[Numpy-discussion] genfromtxt converter question

Olivier Delalleau shish@keba...
Fri Jun 17 05:40:51 CDT 2011


If I understand correctly, your error is that you convert only the second
column, because your converters dictionary contains a single key (1).
If you have it contain keys from 0 to 3 associated to the same function, it
should work.

-=- Olivier

2011/6/17 gary ruben <gruben@bigpond.net.au>

> I'm trying to read a file containing data formatted as in the
> following example using genfromtxt and I'm doing something wrong. It
> almost works. Can someone point out my error, or suggest a simpler
> solution to the ugly converter function? I thought I'd leave in the
> commented-out line for future reference, which I thought was a neat
> way to get genfromtxt to show what it is trying to pass to the
> converter.
>
> import numpy as np
> from StringIO import StringIO
>
> a = StringIO('''\
>  (-3.9700,-5.0400) (-1.1318,-2.5693) (-4.6027,-0.1426) (-1.4249, 1.7330)
>  (-5.4797, 0.0000) ( 1.8585,-1.5502) ( 4.4145,-0.7638) (-0.4805,-1.1976)
>  ( 0.0000, 0.0000) ( 6.2673, 0.0000) (-0.4504,-0.0290) (-1.3467, 1.6579)
>  ( 0.0000, 0.0000) ( 0.0000, 0.0000) (-3.5000, 0.0000) ( 2.5619,-3.3708)
> ''')
>
> #~ b = np.genfromtxt(a,converters={1:lambda
> x:str(x)},dtype=object,delimiter=18)
> b = np.genfromtxt(a,converters={1:lambda
> x:complex(*eval(x))},dtype=None,delimiter=18,usecols=range(4))
>
> print b
>
> --
>
> This produces
> [ (' (-3.9700,-5.0400)', (-1.1318-2.5693j), ' (-4.6027,-0.1426)', '
> (-1.4249, 1.7330)')
>  (' (-5.4797, 0.0000)', (1.8585-1.5502j), ' ( 4.4145,-0.7638)', '
> (-0.4805,-1.1976)')
>  (' ( 0.0000, 0.0000)', (6.2673+0j), ' (-0.4504,-0.0290)', ' (-1.3467,
> 1.6579)')
>  (' ( 0.0000, 0.0000)', 0j, ' (-3.5000, 0.0000)', ' ( 2.5619,-3.3708)')]
>
> which I just need to unpack into a 4x4 array, but I get an error if I
> try to apply a different view.
>
> thanks,
> Gary
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