How to parse a TH1*D hist[l][m][n] to a function

ROOT
1

Dear experts,

I have a 3D TH1D* and I want to parse it to a function. I did [1] but I had the error message[2]. Do you know what is wrong?

Regards

[2]
error: no matching function for call to 'setaxis’
setaxis( hist[ifile][countdir][nvar]);
^~~~~~~
note: candidate function not viable: no known conversion
from 'TH1D ’ to ‘TH1D ()[1][8]’ for 1st argument
void setaxis(TH1D h[4][1][8],
^

[1]

void setaxis(TH1D* h[4][1][8] ){

}

void test(){
TH1D *hist[4][1][8];
…
setaxis(hist);
}

2

If it’s ROOT 5, then see: Multidimensional Array
and try something like this (note: you may need to precompile your source code using ACLiC): [code]#include “TH1.h”

typedef TH1D* (*My3DTH1DArray)[4][1][8];

void setaxis(My3DTH1DArray h) {
// …
}

void test() {
TH1D* hist[4][1][8];
// …
setaxis(&hist);
}[/code]
I guess a better idea would be to move to ROOT 6 (you should not need any tricks then).

3

Dear Pepe,

thank you for your answer. When I’m using [1] with"->" to access method have the error message[2], when I use [3] with “.” I have error message [4]. Do you know what is wrong?

Regards

[1]
#include “TH1.h”

typedef TH1D* (*My3DTH1DArray)[4][1][8];

void setaxis(My3DTH1DArray h,
const std::vectorstd::string &vfile,
const std::vectorstd::string &vdir,
const std::vectorstd::string &vvar
) {

for(int file=0; file<vfile.size(); file++){
for(int dir=0; dir<vdir.size(); dir++){
for(int var=0; var<vvar.size(); var++) {

  int temp = h[file][dir][var] -> FindLastBinAbove(0.0005);

 }

}
}
}

void test() {
TH1D* hist[4][1][8];
vector vfile;
vector vdir;
vector vvar;

setaxis(&hist, vfile, vdir, vvar);
}

[2]
error: member reference
base type ‘TH1D *’ is not a structure or union
temp = h[file][dir][var] -> FindLastBinAbove(0.0005); //get last bin on x axis with data
~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~
In file included from input_line_9:1:
/lstore/cms/calpas/h2taus/CMSSW_8_0_20/src/miniAOD/miniAnalyzer/makeHist/plot_h2taus.cc:123:5: error: no matching function
for call to 'setaxis’
setaxis( &hist, vfile, vdir, vvar);
^~~~~~~
/lstore/cms/calpas/h2taus/CMSSW_8_0_20/src/miniAOD/miniAnalyzer/makeHist/…/func/myfunc.cc:75:6: note: candidate function not
viable: no known conversion from ‘TH1D ()[nfile][ndir][maxvar]’ to ‘My3DTH1DArray’ (aka ‘TH1D ()[4][1][8]’) for 1st
argument
void setaxis(My3DTH1DArray h,

[3]
#include “TH1.h”

typedef TH1D* (*My3DTH1DArray)[4][1][8];

void setaxis(My3DTH1DArray h,
const std::vectorstd::string &vfile,
const std::vectorstd::string &vdir,
const std::vectorstd::string &vvar
) {

for(int file=0; file<vfile.size(); file++){
for(int dir=0; dir<vdir.size(); dir++){
for(int var=0; var<vvar.size(); var++) {

  int temp = h[file][dir][var] . FindLastBinAbove(0.0005);

 }

}
}
}

void test() {
TH1D* hist[4][1][8];
vector vfile;
vector vdir;
vector vvar;

setaxis(&hist, vfile, vdir, vvar);
}

[4]
In function ‘void setaxis(My3DTH1DArray, const std::vector<std::basic_string >&, const std::vector<std::basic_string >&, const std::vector<std::basic_string >&)’:
…/func/myfunc.cc:91:29: error: request for member ‘FindLastBinAbove’ in '((h + ((sizetype)(((long unsigned int)file) * 256ul))))[dir][var]’, which is of non-class type 'TH1D [8]'
temp = h[file][dir][var] . FindLastBinAbove(0.0005);

4

Hi,

The typedef is wrong - it’s an array of function ptrs :slight_smile: For ROOT 6, just do the following:

using My3DTH1DArray = std::array<std::array<std::array<TH1D*,4>,1>,8>;
void setaxis(My3DTH1DArray& h,
const std::vector<std::string> &vfile,
const std::vector<std::string> &vdir,
const std::vector<std::string> &vvar 
)

That will allow the compiler to complain in a much more obvious way than with C-style arrays and pointers.

Cheers, Axel.

5

int temp = ((*h)[file][dir][var]) -> FindLastBinAbove(0.0005);
Note: you need to precompile this source code in ROOT 5 (CINT will choke on it when “interpreted”) … something like … "root [0] .L setaxis.cxx++"
P.S. In ROOT 6, you do not need to play any “My3DTH1DArray” tricks.

6

Dear Axel,

your code works fine. Thank you for your help.

Regards

7

Dear Pepe,

some how Alex’s code worked. Thank you too for your help.

Regards