Reshape a matrix based on indices placed on another matrix

Hi all,

I have a matrix called combinations and a vector whose dimension in 119x119.

The matrix combinations basically includes all the combinations of rows and columns of the desired matrix and the vector collects the values that I would like to be input. To make a practical example with a 9x9 matrix, say combination is made like this:

1	1
2	1
3	1
4	1
5	1
6	1
7	1
8	1
9	1
1	2
2	2
3   2
4	2
5   2
6   2
7   2
8	2
9	2
...
1  9
2  9
3  9
4  9
5  9
6  9
7  9
8  9
9  9

and vector of 81 elemnts is made like this:

NaN
0.78
0.34
...
0.56
...
NaN

where NaN is the 81th element and 0.56 is the element in correspondence of the couple 2-1 in the combination matrix. Notice that the elements of the main diagonal would be all NaNs.

Now what I would like to obtain is the 9x9 matrix with the values in the vector:

NaN 0.56 ...0.88
0.78 NaN ...0.99
...
0.34 ...    NaN

Thank you

Answer 1

[Voss]

v = rand(81,1);    % something like
v(1:10:end) = NaN; % your 81-by-1 vector

reshape(v,9,[])

ans = 9×9

NaN 0.4622 0.7474 0.1754 0.6380 0.7944 0.1442 0.0318 0.6000 0.5074 NaN 0.1426 0.9652 0.0757 0.5693 0.2202 0.9093 0.0783 0.2977 0.4874 NaN 0.7450 0.9238 0.8236 0.2739 0.6859 0.7228 0.4736 0.4040 0.6243 NaN 0.4468 0.9677 0.2733 0.6286 0.5913 0.8471 0.4506 0.6928 0.3567 NaN 0.8600 0.9703 0.4879 0.0925 0.1628 0.1126 0.7963 0.1397 0.9743 NaN 0.8280 0.7346 0.2311 0.0919 0.1964 0.4984 0.3028 0.5550 0.7968 NaN 0.1212 0.8937 0.9366 0.3644 0.5989 0.2283 0.4071 0.9791 0.0451 NaN 0.1535 0.9691 0.9074 0.4224 0.5206 0.1697 0.4725 0.8304 0.1909 NaN