RE: Counting list elements above/below a given value
- To: mathgroup at smc.vnet.net
- Subject: [mg17242] RE: [mg17202] Counting list elements above/below a given value
- From: "Jean-Marie THOMAS" <jmthomas at agat.net>
- Date: Fri, 30 Apr 1999 02:34:35 -0400
- Sender: owner-wri-mathgroup at wolfram.com
Try this: if mat=Table[Random[],{280},{280}]; then evaluating Timing at Count[Flatten@mat,_?(#>0.5&)] I get the following result: (Pentium 150 Mhz) {10.91 Second,39224} which sounds quite reasonable to me. **************************************** Jean-Marie THOMAS mailto:jmthomas at agat.net Conseil et Audit en Ingenierie de Calcul Strasbourg, France http://www.agat.net **************************************** -----Original Message----- From: W.W. Sampson [mailto:w.sampson at umist.ac.uk] To: mathgroup at smc.vnet.net Subject: [mg17242] [mg17202] Counting list elements above/below a given value 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