How to convert week numbers into date format using R

Question

I am trying to convert a column in my dataset that contains week numbers into weekly Dates. I was trying to use the lubridate package but could not find a solution. The dataset looks like the one below:

df <- tibble(week = c("202009", "202010", "202011","202012", "202013", "202014"),
             Revenue = c(4543, 6764, 2324, 5674, 2232, 2323))

So I would like to create a Date column with in a weekly format e.g. (2020-03-07, 2020-03-14).

Would anyone know how to convert these week numbers into weekly dates?

What do you want the weekly date to be? First Monday of the week? Normalized to Week 1 = January 1? I didn't follow the rule. — , Apr 07 '21 at 17:18
Just to clarify: does "202009" mean 9'th week of year 2020, 20'th week of year 2009 or 202009 weeks since your vampire boss's grandmother's birthday? — mrKirushko, Apr 07 '21 at 17:56
This answer might be helpful: https://stackoverflow.com/a/45587644/9022665 — Jonathan V. Solórzano, Apr 07 '21 at 18:10
Hi Adam, from Sunday to Saturday. So the 1st day would be Sunday — BritmechanicalTurk, Apr 09 '21 at 14:58
Hi mrKirushko, yes I meant the '9th week of 2020' then '10th week of 2020'. I should have been more clear. — BritmechanicalTurk, Apr 09 '21 at 14:59

score 0 · Accepted Answer · answered Apr 11 '21 at 13:40

Maybe there is a more automated way, but try something like this. I think this gets the right days, I looked at a 2020 calendar and counted. But if something is off, its a matter of playing with the (week - 1) * 7 - 1 component to return what you want.

This just grabs the first day of the year, adds x weeks worth of days, and then uses ceiling_date() to find the next Sunday.

library(dplyr)
library(tidyr)
library(lubridate)

df %>% 
  separate(week, c("year", "week"), sep = 4, convert = TRUE) %>% 
  mutate(date = ceiling_date(ymd(paste(year, "01", "01", sep = "-")) + 
                               (week - 1) * 7 - 1, "week", week_start = 7))

# # A tibble: 6 x 4
#    year  week Revenue date      
#   <int> <int>   <dbl> <date>    
# 1  2020     9    4543 2020-03-01
# 2  2020    10    6764 2020-03-08
# 3  2020    11    2324 2020-03-15
# 4  2020    12    5674 2020-03-22
# 5  2020    13    2232 2020-03-29
# 6  2020    14    2323 2020-04-05

Hi Adam, this is amazing! Much appreciated! – BritmechanicalTurk Apr 12 '21 at 14:49 — BritmechanicalTurk, Apr 12 '21 at 14:49

How to convert week numbers into date format using R

1 Answers1