[R] Weekdays

[Thomas Lumley]

On Fri, 22 Feb 2002, Whit Armstrong wrote:

> Hello,
>
> I'm trying to write a function that returns the number of weekdays between a
> vector of start dates and a vector of end dates.
>
> Subtracting the 2 times the number of whole weeks is the easy part and works
> if the number of days is a multiple of 7.
>
> However, the number of weekend days in the tail is a little harder.  It
> depends on both the start date of the tail and the number of days in the
> tail.
>
> Any suggestions for a more elegant solution would be helpful.

Well, an efficient brute-force solution is a lookup table.

The weekdays() function returns the day of the week, and so you can
construct a 7x7 table of tail lengths and do

   tail<-tailtable[weekdays(start),weekdays(end)]

I don't know if this counts as elegant.

	-thomas



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