转换日期格式 r 编程

Question

将字符串转换为日期

date_string <- c("1st December 2019" , "2nd December 2019" , "3rd December 2019" ,"4th November 2019" 

, "20th November 2019")

date_string_new <- as.Date(date_string, format= "%d %B %Y")

但输出是“1st December 2019”“2nd December 2019”“3rd December 2019”
[4] “2019 年 11 月 4 日” “2019 年 11 月 20 日”

[1] NA NA NA NA NA

理想情况下是

[1] "1 December 2019"   "2 December 2019"   "3 December 2019"  
[4] "4 Novemeber 2019"  "20 Novemeber 2019

Answer 1

也许您可以考虑使用lubridate包进行日期转换：

library(lubridate)

date_string_new <- dmy(date_string)

R> date_string_new
[1] "2019-12-01" "2019-12-02" "2019-12-03" "2019-11-04" "2019-11-20"

这会将日期结果存储为类Date 。

Answer 2

在基础 R 中，你可以做

as.Date(sub('(\\d+).*?\\s(.*)', '\\1\\2', date_string), "%d%B%Y")
#[1] "2019-12-01" "2019-12-02" "2019-12-03" "2019-11-04" "2019-11-20"

---

如果你想以相同的格式输出，你可以试试

sub('(\\d+).*?\\s(.*)', '\\1 \\2', date_string)
#[1] "1 December 2019"  "2 December 2019"  "3 December 2019"  "4 November 2019"  "20 November 2019"

或者

sub('st|nd|rd|th', "", date_string)

Answer 3

我们可以使用sub删除数字后面的字符并使用as.Date from base R

as.Date(sub("[a-z]+", "", date_string), "%d %B %Y") 
#[1] "2019-12-01" "2019-12-02" "2019-12-03" "2019-11-04" "2019-11-20"