sort by alphabetic order");
   pt->AddText(" \">\"   to sort by decreasing values");
   pt->AddText(" \"<\"   to sort by increasing values");
   pt->Draw();
   return c1;
}

Because the alphanumeric labels are usually longer that the numeric labels, their size is by default equal to 0.66666 * the_numeric_labels_size.

Changing axis labels

Since

ROOT version 6.07/07:

After an axis has been created, TGaxis::ChangeLabel allows to define new text attributes for a given label. A fine tuning of the labels can be done. All the attributes can be changed as well as the text label itself.

When plotting an histogram or a graph the labels can be changed like in the following example which shows a way to produce \(\pi\)-axis :

{
   Double_t pi = TMath::Pi();
   TF1*   f = new TF1("f","TMath::Cos(x/TMath::Pi())", -pi, pi);
   TH1*   h = f->GetHistogram();
   TAxis* a = h->GetXaxis();
   a->SetNdivisions(-502);
   a->ChangeLabel(1,-1,-1,-1,-1,-1,"-#pi");
   a->ChangeLabel(-1,-1,-1,-1,-1,-1,"#pi");
   f->Draw();
}

Number of divisions optimisation

By default the number of divisions on axis is optimised to show a coherent labelling of the main tick marks. The number of division (ndiv) is a composite integer given by:

ndiv = N1 + 100*N2 + 10000*N3

• N1 = number of 1st divisions.
• N2 = number of 2nd divisions.
• N3 = number of 3rd divisions.

by default the value of N1, N2 and N3 are maximum values. After optimisation the real number of divisions will be smaller or equal to these value. If one wants to bypass the optimisation, the option "N" should be given when the TGaxis is created. The option "I" also act on the number of division as it will force an integer labelling of the axis.

On an histogram pointer h the number of divisions can be set in different ways:.

• Directly on the histogram. The following will set the number of division to 510 on the X axis of h. To avoid optimization the number of divisions should be negative (ie: -510);

  h->SetNdivisions(510, "X");

• On the axis itself:

  h->GetXaxis()->SetNdivisions(510, kTRUE);

The first parameter is the number of division. If it is negative of if the second parameter is kFALSE then the number of divisions is not optimised. And other signature is also allowed:

h->GetXaxis()->SetNdivisions(10, 5, 0, kTRUE);

Maximum Number of Digits for the axis labels

The static function TGaxis::SetMaxDigits sets the maximum number of digits permitted for the axis labels above which the notation with 10^N is used. For example, to accept 6 digits number like 900000 on an axis call TGaxis::SetMaxDigits(6). The default value is 5. fgMaxDigits must be greater than 0.

Optional grid

The option "W" allows to draw a grid on the primary tick marks. In case of a log axis, the grid is only drawn for the primary tick marks if the number of secondary and tertiary divisions is 0. SetGridLength() allows to define the length of the grid.

When plotting an histogram or a graph the grid can be set ON or OFF using:

• gPad->SetGridy(1); set the grid on the X axis
• gPad->SetGridx(1); set the grid on the Y axis
• gPad->SetGrid(1,1); set the grid on both axis.

Time axis

Histograms' axis can be defined as "time axis". To do that it is enough to activate the TAxis::SetTimeDisplay attribute on a given axis. If h is an histogram, it is done the following way:

h->GetXaxis()->SetTimeDisplay(1);  // The X axis is a time axis

Two parameters can be adjusted in order to define time axis:

The time format:

Defines the format of the labels along the time axis. It can be changed using the TAxis TAxis::SetTimeFormat. The time format is the one used by the C function strftime(). It's a string containing the following formatting characters:

• for date :
  • a abbreviated weekday name
  • b abbreviated month name
  • d day of the month (01-31)
  • m month (01-12)
  • y year without century
  • Y year with century
• for time :
  • H hour (24-hour clock)
  • I hour (12-hour clock)
  • p local equivalent of AM or PM
  • M minute (00-59)
  • S seconds (00-61)
  • %% %

The other characters are output as is. For example to have a format like dd/mm/yyyy one should do:

h->GetXaxis()->SetTimeFormat("%d\/%m\/%Y");

The time offset:

This is a time in seconds in the UNIX standard UTC format (this is an universal time, not the local time), defining the starting date of an histogram axis. This date should be greater than 01/01/95 and is given in seconds. There are three ways to define the time offset:

By setting the global default time offset:

TDatime da(2003,02,28,12,00,00);
gStyle->SetTimeOffset(da.Convert());

If no time offset is defined for a particular axis, the default time offset will be used. In the example above, notice the usage of TDateTime to translate an explicit date into the time in seconds required by TAxis::SetTimeFormat.

By setting a time offset to a particular axis:

TDatime dh(2001,09,23,15,00,00);
h->GetXaxis()->SetTimeOffset(dh.Convert());

Together with the time format using TAxis::SetTimeFormat:

The time offset can be specified using the control character F after the normal time format. F is followed by the date in the format: yyyy-mm-dd hh:mm:ss.

Example:

h->GetXaxis()->SetTimeFormat("%d\/%m\/%y%F2000-02-28 13:00:01");

Notice that this date format is the same used by the TDateString function AsSQLString. If needed, this function can be used to translate a time in seconds into a character string which can be appended after F. If the time format is not specified (before `F), the automatic one will be used.

If a time axis has no specified time offset, the global time offset will be stored in the axis data structure.

The following example illustrates the various possibilities.

{
   gStyle->SetTitleH(0.08);
 
   TDatime da(2003,2,28,12,00,00);
   gStyle->SetTimeOffset(da.Convert());
 
   auto ct = new TCanvas("ct","Time on axis",0,0,600,600);
   ct->Divide(1,3);
 
   auto ht1 = new TH1F("ht1","ht1",30000,0.,200000.);
   auto ht2 = new TH1F("ht2","ht2",30000,0.,200000.);
   auto ht3 = new TH1F("ht3","ht3",30000,0.,200000.);
   for (Int_t i=1;i<30000;i++) {
      auto noise = gRandom->Gaus(0,120);
      ht1->SetBinContent(i,noise);
      ht2->SetBinContent(i,noise*noise);
      ht3->SetBinContent(i,noise*noise*noise);
   }
 
   ct->cd(1);
   ht1->GetXaxis()->SetLabelSize(0.06);
   ht1->GetXaxis()->SetTimeDisplay(1);
   ht1->GetXaxis()->SetTimeFormat("%d/%m/%y%F2000-02-28 13:00:01");
   ht1->Draw();
 
   ct->cd(2);
   ht2->GetXaxis()->SetLabelSize(0.06);
   ht2->GetXaxis()->SetTimeDisplay(1);
   ht2->GetXaxis()->SetTimeFormat("%d/%m/%y");
   ht2->Draw();
 
   ct->cd(3);
   ht3->GetXaxis()->SetLabelSize(0.06);
   TDatime dh(2001,9,23,15,00,00);
   ht3->GetXaxis()->SetTimeDisplay(1);
   ht3->GetXaxis()->SetTimeOffset(dh.Convert());
   ht3->Draw();
}

The histogram limits times in seconds. If wmin and wmax are the histogram limits, the time axis will spread around the time offset value from TimeOffset+wmin to TimeOffset+wmax. Until now all the examples had a lowest value equal to 0. The following example demonstrates how to define the histogram limits relatively to the time offset value.

