r - 从R中的字符串中提取混合日期

Question

我有一个字符向量，如下表所示，我想从中提取日期并将它们转换为 as.Date。例如，第一行是 09-11-2021。字符串中的最后一个数字是列数而不是日期的一部分。

   <chr>                                                                       
 1 By Leigh-Ann Butler, Shannon Cobb, Michael R. DonaldsonNov 9, 20213 Comments
 2 By Leigh-Ann Butler, Shannon Cobb, Michael R. DonaldsonNov 8, 20212 Comments
 3 By Rick AndersonNov 4, 202114 Comments                                      
 4 By Victoria Ficarra, Rob JohnsonNov 3, 20215 Comments                       
 5 By Roger C. SchonfeldNov 1, 202123 Comments                                 
 6 By Joseph EspositoOct 29, 20211 Comment                                     
 7 By Brigitte ShullOct 20, 20216 Comments                 

example.data <- c("By Leigh-Ann Butler, Shannon Cobb, Michael R. DonaldsonNov 9, 20213 Comments",
"By Leigh-Ann Butler, Shannon Cobb, Michael R. DonaldsonNov 8, 20212 Comments",
"By Rick AndersonNov 4, 202114 Comments",                                      
"By Victoria Ficarra, Rob JohnsonNov 3, 20215 Comments")

Answer 1

你可以使用

as.Date(gsub(".+(\\w{3}\\s\\d{1,2},\\s\\d{4}).*", "\\1", example.data), format = "%b %d, %Y")

#> [1] "2021-11-09" "2021-11-08" "2021-11-04" "2021-11-03"