將字符串轉換爲日期格式：「dd.mm.yyyy」

Question

D <- "06.12.1948"     # which is dd.mm.yyyy 
as.Date(D, "%d.%m.%y")   # convert to date 
[1] "2019-12-06"     # ????  

我錯過了什麼？

Sys.getlocale（類別= 「LC_ALL」） [1] 「LC_COLLATE = German_Austria.1252; LC_CTYPE = German_Austria.1252; LC_MONETARY = German_Austria.1252; LC_NUMERIC = C; LC_TIME = German_Austria.1252」

Answer 1

格式是區分大小寫的（ 「％Y」 是模糊的，依賴於系統的，我相信）：

as.Date(D, "%d.%m.%Y") 
[1] "1948-12-06" 

幫助主題?strptime有更多的細節：

‘%y’ Year without century (00-99). On input, values 00 to 68 are 
     prefixed by 20 and 69 to 99 by 19 - that is the behaviour 
     specified by the 2004 and 2008 POSIX standards, but they do 
     also say ‘it is expected that in a future version the default 
     century inferred from a 2-digit year will change’.