Determine season from Date using lubridate in R

Question

I have a very big dataset with a DateTime Column containing POSIXct-Values. I need to determine the season (Winter - Summer) based on the DateTime

Answer 1

After several hours of debugging I've found my mistake, and it's quite absurd really:

If a season for a DateTimeValue was not found, apply returned list-object instead of a vector (this was the case when the DateTime value equalled 2000-12-31 00:00:00). Returning a list created an an overproportional increase in computation time and the described crashes. Here's a the fixed code:

# input date and return 2 season
getTwoSeasons <- function(input.date) {
  Winter1Start <- as.POSIXct("2000-01-01 00:00:00", tz = "UTC")
  Winter1End <- as.POSIXct("2000-04-15 23:59:59", tz = "UTC")

  SummerStart <- Winter1End + 1
  SummerEnd <- as.POSIXct("2000-10-15 23:59:59", tz = "UTC")

  Winter2Start <- SummerEnd + 1
  Winter2End <- as.POSIXct("2001-01-01 00:00:01", tz = "UTC")

  SeasonStart <- c(Winter1Start,SummerStart,Winter2Start)
  SeasonsEnd <- c(Winter1End,SummerEnd,Winter2End)
  Season_names <- factor(c("WinterHalf","SummerHalf","WinterHalf"))

  year(input.date) <- year(Winter1Start)
  attr(input.date, "tzone") <- attr(Winter1Start, "tzone")

  Season_selectStart <- vapply(X = SeasonStart,function(x,y){x <= input.date},FUN.VALUE = logical(length(input.date)),y = input.date)
  Season_selectEnd   <- vapply(X = SeasonsEnd,function(x,y){x > input.date},FUN.VALUE = logical(length(input.date)),y = input.date)
  Season_selectBoth  <- Season_selectStart & Season_selectEnd
  Season_return <- apply(Season_selectBoth,MARGIN = 1,function(x,y){y[x]}, y = Season_names)
  return(Season_return)
}

The "sub"-functions are now integrated in the main function and two sapply functions replaced with vapply.

PS: There is still an issue with the timezone, since c() strips the timezone away. I'll update the code when I fix it.