On Wed, Feb 29, 2012 at 8:07 PM, Xah Lee <xah...@gmail.com> wrote: > fun example. > > in-place algorithm for reversing a list in Perl, Python, Lisp > http://xahlee.org/comp/in-place_algorithm.html > > plain text follows > ---------------------------------------- > > What's “In-place Algorithm”? > > Xah Lee, 2012-02-29 > > This page tells you what's “In-place algorithm”, using {python, perl, > emacs lisp} code to illustrate. > > Aren't in-place reversals rather non-functional?
> Python > The usual way is list_a.reverse(). This is in place. If you want to be a little weird, you could do this, but it's not in place: list_a = list_a[::-1] If you want to pretend you can't do this the easy ways above, you could do this, which is in place: length = len(list_a) for ind in xrange(length // 2): other=-ind-1 list_a[ind], list_a[other] = list_a[other], list_a[ind] HTH
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