Function to resize global numpy array interactively in ipython

David Sanders dpsanders at gmail.com
Mon Oct 29 07:53:34 CET 2007


Hi,

I have a script with function definitions which I load into ipython
for interactive use.
These functions modify a global numpy array, whose size I need to be
able to change interactively.  I thus have a script which looks like
this:

from numpy import *

def do_resize(N):
	global a
	a = resize(a, N)

a = array([])

N=10; do_resize(N)
print "Length of a is: ", len(a)
N=20; do_resize(N)
print "Length of a is: ", len(a)


If I run this in ipython, using "run resize.py", it correctly outputs
10 and then 20.
If I now type *interactively*  N=30; do_resize(N),  then the length of
a is still 20, rather than 30 as I was hoping -- somehow I seem to be
now dealing with a different copy of a?

Doing the same thing in idle works as I expect, i.e. interactively the
size is changed to 30.

Could somebody please explain what's going on, and how I solve the
problem?

Thanks and best wishes,
David.




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