how to determine if a character vector is a valid numeric or integer vector

Question

I am trying to turn a nested list structure into a dataframe. The list looks similar to the following (it is serialized data from parsed JSON read in using the httr package)

Answer 1

When NAs are included @josliber's function won't work (though it answers the question well for the sample data). @Amy M's function should work but requires loading Hmisc package.

What about something like this:

can.be.numeric <- function(x) {
    stopifnot(is.atomic(x) || is.list(x)) # check if x is a vector
    numNAs <- sum(is.na(x))
    numNAs_new <- suppressWarnings(sum(is.na(as.numeric(x))))
    return(numNAs_new == numNAs)
}

It counts NAs in input vector and NAs in the output of as.numeric() and returns TRUE if the vector can be "safely" converted to numeric (i.e. without adding any additional NA values).