[Miranda65M]

So I’m just starting out in C++ and I managed to convert an image into a text file which contains: x y intensity values.

So this is an example of the file:

   1   1   0.00
   1   2   2.10
   1   3   0.00
   1   4  76.20
   1   5   0.00
   1   6   0.00
   1   7   0.00

The code I’m writing is in C++ but is actually processed in root.

The code I’ve started writing is:

using std::cout;
using std::endl;
using std::string;

string fOutFileName("gaintest.root");
void Usage();
void ParseArgs(int argc, char **argv); 


int main(int argc, char * argv[])
{

  ParseArgs(argc, argv);

TH2D * p001_1 = new TH2D("p001_1","p001_1",640,0,640,480,0,480)

 std::ifstream file1("data_p30.dat");

  int x, y;
  double intensity;

  double getarray[640,480]

if (file1.is_open()) {
    file1.seekg(0);
    while (!file1.eof()) {
      file1 >> x >> y >> intensity;
      p001_1->; //HELP HERE
    }
    file1.close();
  } else cout << "Error, cannot open file 1";
}

Now the part with "p001_1->" is where I'm tripping up, ultimately I'd like an array that looks something like this:

myarray[x,y]=intensity

where I can pick which x,y values I want for it to spit out the intensity value. The only catch is I need those x,y values to correspond to the values in the file. I know I'm close, but I just need a little help over the final hurdle =P

THANKS =)

P.S I've sort of found a solution:

Code: Select all
p001_1->SetBinContent(x,y,intensity);

BUT this isn't brilliant for what I need it for next (taking certain areas of the picture and finding the difference of the intensities)

EDIT:

std::ifstream file1("data_p30.dat");

//int x, y;
//double intensity;

 //double getarray[640,480];
  int i;
  int j ;
  double c[1000,1000];
if (file1.is_open()) {
    file1.seekg(0);
    while (!file1.eof()) {
      file1 >> i >> j >> c[i,j];
      cout<
but then I get this error:

46: error: expected `]' before ‘,’ token
46: error: expected unqualified-id before numeric constant
50: error: ‘c’ was not declared in this scope
50:warning: left-hand operand of comma has no effect

I appreciate you don't know the line numbers, but I think it really doesn't like the way I'm defining the variables 
    

[ShikhaTan]

So on http://root.cern.ch/root/html/src/TH2D.h.html#kvMDeC

It seems to be saying there is a function for:

virtual Double_t GetBinContent(Int_t binx, Int_t biny)

So wouldn’t you be able to just use that instead of making the array of doubles?

But if you really want to make the array of doubles, I don’t think you can initialize with

c[1000,1000]

I think you’d need to use

c[1000][1000]

You can see this in the error where it says the operand of comma has no effect and that it expects to see an end bracket