[SciPy-User] numpy array assignment

[Antonino Ingargiola]

On Thu, Apr 17, 2014 at 7:59 AM, marco cammarata <marcocamma at gmail.com>wrote:

> For the moment I ended up doing something really really inelegant:
>   res = result_of_long_calculation_returning_the_right_shape()
>   s = "out[" + (":,")*axis + "i" + (",:")*(nDim-axis-1) + "]=res"
>   exec(s)
>

When you do a[:, :, :], that's just syntactic sugar for a[(slice(None),
slice(None), slice(None),)] (note that slice(None) means take all
elements). In other words, the index of a ndarray is a tuple of
objects/slices.

You can build the tuple programmatically. Another example:

    import numpy as np
    a = np.arange(1000).reshape(10, 5, 20)
    index = (slice(None), slice(0, 1), slice(None))
    a[index] = 3
    a

Cheers,
Antonio
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