[Numpy-discussion] array not appending

Gael Varoquaux gael.varoquaux@normalesup....
Thu Dec 18 04:33:34 CST 2008


On Thu, Dec 18, 2008 at 03:52:23PM +0530, Prashant Saxena wrote:
>    In [43]: ST = np.empty([], dtype=np.float32)

>    In [44]: np.append(ST, 10.0)
>    Out[44]: array([  3.83333603e-38,   1.00000000e+01])

>    In [45]: np.append(ST, 10.0)
>    Out[45]: array([  3.83333603e-38,   1.00000000e+01])

>    In [46]: print ST
>    3.83333602707e-038

>    What's wrong here?

Nothing. If you look at the documentation, np.append does not modify
in place the array.:

'''
    Returns
    -------
    out : ndarray
        A copy of `arr` with `values` appended to `axis`.  Note that `append`
        does not occur in-place: a new array is allocated and filled.
'''

Modification in place is not possible with the numpy model of an array.

Gaël


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