How to extract values from a matrix using a row - column matrix?
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I have a matrix like
A =
0.2180 0.5714 0.2476 0.3942 0.9253 0.5082
0.3906 0.5881 0.6529 0.3806 0.3819 0.7947
0.3381 0.0287 0.0652 0.3696 0.3735 0.1351
0.7459 0.0911 0.0163 0.7531 0.3298 0.2050
0.3690 0.5010 0.5201 0.6119 0.9038 0.1902
0.4232 0.9183 0.6523 0.2392 0.4661 0.0019
and a matrix having row and column indices
loc =
1 2
2 5
4 3
6 6
I want the extract the values of locations (1,2), (2,5), (4,3) and (6,6) from matrix A when I do this
val = A(loc(:,1),loc(:,2));
it gives me
val =
0.5714 0.9253 0.2476 0.5082
0.5881 0.3819 0.6529 0.7947
0.0911 0.3298 0.0163 0.2050
0.9183 0.4661 0.6523 0.0019
I can use diag(val); to get the locations values but is there any way so that i could get values directly without getting that square matirx
val =
0.5714
0.3819
0.0163
0.0019
0 Comments
Accepted Answer
Stephen23
on 22 Apr 2015
Edited: Stephen23
on 22 Apr 2015
A = [...
0.2180 0.5714 0.2476 0.3942 0.9253 0.5082
0.3906 0.5881 0.6529 0.3806 0.3819 0.7947
0.3381 0.0287 0.0652 0.3696 0.3735 0.1351
0.7459 0.0911 0.0163 0.7531 0.3298 0.2050
0.3690 0.5010 0.5201 0.6119 0.9038 0.1902
0.4232 0.9183 0.6523 0.2392 0.4661 0.0019];
loc = [...
1 2
2 5
4 3
6 6];
X = sub2ind(size(A), loc(:,1), loc(:,2));
and then run this in the command window:
>> A(X)
ans =
0.5714
0.3819
0.0163
0.0019
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