# find index of a matrix through another matrix

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Salvatore Mazzarino 2012 年 9 月 21 日
I have this matrix A = [1 3 4 6 7] and B = [3 4] that it's a subset of A matrix. For example I would find the index of B matrix through A matrix. Having 3 as number I would know the index of 3 in matrix B.How can I do?

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### 回答 (3 件)

Azzi Abdelmalek 2012 年 9 月 21 日

B = [3 4]
idx=find(B==3)

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Azzi Abdelmalek 2012 年 9 月 21 日
Salvatore Mazzarino 2012 年 9 月 21 日
Because in my scripts I don't have directly A matrix.This is an example that permitted me to understand how find works.

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per isakson 2012 年 9 月 21 日

This is possible if A and B are whole numbers
A = [ 1, 3, 4, 6, 7 ];
B = [ 3, 4 ];
ix1 = strfind( A, B );
ix2 = ix1 + numel(B) - 1;
all( B == A(ix1:ix2) )
If I understood you correct

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Image Analyst 2012 年 9 月 21 日
Actually I thought first that what you meant was what per answered, but then I read your response to Azzi. I'm not sure you worded this correctly but when Azzi asked about it, you seemed to indicate it was worded exactly as you wanted. So in that case, I guess that would mean that if B is in A, the index of B (and you did say in B, not A) would always be 1. If B is not in A then there is no solution - obviously since B is not in A.

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