How to detect if a plot has already existed?
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What I want to do is to plot my sampling stations on a map. The map is pre-plotted . I want to delete the previous sampling stations (h1 handle) if they already exist and then plot the new sampling stations.
Below is my code:
if isexist(h1)
delete(h1);
end
hold(app.mapPlot, 'on');
h1 = plot(app.mapPlot, lonlat(:,1), lonlat(:,2), 'o', 'color', 'b','markersize', 5);
Unfortunately, I got the below error:
Unrecognized function or variable 'h1'
Any idea on how to make this work?
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Joe Vinciguerra
2019 年 10 月 23 日
Try this... (note I'm using "exist" instead of "isexist")
clear % I'm starting with no 'h1'. This checks the "False" condition
if exist('h1')
delete(h1); % if 'h1' is a thing, delete it
end
h1=plot([5 8],[12 11]); % now there is an 'h1' either way
hold on; % I insertered this to match your application
pause(3); % wait a few seconds to verify it visually
% Let's do it again to check the "True" condition
if exist('h1')
delete(h1); % if 'h1' is a thing, delete it
end
h1 = plot([1 2],[2 4]); % still works
3 件のコメント
Joe Vinciguerra
2019 年 10 月 23 日
I'm not as familiar with the app designer, but I'll try to help.
Are you sure it's really not deleting? Or is it deleting and replotting the same data quick enough that you don't notice?
Try another command instead of "delete". Perhaps "close"?
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