assign NULL to the column:
> dfxyz <- data.frame(x=1:10,y=11:20,z=factor(c(rep(0,5),rep(1,5))))
> dfxyz
x y z
1 1 11 0
2 2 12 0
3 3 13 0
4 4 14 0
5 5 15 0
6 6 16 1
7 7 17 1
8 8 18 1
9 9 19 1
10 10 20 1
> dfxyz$y <- NULL
> dfxyz
x z
1 1 0
2 2 0
3 3 0
4 4 0
5 5 0
6 6 1
7 7 1
8 8 1
9 9 1
10 10 1
>
On Sun, Dec 26, 2010 at 8:22 PM, John Sorkin
<jsor...@grecc.umaryland.edu> wrote:
> I am trying to drop a column of a data frame. The code below attempts to drop
> a numeric column (which does not work but gives no error or warning) and a
> factor column (which does not work but gives an error).
> I would appreciate someone telling me why my code does not work, and
> suggesting code that will work.
> Thanks,
> John
>
> rm(dfxyz,dfxz,dfxy)
>
> # create the data frame.
> dfxyz <- data.frame(x=1:10,y=11:20,z=factor(c(rep(0,5),rep(1,5))))
> dfxyz
>
> names(dfxyz)
>
> # try to drop y column
> # does not work, does not produce error message
> dfxz <- dfxyz[,-(dfxyz$y)]
> dfxz
>
> # try to drop z column
> # does not work, produces error message:
> # In Ops.factor(df$z) : - not meaningful for factors
> dfxy <- dfxyz[,-dfxyz$z]
> dfxy
>
>
>
> John David Sorkin M.D., Ph.D.
> Chief, Biostatistics and Informatics
> University of Maryland School of Medicine Division of Gerontology
> Baltimore VA Medical Center
> 10 North Greene Street
> GRECC (BT/18/GR)
> Baltimore, MD 21201-1524
> (Phone) 410-605-7119
> (Fax) 410-605-7913 (Please call phone number above prior to faxing)
>
> Confidentiality Statement:
> This email message, including any attachments, is for ...{{dropped:17}}
______________________________________________
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.