{
   // Define the time offset as 2003, January 1st
   TDatime T0(2003,1,1,0,0,0);
   auto X0 = T0.Convert();
   gStyle->SetTimeOffset(X0);
 
   // Define the lowest histogram limit as 2002, September 23rd
   TDatime T1(2002,9,23,0,0,0);
   auto X1 = T1.Convert()-X0;
 
   // Define the highest histogram limit as 2003, March 7th
   TDatime T2(2003,3,7,0,0,0);
   auto X2 = T2.Convert(1)-X0;
 
   auto h1 = new TH1F("h1","test",100,X1,X2);
 
   TRandom r;
   for (Int_t i=0;i<30000;i++) {
      Double_t noise = r.Gaus(0.5*(X1+X2),0.1*(X2-X1));
      h1->Fill(noise);
   }
 
   h1->GetXaxis()->SetTimeDisplay(1);
   h1->GetXaxis()->SetLabelSize(0.03);
   h1->GetXaxis()->SetTimeFormat("%Y/%m/%d");
   h1->Draw();
}

Usually time axis are created automatically via histograms, but one may also want to draw a time axis outside an "histogram context". Therefore it is useful to understand how TGaxis works for such axis.

The time offset can be defined using one of the three methods described before. The time axis will spread around the time offset value. Actually it will go from TimeOffset+wmin to TimeOffset+wmax where wmin and wmax are the minimum and maximum values (in seconds) of the axis. Let's take again an example. Having defined "2003, February 28 at 12h" we would like to see the axis a day before and a day after. A TGaxis can be created the following way (a day has 86400 seconds):

TGaxis *axis = new TGaxis(x1,y1,x2,y2,-100000,150000,2405,"t");

the t option (in lower case) means it is a "time axis". The axis goes form 100000 seconds before TimeOffset and 150000 seconds after.

So the complete macro is:

{
   c1 = new TCanvas("c1","Examples of TGaxis",10,10,700,100);
   c1->Range(-10,-1,10,1);
 
   TGaxis *axis = new TGaxis(-8,0.,8,0.,-100000,150000,2405,"tS");
   axis->SetLabelSize(0.2);
   axis->SetTickSize(0.2);
 
   TDatime da(2003,02,28,12,00,00);
   axis->SetTimeOffset(da.Convert());
   axis->SetTimeFormat("%d-%m-%Y");
   axis->Draw();
   return c1;
}

Thanks to the TLatex directive #splitline it is possible to write the time labels on two lines. In the previous example changing the SetTimeFormat line by

axis->SetLabelOffset(0.15);
axis->SetTimeFormat("#splitline{%Y}{%d\/%m}");

will produce the following axis:

The following example shows time axis on a TGraph:

{
   TDatime da1(2008,02,28,15,52,00);
   TDatime da2(2008,02,28,15,53,00);
 
   double x[2],y[2];
 
   y[0] = 1.;
   y[1] = 2.;
   x[0] = da1.Convert();
   x[1] = da2.Convert();
 
   TGraph mgr(2,x,y);
   mgr.SetMarkerStyle(20);
 
   mgr.Draw("apl");
   mgr.GetXaxis()->SetTimeDisplay(1);
   mgr.GetXaxis()->SetNdivisions(-503);
   mgr.GetXaxis()->SetTimeFormat("%Y-%m-%d %H:%M");
   mgr.GetXaxis()->SetTimeOffset(0,"gmt");
}

The following example compares what the system time function gmtime and localtime give with what gives TGaxis. It can be used as referenced test to check if the time option of TGaxis is working properly.

 
#if defined(G__WIN32) && defined(__CINT__) && !defined(__MAKECINT__)
{
   // timeonaxis3.C has to be run in compiled mode on Windows.
   // the following code does it.
 
   gSystem->CompileMacro("timeonaxis3.C");
   timeonaxis3();
}
#else
 
#include "TAxis.h"
#include "TGaxis.h"
#include "TCanvas.h"
#include "TString.h"
#include "TLine.h"
#include "TLatex.h"
#include <time.h>
#include <stdio.h>
 
TString stime(time_t* t, bool utc = false, bool display_time_zone = true) {
   struct tm* tt;
   if (utc) tt = gmtime(t);
   else     tt = localtime(t);
   char buf[256];
   if (display_time_zone) strftime(buf, sizeof(buf), "%Y-%m-%d  %H:%M:%S %Z", tt);
   else                   strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", tt);
   return TString(buf);
}
 
 
TCanvas *timeonaxis3() {
   double f = 1.8;
 
   TCanvas* c = new TCanvas;
 
   TLatex* tex1 = new TLatex;
   tex1->SetNDC();
   tex1->SetTextFont(102);
   tex1->SetTextSize(0.055*f);
 
   TLatex* tex3 = new TLatex;
   tex3->SetNDC();
   tex3->SetTextFont(102);
   tex3->SetTextSize(0.07*f);
   tex3->SetTextColor(kBlue+2);
 
   TLatex* tex2 = new TLatex;
   tex2->SetNDC();
   tex2->SetTextFont(102);
   tex2->SetTextSize(0.07*f);
   tex2->SetTextColor(kOrange+3);
 
   time_t offset[] = {0,                   0, 1325376000, 1341100800};
   time_t t[]      = {1331150400, 1336417200,          0, 36000};
 
   c->SetTopMargin(0); c->SetBottomMargin(0);
   c->SetLeftMargin(0); c->SetRightMargin(0);
   c->Divide(2, 4, -1, -1);
   TLine l;
   l.DrawLine(0.5, 0, 0.5, 1.);
 
   for(int i = 0; i < 4; ++i){
      for(int gmt = 0; gmt < 2; ++gmt){
         const char* opt = (gmt ? "gmt" : "local");
         TVirtualPad* p = c->cd(2*i + gmt + 1);
         p->SetTopMargin(0); p->SetBottomMargin(0);
         p->SetLeftMargin(0); p->SetRightMargin(0);
         p->SetFillStyle(4000);
 
         TGaxis* ga = new TGaxis (.4, .25, 5., .25, t[i], t[i] + 1,  1, "t");
         ga->SetTimeFormat("TGaxis label: #color[2]{%Y-%m-%d %H:%M:%S}");
         ga->SetLabelFont(102);
         ga->SetLabelColor(kBlue+2);
 
         ga->SetTimeOffset(offset[i], opt);
         ga->SetLabelOffset(0.04*f);
         ga->SetLabelSize(0.07*f);
         ga->SetLineColor(0);
         ga->Draw();
 
         // Get offset string of axis time format: there is not accessor
         // to time format in TGaxis.
         // Assumes TAxis use the same format.
         TAxis a(10, 0, 1600000000);
         a.SetTimeOffset(offset[i], opt);
         const char* offsettimeformat = a.GetTimeFormat();
 
         char buf[256];
         if (offset[i] < t[i]) {
            sprintf(buf, "#splitline{%s, %s}{offset: %ld, option %s}",
                    stime(t+i).Data(), stime(t+i, true).Data(), offset[i], opt);
         } else {
            int h = t[i] / 3600;
            int m = (t[i] - 3600 * h) / 60 ;
            int s = (t[i] - h * 3600 - m * 60);
            sprintf(buf, "#splitline{%d h %d m %d s}{offset: %s, option %s}",
                    h, m, s, stime(offset + i, gmt).Data(), opt);
         }
         tex1->DrawLatex(.01, .75, buf);
         tex2->DrawLatex(.01, .50, offsettimeformat);
         time_t t_ = t[i] + offset[i];
         sprintf(buf, "Expecting:    #color[2]{%s}", stime(&t_, gmt, false).Data());
         tex3->DrawLatex(.01, .24, buf);
         if(i > 0) l.DrawLine(0, 0.95, 1, 0.95);
      }
   }
   return c;
}
#endif

The following macro illustrates the use, with histograms axis, of the time mode on the axis with different time intervals and time formats.

