How can I make vapply return a date vector? (I think that's a different problem: Returning a vector of class POSIXct with vapply ):
f1 <- function(x) {
as.Date(paste0("2000", sprintf("%02d", x), "01"), format = "%Y%m%d")
}
vapply(3:7, f1, as.Date("2000-01-01"))
# [1] 11017 11048 11078 11109 11139
Want:
# "2000-03-01" "2000-04-01" "2000-05-01" "2000-06-01" "2000-07-01"
The problem is that apply family functions drop Date class. Here is one way to do it:
do.call("c", lapply(3:7, f1))
You can also add class(result) <- "Date" after evaluating vapply.
Full version of class(result) <- "Date":
result <- vapply(3:7, f1, numeric(1))
class(result) <- "Date"
result
# "2000-03-01" "2000-04-01" "2000-05-01" "2000-06-01" "2000-07-01"
