提取r因子中的单词

Question

I have a dataset like so:

df <- data.frame(
text = c("Update AV Line 204 to Los Angeles will be ...",
 "91 Line 700 to RiversideDowntown is delayed 15 minutes ...",
 "VC Line 102 to Los Angeles is delayed 1520 minutes ...",
 "Update AV Line 227 to Lancaster is terminated  Via Princessa ",
 "RIV Line 411 to Los Angeles is delayed 10 minutes ...",
 "SB Line 312 to San Bernardino is delayed up to ...",
 "SB Line 327 to Los Angeles is delayed up to 15..."), stringsAsFactors = T)

 df

and I need to extract key words in a new field so that the end product looks something like this:

> df
  text                                                            LinesExtracted
1 Update AV Line 204 to Los Angeles will be ...                   Line 204 to Los Angeles
2 91 Line 700 to RiversideDowntown is delayed 15 minutes ...      Line 700 to Riverside Downtown 
3 VC Line 102 to Los Angeles is delayed 1520 minutes ...          Line 102 to Los Angeles
4 UpdateAV Line 227 to Lancaster is terminated  Via Princessa     Line 227 to Lancaster 
5 RIV Line 411 to Los Angeles is delayed 10 minutes ...           Line 411 to Los Angeles
6 SB Line 312 to San Bernardino is delayed up to ...              Line 312 to San Bernardino
7 SB Line 327 to Los Angeles is delayed up to 15...               Line 327 to Los Angeles

Thanks.

Answer 1

Since regex can be difficult to read, I have split it into steps:

df$LinesExtracted <- gsub("^.*Line","Line",df$text)
df$LinesExtracted <- gsub(" will be .*$","",df$LinesExtracted)
df$LinesExtracted <- gsub(" is .*$","",df$LinesExtracted)
df$LinesExtracted <- gsub("([a-z])([A-Z])","\\1 \\2",df$LinesExtracted,perl=TRUE)