Divide a canvas with only xmargin at 0

ROOT
1

Hello,
I divided a TCanvas in 4x9 pads

TCanvas *c = new TCanvas("c","c"); c->Divide(4,9);
I would like to remove the space between each line but keep in the same time the space between the column. So I tried to do

but I remarked that it does not work; I mean that if I type that line, I have no margin anymore in x and y whereas I should have a margin in y.
Do I something wrong?
Thanks in advance.

2

may be you can try:

root [0] TCanvas *c = new TCanvas("c","c");
root [1] c->Divide(4,4,0.0001,0.01,2);
3

No it does not work. To be more precise, this reduces the margin but the result is different of c->Divide(4,4,0,0). In fact, if I put 0 for the xmargin, the result is that the axis of the pads are not display anymore ( they are hidden by the other pad)
If I use your command, there is no margin between pad but there is still the axis. If it is not clear, I can attach figure

4

Do not put exactly “0” (nor any negative value) as the “[xy]margin” -> use an artificially small positive number -> something like “0.000001”.
For the special case of “0” (and/or any negative value) as the “[xy]margin” see the TPad::Divide method description.

5

I tried to put a very small number. There is no space between all the pads but it is not exactly what I want. In fact, if I put 0 in c->Divide, the axis are not displayed (they are hidden by the neighbouring pads). So, I would like to “remove” the X axis and keep the Y axis.

If I put a very small number, X and Y axes are still there.

6

At some point I wrote a macro giving more control on the canvas division (see attachement). It do not use the Divide() method therefore you can customise it as you wish.
div2.C (1.55 KB)

7

Thanks for your help. I got what I want with that code

[code]{
TCanvas *c = new TCanvas(“c”,“c”);
c->Divide(4,9,0.01,0.00001,2);

for(int i=0 ; i<4*9 ; i++) {
c->cd(i+1);
TH1F *h = new TH1F(TString::Format(“h%d”,i),TString::Format(“h%d”,i),100,0,10);
h->Draw("");
if(i<32) {
gPad->SetBottomMargin(0);
gPad->SetTopMargin(0);
}
}
}[/code]
So I needed to put, “c->Divide(4,9,0.01,0.00001,2);”, and to modify top and bottom margins in all pads.