Applying the split function to a xts object by weeks groups rows into weekly chunks. The default days in the group are Monday to Sunday. What do I do if I want the days in the group to be from Sunday to Saturday?
library(xts)
idx <- as.Date("2018-3-1") + 0:14
v <- 1:15
x <- xts(v, idx)
group <- split(x, f = 'weeks')
group
Output:
[[1]]
[,1]
2018-03-01 1 # Thursday
2018-03-02 2 # Friday
2018-03-03 3 # Saturday
2018-03-04 4 # Sunday
[[2]]
[,1]
2018-03-05 5 # Monday
2018-03-06 6 # Tuesday
2018-03-07 7 # Wednesday
2018-03-08 8 # Thursday
2018-03-09 9 # Friday
2018-03-10 10 # Saturday
2018-03-11 11 # Sunday
[[3]]
[,1]
2018-03-12 12 # Monday
2018-03-13 13 # Tuesday
2018-03-14 14 # Wednesday
2018-03-15 15 # Thursday
Desired Output:
[[1]]
[,1]
2018-03-01 1 # Thursday
2018-03-02 2 # Friday
2018-03-03 3 # Saturday
[[2]]
[,1]
2018-03-04 4 # Sunday
2018-03-05 5 # Monday
2018-03-06 6 # Tuesday
2018-03-07 7 # Wednesday
2018-03-08 8 # Thursday
2018-03-09 9 # Friday
2018-03-10 10 # Saturday
[[3]]
[,1]
2018-03-11 11 # Sunday
2018-03-12 12 # Monday
2018-03-13 13 # Tuesday
2018-03-14 14 # Wednesday
2018-03-15 15 # Thursday
Consider creating an external, equal-length vector of Week Number with %U format for weekdays starting on Sunday. See ?strftime.
%U
Week of the year as decimal number (00–53) using Sunday as the first day 1 of the week (and typically with the first Sunday of the year as day 1 of week 1). The US convention.
week_num <- format(idx, "%U")
group <- unname(split(x, f = week_num))
group
[[1]]
2018-03-01 1
2018-03-02 2
2018-03-03 3
[[2]]
2018-03-04 4
2018-03-05 5
2018-03-06 6
2018-03-07 7
2018-03-08 8
2018-03-09 9
2018-03-10 10
[[3]]
2018-03-11 11
2018-03-12 12
2018-03-13 13
2018-03-14 14
2018-03-15 15