Groups > comp.soft-sys.math.mathematica > #1729

Re: SortBy

From	Bob Hanlon <hanlonr@cox.net>
Newsgroups	comp.soft-sys.math.mathematica
Subject	Re: SortBy
Date	2011-04-16 11:39 +0000
Organization	Steven M. Christensen and Associates, Inc and MathTensor, Inc.
Message-ID	<iobv52$bh8$1@smc.vnet.net> (permalink)

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KS = {{300, 48, 2}, {500, 23, 5}, {120, 55, 7}, {40, 32, 1}};

As shown on the Help page

SortBy[KS, Last]

{{40, 32, 1}, {300, 48, 2}, {500, 23, 5}, {120, 55, 7}}

or

SortBy[KS, #[[-1]] &]

{{40, 32, 1}, {300, 48, 2}, {500, 23, 5}, {120, 55, 7}}


Bob Hanlon

---- graser <graser@gmail.com> wrote: 

=============
Dear Mathematica group,

I have a simple question for you.

Let's say there is a list like

KS = {{300, 48, 2}, {500, 23, 5}, {120, 55, 7}, {40, 32, 1}};

I want to sort it by second element.

I can use

Sort[KS, #2[[2]] > #1[[2]] &]

It gives out like

{{500, 23, 5}, {40, 32, 1}, {300, 48, 2}, {120, 55, 7}}

But if I want to use SortBy, how to do that?

SortBy[KS, ??]

Thanks!

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Re: SortBy Bob Hanlon <hanlonr@cox.net> - 2011-04-16 11:39 +0000

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