### Hooray, Octave supports numpy-style boolean array indexing operations

I've only just discovered that Gnu Octave (the Gnu version of Matlab) supports numpy-style boolean array indexing operations, in particular

- logical operations on vectors to return boolean true/false vectors
- array indexing using vectors on vectors

Create a boolean mask called b with all elements of a greater than 2.octave:2> a=[1 2 3 4 1 2 3 4]

a =

1 2 3 4 1 2 3 4

Now use b to access only those elements of a that are true in the mask array b.octave:3> b=a > 2

b =

0 0 1 1 0 0 1 1

Why use Octave when we have python/numpy/scipy? Sometimes its just faster to fire up octave to get a look at data, and matlab/octave syntax is much less verbose than python.octave:4> a(b)

ans =

3 4 3 4