Extract last word in a string after comma if there are multiple words else the first word

问题

I have data where the words as follows

 location<- c("xyz, sss, New Zealand", "USA", "Pris,France")
 id<- c(1,2,3)
 df<-data.frame(location,id)

I would like to extract the country name from the data. The tricky part is if i extract just the last word then I will have only one record (France).

library(stringr)
df$country<- word(df$location,-1)

Any ideas on how to extract country data from this data?

 id  location                      country
  1   xyz, sss, New Zealand        New Zealand
  2   USA                          USA
  3   Pris,France                  France

回答1:

You can try sub

 df$country <- sub('.*,\\s*', '', df$location)
 df$country
 #[1] "New Zealand" "USA"         "France"   

Or

 library(stringr)
 str_extract(df$location, '\\b[^,]+$')
 #[1] "New Zealand" "USA"         "France"     

回答2:

stringi solution:

require(stringi)
location<- c("xyz, sss, New Zealand", "USA", "Pris,France")
stri_trim(stri_match_first_regex(location, "(^|,)([^,]*?)$")[,3])
## [1] "New Zealand" "USA"         "France"  

stri_trim removes unnecessary spaces before/after country name.

来源：https://stackoverflow.com/questions/31148828/extract-last-word-in-a-string-after-comma-if-there-are-multiple-words-else-the-f