Matrix Element Extraction

*To*: mathgroup at smc.vnet.net*Subject*: [mg46622] Matrix Element Extraction*From*: "Curt Fischer" <crf3 at po.cwru.edu>*Date*: Wed, 25 Feb 2004 13:07:14 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

In a matrix, I want to find the positions of all the integer elements in the rightmost column or the bottom row. In[1]:= mat={{1,2,1},{4,5,6},{7,8,-Infinity}} Out[1]= {{1,2,1},{4,5,6},{7,8,-Infinity}} In[2]:= Position[Map[((MemberQ[Union[Flatten[{mat[[Length[mat]]], mat[[All,Dimensions[mat][[ 2]] ]]}]],#])&&(#!=-Infinity))&,mat,{2}],True] Out[2]= {{1,1},{1,3},{2,3},{3,1},{3,2}} This _mostly_ does what I want, but took me forever to think of. I'm convinced there must be an easier way... Especially, is there an easy way to keep the point {1,1} from appearing on this list, other than using a replacement rule and an If[] command? ({1,1} is not a position in the bottom row or right most column, so I don't want this point returned.) Thanks for any advice. -- Curt Fischer

**Follow-Ups**:**Re: Matrix Element Extraction***From:*Tomas Garza <tgarza01@prodigy.net.mx>

**Re: Matrix Element Extraction***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>