Question

In Matlab 2012b, there is a changem function that allows you to substitute elements of a matrix with other values specified by a set of keys:
Substitute values in data array

Is there an elegant/vectorized way to do the same if I don’t have the Mapping toolbox?

Answer 1

Yes, use ismember:

A       = magic(3);
oldCode = [ 8  9];
newCode = [12 13];

[a,b] = ismember(A,oldCode);

A(a) = newCode(b(a));

I don’t know changem, and I suspect the above will not fully cover its functionality (why else would TMW have introduced changem?), but well, it does what you asked 🙂