[Numpy-discussion] Combining arrays together
Stefan van der Walt
stefan at sun.ac.za
Mon Jul 3 06:48:04 CDT 2006
On Mon, Jul 03, 2006 at 11:16:26AM +0900, Bill Baxter wrote:
> What's the best way to combine say several 2-d arrays together into a grid?
> Here's the best I can see:
>
> >>> a = eye(2,2)
> >>> b = 2*a
> >>> c = 3*a
> >>> d = 4*a
> >>> r_[c_[a,b],c_[c,d]]
> array([[1, 0, 2, 0],
> [0, 1, 0, 2],
> [3, 0, 4, 0],
> [0, 3, 0, 4]])
>
> In matlab you'd get the same effect by saying: [ a, b; c, d ]
>
> Compared to that, r_[c_[a,b],c_[c,d]] looks quite a mess.
You could always explicitly write out what you are doing, i.e.
In [47]: N.vstack((N.hstack((a,b)), N.hstack((c,d))))
Out[47]:
array([[ 1., 0., 2., 0.],
[ 0., 1., 0., 2.],
[ 3., 0., 4., 0.],
[ 0., 3., 0., 4.]])
Stéfan
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