[Numpy-discussion] discussion about array.resize() -- compare to numarray
Russell E Owen
rowen at cesmail.net
Fri Jan 5 16:53:52 EST 2007
In article
<bc657ead0701041629i4f9e2fddg26efac5256bde3cb at mail.gmail.com>,
"Sebastian Haase" <seb.haase at gmx.net> wrote:
> On 1/4/07, Sebastian Haase <haase at msg.ucsf.edu> wrote:
> <snip>
> > >>> N.__version__
> > '1.0.2.dev3487'
> >
> > in any case: inside the script it somehow generated a nan --- is
> > there a bug in numpy !?
>
> No bug here ! see below !
>
> > I remember that there was some discussion about resize !?
> > What should I add to the Scipy Wiki numarray page about this ?
> > ( http://www.scipy.org/Converting_from_numarray )
> >
>
> OK - the reference problem in my interactive shell came from the
> implicit '_' variable that always references the last result. But
> maybe even more worry some for the converting from numarray is this:
> >>> a = N.array([5])
> >>> 999 # to kill '_' - reference
> 999
> >>> a.resize(2)
> >>> a
> [5 0]
>
> in numarray you would get
> >>> a = na.array([5])
> >>> a.resize(2)
> [5 5]
> >>> a
> [5 5]
>
> !! why is numpy filling with 0s and numarray repeats (cycles I think
> is more what it does !) the last element(s) ??
>
> How did numeric do this ?
Here's what I get for Numeric 24.2:
>>> import Numeric as N
>>> a = N.array([5])
>>> a
array([5])
>>> a.resize(2)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: cannot resize an array that has been referenced or is
referencing
another array in this way. Use the resize function.
>>> N.resize(a, 2)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File
"/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-pac
kages/Numeric/Numeric.py", line 422, in resize
total_size = multiply.reduce(new_shape)
ValueError: dimension not in array
>>> N.resize(a, [2])
array([5, 5])
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