how to find the index value

Question

singh 2015-5-13

编辑： James Tursa 2015-5-13

suppose i have on matrix A

i have another matrix B

now i wish to get the value from A 7 and B 23 12 through index value.

suppose 7 value store in A 4 location now i get the 4 location values from B

Answer 1

James Tursa 2015-5-13

编辑：James Tursa 2015-5-13

If you are given the value 7 and want to find it in A and then get the corresponding row in B, then you could do this:

x = find(A==7);
r = B(x,:);

If you don't care about storing the index itself, then you can just use logical indexing directly:

r = B(A==7,:);