Hi,
I have the following datasets:
x=data I am looking through
key=a set of data with the codes I want
I have the following issue:
I want the subset of x which has a code contained in the key dataset. That is,
if x[i] is contained in the key dataset, I want to keep it. Note that x may
contain multiple of the same codes (or obviously none of that code as well)
I currently use two for-loops thusly in my R-code:
k=1
y=data.frame(1,stringsAsFactors=FALSE)
for(i in 1:length(x)){
for(j in 1:length(key)){
if(x[i]==key[j]){
y[k]=x[i]
k=k+1;
}
}
}
However, my dataset (x in this example) is pretty large, so I want to avoid
using two for-loops. Does anybody know an easier way to approach this?
Thanks
Hi Akshaka, Take a look at ?"%in%". Here is an example for the help:> x<-1:10 > key<-c(1,3,5,9) > x %in% key[1] TRUE FALSE TRUE FALSE TRUE FALSE FALSE FALSE TRUE FALSE> x[ x %in% key ][1] 1 3 5 9 HTH, Jorge On Sun, Jan 25, 2009 at 10:27 PM, Akshaya Jha <akshayaj@andrew.cmu.edu>wrote:> Hi, > > I have the following datasets: > x=data I am looking through > key=a set of data with the codes I want > > I have the following issue: > I want the subset of x which has a code contained in the key dataset. That > is, if x[i] is contained in the key dataset, I want to keep it. Note that x > may contain multiple of the same codes (or obviously none of that code as > well) > > I currently use two for-loops thusly in my R-code: > > k=1 > y=data.frame(1,stringsAsFactors=FALSE) > for(i in 1:length(x)){ > for(j in 1:length(key)){ > > if(x[i]==key[j]){ > y[k]=x[i] > k=k+1; > } > > } > } > > However, my dataset (x in this example) is pretty large, so I want to avoid > using two for-loops. Does anybody know an easier way to approach this? > > Thanks > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >[[alternative HTML version deleted]]
Hi: if i understand, i think newx<-x[ x %in% key] should give you what you want. On Sun, Jan 25, 2009 at 10:27 PM, Akshaya Jha wrote:> Hi, > > I have the following datasets: > x=data I am looking through > key=a set of data with the codes I want > > I have the following issue: > I want the subset of x which has a code contained in the key dataset. > That is, if x[i] is contained in the key dataset, I want to keep it. > Note that x may contain multiple of the same codes (or obviously none > of that code as well) > > I currently use two for-loops thusly in my R-code: > > k=1 > y=data.frame(1,stringsAsFactors=FALSE) > for(i in 1:length(x)){ > for(j in 1:length(key)){ > > if(x[i]==key[j]){ > y[k]=x[i] > k=k+1; > } > > } > } > However, my dataset (x in this example) is pretty large, so I > want to avoid using two for-loops. Does anybody know an easier way to > approach this? > > Thanks > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code.