[R] Vector comparison to matrix

[Dimitris Rizopoulos]

or maybe something like this:

nMatches2 <- sum(!is.na( match(apply(A, 1, paste, collapse = ""), 
paste(target, collapse = "")) ))


Best,
Dimitris

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

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


----- Original Message ----- 
From: "Sigurdur Jonsson" <sigurdur at hafro.is>
To: <tkredmund98 at hotmail.com>
Cc: <r-help at stat.math.ethz.ch>
Sent: Tuesday, August 16, 2005 12:47 PM
Subject: [R] Vector comparison to matrix


Hi Todd and list,

I see you have received a few suggestions, here's another:

# set up data: your vector and an a 3x300000 matrix with a few
# matching lines:

target<-c(1,2,3)
A<-matrix(sample(1:3,300000,replace=TRUE),ncol=3)

# count matches:

nMatches<-sum(apply(A,1,function(x,target)
  all.equal(x,target),target)=="TRUE")

# by applying a simple function, which takes 'target' as an 'extra'
# argument, to the rows of A. The function returns a vector of
# differences and 'TRUE'-s, the latter of which can be counted.

This took 1-2 minutes on my >3 year old laptop.

Siggi

> version
         _
platform i686-redhat-linux-gnu
arch     i686
os       linux-gnu
system   i686, linux-gnu
status
major    2
minor    0.0
year     2004
month    10
day      04
language R

Yeah, I know, an update is (over)due.

-- 
-----------------------------------------------------------------------------
Sigurður Þór Jónsson / Sigurdur Tor Jonsson
E-mail: <sigurdur at hafro.is>
Snail-mail: Marine Research Institute,
P.O. Box 1390,
121 Reykjavik,Iceland
Telephone (direct line): +354 5752093
Telephone (switchboard): +354 5752000
Fax: +354 5752001

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