how can I merge matrices

Question

Elbr 2015-5-13

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编辑： Elbr 2015-5-22

Z is a vector and X is a matrix

     for h = 1:length(Z)
          [D , E] = find(Z(h) == X)
     end

vector D and E overwrite in every loop. how can i conserve them in a vector?

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Answer 1

Stephen23 2015-5-13

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编辑：Stephen23 2015-5-13

在 MATLAB Online 中打开

Even better would be to avoid the loop entirely by using bsxfun:

>> F = [1,2,3]
F =
   1     2     3
>> B = [0,1;3,2;0,Inf;9,8]
B =
   0     1
   3     2
   0   Inf
   9     8
>> out = bsxfun(@eq,B,reshape(F,1,1,[]));
>> idx = find(out)
idx =
   5
  14
  18

And of course you can use ind2sub to get more specific index information:

>> [row,col,pag] = ind2sub(size(out),idx)
row =
   1
   2
   2
col =
   2
   2
   1
pag =
   1
   2
   3

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Stephen23 2015-5-13

编辑：Stephen23 2015-5-13

在 MATLAB Online 中打开

I do not understand what you mean by "there are to many numbers in vector the row and column". Your original code would detect all values that match between B and F. That is what my code does too! If you want the code to do something else, then you need to specify what it should do.

The method that I gave in my answer does not depend on the size of B or F. They do not have to have any matching dimensions. Lets have a look at your example data (my code is exactly the same as before):

B = [-2, -2, -2, -1, -2, -2, -2, -2
   -2,  0,  5, -1, 12, 14,  1, -2
   -2,  5, 15, -1, 17, 14,  8, -2
   -2, 15, 12, -1, 15,  0, 14, -2
   -1, -1, -1, -1,  7, 14,  8, -2
   -2,  8, 14, -1, 17, 12,  1, -2
   -2,  9,  0, -1,  1,  4,  1, -2
   -2, -2, -2, -1, -2, -2, -2, -2];
F = [ 5,  1,  5,  7,  1,  1,  4,  1];
out = bsxfun(@eq,B,reshape(F,1,1,[]));
idx = find(out);
[row,col,pag] = ind2sub(size(out),idx);

and then run the script, and try this in the command window:

>> [row,col,pag]
ans =
   2     1
   3     1
   5     2
   7     2
   7     2
   7     2
   2     3
   3     3
   5     4
   5     5
   7     5
   7     5
   7     5
   5     6
   7     6
   7     6
   7     6
   6     7
   5     8
   7     8
   7     8
   7     8

Each row corresponds to one matching value. For example, have a look at the first row: 3,2,1. This tells us that row three and col two in B (==5) is equal to the first element of F (==5). This has located all values that are equal in B and F.

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