How to keep all added plot in one Canvas in TMultigraphe in ROOT


I am working on plotting multiple graphs(from different dozen of file.dat) in a single Canvas by using mg->add(“AL”).
I add all each time my points then I plot by mg->draw() . the problem is the final graph is just for last file. I tried to print the mg and it shows points of all files. but still, the final graph is for a single file.

That’s unexpected.
Are you sure you do not recreate your “mg” for each file?
Are you sure graphs in different files are really different?

I have generate one mg after adding all gr . yes, I have checked the files(about 50) they are slightly different with a margin of the discrepancy of 0.1 to 0.005.

You should create “mg” BEFORE trying to add graphs .

If the graphs are “slightly different” then maybe everything is fine and you cannot simply see these “slight differences” on the plot.

I think I did that. the structure of the code is:

   auto mg new = ....................
     for ....{
     Tgraph  *gr  = ....

TCanvas  *.....

Well, You should have something like this …

TMultiGraph *mg = new ...; // create the multigraph
for (...) { // loop over all files
  // open the "current" file then ...
  TGraph *gr = …; // retrieve or create the graph
  // ... close the "current" file

okay, the structure sames almost same but when I changed the Draw line to from AL to APL it gives out thin red line (as I got it before ) with black wide line overlapped this time .

I think it just changes the painter thickness .

Well, “almost” is not “same”.

You seem to create “gr” once, outside of the for loop over files (so you will get the graph from the last file only).

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.