Too much colum how to fill tree?

ROOT
1

i have data that is made of 131 column, the first column is time,the other is data.So i want to draw each of the data vs time. I want to use tree.

FILE *fp;
fp=fopen(“data.txt”,“r”);
float column[131];
TTree *tree=new TTree(“tree”,“data from ascii file”);
tree->Branch(“column[0]”,&column[0],“column[0]/F”);
tree->Branch(“column[1]”,&column[1],“column[1]/F”);
……
tree->Branch(“column[130]”,&column[130],“column[130]/F”);

while(!feof(fp))
{
fscanf(fp,"%f %f %f……“，&column[0],&column[1],……,&column[130]);
tree->Fill();
}
Is there other way?
thanks!

2

WHY no one answer me?

3

Please do not post twice the same question.
Please bear with us while we come back to work after the week-end.

Philippe

4

[quote=“pcanal”]Please do not post twice the same question.
Please bear with us while we come back to work after the week-end.

Philippe[/quote]
Sorry !
130 Column,I must write 130 branches,it is so diffcult.
LOOP ?
for(i=0;i<130>Branch(“column[i]”,&column[i],“column[i]/F”);
ok?
Thanks!

5

The shortest way is fill the TTree with the array as is the array is dynamic: you must add only an integer with the length of the array:

Int_t nels = 131;
Float_t vals[131];

tree->Branch("nels",&nels,"nels/I");
tree->Branch("vals",vals,"vals[nels]/F");

for (...) {
  vals[0] = ...
  vals[1] = ...
  ...
  tree->Fill();
}
6

[quote=“volpig”]The shortest way is fill the TTree with the array as is the array is dynamic: you must add only an integer with the length of the array:

[code]
Int_t nels = 131;
Float_t vals[131];

tree->Branch(“nels”,&nels,“nels/I”);
tree->Branch(“vals”,vals,“vals[nels]/F”);

for (…) {
vals[0] = …
vals[1] = …
…
tree->Fill();
}
[/code][/quote]
what is the meaning of
tree->Branch(“nels”,&nels,“nels/I”);
tree->Branch(“vals”,vals,“vals[nels]/F”);
thanks!
can it use tntuple?

7

Please re-read the User’s Guide chapter on TTree (you will find the detailed answer).

[quote]can it use tntuple?[/quote]TNtuple should only be used for very simple case (aka only single float variables).

Cheers,
Philippe

8

Please re-read the User’s Guide chapter on TTree (you will find the detailed answer).

[quote]can it use tntuple?[/quote]TNtuple should only be used for very simple case (aka only single float variables).

Cheers,
Philippe[/quote]
Thank you very much!
I have finished my work with you help!