53 lines
1.7 KiB
Plaintext
53 lines
1.7 KiB
Plaintext
From: joe at strout.net (Joe Strout)
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Date: Sat, 10 Apr 1999 10:59:09 -0700
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Subject: Idiom for Getting Slices of a List
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References: <Pine.SUN.3.95-heb-2.07.990410102503.23259A-100000@sunset.ma.huji.ac.il>
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Message-ID: <joe-100419991059096127@chinacat.salk.edu>
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Content-Length: 1363
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X-UID: 103
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[[ This message was both posted and mailed: see
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the "To," "Cc," and "Newsgroups" headers for details. ]]
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In article
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<Pine.SUN.3.95-heb-2.07.990410102503.23259A-100000 at sunset.ma.huji.ac.il>,
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Moshe Zadka <moshez at math.huji.ac.il> wrote:
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> I want a clean, and relatively efficient method to do the following:
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> I have an array of length, n*m and I want to make it an array of
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> length m, where each member is an array of length n.
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>
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> Example: n=2, m=3
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> [0, 1, 2, 3, 4, 5] ==> [[0, 1], [2, 3], [4, 5]]
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Well, if you want efficient and clean you should use Numeric...
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>>> import Numeric
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>>> a = Numeric.array( [0, 1, 2, 3, 4, 5] )
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>>> a
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array([0, 1, 2, 3, 4, 5])
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>>> a.shape = (3,2)
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>>> a
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array([[0, 1],
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[2, 3],
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[4, 5]])
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That last item is equivalent to the nested list-of-lists you asked for.
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(Note: to be picky, it's not an array unless you make it an array using
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either the array module or the Numeric module. What you illustrated
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looked like a list of lists.)
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Cheers,
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-- Joe
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--
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,------------------------------------------------------------------.
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| Joseph J. Strout Biocomputing -- The Salk Institute |
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| joe at strout.net http://www.strout.net |
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`------------------------------------------------------------------'
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Check out the Mac Web Directory! http://www.strout.net/macweb.cgi
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