Re: Text about binwidth below xaxis

Rene Brun (Rene.Brun@cern.ch)
Mon, 23 Feb 1998 18:07:01 +0100

Tadeusz Pytlos wrote:
>
> Hello Rooters,
> Is any easy way to place text below xaxis? Something like SetXTitle,
> but in the middle. I created histogram with methods
> ...
> TH1F *h1 = new TH1F("h1","Example",100,3,8);
> h1.SetLineWidth(2);
> h1->Fill(E);
> h1.SetXTitle("E[MeV]");
> h1.SetYTitle("N");
> h1.SetMinimum(1);
> h1.Draw();
> ...
> and I would like to insert below xaxis in the middle information
> about the width of bin of my histogram, for example text: dE=0.1 MeV,
> where 0.1 wil be automaticly changed, when I change nbins or range.
> I'm not sure if TPaveLabel or TText is the best way to use in this
> case, because I want to use this mechanism in many macros without
> changing coordinates.
> Thanks in advance
> Tadeusz

Here is an example to add a text centered on X and at the bottom
of the pad.

Rene Brun

//-----------------macro axlabel.C
{
TCanvas *c1 = new TCanvas("c1");
gROOT->Reset();
TH1F *h1 = new TH1F("h1","Example",100,3,8);
h1.SetXTitle("E[MeV]");
h1.SetYTitle("N");
h1.SetMinimum(0);
h1.SetMaximum(100);
h1.Draw();
c1->Update(); // this forces painting in the pad
char label[30];
sprintf(label,"DE=%5.2f MeV",h1->GetXaxis()->GetBinWidth(1));
TText *xlabel = new TText();
xlabel->SetTextAlign(21);
Float_t x1 = c1->GetX1();
Float_t x2 = c1->GetX2();
Float_t y1 = c1->GetY1();
Float_t y2 = c1->GetY2();
xlabel->SetTextSize(0.03);
xlabel->DrawText(0.5*(x1+x2), y1 + 0.01*(y2-y1), label);
}