Re: sorting?

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• Subject: [mg129593] Re: sorting?
• From: awnl <awnl at gmx-topmail.de>
• Date: Sat, 26 Jan 2013 16:59:46 -0500 (EST)
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• References: <kdvtkk\$fp2\$1@smc.vnet.net>

```Hi,

> I have a large list of simple numerical lists, and I want to sort it
> using two criteria. in the simplest case, suppose the sublists are of
> length two, and that my first criterion is the quotient of part one
> by part two, and my second criterion is the size of part two (no
> zeros in part 2.  I want to sort using the first criterion, and then
> break the ties using the second one. So for example if I had
> lalista={{0,5},{8,8},{2,2},{3,5},{1,3},{3,9}}, the sorting should
> return
>
> {{8,8},{2,2},{3,5},{3,9},{1,3},{0,5}}
>
> Of course this can be done, but I wonder if it is a way to make this
> only with native Mathematica tools (wich is always far more
> efficient).
>

I think you are looking for SortBy, which can be given a list of pure
functions to define the sorting, e.g. like this (the minus signs reverse
the sorting so I get what you want, it might need adoption depending on
what you really want...):

SortBy[lalista, {-#[[1]]/#[[2]] &, -#[[2]] &}]

hth,

albert

```

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