[R] a function more appropriate than 'sapply'?

[arun]

Hi,
May be this helps:
 wells<-read.table("wells.txt",header=FALSE,stringsAsFactors=F)


 wells2<-wells[-grep(".*\\_.*\\_",wells[,1]),]
  head(wells2)
  #   V1 V2
#1  w7_1  0
#2 w11_1  0
#3 w12_1  0
#4 w13_1  0
#5 w14_1  0
#6 w15_1  0



wellsNew<-wells[grep(".*\\_.*\\_",wells[,1]),]
 head(wellsNew)
#            V1 V2
#851 99_10_4395  0
#852 99_10_4396  0
#853 99_10_4400  0
#854 99_10_4403  0
#855 99_10_4404  0
#856 99_10_4606  0
 nrow(wells)
#[1] 46366
nrow(wells2)
#[1] 38080
 nrow(wellsNew)
#[1] 8286
 38080+8286
#[1] 46366
A.K.



----- Original Message -----
From: emorway <emorway at usgs.gov>
To: r-help at r-project.org
Cc: 
Sent: Saturday, January 26, 2013 1:43 PM
Subject: [R] a function more appropriate than 'sapply'?

I'm wondering if I need to use a function other than sapply as the following
line of code runs indefinitely (or > 30 min so far) and uses up all 16Gb of
memory on my machine for what seems like a very small dataset (data attached
in a txt file  wells.txt
<http://r.789695.n4.nabble.com/file/n4656723/wells.txt>  ).  The R code is:

wells<-read.table("c:/temp/wells.txt",col.names=c("name","plc_hldr"))
wells2<-wells[sapply(wells[,1],function(x)length(strsplit(as.character(x),
"_")[[1]])==2),]

The 2nd line of R code above gets bogged down and takes all my RAM with it:
<http://r.789695.n4.nabble.com/file/n4656723/memory_loss.png> 

I'm simply trying to extract all of the lines of data that have a single "_"
in the first column and place them into a dataset called "wells2".  If that
were to work, I then want to extract the lines of data that have two "_" and
put them into a separate dataset, say "wells3".  Is there a better way to do
this than the one-liner above?

-Eric



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