如何将floor_date()舍入为任意日期? [英] How to round floor_date() to arbitrary date?

问题描述

我正在使用floor_date将日期四舍五入为星期几:

I am using floor_date to round dates to the weeks:

library(lubridate)
floor_date(ymd_hms('2016-08-26 16:27:15'), '7 days')
[1] "2016-08-22 UTC"

但是，我想将一个特定的日期设置为第一周的开始. 例如，我想将"2016-08-26 UTC"设置为第一周.作为一种解决方法，我试图调整getOption("lubridate.week.start")，但是无论我通过什么，我都无法更改开始的工作日:

However, I would like to set a specific date as the beginning of the first week. For instance, I would like to set "2016-08-26 UTC" as first week. As a workaround I was trying to tweak getOption("lubridate.week.start"), but I cannot get to change the starting weekday regardless of what I pass:

> floor_date(ymd_hms('2016-08-26 16:27:15'), '7 days', week_start = getOption("lubridate.week.start", 1))
[1] "2016-08-22 UTC"
> floor_date(ymd_hms('2016-08-26 16:27:15'), '7 days', week_start = getOption("lubridate.week.start", 7))
[1] "2016-08-22 UTC"

推荐答案

您需要设置unit = "week".来自?round_date

week_start:当单位为周时，指定参考日； 7是星期天.

week_start: when unit is weeks specify the reference day; 7 being Sunday.

示例

library(lubridate)
lapply(c(1, 5), function(x) floor_date(ymd('2016-08-26'), 'week', week_start = x))
#[[1]]
#[1] "2016-08-22"
#
#[[2]]
#[1] "2016-08-26"

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