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Reference Guide
timeSeriesFromCSV_TDF.C
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1/// \file
2/// \ingroup tutorial_graphs
3/// \notebook -js
4/// This macro illustrates the use of the time axis on a TGraph
5/// with data read from a text file containing the SWAN usage
6/// statistics during July 2017.
7/// We exploit the TDataFrame for reading from the file
8///
9/// \macro_image
10/// \macro_code
11///
12/// \authors Danilo Piparo, Olivier Couet
13
14void timeSeriesFromCSV_TDF()
15{
16 // Open the data file. This csv contains the usage statistics of a CERN IT
17 // service, SWAN, during two weeks. We would like to plot this data with
18 // ROOT to draw some conclusions from it.
19 TString dir = gROOT->GetTutorialDir();
20 dir.Append("/graphs/");
21 dir.ReplaceAll("/./", "/");
22
23 // Read the data from the file using TDataFrame. We do not have headers and
24 // we would like the delimiter to be a space
25 auto tdf = ROOT::RDF::MakeCsvDataFrame(Form("%sSWAN2017.dat", dir.Data()), false, ' ');
26
27 // We now prepare the graph input
28 auto d = tdf.Define("TimeStamp", "auto s = string(Col0) + ' ' + Col1; return (float) TDatime(s.c_str()).Convert();")
29 .Define("Value", "(float)Col2");
30 auto timeStamps = d.Take<float>("TimeStamp");
31 auto values = d.Take<float>("Value");
32
33 // Create the time graph
34 auto g = new TGraph(values->size(), timeStamps->data(), values->data());
35 g->SetTitle("SWAN Users during July 2017;Time;Number of Sessions");
36
37 // Draw the graph
38 auto c = new TCanvas("c", "c", 950, 500);
39 c->SetLeftMargin(0.07);
40 c->SetRightMargin(0.04);
41 c->SetGrid();
42 g->SetLineWidth(3);
43 g->SetLineColor(kBlue);
44 g->Draw("al");
45 g->GetYaxis()->CenterTitle();
46
47 // Make the X axis labelled with time.
48 auto xaxis = g->GetXaxis();
49 xaxis->SetTimeDisplay(1);
50 xaxis->CenterTitle();
51 xaxis->SetTimeFormat("%a %d");
52 xaxis->SetTimeOffset(0);
53 xaxis->SetNdivisions(-219);
54 xaxis->SetLimits(TDatime(2017, 7, 3, 0, 0, 0).Convert(), TDatime(2017, 7, 22, 0, 0, 0).Convert());
55 xaxis->SetLabelSize(0.025);
56 xaxis->CenterLabels();
57}
#define d(i)
Definition: RSha256.hxx:102
#define c(i)
Definition: RSha256.hxx:101
@ kBlue
Definition: Rtypes.h:66
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 g
#define gROOT
Definition: TROOT.h:404
char * Form(const char *fmt,...)
Formats a string in a circular formatting buffer.
Definition: TString.cxx:2456
The Canvas class.
Definition: TCanvas.h:23
This class stores the date and time with a precision of one second in an unsigned 32 bit word (950130...
Definition: TDatime.h:37
A TGraph is an object made of two arrays X and Y with npoints each.
Definition: TGraph.h:41
Basic string class.
Definition: TString.h:136
const char * Data() const
Definition: TString.h:369
TString & ReplaceAll(const TString &s1, const TString &s2)
Definition: TString.h:692
TString & Append(const char *cs)
Definition: TString.h:564
RDataFrame MakeCsvDataFrame(std::string_view fileName, bool readHeaders=true, char delimiter=',', Long64_t linesChunkSize=-1LL, std::unordered_map< std::string, char > &&colTypes={})
Factory method to create a CSV RDataFrame.
Definition: RCsvDS.cxx:556