Using Logical Indexing to Plot Points Meeting a Specific Criteria Only

(Originally posted on Doug's MATLAB Video Tutorials blog.)

If you have a vector of coordinate for a set of points, you might want to differentiate those points. To do that a concept called logical indexing will help you pull out a subset of those points easily.

Here is a quick example.

>> L = logical([0 1 0 1])

L =

     0     1     0     1

>> a = [1 2 3 4]

a =

     1     2     3     4

>> a(L)

ans =

     2     4