[Numpy-discussion] loadtxt issues

A B python6009@gmail....
Wed Feb 11 23:04:13 CST 2009


On Wed, Feb 11, 2009 at 6:27 PM, A B <python6009@gmail.com> wrote:
> On Tue, Feb 10, 2009 at 9:52 PM, Brent Pedersen <bpederse@gmail.com> wrote:
>> On Tue, Feb 10, 2009 at 9:40 PM, A B <python6009@gmail.com> wrote:
>>> Hi,
>>>
>>> How do I write a loadtxt command to read in the following file and
>>> store each data point as the appropriate data type:
>>>
>>> 12|h|34.5|44.5
>>> 14552|bbb|34.5|42.5
>>>
>>> Do the strings have to be read in separately from the numbers?
>>>
>>> Why would anyone use 'S10' instead of 'string'?
>>>
>>> dt = {'names': ('gender','age','weight','bal'), 'formats': ('i4',
>>> 'S4','f4', 'f4')}
>>>
>>> a = loadtxt("sample_data.txt", dtype=dt)
>>>
>>> gives
>>>
>>> ValueError: need more than 1 value to unpack
>>>
>>> I can do a = loadtxt("sample_data.txt", dtype="string") but can't use
>>> 'string' instead of S4 and all my data is read into strings.
>>>
>>> Seems like all the examples on-line use either numeric or textual
>>> input, but not both.
>>>
>>> Thanks.
>>> _______________________________________________
>>> Numpy-discussion mailing list
>>> Numpy-discussion@scipy.org
>>> http://projects.scipy.org/mailman/listinfo/numpy-discussion
>>>
>>
>> works for me but not sure i understand the problem, did you try
>> setting the delimiter?
>>
>>
>> import numpy as np
>> from cStringIO import StringIO
>>
>> txt = StringIO("""\
>> 12|h|34.5|44.5
>> 14552|bbb|34.5|42.5""")
>>
>> dt = {'names': ('gender','age','weight','bal'), 'formats': ('i4',
>> 'S4','f4', 'f4')}
>> a = np.loadtxt(txt, dtype=dt, delimiter="|")
>> print a.dtype
>
> I had tried both with and without the delimiter. In any event, it just
> worked for me as well. Not sure what I was missing before. Anyway,
> thank you.
>

Actually, I was using two different machines and it appears that the
version of numpy available on Ubuntu is seriously out of date (1.0.4).
Wonder why ...
Version 1.2.1 on a RedHat box worked fine.


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