[Numpy-discussion] ticket 1562 on loadtxt (was Re: Numpy 2.0 schedule)

Bruce Southey bsouthey@gmail....
Mon Feb 28 11:45:26 CST 2011


On 02/28/2011 09:47 AM, Benjamin Root wrote:
> On Mon, Feb 28, 2011 at 9:25 AM, Bruce Southey <bsouthey@gmail.com 
> <mailto:bsouthey@gmail.com>> wrote:
>
>     On 02/28/2011 09:02 AM, Benjamin Root wrote:
>     [snip]
>     >
>     >
>     > So, is there still no hope in addressing this old bug report of
>     mine?
>     >
>     > http://projects.scipy.org/numpy/ticket/1562
>     >
>     > Ben Root
>     >
>     I think you need to add more details to this. So do you have an
>     example
>     of the problem that includes code and expected output?
>
>     Perhaps genfromtxt is probably more appropriate than loadtxt for what
>     you want:
>
>     from StringIO import StringIO
>     import numpy as np
>     t = StringIO("1,1.3,abcde\n2,2.3,wxyz\n1\n3,3.3,mnop")
>     data = np.genfromtxt(t,
>     [('myint','i8'),('myfloat','f8'),('mystring','S5')], names =
>     ['myint','myfloat','mystring'], delimiter=",", invalid_raise=False)
>     print 'Bad data raise\n',data
>
>     This gives the output that skips the incomplete 3rd line:
>
>     /usr/lib64/python2.7/site-packages/numpy/lib/npyio.py:1507:
>     ConversionWarning: Some errors were detected !
>         Line #3 (got 1 columns instead of 3)
>       warnings.warn(errmsg, ConversionWarning)
>     Bad data raise
>     [(1, 1.3, 'abcde') (2, 2.3, 'wxyz') (3, 3.3, 'mnop')]
>
>
>     Bruce
>
>
> Bruce,
>
> I think you mis-understood the problem I was reporting.
Probably - which is why I asked for more details.
> You can find the discussion thread here:
>
> http://www.mail-archive.com/numpy-discussion@scipy.org/msg26235.html
>
> I have proposed that at the very least, an example of this problem is 
> added to the documentation of loadtxt so that users know to be aware 
> of this possibility.
I did not connect the ticket to that email thread. Removing the 
structured array part of your email, I think essentially the argument is 
which should be the output of:
np.loadtxt(StringIO("89.23"))
np.arange(5)[1]

These return an 0-d array and an rather old argument about that (which 
may address the other part of the ticket). Really I see this behavior as 
standard so you add an example to the documentation to reflect that.


> In addition, loadtxt fails on empty files even when provided with a 
> dtype.  I believe genfromtxt also fails as well in this case.
>
> Ben Root
>
Errors on empty files probably should be a new bug report as that was 
not in the ticket.

Bruce
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