 
#include <time.h>
 
TCanvas *timeonaxis()
{
 
   time_t script_time;
   script_time = time(0);
   script_time = 3600*(int)(script_time/3600);
 
// The time offset is the one that will be used by all graphs.
// If one changes it, it will be changed even on the graphs already defined
   gStyle->SetTimeOffset(script_time);
 
   TCanvas *ct = new TCanvas("ct","Time on axis",10,10,700,900);
   ct->Divide(1,3);
 
   int i;
 
//### Build a signal : noisy damped sine 
//        Time interval : 30 minutes
 
   gStyle->SetTitleH(0.08);
   float noise;
   TH1F *ht = new TH1F("ht","Love at first sight",3000,0.,2000.);
   for (i=1;i<3000;i++) {
      noise = gRandom->Gaus(0,120);
      if (i>700) {
         noise += 1000*sin((i-700)*6.28/30)*exp((double)(700-i)/300);
      }
      ht->SetBinContent(i,noise);
   }
   ct->cd(1);
   ht->SetLineColor(2);
   ht->GetXaxis()->SetLabelSize(0.05);
   ht->Draw();
// Sets time on the X axis
// The time used is the one set as time offset added to the value
// of the axis. This is converted into day/month/year hour:min:sec and
// a reasonable tick interval value is chosen.
   ht->GetXaxis()->SetTimeDisplay(1);
 
//### Build a simple graph beginning at a different time 
//        Time interval : 5 seconds
 
   float x[100], t[100];
   for (i=0;i<100;i++) {
      x[i] = sin(i*4*3.1415926/50)*exp(-(double)i/20);
      t[i] = 6000+(double)i/20;
   }
   TGraph *gt = new TGraph(100,t,x);
   gt->SetTitle("Politics");
   ct->cd(2);
   gt->SetLineColor(5);
   gt->SetLineWidth(2);
   gt->Draw("AL");
   gt->GetXaxis()->SetLabelSize(0.05);
// Sets time on the X axis
   gt->GetXaxis()->SetTimeDisplay(1);
   gPad->Modified();
 
//### Build a second simple graph for a very long time interval 
//        Time interval : a few years
 
   float x2[10], t2[10];
   for (i=0;i<10;i++) {
      x2[i] = gRandom->Gaus(500,100)*i;
      t2[i] = i*365*86400;
   }
   TGraph *gt2 = new TGraph(10,t2,x2);
   gt2->SetTitle("Number of monkeys on the moon");
   ct->cd(3);
   gt2->SetMarkerColor(4);
   gt2->SetMarkerStyle(29);
   gt2->SetMarkerSize(1.3);
   gt2->Draw("AP");
   gt2->GetXaxis()->SetLabelSize(0.05);
// Sets time on the X axis
   gt2->GetXaxis()->SetTimeDisplay(1);
//
// One can choose a different time format than the one chosen by default
// The time format is the same as the one of the C strftime() function
// It's a string containing the following formats :
//
//    for date :
//      %a abbreviated weekday name
//      %b abbreviated month name
//      %d day of the month (01-31)
//      %m month (01-12)
//      %y year without century
//      %Y year with century
//
//    for time :
//      %H hour (24-hour clock)
//      %I hour (12-hour clock)
//      %p local equivalent of AM or PM
//      %M minute (00-59)
//      %S seconds (00-61)
//      %% %
// The other characters are output as is.
 
   gt2->GetXaxis()->SetTimeFormat("y. %Y %F2000-01-01 00:00:00");
   gPad->Modified();
   return ct;
}

Definition at line 24 of file TGaxis.h.

