How to find particular elements of matrix?
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Ammy
am 22 Aug. 2021
Kommentiert: Walter Roberson
am 22 Aug. 2021
A=reshape(1:36,6,6);
How to select the following elements of matrix
7,25,
2,14,20,32
9,27
10,28
5,17,23,35
12,30
these can be find like this
A(1,2)=7, A(1,4)=25....
But is there any generalized way which help even for large matrices.
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Walter Roberson
am 22 Aug. 2021
A=reshape(1:36,6,6)
targets = {
[7,25]
[2,14,20,32]
[9,27]
[10,28]
[5,17,23,35]
[12,30]
}
for K = 1 : length(targets)
[~, locations{K}] = ismember(targets{K}, A(K,:));
end
celldisp(locations)
3 Kommentare
Image Analyst
am 22 Aug. 2021
Could be but you don't seem to have any regular recipe like that. The indexes you gave seem to be fairly random with no obvious formula to get them. However you gave only two locations (1,4) and (1,4) so that's not enough to detect any pattern.
If you need anymore help, upload your values in a matrix, like
linearIndexes = [7,25,...
2,14,20,32,...
9,27,...
10,28,...
5,17,23,35,...
12,30]
all in a row vector (did I do it right?), and give more than 2 location for where to assign those values.
Walter Roberson
am 22 Aug. 2021
You have two index patterns:
- columns 2 and 5
- columns 1, 3, 4, 6
However, it is not obvious which pattern is to be applied to which row. The longer extracts are rows 2 and 5, which happens to match the column numbers for the shorter rows, but will that always be the case?
You talk about larger matrices, but do not give us any information about how the accesses will generalize. For example are we to deduce that 2, 5 is "second and second-last" ? Are we to deduce that 1, 3, 4, 6 is "first, two middle, last", or are we to deduce that it "everything not selected by the previous pattern" ?
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