函數R與month.abb中月份唯一的第一個字母相似嗎？

Question

在R中是否有與month.abb類似的功能來顯示每月的第一個字母？ 如month.abb返回「一月」，「二月」 ......我想尋求函數返回「J」，「F」，...

Answer 1

R> month.abb 
[1] "Jan" "Feb" "Mar" "Apr" "May" "Jun" "Jul" "Aug" "Sep" "Oct" "Nov" "Dec" 
R> substr(month.abb, 1, 1) 
[1] "J" "F" "M" "A" "M" "J" "J" "A" "S" "O" "N" "D" 
R> 

的功能只是這個包起來。

Answer 2

month.abb對象不是函數，而是一個向量。這是所要求的模擬：

short.mo <- substr(month.abb, 1,1) 

你可以看到其他的內置常數隨：

?Constants 

Answer 3

這是另一種方式，指標縮寫的名字。

abbreviate(month.name, 1, strict=TRUE) 
# January February  March  April  May  June  July 
#  "J"  "F"  "M"  "A"  "M"  "J"  "J" 
# August September October November December 
#  "A"  "S"  "O"  "N"  "D"