r - 将日期转换为年份和周数并返回
问题描述
我想将日期转换为年份和周数的组合。稍后我想再次转换回日期。我不明白为什么不能在相同的原始日期返回,即使我尝试了所有不同的星期开始数字:
library(dplyr)
df <- tidyr::expand_grid(
date = as.Date(paste("2021 12 29"), "%Y %m %d") + 0:10,
weekday = 0:6
)
df <- df %>%
mutate(
year = format(date, "%Y"),
week = format(date, "%W"),
newDate = as.Date(paste(year, week, weekday), format = "%Y %W %w")
) %>%
tidyr::pivot_wider(
id_cols = c("date"), names_from = "weekday",
values_from = "newDate"
)
print(df)
# A tibble: 11 x 8
date `0` `1` `2` `3` `4` `5` `6`
<date> <date> <date> <date> <date> <date> <date> <date>
1 2021-12-29 2021-12-26 2021-12-27 2021-12-28 2021-12-29 2021-12-30 2021-12-31 NA
2 2021-12-30 2021-12-26 2021-12-27 2021-12-28 2021-12-29 2021-12-30 2021-12-31 NA
3 2021-12-31 2021-12-26 2021-12-27 2021-12-28 2021-12-29 2021-12-30 2021-12-31 NA
4 2022-01-01 NA NA NA NA NA NA 2022-01-01
5 2022-01-02 NA NA NA NA NA NA 2022-01-01
6 2022-01-03 2022-01-02 2022-01-03 2022-01-04 2022-01-05 2022-01-06 2022-01-07 2022-01-08
7 2022-01-04 2022-01-02 2022-01-03 2022-01-04 2022-01-05 2022-01-06 2022-01-07 2022-01-08
8 2022-01-05 2022-01-02 2022-01-03 2022-01-04 2022-01-05 2022-01-06 2022-01-07 2022-01-08
9 2022-01-06 2022-01-02 2022-01-03 2022-01-04 2022-01-05 2022-01-06 2022-01-07 2022-01-08
10 2022-01-07 2022-01-02 2022-01-03 2022-01-04 2022-01-05 2022-01-06 2022-01-07 2022-01-08
11 2022-01-08 2022-01-02 2022-01-03 2022-01-04 2022-01-05 2022-01-06 2022-01-07 2022-01-08
为什么没有不包含 NA 的列?
输出sessionInfo()
:
R version 3.6.2 (2019-12-12)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 17763)
Matrix products: default
locale:
[1] LC_COLLATE=English_United Kingdom.1252 LC_CTYPE=English_United Kingdom.1252
[3] LC_MONETARY=English_United Kingdom.1252 LC_NUMERIC=C
[5] LC_TIME=English_United Kingdom.1252
解决方案
现在,您将 newDate 设置为等于特定年份和特定月份,然后是 7 天范围内的范围。这就是为什么 newDate 目前是:
"2021-01-03" "2021-01-04" "2021-01-05" "2021-01-06" "2021-01-07" "2021-01-01" "2021-01-02" NA
要获得返回最初拥有的相同日期的所需输出,您还必须存储日期并在创建 newDate 时引用它。简而言之,这样做:
date <- as.Date(paste("2021 01 03"), "%Y %m %d")
year <- format(date, "%Y")
week <- format(date, "%W")
day <- format(date, "%d")
newDate <- as.Date(paste(year, week, day), format = "%Y %W %w")
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