Re: How Do You Reduce Multiple Elements in a List?
- To: mathgroup at smc.vnet.net
- Subject: [mg33887] Re: How Do You Reduce Multiple Elements in a List?
- From: dennisw555 at aol.com (DennisW555)
- Date: Sun, 21 Apr 2002 06:14:24 -0400 (EDT)
- References: <a9r3ve$ltc$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
>Given a list of integers that generally contains the same number many times,
>I'd like to reduce it to a list that just gives me the number/count pairs.
>For example, I'd like to convert the list
> {1, 1, 1, 1, 1, 2, 2, 2, 4, 4, 4, 4, 4, 4}
>into
> {{1,5}, {2,3}, (4,6}}
Try
Map[{First#],Length[#]}&,Split[list]]
If you want all the numbers on ascending order use
Map[{First#],Length[#]}&,Split[Sort[list]]]
Dennis