List all column except for one in R

Question

Possible Duplicate:
Drop Columns R Data frame

Let's say I have a dataframe with column c1, c2, c3.

I want to list just c1 and c2. How do I do that?

I've tried:

head(data[column!="c3"])
head(data)[,2]
head(data[!"c3"])

score 154 · Answer 1 · edited Dec 07 '21 at 21:14

If you are looking for negative indexing by name (in addition to tcash21's numeric indexing), here's a few ways I know, some riskier than others:

mtcars[, -which(names(mtcars) == "carb")]  #only works on a single column
mtcars[, names(mtcars) != "carb"]          #only works on a single column
mtcars[, !names(mtcars) %in% c("carb", "mpg")] 
mtcars[, -match(c("carb", "mpg"), names(mtcars))] 
mtcars2 <- mtcars; mtcars2$hp <- NULL         #lost column (risky)


library(gdata) 
remove.vars(mtcars2, names=c("mpg", "carb"), info=TRUE)

Generally I use:

mtcars[, !names(mtcars) %in% c("carb", "mpg")]

because I feel it's safe and efficient.

And see http://markmail.org/message/sdg7mopk4towqbm4 for Brian Ripley's comment on mtcars[,-c("carb","mpg")] — Dieter Menne, Oct 14 '12 at 10:16

score 93 · Accepted Answer · edited Oct 11 '21 at 02:41

93

You can index and use a negative sign to drop the 3rd column:

data[,-3]

Or you can list only the first 2 columns:

data[,c("c1", "c2")]
data[,1:2]

Don't forget the comma and referencing data frames works like this: data[row,column]

edited Oct 11 '21 at 02:41

Penny Liu

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answered Oct 12 '12 at 23:53

tcash21

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Regarding to your last sentence, you don't actually need the comma when working with data frames, since they are lists. – Rich Scriven Dec 26 '16 at 01:58
Sure, but if you're going to make that comment at least show an example of how not to use a comma aka accessing lists. – tcash21 Dec 27 '16 at 04:10
2

for example `x[1,2]` = `x[[2]][[1]]` – tcash21 Dec 27 '16 at 04:11

List all column except for one in R

2 Answers2