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
column. I've created a function which works fine on a small dataset, but crashes when I use it on the large one. Can anybody see my mistake?
I've created 4 functions:
- 3 subfunctions so that I can do logical comparisons and selection
using *apply functions
- 1 function to determine the season
Here are thefunctions:
require(lubridate)
# function for logical comparison (to be used in *apply)
greaterOrEqual <- function(x,y){
ifelse(x >= y,T,F)
}
# function for logical comparison (to be used in *apply)
less <- function(x,y){
ifelse(x < y,T,F)
}
# function for logical comparison (to be used in *apply)
selFromLogic <- function(VecLogic,VecValue){
VecValue[VecLogic]
}
# Main Function to determine the 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("2000-12-31 00:00:00", tz = "UTC")
year(input.date) <- year(Winter1Start)
attr(input.date, "tzone") <- attr(Winter1Start, "tzone")
SeasonStart <- c(Winter1Start,SummerStart,Winter2Start)
SeasonsEnd <- c(Winter1End,SummerEnd,Winter2End)
Season_names <- as.factor(c("WinterHalfYear","SummerHalfYear","WinterHalfYear"))
Season_select <- sapply(SeasonStart, greaterOrEqual, x = input.date) & sapply(SeasonsEnd, less, x = input.date)
Season_return <- apply(Season_select,MARGIN = 1,selFromLogic,VecValue = Season_names)
return(Season_return)
}
And here's a way to test the function:
dates <- Sys.time() + seq(0,10000,10)
getTwoSeasons(dates)
I would be thankful for any help, this is driving me crazy!
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