How can I build vertical line on the graphic?

ROOT
1

I need build vertical line on my graphic. For example: x=0. How can I make it?

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ROOT Version: 6.19/01
Platform: Ubuntu
Compiler: Not Provided

2

Hi,
you can use the TLine object.

Cheers,
Stefano

3

TLineObject->Draw() doesn’t work. I haven’t line on my dask.

4

Something like this should work

//your code 
TLine *v_line= new TLine(0,-2,0,3); //declare the vertical line 
//Set line attributes 
v_line->SetLineColor(kRed);
v_line->SetLineWidth(2);
v_line->SetLineStyle(kDashed);
//draw the line
v_line->Draw("same");

Stefano

5

I made vector<TLine> lines and work with it. lines[i].Draw() doesn’t work. All part of my code:

...
void DrawWalls(vector<double>& walls)
{
  vector<TLine> lines(walls.size());
  for ( int i = 0; i < walls.size(); i++ )
    {
      lines[i].SetX1(walls[i]);
      lines[i].SetX2(walls[i]);
      lines[i].SetY1(0);
      lines[i].SetY2(0.4);
    }
  for ( int i = 0; i < walls.size(); i++ )
      lines[i].Draw();
}
6

Hi,

You create TLine objects in stack and they are destroyed immediately after leave of function scope.
Just create TLine objects dynamically:

vector<TLine*> lines(walls.size());
for ( int i = 0; i < walls.size(); i++ )
    {
     lines[i] = new TLine();    
      lines[i]->SetX1(walls[i]);
      lines[i]->SetX2(walls[i]);
      lines[i]->SetY1(0);
      lines[i]->SetY2(0.4);
    }
  for ( int i = 0; i < walls.size(); i++ )
      lines[i]->Draw();
7

yes, it works, thanks

8

As a side note: The “same” option is not a TLine Drawing option.
TLine::Draw() is the generic Draw() method inherited from TObject, therefore it has no option. Simply use v_line->Draw();

1 Like
9

You can also create a single TLine l;
And if all line should use same style, call
l.DrawLine( xmin, ymin, xmax, ymax).
I.e you can drop the vector if you want.

10

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