Re: Help! Delete Casses based on column
- To: mathgroup at smc.vnet.net
- Subject: [mg58345] Re: Help! Delete Casses based on column
- From: Rolf Mertig <rolf at mertig.com>
- Date: Tue, 28 Jun 2005 21:56:43 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
>I need to take a large numeric matrix and remove all the rows that have a
>value less than X in column N
Mathematica 5.1 for Linux x86 (64 bit)
Copyright 1988-2004 Wolfram Research, Inc.
-- Motif graphics initialized --
In[1]:= !!f.m
f[m_?MatrixQ, n_Integer, threshold_?NumberQ] := Select[m, #1[[n]] > threshold
& ];
test = Table[Random[],{5000},{5000}];
Print[Timing[r=f[test, 1234, .2];]] ;
Print[Length[r]];
In[1]:= <<f.m
{0.32995 Second, Null}
3981
---
Greetings,
Rolf Mertig