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pyroot003_prettyPrinting.py File Reference

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This tutorial illustrates the pretty printing feature of PyROOT, which reveals the content of the object if a string representation is requested, e.g., by Python's print statement.

The printing behaves similar to the ROOT prompt powered by the C++ interpreter cling.

import ROOT
# Create an object with PyROOT
obj = ROOT.std.vector("int")(3)
for i in range(obj.size()):
obj[i] = i
# Print the object, which reveals the content. Note that `print` calls the special
# method `__str__` of the object internally.
# The output can be retrieved as string by any function that triggers the `__str__`
# special method of the object, e.g., `str` or `format`.
# Note that the interactive Python prompt does not call `__str__`, it calls
# `__repr__`, which implements a formal and unique string representation of
# the object.
# The print output behaves similar to the ROOT prompt, e.g., here for a ROOT histogram.
hist = ROOT.TH1F("name", "title", 10, 0, 1)
# If cling cannot produce any nice representation for the class, we fall back to a
# "<ClassName at address>" format, which is what `__repr__` returns
ROOT.gInterpreter.Declare('class MyClass {};')
m = ROOT.MyClass()
print(str(m) == repr(m))
Option_t Option_t TPoint TPoint const char GetTextMagnitude GetFillStyle GetLineColor GetLineWidth GetMarkerStyle GetTextAlign GetTextColor GetTextSize void char Point_t Rectangle_t WindowAttributes_t Float_t Float_t Float_t Int_t Int_t UInt_t UInt_t Rectangle_t Int_t Int_t Window_t TString Int_t GCValues_t GetPrimarySelectionOwner GetDisplay GetScreen GetColormap GetNativeEvent const char const char dpyName wid window const char font_name cursor keysym reg const char only_if_exist regb h Point_t winding char text const char depth char const char Int_t count const char ColorStruct_t color const char Pixmap_t Pixmap_t PictureAttributes_t attr const char char ret_data h unsigned char height h Atom_t Int_t ULong_t ULong_t unsigned char prop_list Atom_t Atom_t Atom_t Time_t format
{ 0, 1, 2 }
{ 0, 1, 2 }
{ 0, 1, 2 }
vector<int>{ 0, 1, 2 }
Name: name Title: title NbinsX: 10
<cppyy.gbl.MyClass object at 0x73d2e40>
June 2018
Stefan Wunsch, Enric Tejedor

Definition in file pyroot003_prettyPrinting.py.