Changing lubridate function to start on Monday rather than Sunday

问题

dates <- NULL

date <- as.Date("01/01/2014","%d/%m/%Y")

dates <- data.frame(date=as.Date(character())
                    ,cal_day_in_year_num = numeric()
                    ,cal_week_id = numeric()
                    ,cal_week_start_date = as.Date(character())
                    ,cal_week_end_date = as.Date(character())
)

for (i in 1:365) {

  dates[i,1] <- date + days(i-1) ## date

  dates[i,2] <- yday(dates[i,1]) ## cal_day_in_year_num

  dates[i,3] <- paste(year(dates[i,1]),sprintf("%02d",week(dates[i,1])),sep="") ## cal_week_id

  dates[i,4] <- floor_date(dates[i,1], "week") ## cal_week_start_date

  dates[i,5] <- ceiling_date(dates[i,1], "week") ## cal_week_end_date

}

View(dates)

For given dates I'm trying to use the lubridate function to calculate the corresponding start and end dates of the week

The issue I'm having is that lubridate is taking the first day of the week to be Sunday, where as I need it to be Monday - does anyone have a way round this?

回答1:

You can make your own functions to do this in base. For example,

start.of.week <- function(date)
  date - (setNames(c(6,0:5),0:6) [strftime(date,'%w')])

end.of.week <- function(date)
  date + (setNames(c(0,6:1),0:6) [strftime(date,'%w')])

start.of.week(as.Date(c('2014-01-05','2014-10-02','2014-09-22','2014-09-27')))
# "2013-12-30" "2014-09-29" "2014-09-22" "2014-09-22"
end.of.week(as.Date(c('2014-01-05','2014-10-02','2014-09-22','2014-09-27')))
# "2014-01-05" "2014-10-05" "2014-09-28" "2014-09-28"

回答2:

As Wave commented, you can just use +1 to change the date. You can also do the same as you have done without the need of the slow for loop.

date <- as.Date("01/01/2014","%d/%m/%Y")

yday(date) <-yday(date) + 0:364
dates <- data.frame(date = date,
                    cal_day_in_year_num = yday(date),
                    cal_week_id = paste(year(date),sprintf("%02d",week(date)),sep=""),
                    cal_week_start_date = NA,
                    cal_week_end_date = NA
                    )

# find the minimum date in the time series
min_date <- min(dates$date)
# find the previous Monday of the minimum date
for(i in 1:7){
  if(wday(min_date-i, label=TRUE)=="Mon"){
    start_date <- min_date-i
  }
}

# get the number of days between the minimum date and all days
diff_days <- as.numeric(difftime(dates$date,start_date, units="days"))
# Remove the excess days from each date
dates$cal_week_start_date <- dates$date-diff_days%%7
# Fix up the end of the week based on the start of the week
dates$cal_week_end_date <- dates$cal_week_start_date+7

来源：https://stackoverflow.com/questions/26160117/changing-lubridate-function-to-start-on-monday-rather-than-sunday

标签

lubridate