Array reductions

[mrocklin]

Add axis keyword to Reduction expression.

In [1]: from blaze import *

In [2]: x = Symbol('x', '5 * 3 * float32')

In [3]: x.sum().dshape
Out[3]: dshape("float32")

In [4]: x.sum(axis=0).dshape
Out[4]: dshape("3 * float32")

In [5]: x.sum(axis=1).dshape
Out[5]: dshape("5 * float32")

[mrocklin]

@mwiebe can I ask you to review this?

[mwiebe]

Taking a look

[mwiebe]

There's also the tuple of axes case, which would need a 3 dim array to test effectively. ``a.sum(axis=(0,2)) for example.

[mrocklin]

Fixed

[mwiebe]

Looks good to me.