Find index to rows of one matrix in another

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Bill Tubbs
Bill Tubbs 2022-8-31
编辑： Bill Tubbs 2022-8-31
Suppose I have two matrices:
>> A = eye(3)
A =
1 0 0
0 1 0
0 0 1
>> idx = [1 3 2 2];
>> B = A(idx, :)
B =
1 0 0
0 0 1
0 1 0
0 1 0
But I don't know idx. How would I find the vector idx such that isequal(B, A(idx, :))?
I found answers for calculating the index of one row at a time:
>> find(ismember(A, B(2,:), 'rows'))
ans =
3

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Bill Tubbs
Bill Tubbs 2022-8-31
编辑：Bill Tubbs 2022-8-31
I figured out the answer:
>> [~, idx] = ismember(B, A, 'rows')
idx =
1
3
2
2
In case you want to check that all rows in B where found in A you can do this:
[matches, idx] = ismember(B, A, 'rows')
assert(all(matches))

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