Public Member Functions
	TGaxis ()
	TGaxis default constructor. More...
	TGaxis (Double_t xmin, Double_t ymin, Double_t xmax, Double_t ymax, const char *funcname, Int_t ndiv=510, Option_t *chopt="", Double_t gridlength=0)
	Constructor with a TF1 to map axis values. More...
	TGaxis (Double_t xmin, Double_t ymin, Double_t xmax, Double_t ymax, Double_t wmin, Double_t wmax, Int_t ndiv=510, Option_t *chopt="", Double_t gridlength=0)
	TGaxis normal constructor. More...
virtual	~TGaxis ()
	TGaxis default destructor. More...
virtual void	AdjustBinSize (Double_t A1, Double_t A2, Int_t nold, Double_t &BinLow, Double_t &BinHigh, Int_t &nbins, Double_t &BinWidth)
	Internal method for axis labels optimisation. More...
virtual void	CenterLabels (Bool_t center=kTRUE)
	If center = kTRUE axis labels are centered in the center of the bin. More...
virtual void	CenterTitle (Bool_t center=kTRUE)
	If center = kTRUE axis title will be centered. The default is right adjusted. More...
void	ChangeLabel (Int_t labNum=0, Double_t labAngle=-1., Double_t labSize=-1., Int_t labAlign=-1, Int_t labColor=-1, Int_t labFont=-1, TString labText="")
	Define new text attributes for the label number "labNum". More...
void	ChangeLabelAttributes (Int_t i, Int_t nlabels, TLatex *t, char *c)
virtual void	DrawAxis (Double_t xmin, Double_t ymin, Double_t xmax, Double_t ymax, Double_t wmin, Double_t wmax, Int_t ndiv=510, Option_t *chopt="", Double_t gridlength=0)
	Draw this axis with new attributes. More...
TF1 *	GetFunction () const
Float_t	GetGridLength () const
Int_t	GetLabelColor () const
Int_t	GetLabelFont () const
Float_t	GetLabelOffset () const
Float_t	GetLabelSize () const
virtual const char *	GetName () const
	Returns name of object. More...
Int_t	GetNdiv () const
virtual const char *	GetOption () const
Float_t	GetTickSize () const
virtual const char *	GetTitle () const
	Returns title of object. More...
Float_t	GetTitleOffset () const
Float_t	GetTitleSize () const
Double_t	GetWmax () const
Double_t	GetWmin () const
virtual void	ImportAxisAttributes (TAxis *axis)
	Internal method to import TAxis attributes to this TGaxis. More...
void	LabelsLimits (const char *label, Int_t &first, Int_t &last)
	Internal method to find first and last character of a label. More...
virtual void	Paint (Option_t *chopt="")
	Draw this axis with its current attributes. More...
virtual void	PaintAxis (Double_t xmin, Double_t ymin, Double_t xmax, Double_t ymax, Double_t &wmin, Double_t &wmax, Int_t &ndiv, Option_t *chopt="", Double_t gridlength=0, Bool_t drawGridOnly=kFALSE)
	Control function to draw an axis. More...
void	ResetLabelAttributes (TLatex *t)
	Reset the label attributes to the value they have before the last call to ChangeLabelAttributes. More...
virtual void	Rotate (Double_t X, Double_t Y, Double_t CFI, Double_t SFI, Double_t XT, Double_t YT, Double_t &U, Double_t &V)
	Internal method to rotate axis coordinates. More...
virtual void	SavePrimitive (std::ostream &out, Option_t *option="")
	Save primitive as a C++ statement(s) on output stream out. More...
virtual void	SetDecimals (Bool_t dot=kTRUE)
	Set the decimals flag. More...
void	SetFunction (const char *funcname="")
	Specify a function to map the axis values. More...
void	SetGridLength (Float_t gridlength)
void	SetLabelColor (Int_t labelcolor)
void	SetLabelFont (Int_t labelfont)
void	SetLabelOffset (Float_t labeloffset)
void	SetLabelSize (Float_t labelsize)
virtual void	SetMoreLogLabels (Bool_t more=kTRUE)
	Set the kMoreLogLabels bit flag. More...
virtual void	SetName (const char *name)
	Change the name of the axis. More...
virtual void	SetNdivisions (Int_t ndiv)
virtual void	SetNoExponent (Bool_t noExponent=kTRUE)
	Set the NoExponent flag. More...
void	SetOption (Option_t *option="")
	To set axis options. More...
void	SetTickLength (Float_t ticklength)
void	SetTickSize (Float_t ticksize)
void	SetTimeFormat (const char *tformat)
	Change the format used for time plotting. More...
void	SetTimeOffset (Double_t toffset, Option_t *option="local")
	Change the time offset. If option = "gmt", set display mode to GMT. More...
virtual void	SetTitle (const char *title="")
	Change the title of the axis. More...
void	SetTitleColor (Int_t titlecolor)
void	SetTitleFont (Int_t titlefont)
void	SetTitleOffset (Float_t titleoffset=1)
void	SetTitleSize (Float_t titlesize)
void	SetWmax (Double_t wmax)
void	SetWmin (Double_t wmin)
Public Member Functions inherited from TLine
	TLine ()=default
	TLine (const TLine &line)
	Line copy constructor. More...
	TLine (Double_t x1, Double_t y1, Double_t x2, Double_t y2)
	Line normal constructor. More...
virtual	~TLine ()=default
void	Copy (TObject &line) const
	Copy this line to line. More...
virtual Int_t	DistancetoPrimitive (Int_t px, Int_t py)
	Compute distance from point px,py to a line. More...
virtual TLine *	DrawLine (Double_t x1, Double_t y1, Double_t x2, Double_t y2)
	Draw this line with new coordinates. More...
virtual TLine *	DrawLineNDC (Double_t x1, Double_t y1, Double_t x2, Double_t y2)
	Draw this line with new coordinates in NDC. More...
virtual void	ExecuteEvent (Int_t event, Int_t px, Int_t py)
	Execute action corresponding to one event. More...
virtual Rectangle_t	GetBBox ()
	Return the bounding Box of the Line. More...
virtual TPoint	GetBBoxCenter ()
	Return the center of the BoundingBox as TPoint in pixels. More...
Double_t	GetX1 () const
Double_t	GetX2 () const
Double_t	GetY1 () const
Double_t	GetY2 () const
Bool_t	IsHorizontal ()
	Check whether this line is to be drawn horizontally. More...
Bool_t	IsVertical ()
	Check whether this line is to be drawn vertically. More...
virtual void	ls (Option_t *option="") const
	List this line with its attributes. More...
TLine &	operator= (const TLine &src)
	Assignment operator. More...
virtual void	Paint (Option_t *option="")
	Paint this line with its current attributes. More...
virtual void	PaintLine (Double_t x1, Double_t y1, Double_t x2, Double_t y2)
	Draw this line with new coordinates. More...
virtual void	PaintLineNDC (Double_t u1, Double_t v1, Double_t u2, Double_t v2)
	Draw this line with new coordinates in NDC. More...
virtual void	Print (Option_t *option="") const
	Dump this line with its attributes. More...
virtual void	SavePrimitive (std::ostream &out, Option_t *option="")
	Save primitive as a C++ statement(s) on output stream out. More...
virtual void	SetBBoxCenter (const TPoint &p)
	Set center of the BoundingBox. More...
virtual void	SetBBoxCenterX (const Int_t x)
	Set X coordinate of the center of the BoundingBox. More...
virtual void	SetBBoxCenterY (const Int_t y)
	Set Y coordinate of the center of the BoundingBox. More...
virtual void	SetBBoxX1 (const Int_t x)
	Set left hand side of BoundingBox to a value (resize in x direction on left) More...
virtual void	SetBBoxX2 (const Int_t x)
	Set right hand side of BoundingBox to a value (resize in x direction on right) More...
virtual void	SetBBoxY1 (const Int_t y)
	Set top of BoundingBox to a value (resize in y direction on top) More...
virtual void	SetBBoxY2 (const Int_t y)
	Set bottom of BoundingBox to a value (resize in y direction on bottom) More...
void	SetHorizontal (Bool_t set=kTRUE)
	Force the line to be drawn horizontally. More...
virtual void	SetNDC (Bool_t isNDC=kTRUE)
	Set NDC mode on if isNDC = kTRUE, off otherwise. More...
void	SetVertical (Bool_t set=kTRUE)
	Force the line to be drawn vertically. More...
virtual void	SetX1 (Double_t x1)
virtual void	SetX2 (Double_t x2)
virtual void	SetY1 (Double_t y1)
virtual void	SetY2 (Double_t y2)
Public Member Functions inherited from TObject
	TObject ()
	TObject constructor. More...
	TObject (const TObject &object)
	TObject copy ctor. More...
virtual	~TObject ()
	TObject destructor. More...
void	AbstractMethod (const char *method) const
	Use this method to implement an "abstract" method that you don't want to leave purely abstract. More...
virtual void	AppendPad (Option_t *option="")
	Append graphics object to current pad. More...
virtual void	Browse (TBrowser *b)
	Browse object. May be overridden for another default action. More...
ULong_t	CheckedHash ()
	Check and record whether this class has a consistent Hash/RecursiveRemove setup (*) and then return the regular Hash value for this object. More...
virtual const char *	ClassName () const
	Returns name of class to which the object belongs. More...
virtual void	Clear (Option_t *="")
virtual TObject *	Clone (const char *newname="") const
	Make a clone of an object using the Streamer facility. More...
virtual Int_t	Compare (const TObject *obj) const
	Compare abstract method. More...
virtual void	Copy (TObject &object) const
	Copy this to obj. More...
virtual void	Delete (Option_t *option="")
	Delete this object. More...
virtual Int_t	DistancetoPrimitive (Int_t px, Int_t py)
	Computes distance from point (px,py) to the object. More...
virtual void	Draw (Option_t *option="")
	Default Draw method for all objects. More...
virtual void	DrawClass () const
	Draw class inheritance tree of the class to which this object belongs. More...
virtual TObject *	DrawClone (Option_t *option="") const
	Draw a clone of this object in the current selected pad for instance with: gROOT->SetSelectedPad(gPad). More...
