Question

I’m trying to write an R function to calculate the number of weekdays between two dates. For example, something like Nweekdays('01/30/2011','02/04/2011') that would return 5.

Similar to this question.

Update: I was wondering if anyone could think of a way to vectorize this, so that it’ll work on 2 columns of dates.

Answer 1

Date1 <- as.Date("2011-01-30")
Date2 <- as.Date("2011-02-04")    
sum(!weekdays(seq(Date1, Date2, "days")) %in% c("Saturday", "Sunday"))

EDIT: This can be vectorized:

Dates1 <- as.Date("2011-01-30") + rep(0, 10)
Dates2 <- as.Date("2011-02-04") + seq(0, 9)
Nweekdays <- Vectorize(function(a, b) 
  sum(!weekdays(seq(a, b, "days")) %in% c("Saturday", "Sunday")))
Nweekdays(Dates1, Dates2)