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hprod.C
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1/// \file
2/// \ingroup tutorial_net
3/// Histogram producer script. This script creates a memory mapped
4/// file and stores three histogram objects in it (a TH1F, a TH2F and a
5/// TProfile). It then fills, in an infinite loop (so use ctrl-c to
6/// stop this script), the three histogram objects with random numbers.
7/// Every 10 fills the objects are updated in shared memory.
8/// Use the hcons.C script to map this file and display the histograms.
9///
10/// \macro_code
11///
12/// \author Fons Rademakers
13
14{
15 gROOT->Reset();
16
17 // Create a new memory mapped file. The memory mapped file can be
18 // opened in an other process on the same machine and the objects
19 // stored in it can be accessed.
20
21 mfile = TMapFile::Create("hsimple.map", "RECREATE", 1000000,
22 "Demo memory mapped file with histograms");
23
24 // Create a 1d, a 2d and a profile histogram. These objects will
25 // be automatically added to the current directory, i.e. mfile.
26 hpx = new TH1F("hpx","This is the px distribution",100,-4,4);
27 hpxpy = new TH2F("hpxpy","py vs px",40,-4,4,40,-4,4);
28 hprof = new TProfile("hprof","Profile of pz versus px",100,-4,4,0,20);
29
30 // Set a fill color for the TH1F
31 hpx->SetFillColor(48);
32
33 // Print status of mapped file
34 mfile->Print();
35
36 // Endless loop filling histograms with random numbers
37 Float_t px, py, pz;
38 int ii = 0;
39 while (1) {
40 gRandom->Rannor(px,py);
41 pz = px*px + py*py;
42 hpx->Fill(px);
43 hpxpy->Fill(px,py);
44 hprof->Fill(px,pz);
45 if (!(ii % 10)) {
46 mfile->Update(); // updates all objects in shared memory
47 if (!ii) mfile->ls(); // print contents of mapped file after
48 } // first update
49 ii++;
50 }
51}
float Float_t
Definition RtypesCore.h:57
#define gROOT
Definition TROOT.h:407
R__EXTERN TRandom * gRandom
Definition TRandom.h:62
1-D histogram with a float per channel (see TH1 documentation)}
Definition TH1.h:577
2-D histogram with a float per channel (see TH1 documentation)}
Definition TH2.h:258
static TMapFile * Create(const char *name, Option_t *option="READ", Int_t size=kDefaultMapSize, const char *title="")
Create a memory mapped file.
Profile Histogram.
Definition TProfile.h:32
virtual void Rannor(Float_t &a, Float_t &b)
Return 2 numbers distributed following a gaussian with mean=0 and sigma=1.
Definition TRandom.cxx:500