Making histogram from a ascii data file

From: Ivan Pulido <mefistofeles87_at_gmail.com>
Date: Fri, 8 May 2009 01:28:14 -0500


Hi, Im trying to make a histogram from a plain text data file. I tried following instructions from http://root.cern.ch/drupal/content/binned-data

The histrogram I want to make is in 1D, I try to make an array from a plain text data file before filling the histogram as suggested in the site. Here are the steps/instructions Im following to make this happen, please let me know what is wrong. The result is just the canvas with no data in it, just the axis, axis tittles and no data.

TH1F* ydata = new TH1F("ydata","times measured; Energy (q^2)",100,0.64,1.63);
float ydata2[100];
FILE * f = fopen ("tau_ydata.dat","r");
int i=0;
while(fscanf(f,"%lf",&ydata2[i]) == 1) i++; for (i=0; i<100; ++i) ydata->Fill(ydata2[i]); ydata->Draw();

I must tell that the tau_ydata.dat file is read correctly and the array ydata2 has the correct values, so I think the problem is filling the histogram, since when I draw it Im getting nothing. Please help me on this, Im new with ROOT so maybe you can point where to find the solution to this or anything, maybe this is not the correct way to do it. Thanks for the attention. Received on Fri May 08 2009 - 08:28:18 CEST

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