virtual void	Dump () const
	Dump contents of object on stdout. More...
virtual void	Error (const char *method, const char *msgfmt,...) const
	Issue error message. More...
virtual void	Execute (const char *method, const char *params, Int_t *error=0)
	Execute method on this object with the given parameter string, e.g. More...
virtual void	Execute (TMethod *method, TObjArray *params, Int_t *error=0)
	Execute method on this object with parameters stored in the TObjArray. More...
virtual void	ExecuteEvent (Int_t event, Int_t px, Int_t py)
	Execute action corresponding to an event at (px,py). More...
virtual void	Fatal (const char *method, const char *msgfmt,...) const
	Issue fatal error message. More...
virtual TObject *	FindObject (const char *name) const
	Must be redefined in derived classes. More...
virtual TObject *	FindObject (const TObject *obj) const
	Must be redefined in derived classes. More...
virtual Option_t *	GetDrawOption () const
	Get option used by the graphics system to draw this object. More...
virtual const char *	GetIconName () const
	Returns mime type name of object. More...
virtual const char *	GetName () const
	Returns name of object. More...
virtual char *	GetObjectInfo (Int_t px, Int_t py) const
	Returns string containing info about the object at position (px,py). More...
virtual Option_t *	GetOption () const
virtual const char *	GetTitle () const
	Returns title of object. More...
virtual UInt_t	GetUniqueID () const
	Return the unique object id. More...
virtual Bool_t	HandleTimer (TTimer *timer)
	Execute action in response of a timer timing out. More...
virtual ULong_t	Hash () const
	Return hash value for this object. More...
Bool_t	HasInconsistentHash () const
	Return true is the type of this object is known to have an inconsistent setup for Hash and RecursiveRemove (i.e. More...
virtual void	Info (const char *method, const char *msgfmt,...) const
	Issue info message. More...
virtual Bool_t	InheritsFrom (const char *classname) const
	Returns kTRUE if object inherits from class "classname". More...
virtual Bool_t	InheritsFrom (const TClass *cl) const
	Returns kTRUE if object inherits from TClass cl. More...
virtual void	Inspect () const
	Dump contents of this object in a graphics canvas. More...
void	InvertBit (UInt_t f)
virtual Bool_t	IsEqual (const TObject *obj) const
	Default equal comparison (objects are equal if they have the same address in memory). More...
virtual Bool_t	IsFolder () const
	Returns kTRUE in case object contains browsable objects (like containers or lists of other objects). More...
R__ALWAYS_INLINE Bool_t	IsOnHeap () const
virtual Bool_t	IsSortable () const
R__ALWAYS_INLINE Bool_t	IsZombie () const
virtual void	ls (Option_t *option="") const
	The ls function lists the contents of a class on stdout. More...
void	MayNotUse (const char *method) const
	Use this method to signal that a method (defined in a base class) may not be called in a derived class (in principle against good design since a child class should not provide less functionality than its parent, however, sometimes it is necessary). More...
virtual Bool_t	Notify ()
	This method must be overridden to handle object notification. More...
void	Obsolete (const char *method, const char *asOfVers, const char *removedFromVers) const
	Use this method to declare a method obsolete. More...
void	operator delete (void *ptr)
	Operator delete. More...
void	operator delete[] (void *ptr)
	Operator delete []. More...
void *	operator new (size_t sz)
void *	operator new (size_t sz, void *vp)
void *	operator new[] (size_t sz)
void *	operator new[] (size_t sz, void *vp)
TObject &	operator= (const TObject &rhs)
	TObject assignment operator. More...
virtual void	Paint (Option_t *option="")
	This method must be overridden if a class wants to paint itself. More...
virtual void	Pop ()
	Pop on object drawn in a pad to the top of the display list. More...
virtual void	Print (Option_t *option="") const
	This method must be overridden when a class wants to print itself. More...
virtual Int_t	Read (const char *name)
	Read contents of object with specified name from the current directory. More...
virtual void	RecursiveRemove (TObject *obj)
	Recursively remove this object from a list. More...
void	ResetBit (UInt_t f)
virtual void	SaveAs (const char *filename="", Option_t *option="") const
	Save this object in the file specified by filename. More...
virtual void	SavePrimitive (std::ostream &out, Option_t *option="")
	Save a primitive as a C++ statement(s) on output stream "out". More...
void	SetBit (UInt_t f)
void	SetBit (UInt_t f, Bool_t set)
	Set or unset the user status bits as specified in f. More...
virtual void	SetDrawOption (Option_t *option="")
	Set drawing option for object. More...
virtual void	SetUniqueID (UInt_t uid)
	Set the unique object id. More...
virtual void	SysError (const char *method, const char *msgfmt,...) const
	Issue system error message. More...
R__ALWAYS_INLINE Bool_t	TestBit (UInt_t f) const
Int_t	TestBits (UInt_t f) const
virtual void	UseCurrentStyle ()
	Set current style settings in this object This function is called when either TCanvas::UseCurrentStyle or TROOT::ForceStyle have been invoked. More...
virtual void	Warning (const char *method, const char *msgfmt,...) const
	Issue warning message. More...
virtual Int_t	Write (const char *name=0, Int_t option=0, Int_t bufsize=0)
	Write this object to the current directory. More...
virtual Int_t	Write (const char *name=0, Int_t option=0, Int_t bufsize=0) const
	Write this object to the current directory. More...
Public Member Functions inherited from TAttLine
	TAttLine ()
	AttLine default constructor. More...
	TAttLine (Color_t lcolor, Style_t lstyle, Width_t lwidth)
	AttLine normal constructor. More...
virtual	~TAttLine ()
	AttLine destructor. More...
void	Copy (TAttLine &attline) const
	Copy this line attributes to a new TAttLine. More...
Int_t	DistancetoLine (Int_t px, Int_t py, Double_t xp1, Double_t yp1, Double_t xp2, Double_t yp2)
	Compute distance from point px,py to a line. More...
virtual Color_t	GetLineColor () const
	Return the line color. More...
virtual Style_t	GetLineStyle () const
	Return the line style. More...
virtual Width_t	GetLineWidth () const
	Return the line width. More...
virtual void	Modify ()
	Change current line attributes if necessary. More...
virtual void	ResetAttLine (Option_t *option="")
	Reset this line attributes to default values. More...
virtual void	SaveLineAttributes (std::ostream &out, const char *name, Int_t coldef=1, Int_t stydef=1, Int_t widdef=1)
	Save line attributes as C++ statement(s) on output stream out. More...
virtual void	SetLineAttributes ()
	Invoke the DialogCanvas Line attributes. More...
virtual void	SetLineColor (Color_t lcolor)
	Set the line color. More...
virtual void	SetLineColorAlpha (Color_t lcolor, Float_t lalpha)
	Set a transparent line color. More...
virtual void	SetLineStyle (Style_t lstyle)
	Set the line style. More...
virtual void	SetLineWidth (Width_t lwidth)
	Set the line width. More...
Public Member Functions inherited from TAttBBox2D
virtual	~TAttBBox2D ()
virtual Rectangle_t	GetBBox ()=0
virtual TPoint	GetBBoxCenter ()=0
virtual void	SetBBoxCenter (const TPoint &p)=0
virtual void	SetBBoxCenterX (const Int_t x)=0
virtual void	SetBBoxCenterY (const Int_t y)=0
virtual void	SetBBoxX1 (const Int_t x)=0
virtual void	SetBBoxX2 (const Int_t x)=0
virtual void	SetBBoxY1 (const Int_t y)=0
virtual void	SetBBoxY2 (const Int_t y)=0
Public Member Functions inherited from TAttText
	TAttText ()
	AttText default constructor. More...
	TAttText (Int_t align, Float_t angle, Color_t color, Style_t font, Float_t tsize)
	AttText normal constructor. More...
virtual	~TAttText ()
	AttText destructor. More...
void	Copy (TAttText &atttext) const
	Copy this text attributes to a new TAttText. More...
virtual Short_t	GetTextAlign () const
	Return the text alignment. More...
virtual Float_t	GetTextAngle () const
	Return the text angle. More...
virtual Color_t	GetTextColor () const
	Return the text color. More...
virtual Font_t	GetTextFont () const
	Return the text font. More...
virtual Float_t	GetTextSize () const
	Return the text size. More...
virtual void	Modify ()
	Change current text attributes if necessary. More...
virtual void	ResetAttText (Option_t *toption="")
	Reset this text attributes to default values. More...
virtual void	SaveTextAttributes (std::ostream &out, const char *name, Int_t alidef=12, Float_t angdef=0, Int_t coldef=1, Int_t fondef=61, Float_t sizdef=1)
	Save text attributes as C++ statement(s) on output stream out. More...
virtual void	SetTextAlign (Short_t align=11)
	Set the text alignment. More...
virtual void	SetTextAngle (Float_t tangle=0)
	Set the text angle. More...
virtual void	SetTextAttributes ()
	Invoke the DialogCanvas Text attributes. More...
virtual void	SetTextColor (Color_t tcolor=1)
	Set the text color. More...
virtual void	SetTextColorAlpha (Color_t tcolor, Float_t talpha)
	Set a transparent marker color. More...
virtual void	SetTextFont (Font_t tfont=62)
	Set the text font. More...
virtual void	SetTextSize (Float_t tsize=1)
	Set the text size. More...
virtual void	SetTextSizePixels (Int_t npixels)
	Set the text size in pixels. More...

