On Feb 23, 2010, at 10:13 AM, adam naples wrote:
try
test <- subset(test, select = -c(Y))
That approach has the deficiency (or feature?) that it will throw an
error if Y is not a column in test, whereas test[ , -grep("Y",
names(test))] will not.
However, the grep approach will return an empty dataframe when given a
non-existent column name which seems very unintuitive. I think the
best approach is:
> test[,!names(test)%in%"A"] # same as
> test[,!colnames(test)%in%"A"]
X Y Z
1 1 5 8
2 2 6 9
3 3 7 10
4 4 8 11
--
David.
The key is the minus sign before c() in the select argument.
You can put in as many columns as you like.
-a
On Feb 23, 2010, at 11:02 AM, David Winsemius wrote:
On Feb 23, 2010, at 6:04 AM, Knut Krueger wrote:
Hi to all,
test <- data.frame("X"=c(1:4),"Y"=c(5:8),"Z"=c(8:11))
test <- test[,-2]
Is there a way to specify the col name "Y" to delete instead the
number?
I believe that negative indexing only works with numeric arguments.
You could dummy up a negation approach for character vectors with:
> test[, !(names(test) %in% c("Y"))] #non-negated logical vector
to index
X Z
1 1 8
2 2 9
3 3 10
4 4 11
> test[, -grep("Y",names(test))] # negated numeric vector to index
X Z
1 1 8
2 2 9
3 3 10
4 4 11
--
David
Kind regards Knut
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