R: as.不解析的日期是每月的30日和31日

Question

在下面的例子中，如。Date无法解析每月30日和31日的日期。

dates <- c("28/03/2020", "29/03/2020","30/03/2020", "31/03/2020",
"28/04/2020", "29/04/2020", "30/04/2020",
"28/05/2020", "29/05/2020", "30/05/2020", "31/05/2020")
as.Date(dates, format = "%d/%M/%Y")

我得到的结果是:

[1] "2020-02-28" "2020-02-29" NA           NA           "2020-02-28" "2020-02-29"
[7] NA           "2020-02-28" "2020-02-29" NA           NA  

我在Windows机器上运行R Studio Version 1.4.1103。

Answer 1

在格式参数中需要一个小m。

dates <- c("28/03/2020", "29/03/2020","30/03/2020", "31/03/2020",
"28/04/2020", "29/04/2020", "30/04/2020",
"28/05/2020", "29/05/2020", "30/05/2020", "31/05/2020")
> as.Date(dates, format = "%d/%m/%Y")
[1] "2020-03-28" "2020-03-29" "2020-03-30" "2020-03-31" "2020-04-28" "2020-04-29" "2020-04-30" "2020-05-28" "2020-05-29" "2020-05-30"
[11] "2020-05-31"