[SciPy-User] [scipy-user] How to add a 1D np.array to another np.array?

Warren Weckesser warren.weckesser at enthought.com
Wed Feb 1 11:35:25 EST 2012


On Wed, Feb 1, 2012 at 10:21 AM, Fabien Lafont <lafont.fabien at gmail.com>wrote:

> Hello everyone,
>
> I try to add an array to another (to build a 2D array).
>
> I try that
>
>
>
> a = np.zeros(2)
> b=np.array([2,4])
> a[[0]] = b
>
> print a
> [2,0]
>
> And I want a= [[2,4],0]
>
>
But that is not a 2D array.  Do you want to "stack" b above the zeros?
Perhaps something like this:

In [7]: a = np.zeros(2)

In [8]: b = np.array([2,4])

In [9]: c = np.vstack((b,a))

In [10]: c
Out[10]:
array([[ 2.,  4.],
       [ 0.,  0.]])


Warren
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