how to erase a line?

Hai,

I have drawn a few lines. At the later part of my program I need to delete (remove/erase) those lines, which do not satisfy the required conditions. So, is it possible to remove or erase the lines which have already been drawn, in matlab. Is there any function that supports this. Looking for your reply.

BSD

Answer 1

[Fangjun Jiang]

f=figure(1);hold on;
c1=plot(1:10);
c2=plot(10:-1:1);

delete(c1);

[Emir Akyildiz]

Thank you so much!

Answer 2

[Image Analyst]

If you want to clear just certain specific lines, you can keep track of all your line handles and clear them like Fangjun and Nick showed you. If you want to clear all lines from the axes, then call this function:

%=====================================================================
function ClearLinesFromAxes()
  axesHandlesToChildObjects = findobj(gca, 'Type', 'line');
  if ~isempty(axesHandlesToChildObjects)
    delete(axesHandlesToChildObjects);
  end  
  return; % from ClearLinesFromAxes

If you want, you can pass in an argument via the argument list and use that instead of gca, which is the axes you used last.

function ClearLinesFromAxes(axesToClear)
    axesHandlesToChildObjects = findobj(axesToClear, 'Type', 'line');
    if ~isempty(axesHandlesToChildObjects)
      delete(axesHandlesToChildObjects);
    end  
    return; % from ClearLinesFromAxes

[Felix Crazzolara]

In Matlab 2018b this might change the scale of the plot. How can this be prevented? That is, how can lines be removed without the axis limits to change?

[Image Analyst]

You can use hold on.

hold on;

That should lock the axes down. If not, use xlim() and ylim() to remember the limits before deletion, then call them again to set the values to the original values after deletion.

[RK DISSANAYAKA]

how select two colomns of each matric

[Image Analyst]

@RK DISSANAYAKA I think you commented on the wrong answer or comment. Your question has nothing to do with anything on this page that I can see. But anyway, to get column #9 from a matrix, you can do

oneColumn = yourMatrix(:, 9);

Which you'll learn after taking this short course:

MATLAB Academy - Free 2 hour training

Answer 3

[Nick]

Are these lines in a figure?

I suppose the easiest way would be to select the lines you dont want with the cursor and hit delete. If you want to do it in your code you could create a seperate handle for each of your line objects and use the delete function.

h(1)=plot(x,y); hold on
h(2)=plot(x,z);
delete(h(2))

Could you be more specific on what your trying to do?