Re: Counting list elements above/below a given value
- To: mathgroup at smc.vnet.net
- Subject: [mg17268] Re: [mg17202] Counting list elements above/below a given value
- From: Clemens Frey <btml01 at uni-bayreuth.de>
- Date: Fri, 30 Apr 1999 02:34:48 -0400
- Sender: owner-wri-mathgroup at wolfram.com
Dear Bill,
since Count expects a pattern as a second argument (and not a criterion
like Select, e.g.) , try something like this:
lst = Table[Random[],{10000}];
Count[lst, x_ /; x>0.5]
Here a conditional pattern is used.
Hope this helped
Clemens
------------------------------------------------------------
Clemens Frey
Post-Graduate Student/Doctoral Candidate
Department of Mathematics/BITOEK
University of Bayreuth(Germany)
clemens.frey at uni-bayreuth.de
http://www.bitoek.uni-bayreuth.de/~Clemens.Frey
------------------------------------------------------------
On Mon, 26 Apr 1999, W.W. Sampson wrote:
> I wish to count the number of elements within a list above
> a given value. I can do this using the following:
>
> Length[Select[Flatten[listname], value > #1&]]
>
> However, my list is a 280 x 280 matrix and consequently
> this takes a while to evaluate. My guess is that there
> must be something more efficient. I've tried:
>
> Count[listname, value > #1&]
>
> but the output given is 0, which I know to be incorrect.
>
> Any ideas appreciated.
>
> Bill
>