I am writing a PyROOT script to create a histogram showing the trigger rate per run.
Since I only have a finite number of runs & they are non-consecutive, I would like the bins in the histogram to exactly correspond to the run numbers. As I understand it, I should be able to do this by creating a histogram using this constructor:
Unfortunately, when I pass the construtor a Python array for the parameter “xbins”, I get the following errors:
[quote]Error in TAxis::TAxis::Set: bins must be in increasing order
Error in TAxis::TAxis::Set: bins must be in increasing order
TCanvas::MakeDefCanvas: created default TCanvas with name c1
Error in TCanvas::Range: illegal world coordinates range: x1=167472.001386, y1=-0.131250, x2=-18608.001386, y2=1.181250
Error in TCanvas::RangeAxis: illegal axis coordinates range: xmin=148864.000000, ymin=0.000000, xmax=0.000000, ymax=1.050000
Error in TGraphPainter::PaintGraphHist: X must be in increasing order[/quote]
What am I doing wrong? How does one correctly pass the xbins parameter from a Python script to ROOT?
Below is a simpler version of my script (with many fewer runs), which I used to produce the exact errors above.
[code]#! /usr/bin/env python
from ROOT import *
from array import *
Open root file, get TTree
infileName = "hltanalysis.root"
infile = TFile(infileName)
tree = infile.Get(“stoppedHSCPTree/StoppedHSCPTree”)
Create histogram of trigger rate vs. run#
runArray = array(‘d’,[148864, 149291, 146436, 148822, 149063])
histogram = TH1F(“hist”, “HLT Rate”, len(runArray), runArray)
Set bin labels to match run numbers
for i in xrange(1,len(runArray)):