Hi
I want to extract columns from a data frame using a vector with the desired
column names.
This short example uses the select argument in the subset function to
accomplish what I am trying to do. Is there a better solution?
#names of desired columns
colnames <- c("col1","col3")
#my data
data <-
data.frame("col1"=c(1,2,3),"col2"=c("A","B","C"),"col3"=c(4,5,6))
fun <- function(colname,dframe){
nframe <- subset(dframe,select=colname)
vec <- nframe[,1]
return(vec)
}
fun(colnames[1],data)
fun(colnames[2],data)
[[alternative HTML version deleted]]
How about
data[,colnames(data)%in%colnames]
-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Jonathan Flowers
Sent: Friday, July 09, 2010 11:27 AM
To: r-help at r-project.org
Subject: [R] select columns from vector of column names
Hi
I want to extract columns from a data frame using a vector with the desired
column names.
This short example uses the select argument in the subset function to
accomplish what I am trying to do. Is there a better solution?
#names of desired columns
colnames <- c("col1","col3")
#my data
data <-
data.frame("col1"=c(1,2,3),"col2"=c("A","B","C"),"col3"=c(4,5,6))
fun <- function(colname,dframe){
nframe <- subset(dframe,select=colname)
vec <- nframe[,1]
return(vec)
}
fun(colnames[1],data)
fun(colnames[2],data)
[[alternative HTML version deleted]]
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
How about data[ , colnames] Or data[ , colnames[1]] data[ , colnames[2]] -Don On 7/9/10 11:27 AM, "Jonathan Flowers" <jonathanmflowers at gmail.com> wrote:> Hi > > I want to extract columns from a data frame using a vector with the desired > column names. > > This short example uses the select argument in the subset function to > accomplish what I am trying to do. Is there a better solution? > > #names of desired columns > colnames <- c("col1","col3") > > #my data > data <- data.frame("col1"=c(1,2,3),"col2"=c("A","B","C"),"col3"=c(4,5,6)) > > fun <- function(colname,dframe){ > nframe <- subset(dframe,select=colname) > vec <- nframe[,1] > return(vec) > } > > fun(colnames[1],data) > fun(colnames[2],data) > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. >-- Don MacQueen Environmental Protection Department Lawrence Livermore National Laboratory 925 423-1062