[Numpy-discussion] Slow conversion from list to arrays

Todd Miller jmiller at stsci.edu
Tue Dec 30 06:36:03 CST 2003


On Thu, 2003-12-25 at 03:27, Nadav Horesh wrote: 
> The conversion for a list of large arrays into a matrix is very slow in
> numarray while reasonably fast:
> 
> >>> from numarray import *
> >>> a = [arange(200000), arange(200000), arange(200000), arange(200000)]
> >>> aa = array(a)   # Very slow
> 
> --------------------------------
> 
> >>> from Numeric import *
> >>> a = [arange(200000), arange(200000), arange(200000), arange(200000)]
> >>> aa = array(a)   # Fast
> 
> Python version:    2.3.3
> numarray version:  Official 0.8
> 
> Tested under WinXP and RH9 linux.
> 
> Any workaround?
> 
Try concatenate.  For the array sizes you're looking at,  numarray does
OK.  You may have to adjust the result shape.

Todd 

>   Nadav
> 
> 
> 
> 
> 
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Todd Miller 			
Space Telescope Science Institute
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