[Numpy-discussion] Binning

[josef.pktd at gmail.com]

On Thu, Dec 22, 2011 at 6:27 AM, Adrien Gaidon <adnothing at gmail.com> wrote:
> Hello Nicola,
>
> I am not aware of a magical "one function" numpy solution (is there one
> numpy gurus?).
>
> I don't know if it's optimal, but here's how I usually do similar things.
>
> I wrote a simple function that assigns points (any number of dimensions) to
> a regular multi-dimensional grid. It is
> here: https://gist.github.com/1509853 It is short, commented and should be
> straightforward to use.
>
> Once you have the assignments, you can:
> - get the non-empty cell indexes with `np.unique(assignments)`
> - retrieve the points assigned to a cell with `points[assignments ==
> cell_index]`
> - iterate over assignments to select the points you want for each cell.

looks nice, reading through it.
line 71 looks like a nice trick

BSD licensed, so we can keep it?

as far as I know numpy doesn't have anything like a digitize_nd

Thanks,

Josef

>
> Hope this helps,
>
> Adrien
>
> PS: This is one of the first times I post an answer on this list, so if I
> did anything wrong, let me know. Numpy is such a wonderful thing and you
> guys do such an amazing work, that I though it is time to give back at least
> epsilon of what I got from you :-)
>
>
> 2011/12/22 Nicola Creati <ncreati at inogs.it>
>>
>> Hello,
>>
>> I have a cloud on sparse points that can be described by a Nx3 array (N
>> is the number of points). Each point is defined by an x, y and z
>> coordinate:
>>
>> x0 y0 z0
>> x1 y1 z1
>>   .    .    .
>>   .    .    .
>>   .    .    .
>> xn yn zn
>>
>>
>> I need to bin the cloud to a regular 2D array according to a desired bin
>> size assigning to each cell (bin) the minimum z of all points that fall
>> in that cell(bin). Moreover I need indexes of points that fall in each
>> cell(bin).
>>
>> Is there any way to accomplish this task in numpy?
>>
>> Thanks.
>>
>> Nicola Creati
>>
>>
>>
>>
>> --
>> Nicola Creati
>> Istituto Nazionale di Oceanografia e di Geofisica Sperimentale - OGS
>> www.inogs.it Dipartimento di Geofisica della Litosfera Geophysics of
>> Lithosphere Department CARS (Cartography and Remote Sensing) Research Group
>> http://www.inogs.it/Cars/ Borgo Grotta Gigante 42/c 34010 Sgonico - Trieste
>> - ITALY ncreati at ogs.trieste.it
>> off.   +39 040 2140 213
>> fax.   +39 040 327307
>>
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