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Reference Guide
timeSeriesFromCSV.C File Reference

Detailed Description

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This macro illustrates the use of the time axis on a TGraph with data read from a text file containing the SWAN usage statistics during July 2017.

{
// Open the data file. This csv contains the usage statistics of a CERN IT
// service, SWAN, during two weeks. We would like to plot this data with
// ROOT to draw some conclusions from it.
TString dir = gROOT->GetTutorialDir();
dir.Append("/graphs/");
dir.ReplaceAll("/./", "/");
FILE *f = fopen(Form("%sSWAN2017.dat", dir.Data()), "r");
// Create the time graph
auto g = new TGraph();
g->SetTitle("SWAN Users during July 2017;Time;Number of Sessions");
// Read the data and fill the graph with time along the X axis and number
// of users along the Y axis
char line[80];
float v;
char dt[20];
int i = 0;
while (fgets(line, 80, f)) {
sscanf(&line[20], "%f", &v);
strncpy(dt, line, 18);
dt[19] = '\0';
g->SetPoint(i, TDatime(dt).Convert(), v);
i++;
}
fclose(f);
// Draw the graph
auto c = new TCanvas("c", "c", 950, 500);
c->SetLeftMargin(0.07);
c->SetRightMargin(0.04);
c->SetGrid();
g->SetLineWidth(3);
g->SetLineColor(kBlue);
g->Draw("al");
g->GetYaxis()->CenterTitle();
// Make the X axis labelled with time.
auto xaxis = g->GetXaxis();
xaxis->SetTimeDisplay(1);
xaxis->CenterTitle();
xaxis->SetTimeFormat("%a %d");
xaxis->SetTimeOffset(0);
xaxis->SetNdivisions(-219);
xaxis->SetLimits(TDatime(2017, 7, 3, 0, 0, 0).Convert(), TDatime(2017, 7, 22, 0, 0, 0).Convert());
xaxis->SetLabelSize(0.025);
xaxis->CenterLabels();
}
#define f(i)
Definition: RSha256.hxx:104
#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
TLine * line
Authors
Danilo Piparo, Olivier Couet

Definition in file timeSeriesFromCSV.C.