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Selecting array column elements using a vector..?

Hi everyone,
I need to select elements from a 2D array. I have an index vector whose (i)'th value is the desired row to select from the array. Is there a good, simple method to do this..?
In the following code, I want to extract the following (row,column) array elements: (3,1), (2,2), (4,3), (1,4) : giving the vector: [9 11 15 13]
>> A = magic(4)
A =
16 2 3 13
5 11 10 8
9 7 6 12
4 14 15 1
>> viRow = [3 2 4 1]
viRow =
3 2 4 1
Referring to the doc page on Matrix Indexing, I thought my solution would have been: A(viRow,:) However, this code applies the index vector to each column, which isn't what I want.
>> A(viRow,:)
ans =
9 7 6 12
5 11 10 8
4 14 15 1
16 2 3 13
Could someone please point me in the right direction?
Thanks, Brad

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1 Answer

Answer by Fangjun Jiang
on 7 Sep 2011
 Accepted Answer

Vi=[3 2 4 1];
A=magic(4);
Index=sub2ind(size(A),Vi,1:4);
B=A(Index)

  1 Comment

this looks like the perfect, straightforward solution :) very appreciated, thank you very much. brad

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