Replacing values in array with values from another array

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The values in each row of an array correspond to the values i, j of an upper triangular array. How do I return a vector with elements that are the corresponding i, j value in the array? For example:
test_array = [1 2; 2 3; 1 3];
test_upper_triangular_array = [0.5 0.25 0.7; 0 0.8 0.6; 0 0 1.1];
desired_vector = [0.25 0.6 0.7]

Accepted Answer

Star Strider
Star Strider on 17 Jul 2022
Edited: Star Strider on 17 Jul 2022
Try this —
test_array = [1 2; 2 3; 1 3];
test_upper_triangular_array = [0.5 0.25 0.7; 0 0.8 0.6; 0 0 1.1]
test_upper_triangular_array = 3×3
0.5000 0.2500 0.7000 0 0.8000 0.6000 0 0 1.1000
lidx = sub2ind(size(test_upper_triangular_array), test_array(:,1), test_array(:,2)) % Convert Subscripts To Linear Indices
lidx = 3×1
4 8 7
result = test_upper_triangular_array(lidx)
result = 3×1
0.2500 0.6000 0.7000
% desired_vector = [0.25 0.6 0.7]
EDIT —
Transpose to get row vector:
result_row = result.'
result_row = 1×3
0.2500 0.6000 0.7000
.

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