On Wed, Feb 6, 2013 at 2:17 PM, Sebastian Berg wrote:

On Wed, 2013-02-06 at 13:08 -0500, josef.pktd@gmail.com wrote:

...

I'm convinced that I saw a while ago a function that uses a list of interval boundaries to index into an array, either to iterate or to take. I thought that's very useful, but didn't make a note.

Now, I have no idea where I saw this (I thought numpy), and I cannot find it anywhere.

any clues?

It does not quite sound like what you are looking for, but the only thing I can think of in numpy right now that does something in that direction is the ufunc.reduceat functionality:

In [1]: a = np.arange(10)

In [2]: a[2:5].sum(), a[5:9].sum(), a[9:].sum() Out[2]: (9, 26, 9)

In [3]: np.add.reduceat(a, [2, 5, 9]) Out[3]: array([ 9, 26, 9])

That's what I remembered seeing, but obviously I didn't remember it correctly. Not useful for my current case, but I will keep it in mind to clean up some other code. I will need a python loop after all to take a list of (unequal length) slices out of an array. Thank you, Josef

Regards,

Sebastian

...

Thanks,

Josef _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion

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On Wed, Feb 6, 2013 at 2:45 PM, Benjamin Root wrote:

On Wed, Feb 6, 2013 at 1:08 PM, wrote:

...

I'm convinced that I saw a while ago a function that uses a list of interval boundaries to index into an array, either to iterate or to take. I thought that's very useful, but didn't make a note.

Now, I have no idea where I saw this (I thought numpy), and I cannot find it anywhere.

any clues?

Some possibilities:

np.array_split() np.split()

perfect (haven't gotten further down the list yet)

...

...

np.split(np.arange(15), [3,4,6, 13]) [array([0, 1, 2]), array([3]), array([4, 5]), array([ 6, 7, 8, 9, 10, 11, 12]), array([13, 14])]

docstring says equal size, which fortunately is not correct http://docs.scipy.org/doc/numpy/reference/generated/numpy.split.html Thank you, Josef

np.ndindex() np.nditer() np.nested_iters() np.ravel_multi_index()

Your description reminded me of a function I came across once, but I can't remember if one of these was it or if it was another one.

IHTH, Ben Root

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