Merge and visualize root file

ROOT
1

Hello ROOTers,

I have 6 .root file named Data_x.root and I want to merge them in order to generate one Data.root file and see it with TBrowser, it is possible? How can i do that?

Thanks in Advance.

2

Try: hadd Data.root Data_*.root

3 Likes
3

I tried:

add RUN4_2.root RUN4_1.root
^
root [1] hadd RUN4_2.root RUN4_1.root
ROOT_prompt_1:1:5: error: expected ‘;’ after expression

hadd RUN4_2.root RUN4_1.root
^
;

Doesn’t work.

4

hadd is not a root command it is a standalone application based on root. You should execute it at the shell prompt.

$ hadd Data.root Data_*.root
5

Ok, I understand. By the way:

hadd RUN4_1.root RUN4.root;

output:

hadd Target file: RUN4_1.root
hadd compression setting for all output: 1
Error in <TFile::TFile>: file ~/Scrivania/RUN4_1.root already exists
Error in <TFileMerger::OutputFile>: cannot open the MERGER output file 
hadd error opening target file (does RUN4_1.root exist?).
Pass "-f" argument to force re-creation of output file.

Maybe I understand… I need to merge a file with another file that already exist like:

hadd RUN4_2.root RUN4_1.root;

then:

hadd RUN4_3.root RUN4_1.root;

until…

hadd RUN4_6.root RUN4_1.root;

So the file RUN4_1.root will be the merged file?

EDIT: I did this for several times:

hadd -f RUN4.root RUN4_6.root;

with output:

hadd Target file: RUN4.root
hadd compression setting for all output: 1
hadd Source file 1: RUN4_6.root
hadd Target path: RUN4.root:/

seems to work…

6

This mean the file you chose for output already exists. Remove it or use option -f

7

LIke i said, EDIT: I did this for RUN4_1 to RUN4_6, creating for zero a the RUN4 file:

hadd -f RUN4.root RUN4_1.root;

with output:

hadd Target file: RUN4.root
hadd compression setting for all output: 1
hadd Source file 1: RUN4_6.root
hadd Target path: RUN4.root:/

It is correct?

I open the merged file and the number of entries is < then the singol RUN4_X.root files…

I also tried the advice of @Wile_E_Coyote :

hadd -f RUN4.root RUN4_*.root;
hadd Target file: RUN4.root
hadd compression setting for all output: 1
hadd Source file 1: RUN4_1.root
hadd Source file 2: RUN4_2.root
hadd Source file 3: RUN4_3.root
hadd Source file 4: RUN4_4.root
hadd Source file 5: RUN4_5.root
hadd Source file 6: RUN4_6.root
hadd Target path: RUN4.root:/

and works. Last question:

Now i see all the entries

Canvas_1
Canvas_11656×848 7.38 KB

I’m interested to save the number of entries for a particolar condition “mult==4”.

I tried with the comand:

tree_arduino->Draw("mult==4")

Canvas_1
Canvas_11656×848 25.5 KB

but with this i visualize only th graph with this particular condition. How command i need to execute in order to visualize the number of entries with this condition?

8

hadd usage is:

usage: hadd [-a A] [-k K] [-T T] [-O O] [-v V] [-j J] [-dbg DBG] [-d D] [-n N] [-cachesize CACHESIZE] [-experimental-io-features EXPERIMENTAL_IO_FEATURES] [-f F]
            [-fk FK] [-ff FF] [-f0 F0] [-f6 F6]
            TARGET SOURCES

So you need to specify first the target file and then the list of files you want to merge:

hadd target.root source1.root source2.root source3.root

tha will merge the 3 file source*.root in target .root

you can also do:

hadd target.root source*.root

That will merge all the files matching the regular expression source*.root in target.root

1 Like
9 
tree_arduino->Draw("mult","mult==4")
double n = htemp->GetEntries()
cout << n << endl;
10

Long64_t n = tree_arduino->Draw("mult", "mult==4", "goff");

11

This command give me the total number of entries (maybe it is my fault, i dont know)

This command works (in my specific case). What mean the goff option?

12

graphics off

1 Like
13

Actually, one can do it in a more simple way:

Long64_t n = tree_arduino->Draw("", "mult==4");

1 Like
14

Thanks for all the reply :slight_smile:

15

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