Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: sorting?
Replies: 3   Last Post: Jan 28, 2013 2:23 AM

 Messages: [ Previous | Next ]
 Bob Hanlon Posts: 906 Registered: 10/29/11
Re: sorting?
Posted: Jan 26, 2013 4:58 PM

lalista = {{0, 5}, {8, 8}, {2, 2}, {3, 5}, {1, 3}, {3, 9}};

SortBy[lalista, (Divide @@ #) + 10^-6*#[[2]] &] // Reverse

{{8, 8}, {2, 2}, {3, 5}, {3, 9}, {1, 3}, {0, 5}}

Bob Hanlon

On Sat, Jan 26, 2013 at 1:39 AM, Francisco Gutierrez
<fgutiers2002@yahoo.com> wrote:
>
> Friends:
> 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).
>