[Matrix-SIG] binarysearch? & Little more on combine 1D arrays into 2D arrays?

[David Ascher]

On Thu, 8 Oct 1998, Yoon, Hoon (CICG - NY Program Trading) wrote:
>    Just wanted to see I can extend this ? a bit more.
> Let's say I wanted to see 
>   a | d
> 
> Is there a simpler way? (This isn't too bad, but I would like to skip
> a.shape = () step).
> 
> a.shape = (1,3)
> concatenate((a,d),0)
> array([[0, 1, 2],
>        [0, 1, 2],
>        [3, 4, 5]]) 

The trick is to remember to use NewAxis:

>>> a
array([0, 1, 2])
>>> d
array([[0, 1, 2],
       [3, 4, 5]])
>>> concatenate((a[NewAxis,:], d))
array([[0, 1, 2],
       [0, 1, 2],
       [3, 4, 5]])

Whenever you find yourself doing a reshape w/ a 1 somewhere, chances are
you can get away with a NewAxis operation instead, which is quicker and
simpler to read (IMO).

--david