Hi,
If df is a dataframe, its last column can't be deleted using "[<-", but
other columns can be deleted this way.
Example:
> (df <- df0 <- data.frame(x = 1:3, y = 4:6, z = 7:9))
x y z
1 1 4 7
2 2 5 8
3 3 6 9
> df[, "z"] <- NULL
Error in x[[jj]] : subscript out of bounds
> df[, 3] <- NULL
Error in x[[jj]] : subscript out of bounds
> df["z"] <- NULL
Error in x[[jj]] : subscript out of bounds
> df[3] <- NULL
Error in x[[jj]] : subscript out of bounds
> df[, "y"] <- NULL
> df
x z
1 1 7
2 2 8
3 3 9
> df <- df0; df[, 2] <- NULL
> df <- df0; df["y"] <- NULL
> df <- df0; df[2] <- NULL
Deleting using "$<-" and "[[<-" works for all columns. Is it wrong to use
"[<-" for deleting? help("[<-.data.frame") has an example, but it doesn't work
for deleting the last column either:
> sw <- swiss[1:5, 1:4] # select a manageable subset
> ## adding a column
> sw["new1"] <- LETTERS[1:5] # adds a character column
> sw[["new2"]] <- letters[1:5] # ditto
> sw[, "new3"] <- LETTERS[1:5] # ditto
> sw$new4 <- 1:5
> sw$new4 <- NULL # delete the column
> (sw0 <- sw)
Fertility Agriculture Examination Education new1 new2 new3
Courtelary 80.2 17.0 15 12 A a A
Delemont 83.1 45.1 6 9 B b B
Franches-Mnt 92.5 39.7 5 5 C c C
Moutier 85.8 36.5 12 7 D d D
Neuveville 76.9 43.5 17 15 E e E
> # This works:
> sw[6:8] <- list(letters[10:14], NULL, aa=1:5) # delete col7, update 6, append
> # But this doesn't:
> sw <- sw0
> sw[6:8] <- list(letters[10:14], aa=1:5, NULL)
Error in x[[jj]] : subscript out of bounds
Best,
Hsiu-Khuern.
----------
Version:
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arch = i486
os = linux-gnu
system = i486, linux-gnu
status =
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minor = 4.1
year = 2006
month = 12
day = 18
svn rev = 40228
language = R
version.string = R version 2.4.1 (2006-12-18)
Locale:
C
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