I have a data frame A and a vector b.

I want to eliminate any columns in A with indices that are in b by doing A[,-b]

Sometimes vector b has length 0. In this case I would like the whole of data frame A to be returned. Instead I get this error:

data frame with 0 columns and 1259 rows

How can I make sure this doesn't happen in this case?

CodePudding user response：

Any reason a control statement won't work? Most of the time there's no need to over-complicate things. It also makes it simple for other people who may need to read or edit your code.

ret_a = function(A, b) {
    if (length(b) == 0) {
        A
    } else {
        A[,-b]
    }
}

CodePudding user response：

You could use setdiff():

A[, setdiff(1:ncol(A), b)]

This method can handle

• b <- NA
• b <- NULL
• b <- integer(0)

and returns the entire data A.