Different coloured bins in 1-d histo

ROOT
1

Hello,

     Is it possible to designate a bin in a 1d histogram to have a different

fill colour to the others ? ( eg. say, one bin red, in a white filled histo ).

                                                    Regards,
                                                        Kyle Stevenson.
2 
// File bincolor.C
void PaintBin (TH1 *h, Int_t bin, Int_t color)
{
   printf("%d %d %d\n", bin, color, h->GetBinContent(bin));
   TBox *b = new TBox(h->GetBinLowEdge(bin),
                      h->GetMinimum(),
                      h->GetBinWidth(bin)+h->GetBinLowEdge(bin),
                      h->GetBinContent(bin));
   b->SetFillColor(color);
   b->Draw();

}

void bincolor()
{
  TH1F *h1 = new TH1F("h1","h1",100,-10,10);
  h1->FillRandom("gaus");
  h1->Draw();
  PaintBin (h1, 60, kRed);
  PaintBin (h1, 50, kBlue);
}
3

Thankyou,

     This is almost ok for what I want but there are problems with the

minimum ( the y-minimum is set to the lowest entry rather than the
y-axis minimum ). Also how would I avoid over-writing the lines of the x-
axis ?

                                                  Cheers,
                                                       Kyle.

cc2.gif696×472 6.15 KB

4

Can you send a small macro reproducing this effect ?

5

Hello,

    I've included the macro & root file I'm using. Should run ok out the box. 
                        
                                 Cheers,
                                          Kyle.

ps. I’m on ROOT v5.22/00b
Results.root (33.6 KB)
turnoncurves.c (3.43 KB)

6

see your macro modified in attachment.
Look at the 2 lines with //<=========
and the line h->GetMinimum() replaced by gPad->GetUymin().

Rene
turnoncurves.C (3.51 KB)