Matrix Error- data length doesn't match, even though it should - r

Question

I am trying to write a function that will return the number of business days between two dates (not just excluding weekends, but holidays as well). I'm approaching it by building a matrix with rownames corresponding to days of the week with the elements of the matrix either a 1 or a 0: a 0 if it is a holiday or the extra couple elements to fill the matrix.
I've checked the length of each vector in the code. It checks out. I've run the code manually in the console, one line at a time, and it works perfectly. BUT if I run the function, it displays this error message:
Warning message:
In matrix(da, nrow = 7, dimnames = list(n)) :
data length [132] is not a sub-multiple or multiple of the number of rows [7]
I'm using R 3.1.1, mostly working in Rstudio. The cal mentioned in the code can be found here.
Here's the code:
dte <- function(date) {
#Input a date and it tells you the number of business (not including holidays)
#days until that date
#Take the target date and turn it into a date
d <- strptime(date,format="%Y-%m-%d")
#Obtain current date
c <- strptime(Sys.Date(), format="%Y-%m-%d")
#Calculate the difference in days
diff <- d-c
#Extract the actual number difference
f <- diff[[1]]
#Get the list of holidays
cal <- dget("cal")
cal <- as.Date(cal)
#Get the full list of dates between now and the target date
b <- Sys.Date()+0:f
#Find which days in the range are holidays
if(any(b %in% cal)) {
bt <- b[b %in% cal]
#Return the position of the holidays within the range
bn <- which(b %in% bt)
} else {
#Set holidays present to 0
bn <- 0
}
#Build a vector of the weekdays starting with the current weekday
n <- weekdays(Sys.Date()+0:6)
#Create a vector as long as the difference with a 1 in each place
v <- rep(1,f)
#Set each holiday to 0
v[bn] <- v[bn]-1
#Extra steps to make sure that the matrix is full but only with 1s where we want them.
g <- ((trunc(f/7)+1)*7)-f
u <- rep(0,g)
da <- c(v,u)
#Create the matrix
m <- matrix(da,nrow=7,dimnames=list(n))
#Extract all of the workweeks and add them up
ww <- m[c("Monday","Tuesday","Wednesday","Thursday","Friday"),]
r <- sum(ww)
r
}

Answer 1

The problem is that your strptime calls return POSIXt objects which have time components and are then effected by daylight savings time. Observe
(d1<-strptime("2014-08-24",format="%Y-%m-%d"))
# [1] "2014-08-24 EDT"
(d2<-strptime("2014-12-31",format="%Y-%m-%d"))
# [1] "2014-12-31 EST"
d2-d1
# Time difference of 129.0417 days
So there are not a while number of dates between the two values which causes complications for you later in your code. If you use as.Date rather than strptime then you won't have this problem because Date objects don't care about time.
But i'm not sure really why you're even bothering with the matrix at all. I think a simpler implementation would look like
dte <- function(date) {
d <- as.Date(date,format="%Y-%m-%d")
c <- Sys.Date()
cal <- dget("cal")
cal <- as.Date(cal)
#Get the full list of dates between now and the target date
b <- seq(c, d, by="1 day")
return(sum(as.POSIXlt(b)$wday %in% 1:5 & (!b %in% cal)))
}