[R] How I can rearrange columns in data.frame?

[peter dalgaard]

On May 27, 2013, at 20:17 , Kristi Glover wrote:

> Hi R-User,
> I am wondering how I can rearrange columns in a table in R. I do have very big data set (4500 columns). I have given an example of the data set.
> 
>> dput(dat)
> structure(list(preV1001A1b = c(0.59, 0.3, 0.78, 0.43), preV15A1b = c(0.57, 
> 0.62, 0.51, 0.95), preV2032A1b = c(0.4, 0.8, 0.24, 0.34), preV2035A1b = c(0.95, 
> 0.67, 0.81, 0.8), preV59A1b = c(0.05, 0.57, 0.03, 0.5)), .Names = c("preV1001A1b", 
> "preV15A1b", "preV2032A1b", "preV2035A1b", "preV59A1b"), class = "data.frame", row.names = c(NA, 
> -4L))
> 
> I wanted to make like this 
>> dput(dat1)
> structure(list(preV15A1b = c(0.57, 0.62, 0.51, 0.95), preV59A1b = c(0.05, 
> 0.57, 0.03, 0.5), preV1001A1b = c(0.59, 0.3, 0.78, 0.43), preV2032A1b = c(0.4, 
> 0.8, 0.24, 0.34), preV2035A1b = c(0.95, 0.67, 0.81, 0.8)), .Names = c("preV15A1b", 
> "preV59A1b", "preV1001A1b", "preV2032A1b", "preV2035A1b"), class = "data.frame", row.names = c(NA, 
> -4L))
> Any suggestions. 
> KG

Is there a particular logic to that ordering? Otherwise, the obvious way is

nm <- c("preV15A1b", "preV59A1b", "preV1001A1b", "preV2032A1b", "preV2035A1b")
dat1 <- dat[nm]

Or, maybe you are looking for something like this?

o <- order(as.numeric(sub("preV([0-9]*)A1b", "\\1", names(dat))))
(dat1 <- dat[o])

-- 
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com