Static Public Member Functions
static Int_t	GetMaxDigits ()
	Static function returning fgMaxDigits (See SetMaxDigits). More...
static void	SetExponentOffset (Float_t xoff=0., Float_t yoff=0., Option_t *axis="xy")
	Static function to set X and Y offset of the axis 10^n notation. More...
static void	SetMaxDigits (Int_t maxd=5)
	Static function to set fgMaxDigits for axis. More...
Static Public Member Functions inherited from TObject
static Long_t	GetDtorOnly ()
	Return destructor only flag. More...
static Bool_t	GetObjectStat ()
	Get status of object stat flag. More...
static void	SetDtorOnly (void *obj)
	Set destructor only flag. More...
static void	SetObjectStat (Bool_t stat)
	Turn on/off tracking of objects in the TObjectTable. More...

Protected Member Functions
	TGaxis (const TGaxis &)
	Copy constructor. More...
TGaxis &	operator= (const TGaxis &)
	Assignment operator. More...
Protected Member Functions inherited from TObject
virtual void	DoError (int level, const char *location, const char *fmt, va_list va) const
	Interface to ErrorHandler (protected). More...
void	MakeZombie ()

Protected Attributes
TAxis *	fAxis
	! Pointer to original TAxis axis (if any) More...
TString	fChopt
	Axis options. More...
TF1 *	fFunction
	! Pointer to function computing axis values More...
TString	fFunctionName
	Name of mapping function pointed by fFunction. More...
Float_t	fGridLength
	Length of the grid in NDC. More...
Int_t	fLabelColor
	Color for labels. More...
Int_t	fLabelFont
	Font for labels. More...
Float_t	fLabelOffset
	Offset of label wrt axis. More...
Float_t	fLabelSize
	Size of labels in NDC. More...
TList *	fModLabs
	List of modified labels. More...
TString	fName
	Axis name. More...
Int_t	fNdiv
	Number of divisions. More...
Int_t	fNModLabs
	Number of modified labels. More...
Float_t	fTickSize
	Size of primary tick mark in NDC. More...
TString	fTimeFormat
	Time format, ex: 09/12/99 12:34:00. More...
TString	fTitle
	Axis title. More...
Float_t	fTitleOffset
	Offset of title wrt axis. More...
Float_t	fTitleSize
	Size of title in NDC. More...
Double_t	fWmax
	Highest value on the axis. More...
Double_t	fWmin
	Lowest value on the axis. More...
Protected Attributes inherited from TLine
Double_t	fX1 {0}
	X of 1st point. More...
Double_t	fX2 {0}
	X of 2nd point. More...
Double_t	fY1 {0}
	Y of 1st point. More...
Double_t	fY2 {0}
	Y of 2nd point. More...
Protected Attributes inherited from TAttLine
Color_t	fLineColor
	Line color. More...
Style_t	fLineStyle
	Line style. More...
Width_t	fLineWidth
	Line width. More...
Protected Attributes inherited from TAttText
Short_t	fTextAlign
	Text alignment. More...
Float_t	fTextAngle
	Text angle. More...
Color_t	fTextColor
	Text color. More...
Font_t	fTextFont
	Text font. More...
Float_t	fTextSize
	Text size. More...

Static Protected Attributes
static Int_t	fgMaxDigits = 5
	! Number of digits above which the 10>N notation is used More...
static Float_t	fXAxisExpXOffset = 0.
	! Exponent X offset for the X axis More...
static Float_t	fXAxisExpYOffset = 0.
	! Exponent Y offset for the X axis More...
static Float_t	fYAxisExpXOffset = 0.
	! Exponent X offset for the Y axis More...
static Float_t	fYAxisExpYOffset = 0.
	! Exponent Y offset for the Y axis More...

Additional Inherited Members
Public Types inherited from TLine
enum	{ kLineNDC = BIT(14) , kVertical = BIT(15) , kHorizontal = BIT(16) }
Public Types inherited from TObject
enum	{   kIsOnHeap = 0x01000000 , kNotDeleted = 0x02000000 , kZombie = 0x04000000 , kInconsistent = 0x08000000 ,   kBitMask = 0x00ffffff }
enum	{ kSingleKey = BIT(0) , kOverwrite = BIT(1) , kWriteDelete = BIT(2) }
enum	EDeprecatedStatusBits { kObjInCanvas = BIT(3) }
enum	EStatusBits {   kCanDelete = BIT(0) , kMustCleanup = BIT(3) , kIsReferenced = BIT(4) , kHasUUID = BIT(5) ,   kCannotPick = BIT(6) , kNoContextMenu = BIT(8) , kInvalidObject = BIT(13) }

#include <TGaxis.h>

Inheritance diagram for TGaxis:

Constructor & Destructor Documentation

TGaxis() [1/4]

TGaxis::TGaxis ( const TGaxis &  ax )

protected

Copy constructor.

Definition at line 776 of file TGaxis.cxx.

TGaxis() [2/4]

TGaxis::TGaxis

(

)

TGaxis default constructor.

Definition at line 680 of file TGaxis.cxx.

TGaxis() [3/4]

TGaxis::TGaxis	(	Double_t	xmin,
		Double_t	ymin,
		Double_t	xmax,
		Double_t	ymax,
		Double_t	wmin,
		Double_t	wmax,
		Int_t	ndiv = 510,
		Option_t *	chopt = "",
		Double_t	gridlength = 0
	)

TGaxis normal constructor.

Definition at line 708 of file TGaxis.cxx.

TGaxis() [4/4]

TGaxis::TGaxis	(	Double_t	xmin,
		Double_t	ymin,
		Double_t	xmax,
		Double_t	ymax,
		const char *	funcname,
		Int_t	ndiv = 510,
		Option_t *	chopt = "",
		Double_t	gridlength = 0
	)

Constructor with a TF1 to map axis values.

Definition at line 739 of file TGaxis.cxx.

~TGaxis()

TGaxis::~TGaxis ( )

virtual

TGaxis default destructor.

Definition at line 838 of file TGaxis.cxx.

Member Function Documentation

AdjustBinSize()

void TGaxis::AdjustBinSize ( Double_t  A1, Double_t  A2, Int_t  nold, Double_t &  binLow, Double_t &  binHigh, Int_t &  nbins, Double_t &  binWidth  )

virtual

Internal method for axis labels optimisation.

This method adjusts the bining of the axis in order to have integer values for the labels.

Parameters

[in]	A1,A2	Old WMIN,WMAX
[out]	binLow,binHigh	New WMIN,WMAX
[in]	nold	Old NDIV (primary divisions)
[out]	nbins	New NDIV
[out]	binWidth	Bin width

Definition at line 2376 of file TGaxis.cxx.

CenterLabels()

void TGaxis::CenterLabels ( Bool_t  center = kTRUE )

virtual

If center = kTRUE axis labels are centered in the center of the bin.

The default is to center on the primary tick marks. This option does not make sense if there are more bins than tick marks.

Definition at line 847 of file TGaxis.cxx.

CenterTitle()

void TGaxis::CenterTitle ( Bool_t  center = kTRUE )

virtual

If center = kTRUE axis title will be centered. The default is right adjusted.

Definition at line 857 of file TGaxis.cxx.

ChangeLabel()

void TGaxis::ChangeLabel	(	Int_t	labNum = 0,
		Double_t	labAngle = -1.,
		Double_t	labSize = -1.,
		Int_t	labAlign = -1,
		Int_t	labColor = -1,
		Int_t	labFont = -1,
		TString	labText = ""
	)

Define new text attributes for the label number "labNum".

It allows to do a fine tuning of the labels. All the attributes can be changed, even the label text itself.

