numpy array question

[edmondo.giovannozzi at gmail.com]

Il giorno giovedì 2 aprile 2020 06:30:22 UTC+2, jagmit sandhu ha scritto:
> python newbie. I can't understand the following about numpy arrays:
> 
> x = np.array([[0, 1],[2,3],[4,5],[6,7]])
> x
> array([[0, 1],
>        [2, 3],
>        [4, 5],
>        [6, 7]])
> x.shape
> (4, 2)
> y = x[:,0]
> y
> array([0, 2, 4, 6])
> y.shape
> (4,)
> 
> Why is the shape for y reported as (4,) ? I expected it to be a (4,1) array.
> thanks in advance

Because is not Matlab where everything is at least a 2d array.
If you fix a dimension that dimension disappear. It is the same behaviour as that of Fortran.

Personally I think that the Python behaviour is more natural and obvious. As always it is a choice of who has written the library what will happen with a slice.