[Numpy-discussion] tostring() for array rows

josef.pktd@gmai... josef.pktd@gmai...
Tue Oct 6 15:47:50 CDT 2009


On Tue, Oct 6, 2009 at 4:39 PM, Christopher Barker
<Chris.Barker@noaa.gov> wrote:
> josef.pktd@gmail.com wrote:
>> If I have a structured or a regular array, is the use of strides in
>> the following always correct for the length of the row memory?
>>
>> I would like to do tostring() but on each row, by creating a string
>> view of the memory in a 1d array.
>
> Maybe I'm missing what you want, but why not just:
>
> In [15]: tmp
> Out[15]:
> array([[ 1.07810097, -1.74157351,  0.29740878],
>        [-0.16786436,  0.45752272, -0.8038045 ],
>        [-0.17195028, -1.16753882,  0.04329128],
>        [ 0.45460137, -0.44584955, -0.77140505]])
>
> In [16]: rows = []
>
> In [17]: for r in range(tmp.shape[0]):
>              rows.append(tmp[r,:].tostring())
>    ....:
>
> In [19]: rows
> Out[19]:
> ['?\xf1?\xe6\xce\x1f9\xce\xbf\xfb\xdd|.\xc85Z?\xd3\x08\xbe\xd6\xb7\xb6\xe8',
>  '\xbf\xc5|\x94Sx\x92\x18?\xddH\r\\T\xfbT\xbf\xe9\xb8\xc45\xff\x92\xdf',
>  '\xbf\xc6\x02w\x82\x18i\xaf\xbf\xf2\xae=/\xfe\xff\x0b?\xa6*FD\xae\xd1F',
>
> '?\xdd\x180Z\xcet\xa5\xbf\xdc\x88\xcc\x8a\x8c\x8b\xe7\xbf\xe8\xafY\xa2\xf8\xac
> ']
>
>
> in general, you can let numpy worry about the strides, etc.

I wanted to avoid the python loop and thought creating the view will be faster
with large arrays. But for this I need to know the memory length of a
row of arbitrary types for the conversion to strings, strides was the only
thing I could think of.

>
> -Chris
>
> --
> Christopher Barker, Ph.D.
> Oceanographer
>
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