Parameters

[in]	labNum	Number of the label to be changed, negative numbers start from the end
[in]	labAngle	New angle value
[in]	labSize	New size (0 erase the label)
[in]	labAlign	New alignment value
[in]	labColor	New label color
[in]	labFont	New label font
[in]	labText	New label text

If an attribute should not be changed just give the value "-1".The following macro gives an example:

{
   c1 = new TCanvas("c1","Examples of Gaxis",10,10,900,500);
   c1->Range(-6,-0.1,6,0.1);
   TGaxis *axis1 = new TGaxis(-5.5,0.,5.5,0.,0.0,100,510,"");
   axis1->SetName("axis1");
   axis1->SetTitle("Axis Title");
   axis1->SetTitleSize(0.05);
   axis1->SetTitleColor(kBlue);
   axis1->SetTitleFont(42);
   axis1->ChangeLabel(1,-1,-1,-1,2);
   axis1->ChangeLabel(3,-1,0.);
   axis1->ChangeLabel(5,30.,-1,0);
   axis1->ChangeLabel(6,-1,-1,-1,3,-1,"6th label");
   axis1->ChangeLabel(-2,-1,-1,-1,3,-1,"2nd to last label");
   axis1->Draw();
}

If labnum=0 the list of modified labels is reset.

Definition at line 2561 of file TGaxis.cxx.

ChangeLabelAttributes()

void TGaxis::ChangeLabelAttributes	(	Int_t	i,
		Int_t	nlabels,
		TLatex *	t,
		char *	c
	)

Definition at line 2602 of file TGaxis.cxx.

DrawAxis()

void TGaxis::DrawAxis ( Double_t  xmin, Double_t  ymin, Double_t  xmax, Double_t  ymax, Double_t  wmin, Double_t  wmax, Int_t  ndiv = 510, Option_t *  chopt = "", Double_t  gridlength = 0  )

virtual

Draw this axis with new attributes.

Definition at line 867 of file TGaxis.cxx.

GetFunction()

TF1 * TGaxis::GetFunction ( ) const

inline

Definition at line 78 of file TGaxis.h.

GetGridLength()

Float_t TGaxis::GetGridLength ( ) const

inline

Definition at line 77 of file TGaxis.h.

GetLabelColor()

Int_t TGaxis::GetLabelColor ( ) const

inline

Definition at line 79 of file TGaxis.h.

GetLabelFont()

Int_t TGaxis::GetLabelFont ( ) const

inline

Definition at line 80 of file TGaxis.h.

GetLabelOffset()

Float_t TGaxis::GetLabelOffset ( ) const

inline

Definition at line 81 of file TGaxis.h.

GetLabelSize()

Float_t TGaxis::GetLabelSize ( ) const

inline

Definition at line 82 of file TGaxis.h.

GetMaxDigits()

Int_t TGaxis::GetMaxDigits ( )

static

Static function returning fgMaxDigits (See SetMaxDigits).

Definition at line 897 of file TGaxis.cxx.

GetName()

virtual const char * TGaxis::GetName ( ) const

inlinevirtual

Returns name of object.

This default method returns the class name. Classes that give objects a name should override this method.

Reimplemented from TObject.

Definition at line 85 of file TGaxis.h.

GetNdiv()

Int_t TGaxis::GetNdiv ( ) const

inline

Definition at line 89 of file TGaxis.h.

GetOption()

virtual const char * TGaxis::GetOption ( ) const

inlinevirtual

Reimplemented from TObject.

Definition at line 86 of file TGaxis.h.

GetTickSize()

Float_t TGaxis::GetTickSize ( ) const

inline

Definition at line 92 of file TGaxis.h.

GetTitle()

virtual const char * TGaxis::GetTitle ( ) const

inlinevirtual

Returns title of object.

This default method returns the class title (i.e. description). Classes that give objects a title should override this method.

Reimplemented from TObject.

Definition at line 87 of file TGaxis.h.

GetTitleOffset()

Float_t TGaxis::GetTitleOffset ( ) const

inline

Definition at line 83 of file TGaxis.h.

GetTitleSize()

Float_t TGaxis::GetTitleSize ( ) const

inline

Definition at line 84 of file TGaxis.h.

GetWmax()

Double_t TGaxis::GetWmax ( ) const

inline

Definition at line 91 of file TGaxis.h.

GetWmin()

Double_t TGaxis::GetWmin ( ) const

inline

Definition at line 90 of file TGaxis.h.

ImportAxisAttributes()

void TGaxis::ImportAxisAttributes ( TAxis *  axis )

virtual

Internal method to import TAxis attributes to this TGaxis.

Definition at line 906 of file TGaxis.cxx.

LabelsLimits()

void TGaxis::LabelsLimits	(	const char *	label,
		Int_t &	first,
		Int_t &	last
	)

Internal method to find first and last character of a label.

Definition at line 2411 of file TGaxis.cxx.

operator=()

TGaxis & TGaxis::operator= ( const TGaxis &  ax )

protected

Assignment operator.

Definition at line 805 of file TGaxis.cxx.

Paint()

void TGaxis::Paint ( Option_t *  chopt = "" )

virtual

Draw this axis with its current attributes.

Reimplemented from TLine.

Definition at line 935 of file TGaxis.cxx.

PaintAxis()

void TGaxis::PaintAxis ( Double_t  xmin, Double_t  ymin, Double_t  xmax, Double_t  ymax, Double_t &  wmin, Double_t &  wmax, Int_t &  ndiv, Option_t *  chopt = "", Double_t  gridlength = 0, Bool_t  drawGridOnly = kFALSE  )

virtual

Control function to draw an axis.

Original authors: O.Couet C.E.Vandoni N.Cremel-Somon. Modified and converted to C++ class by Rene Brun.

Definition at line 956 of file TGaxis.cxx.

ResetLabelAttributes()

void TGaxis::ResetLabelAttributes

(

TLatex *

t

)

Reset the label attributes to the value they have before the last call to ChangeLabelAttributes.

Definition at line 2633 of file TGaxis.cxx.

Rotate()

void TGaxis::Rotate ( Double_t  X, Double_t  Y, Double_t  CFI, Double_t  SFI, Double_t  XT, Double_t  YT, Double_t &  U, Double_t &  V  )

virtual

Internal method to rotate axis coordinates.

Definition at line 2423 of file TGaxis.cxx.

SavePrimitive()

void TGaxis::SavePrimitive ( std::ostream &  out, Option_t *  option = ""  )

virtual

Save primitive as a C++ statement(s) on output stream out.

Reimplemented from TLine.

Definition at line 2433 of file TGaxis.cxx.

SetDecimals()

void TGaxis::SetDecimals ( Bool_t  dot = kTRUE )

virtual

Set the decimals flag.

By default, blank characters are stripped, and then the label is correctly aligned. The dot, if last character of the string, is also stripped, unless this option is specified. One can disable the option by calling axis.SetDecimals(kTRUE). Note the bit is set in fBits (as opposed to fBits2 in TAxis!)

Definition at line 2499 of file TGaxis.cxx.

SetExponentOffset()

void TGaxis::SetExponentOffset ( Float_t  xoff = 0., Float_t  yoff = 0., Option_t *  axis = "xy"  )

static

Static function to set X and Y offset of the axis 10^n notation.

It is in % of the pad size. It can be negative. axis specifies which axis ("x","y"), default = "x" if axis="xz" set the two axes

Definition at line 2787 of file TGaxis.cxx.

SetFunction()

void TGaxis::SetFunction

(

const char *

funcname = ""

)

Specify a function to map the axis values.

Definition at line 2508 of file TGaxis.cxx.

SetGridLength()

void TGaxis::SetGridLength ( Float_t  gridlength )

inline

Definition at line 121 of file TGaxis.h.

SetLabelColor()

void TGaxis::SetLabelColor ( Int_t  labelcolor )

inline

Definition at line 105 of file TGaxis.h.

SetLabelFont()

void TGaxis::SetLabelFont ( Int_t  labelfont )

inline

Definition at line 106 of file TGaxis.h.

