[email protected] wrote: > On Mon, Aug 10, 2009 at 8:52 PM, Brennan > Williams<[email protected]> wrote: > >> Hi >> >> No doubt asked many times before so apologies.... >> >> I'm pulling a subset array out of a data array where I have a list of >> the indices I want (could be an array rather than a list actually - I >> have it in both). >> >> Potentially the number of points and the number of times I do this can >> get very large so any saving in time is good. >> >> So, paraphrasing what I've currently got.... say I have... >> >> subsetpointerlist=[0,1,2,5,8,15,25...] >> subsetsize=len(subsetpointerlist) >> subsetarray=zeros(subsetsize,dtype=float) >> for index,pos in enumerate(subsetpointerlist): >> subsetarray[index]=dataarray[pos] >> >> How do I speed this up in numpy, i.e. by removing the for loop? >> >> Do I set up some sort of a subsetpointerarray as a mask and then somehow >> apply that to dataarray to get the values into subsetarray? >> >> Thanks >> >> Brennan >> >> >> > > looks to me like > > subsetarray = dataarray[subsetpointerlist] > > or with type conversion > > subsetarray = dataarray[subsetpointerlist].astype(float) > > Josef > Thanks, with a little bit of googling/rtfm I'm getting there. Think I overdid my thinking on mask based on something else that Robert Kern helped me out with. > >> _______________________________________________ >> NumPy-Discussion mailing list >> [email protected] >> http://mail.scipy.org/mailman/listinfo/numpy-discussion >> >> > _______________________________________________ > NumPy-Discussion mailing list > [email protected] > http://mail.scipy.org/mailman/listinfo/numpy-discussion > >
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