Grouping dates into weeks using cut and breaks-CodePudding

I have some data that looks like this:

#   order_date quantity
# 1 2021-01-01       54
# 2 2021-01-01       32
# 3 2021-01-02       42
# 4 2021-01-01      132
# 5 2021-01-01       56
# 6 2021-01-02       88
# 7 2021-01-08       99
# 8 2021-01-10       54

When I use the following code:

df$week <- cut(as.Date(df$order_date), breaks="week")

I get the following:

#   order_date quantity       week
# 1 2021-01-01       54 2020-12-28
# 2 2021-01-01       32 2020-12-28
# 3 2021-01-02       42 2020-12-28
# 4 2021-01-01      132 2020-12-28
# 5 2021-01-01       56 2020-12-28
# 6 2021-01-02       88 2020-12-28
# 7 2021-01-08       99 2021-01-04
# 8 2021-01-10       54 2021-01-04

Since my data starts on 1/1/21 I would like the week grouping to start on 1/1/21 and not 12/28/2020 (The nearest Sunday). So my groups would look like this:

#   order_date quantity       week
# 1 2021-01-01       54 2021-01-01
# 2 2021-01-01       32 2021-01-01
# 3 2021-01-02       42 2021-01-01
# 4 2021-01-01      132 2021-01-01
# 5 2021-01-01       56 2021-01-01
# 6 2021-01-02       88 2021-01-01
# 7 2021-01-08       99 2021-01-07
# 8 2021-01-10       54 2021-01-07

open to other libraries / syntax.

CodePudding user response：

You may use seq.Dat on the date range plus one week. No packages needed.

dat |> 
  transform(week=cut(order_date,
                     breaks=seq.Date(min(order_date), max(order_date)   7, 
                                     by='week')))
#    order_date quantity       week
# 1  2021-01-01       54 2021-01-01
# 2  2021-01-01       32 2021-01-01
# 3  2021-01-01       42 2021-01-01
# 4  2021-01-01      132 2021-01-01
# 5  2021-01-01       56 2021-01-01
# 6  2021-01-02       88 2021-01-01
# 7  2021-01-03       99 2021-01-01
# 8  2021-01-03       54 2021-01-01
# 9  2021-01-08       23 2021-01-08
# 10 2021-01-10       11 2021-01-08

Note: R >= 4.1 used.

Data:

dat <- structure(list(order_date = structure(c(18628, 18628, 18628, 
18628, 18628, 18629, 18630, 18630, 18635, 18637), class = "Date"), 
    quantity = c(54, 32, 42, 132, 56, 88, 99, 54, 23, 11)), class = "data.frame", row.names = c(NA, 
-10L))

CodePudding user response：

You can manually set the first day of the week using lubridate::floor_date.

dat$Week <- lubridate::floor_date(dat$order_date, "weeks", week_start = 5)

> dat
#   order_date quantity       week
#1  2021-01-01       54 2021-01-01
#2  2021-01-01       32 2021-01-01
#3  2021-01-01       42 2021-01-01
#4  2021-01-01      132 2021-01-01
#5  2021-01-01       56 2021-01-01
#6  2021-01-02       88 2021-01-01
#7  2021-01-03       99 2021-01-01
#8  2021-01-03       54 2021-01-01
#9  2021-01-02       23 2021-01-01
#10 2021-01-10       11 2021-01-08

Data

order_date <- c("2021-01-01", "2021-01-01","2021-01-01","2021-01-01","2021-01-01","2021-01-02","2021-01-03","2021-01-03","2021-01-02","2021-01-10")
quantity <- c(54,32,42,132,56,88,99,54,23,11)
dat <- data.frame(order_date=as.Date(order_date), quantity)