Hi, I want to plot the histogram of number of emc points for each runid to check bad runs. The runid is an integer. However, the runid has 7 digits. For a whole year's experiment, there would be only like a hundred of different runids. To make it worse, the last 6 digits of the integer runid can be anything. So, by using TH1F with 1000000 bins, each bin will be slim as a line on the plot. I found I can convert the integer runid to string and fill the histogram with the string and a weight(hlabel1.C and hlabel2.C in root tutorial). It worked fine. I submitted hundreds of jobs and each job generated a root file containing a histogram like that. But finally I want to merge these root files. I ever used the example macro hadd.C to do it. But root complained histograms in each root file have different bin size. It's true. Because not every runid would present for a job, so not every runid string would fill the histogram. Later I found hadd.C used TH1->Add(TH1 *) method and the "Add" method requires each histogram should have the same bin size. Then I changed the hadd.C macro a little bit. This time I used TH1->Merge(TList *). Root didn't complain anything this time, but the result is strange and not correct. Am I doing right or I missed something? Is there any other simple way to do this? Thanks. Weijiang
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