xts 按周拆分函数将一周的第一天指定为星期日而不是默认的星期一 [英] xts split by week function specify first day of week as Sunday instead of default of Monday

问题描述

通过weeks 将split 函数应用于xts 对象，将行分组为每周块.组中的默认天数是 Monday 到 Sunday.如果我希望小组中的日子从Sunday 到Saturday 怎么办?

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

推荐答案

考虑为工作日开始创建具有 %U 格式的 Week Number 的外部等长向量在星期天.参见 ?strftime.

Consider creating an external, equal-length vector of Week Number with %U format for weekdays starting on Sunday. See ?strftime.

%U

以星期日为第一个十进制数 (00–53) 的一年中的第几周一周的第 1 天(通常将一年的第一个星期日作为第 1 周的第 1 天).美国公约.

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

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