Change lubridate function to run on monday, not sunday

Question

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 the given dates, I try to use the lubridate function to calculate the corresponding start and end dates of the week.

The problem I am facing is that lubridate takes the first day of the week on Sunday, where, when I need it to be on Monday - can anyone get around this?

Answer 1

You can make your own functions to do this in the database. For instance,

 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" 

Answer 2

As Wave commented, you can simply use +1 to change the date. You can also do the same as you, without the need for a 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