Convert xy Coordinates to Matrix

53 views (last 30 days)
John
John on 26 May 2013
Commented: Image Analyst on 24 Mar 2021
I have an xy coordinates positions (100x2) and another z vector (100x1) with values corresponding to each xy coordinate. How can I make a matrix of the coordinates with the position of each coordinate having the corresponding z value? Thanks!

Accepted Answer

Andrei Bobrov
Andrei Bobrov on 27 May 2013
Edited: Andrei Bobrov on 27 May 2013
after John's comment in Image Analyst's answer:
out = accumarray([x(:),y(:)],z(:),[10 10]);
or
out = zeros(10);
out(sub2ind(size(out),x,y)) = z;
  4 Comments
John
John on 27 May 2013
Now I get it, thanks for the clarification.
cecilia dip
cecilia dip on 28 Nov 2016
Hi, I have to do the same thing, and i've tried this, but my coordinates (x,y) are negative and non-integer numbers, as they are latitude,longitude.. how can i do this? I want a plot where for each(lat,long) i can have my Z value (in a color scale, as i will compare it with interpolation methos later). Thank you!

Sign in to comment.

More Answers (2)

Image Analyst
Image Analyst on 26 May 2013
Try this:
% Setup / initialization.
% Start out matrix as zeros.
m = zeros(20,10);
% Generate 100 random coordinates.
xy = int32(randi(10, 100, 2));
% Get matrix values for those x,y locations
z = randi(255, 100, 1); % 100 values.
% Now, do what the poster, John, wants to do.
% Assign the z values to the (x,y) coordinates at the corresponding row.
% E.g. m at (x(1), y(1)) will have a value of z(1).
% m at (x(2), y(2)) will have a value of z(2). And so on.
indexes = sub2ind([20, 10], xy(:,1), xy(:,2))
m(indexes) = z
  6 Comments
Luigi Izzo
Luigi Izzo on 24 Mar 2021
what about if xy(k,1) or xy(k,1) are negative numbers?
Thanks
Image Analyst
Image Analyst on 24 Mar 2021
Try using a scatteredInterpolant. Demo attached.
If you still need help, attach your x, y, and z data in a new question (not here) so people can help you.

Sign in to comment.


Annisa Dewanti Putri
Annisa Dewanti Putri on 10 Jul 2018
thanks for the help

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!