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df005_fillAnyObject.C
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1 /// \file
2 /// \ingroup tutorial_dataframe
3 /// \notebook -draw
4 /// Using the generic Fill action.
5 ///
6 /// This tutorial shows how to fill any object the class of which exposes a
7 /// `Fill` method.
8 ///
9 /// \macro_code
10 /// \macro_image
11 ///
12 /// \date March 2017
13 /// \author Danilo Piparo (CERN)
14 
15 // A simple helper function to fill a test tree: this makes the example
16 // stand-alone.
17 void fill_tree(const char *treeName, const char *fileName)
18 {
19  ROOT::RDataFrame d(100);
20  auto i = 0.;
21  d.Define("b1", [&i]() { return i; })
22  .Define("b2",
23  [&i]() {
24  float j = i * i;
25  ++i;
26  return j;
27  })
28  .Snapshot(treeName, fileName);
29 }
30 
31 int df005_fillAnyObject()
32 {
33 
34  // We prepare an input tree to run on
35  auto fileName = "df005_fillAnyObject.root";
36  auto treeName = "myTree";
37  fill_tree(treeName, fileName);
38 
39  // We read the tree from the file and create a RDataFrame.
40  ROOT::RDataFrame d(treeName, fileName);
41 
42  // ## Filling any object
43  // We now fill some objects which are instances of classes which expose a
44  // `Fill` method with some input arguments.
45  auto th1d = d.Fill<double>(TH1D("th1d", "th1d", 64, 0, 128), {"b1"});
46  auto th1i = d.Fill<float>(TH1I("th1i", "th1i", 64, 0, 128), {"b2"});
47  auto th2d = d.Fill<double, float>(TH2D("th2d", "th2d", 64, 0, 128, 64, 0, 1024), {"b1", "b2"});
48 
49  auto c1 = new TCanvas();
50  th1d->DrawClone();
51 
52  auto c2 = new TCanvas();
53  th1i->DrawClone();
54 
55  auto c3 = new TCanvas();
56  th2d->DrawClone("COLZ");
57 
58  return 0;
59 }
c3
return c3
Definition: legend3.C:15
TH1I
1-D histogram with an int per channel (see TH1 documentation)}
Definition: TH1.h:534
TH1D
1-D histogram with a double per channel (see TH1 documentation)}
Definition: TH1.h:618
ROOT::RDataFrame
ROOT's RDataFrame offers a high level interface for analyses of data stored in TTrees,...
Definition: RDataFrame.hxx:42
TH2D
2-D histogram with a double per channel (see TH1 documentation)}
Definition: TH2.h:292
double
double
Definition: Converters.cxx:921
TCanvas
The Canvas class.
Definition: TCanvas.h:23
d
#define d(i)
Definition: RSha256.hxx:102
c2
return c2
Definition: legend2.C:14
c1
return c1
Definition: legend1.C:41