# How to display coordinates of points in "contourf"?

34 views (last 30 days)
Ali Baig on 6 Aug 2018
Answered: Afshin Aghayan on 8 Oct 2019
I have three matrices, X, Y, and Z. I am creating a filled contour plot using the command
contourf(X,Y,Z)
How can I display the coordinates of all points in the plot? I can use "Data Cursor" in figure environment to mark coordinates of points individually but this may take a lot of time depending on the number of points.
Ali Baig on 6 Aug 2018
Yes! this is exactly what I want to do. Thank you!

jonas on 6 Aug 2018
Edited: jonas on 6 Aug 2018
It's going to look real messy when you have high resolution x and y data.
%%Some data
[x,y,z]=peaks(20);
[~,c]=contourf(x,y,z);hold on
set(gca,'XTick',[],'YTick',[]);
%%Create cell array with coordinates
C = reshape([x(:)'; y(:)'], [], 1)';
str=sprintf('[%.2g;%.2g],',C);
str=strsplit(str,',')
str(end) = [];
%%Plot labels
text(x(:),y(:),str(:),'fontsize',6,'horizontalalignment','center','verticalalignment','mid')
Or alternatively, with the undocumented sprintfc (courtesy Walter Roberson)
%%Same code as above, until:
str=sprintfc('[%.2g;%.2g]',C);
text(x(:),y(:),str(:),'fontsize',6,'horizontalalignment','center','verticalalignment','mid')
jonas on 6 Aug 2018
Managed to do it with sprintf, although it was a bit of a hassle. Will definitely look into sprinfc! Thanks

Afshin Aghayan on 8 Oct 2019
you can use this code for displaying any data in the form of [x, y, f(x,y)] or data with coordinate