我有一个很大的数据集，其中DateTime包含一个包含POSIXct-Values的列。我需要根据该DateTime列确定季节（冬季-夏季）。我创建了一个在小型数据集上可以正常运行的函数，但是在大型数据集上使用时会崩溃。有人可以看到我的错误吗？
我创建了4个函数：
功能如下：
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)
}
这是测试功能的一种方法：
dates <- Sys.time() + seq(0,10000,10)
getTwoSeasons(dates)
我将不胜感激，这让我发疯！
我将@Lars Arne Jordanger的更为优雅的方法打包为一个函数：
getTwoSeasons <- function(input.date){
numeric.date <- 100*month(input.date)+day(input.date)
## input Seasons upper limits in the form MMDD in the "break =" option:
cuts <- base::cut(numeric.date, breaks = c(0,415,1015,1231))
# rename the resulting groups (could've been done within cut(...levels=) if "Winter" wasn't double
levels(cuts) <- c("Winter", "Summer","Winter")
return(cuts)
}
在一些样本数据上对其进行测试似乎可以正常工作：
getTwoSeasons(as.POSIXct("2016-01-01 12:00:00")+(0:365)*(60*60*24))
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