How can I sort a list and also get a list of indices that sort this list? For example: primary list is a
a={1,4,6,7,0,2};
sorted list is b
b={7,6,4,2,1,0}
and also return list c
c={4,3,2,6,1,5}
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1 Answer
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To get list b, you need Sort[]: Sort[{1, 4, 6, 7, 0, 2}, GreaterEqual].
To get list c, you need Ordering[]: Ordering[{1, 4, 6, 7, 0, 2}, All, GreaterEqual].
answered Jun 24, 2012 at 11:57
J. M.'s missing motivation♦J. M.'s missing motivation
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$\begingroup$ @Heike: I guess there is such a thing as being in the right place at the right time... :) $\endgroup$ Commented Jun 24, 2012 at 12:00
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6$\begingroup$ Also, if you need both, you might first do
Orderingand thenb=a[[c]]$\endgroup$– RojoCommented Jun 24, 2012 at 14:00 -
$\begingroup$ @Rojo: that's a good point with respect to saving sorting effort. :) $\endgroup$ Commented Jun 24, 2012 at 14:04