[R] matrix indexing

[Dimitris Rizopoulos]

matA[matB] or matA[!matB]

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://www.med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: "tom wright" <tom at maladmin.com>
To: "R-Stat Help" <R-help at stat.math.ethz.ch>
Sent: Wednesday, March 15, 2006 12:03 PM
Subject: [R] matrix indexing


> Can someone please give me a pointer here.
> I have two matrices
>
> matA
> A B C
> 1 5 2 4
> 2 2 4 3
> 3 1 2 4
>
> matB
> A B C
> 1 TRUE FALSE TRUE
> 2 FALSE TRUE TRUE
> 3 FALSE FALSE FALSE
>
> how do I extract all the values from matA where the coresponding 
> entry
> in matB == TRUE (or FALSE), perferably in vector form.
>
> Many thanks
> tom
>
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