[R] How to handle Which on two matrices that do not have samenumber of rows

[Yinghai Deng]

How about this?

PC[na.omit(match(P1[,1],PC[,1])),]

HTH,

DYH

-----Original Message-----
From: r-help-bounces at r-project.org
[mailto:r-help-bounces at r-project.org]On Behalf Of My Coyne
Sent: February 13, 2008 2:07 PM
To: r-help at stat.math.ethz.ch
Subject: [R] How to handle Which on two matrices that do not have
samenumber of rows


R-newbie question



I have 2 matrices

(a)   P1 has only one column of 32K rows

(b)   PC  has 2 column {P, C} of 3200 rows



Every values in P1 matches with a value in PC[,p] (column p).  I would like
to use Which to search for all value in P1 that matchex PC[,p] and get the
PC[,c].  However because P1 and PC does not have the same number of rows, I
got lots of 'NA'.  Thanks for your help.



Example..



P1 <- {'p001', 'p001', 'p002', 'p010'..}

PC <- { c('p001','class a'), c('p002', 'class b'),.. , c('p010', 'class
10')}



Result <- {c('p001', 'class a'), c('p001', 'class a'), c ('p002', 'class
b'), c('p010', 'class 10')...}





My D. Coyne








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