SetLabelOffset()

void TGaxis::SetLabelOffset ( Float_t  labeloffset )

inline

Definition at line 107 of file TGaxis.h.

SetLabelSize()

void TGaxis::SetLabelSize ( Float_t  labelsize )

inline

Definition at line 108 of file TGaxis.h.

SetMaxDigits()

void TGaxis::SetMaxDigits ( Int_t  maxd = 5 )

static

Static function to set fgMaxDigits for axis.

fgMaxDigits is the maximum number of digits permitted for the axis labels above which the notation with 10^N is used.For example, to accept 6 digits number like 900000 on an axis call TGaxis::SetMaxDigits(6). The default value is 5. fgMaxDigits must be greater than 0.

Definition at line 2649 of file TGaxis.cxx.

SetMoreLogLabels()

void TGaxis::SetMoreLogLabels ( Bool_t  more = kTRUE )

virtual

Set the kMoreLogLabels bit flag.

When this option is selected more labels are drawn when in logarithmic scale and there is a small number of decades (less than 3). Note that this option is automatically inherited from TAxis

Definition at line 2668 of file TGaxis.cxx.

SetName()

void TGaxis::SetName ( const char *  name )

virtual

Change the name of the axis.

Definition at line 2658 of file TGaxis.cxx.

SetNdivisions()

virtual void TGaxis::SetNdivisions ( Int_t  ndiv )

inlinevirtual

Definition at line 115 of file TGaxis.h.

SetNoExponent()

void TGaxis::SetNoExponent ( Bool_t  noExponent = kTRUE )

virtual

Set the NoExponent flag.

By default, an exponent of the form 10^N is used when the label values are either all very small or very large. One can disable the exponent by calling axis.SetNoExponent(kTRUE).

Definition at line 2679 of file TGaxis.cxx.

SetOption()

void TGaxis::SetOption

(

Option_t *

option = ""

)

To set axis options.

Definition at line 2688 of file TGaxis.cxx.

SetTickLength()

void TGaxis::SetTickLength ( Float_t  ticklength )

inline

Definition at line 120 of file TGaxis.h.

SetTickSize()

void TGaxis::SetTickSize ( Float_t  ticksize )

inline

Definition at line 119 of file TGaxis.h.

SetTimeFormat()

void TGaxis::SetTimeFormat

(

const char *

tformat

)

Change the format used for time plotting.

The format string for date and time use the same options as the one used in the standard strftime C function, i.e. :

for date :

• a abbreviated weekday name
• b abbreviated month name
• d day of the month (01-31)
• m month (01-12)
• y year without century

for time :

• H hour (24-hour clock)
• I hour (12-hour clock)
• p local equivalent of AM or PM
• M minute (00-59)
• S seconds (00-61)
• %% %

Definition at line 2723 of file TGaxis.cxx.

SetTimeOffset()

void TGaxis::SetTimeOffset	(	Double_t	toffset,
		Option_t *	option = "local"
	)

Change the time offset. If option = "gmt", set display mode to GMT.

Definition at line 2747 of file TGaxis.cxx.

SetTitle()

void TGaxis::SetTitle ( const char *  title = "" )

virtual

Change the title of the axis.

Definition at line 2696 of file TGaxis.cxx.

SetTitleColor()

void TGaxis::SetTitleColor ( Int_t  titlecolor )

inline

Definition at line 128 of file TGaxis.h.

SetTitleFont()

void TGaxis::SetTitleFont ( Int_t  titlefont )

inline

Definition at line 127 of file TGaxis.h.

SetTitleOffset()

void TGaxis::SetTitleOffset ( Float_t  titleoffset = 1 )

inline

Definition at line 125 of file TGaxis.h.

SetTitleSize()

void TGaxis::SetTitleSize ( Float_t  titlesize )

inline

Definition at line 126 of file TGaxis.h.

SetWmax()

void TGaxis::SetWmax ( Double_t  wmax )

inline

Definition at line 130 of file TGaxis.h.

SetWmin()

void TGaxis::SetWmin ( Double_t  wmin )

inline

Definition at line 129 of file TGaxis.h.

Member Data Documentation

fAxis

TAxis* TGaxis::fAxis

protected

! Pointer to original TAxis axis (if any)

Definition at line 46 of file TGaxis.h.

fChopt

TString TGaxis::fChopt

protected

Axis options.

Definition at line 40 of file TGaxis.h.

fFunction

TF1* TGaxis::fFunction

protected

! Pointer to function computing axis values

Definition at line 45 of file TGaxis.h.

fFunctionName

TString TGaxis::fFunctionName

protected

Name of mapping function pointed by fFunction.

Definition at line 44 of file TGaxis.h.

fgMaxDigits

Int_t TGaxis::fgMaxDigits = 5

staticprotected

! Number of digits above which the 10>N notation is used

Definition at line 49 of file TGaxis.h.

fGridLength

Float_t TGaxis::fGridLength

protected

Length of the grid in NDC.

Definition at line 30 of file TGaxis.h.

fLabelColor

Int_t TGaxis::fLabelColor

protected

Color for labels.

Definition at line 37 of file TGaxis.h.

fLabelFont

Int_t TGaxis::fLabelFont

protected

Font for labels.

Definition at line 38 of file TGaxis.h.

fLabelOffset

Float_t TGaxis::fLabelOffset

protected

Offset of label wrt axis.

Definition at line 32 of file TGaxis.h.

fLabelSize

Float_t TGaxis::fLabelSize

protected

Size of labels in NDC.

Definition at line 33 of file TGaxis.h.

fModLabs

TList* TGaxis::fModLabs

protected

List of modified labels.

Definition at line 47 of file TGaxis.h.

fName

TString TGaxis::fName

protected

Axis name.

Definition at line 41 of file TGaxis.h.

fNdiv

Int_t TGaxis::fNdiv

protected

Number of divisions.

Definition at line 36 of file TGaxis.h.

fNModLabs

Int_t TGaxis::fNModLabs

protected

Number of modified labels.

Definition at line 39 of file TGaxis.h.

fTickSize

Float_t TGaxis::fTickSize

protected

Size of primary tick mark in NDC.

Definition at line 31 of file TGaxis.h.

fTimeFormat

TString TGaxis::fTimeFormat

protected

Time format, ex: 09/12/99 12:34:00.

Definition at line 43 of file TGaxis.h.

fTitle

TString TGaxis::fTitle

protected

Axis title.

Definition at line 42 of file TGaxis.h.

fTitleOffset

Float_t TGaxis::fTitleOffset

protected

Offset of title wrt axis.

Definition at line 34 of file TGaxis.h.

fTitleSize

Float_t TGaxis::fTitleSize

protected

Size of title in NDC.

Definition at line 35 of file TGaxis.h.

fWmax

Double_t TGaxis::fWmax

protected

Highest value on the axis.

Definition at line 29 of file TGaxis.h.

fWmin

Double_t TGaxis::fWmin

protected

Lowest value on the axis.

Definition at line 28 of file TGaxis.h.

fXAxisExpXOffset

Float_t TGaxis::fXAxisExpXOffset = 0.

staticprotected

! Exponent X offset for the X axis

Definition at line 50 of file TGaxis.h.

fXAxisExpYOffset

Float_t TGaxis::fXAxisExpYOffset = 0.

staticprotected

! Exponent Y offset for the X axis

Definition at line 51 of file TGaxis.h.

fYAxisExpXOffset

Float_t TGaxis::fYAxisExpXOffset = 0.

staticprotected

! Exponent X offset for the Y axis

Definition at line 52 of file TGaxis.h.

fYAxisExpYOffset

Float_t TGaxis::fYAxisExpYOffset = 0.

staticprotected

! Exponent Y offset for the Y axis

Definition at line 53 of file TGaxis.h.

Libraries for TGaxis:

[legend]