Interpolate matrices for different times in Matlab
4 views (last 30 days)
Show older comments
I have computed variables stored in a matrix for a specific time vector. Now I want to interpolate between those whole matrices for a new time vector to get the matrices for the desired new time vector.
I've came up with the following solution but it seems clunky and computational demanding:
clear all;
a(:,:,1) = [1 1 1;2 2 2;3 3 3]; % Matrix 1
a(:,:,2) = [4 4 4;6 6 6;8 8 8]; % Matrix 2
t1 = [1 2]; % Old time vector
t2 = [1 1.5 2]; % New time vector
% Interpolation for each matrix element
for r = 1:1:size(a,2)
for c = 1:1:size(a,1)
tab(:) = a(r,c,:);
tabInterp(r,c,:) = interp1(t1,tab(:),t2);
end
end
The result is and should be:
[2.5000 2.5000 2.5000
4.0000 4.0000 4.0000
5.5000 5.5000 5.5000]
Any thoughts?
0 Comments
Accepted Answer
Stephen23
on 10 Aug 2018
Edited: Stephen23
on 10 Aug 2018
Simpler in just one line and more efficient without all of those intermediate variables:
>> a(:,:,1) = [1 1 1;2 2 2;3 3 3];
>> a(:,:,2) = [4 4 4;6 6 6;8 8 8];
>> b = permute(interp1([1,2],permute(a,[3,2,1]),[1,1.5,2]),[3,2,1])
b(:,:,1) =
1 1 1
2 2 2
3 3 3
b(:,:,2) =
2.5000 2.5000 2.5000
4.0000 4.0000 4.0000
5.5000 5.5000 5.5000
b(:,:,3) =
4 4 4
6 6 6
8 8 8
And compared to your original code:
>> isequal(tabInterp,b)
ans = 1
More Answers (1)
Ameer Hamza
on 9 Aug 2018
You can use interp3 as follow:
clear all;
a(:,:,1) = [1 1 1;2 2 2;3 3 3]; % Matrix 1
a(:,:,2) = [4 4 4;6 6 6;8 8 8]; % Matrix 2
t1 = [1 2]; % Old time vector
t2 = [1 1.5 2]; % New time vector
% Interpolation for each matrix element
[X, Y, Z] = meshgrid(1:size(a,1), 1:size(a,2), t1);
[X2, Y2, Z2] = meshgrid(1:size(a,1), 1:size(a,2), t2);
tabInterp = interp3(X,Y,Z,a,X2,Y2,Z2);
See Also
Categories
Find more on Matrices and Arrays in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!