Vectorized FIND

This function returns the locations of the elements of a vector in a matrix.

Description

If A is a matrix and b is a column vector, this function returns a column vector of indices I such that A(I)==b if the elements of b are in A. If an element of b is not in A, then the corresponding element of I is Inf.

As an example, you can execute the following code:

rand('state',0)
A=floor(20*rand(5))
b=[18;8;9;6]
I=findin(A,b)
A(I(1:3))

The example above uses I(1:3) because I(4) is Inf; the matrix A does not have 6 as an entry.

• MATLAB release: MATLAB 6.0 (R12)
• Other requirements: This function has been tested in MATLAB 5.3 (R11) and MATLAB 6.0 (R12).

[u s]

nicely implements

J=ismember(b,A(find(ismember(A,b))))
% followed by
b(J)

[Ofek Shilon]

the native -

>> [dmp,I]=ismember(b,A);

achieves identical results in ~1% of the time.