Regex match for singular version BUT NOT plural in R

Question

I might be missing something very obvious but how can I write efficient code to get all matches of a singular version of a noun but NOT its plural? for example, I want to match

angel investor

angel

BUT NOT

angels

try angels

If I try

grep("angel ", string)

Then a string with JUST the word angel won't match.

Please help!

"angel\s?" ? is part of the pattern, which means optional space character — rootkonda, Aug 01 '20 at 12:57
Do you want to match **only** the word `angel`? Or some other words also? Does `\bangel\b` work for you? — Toto, Aug 01 '20 at 14:03

score 0 · Answer 1 · answered Aug 01 '20 at 14:12

You can try the following approach. It still believe there are other excellent ways to solve this problem.

df <- data.frame(obs = 1:4, words = c("angle", "try angles", "angle investor", "angles"))

df %>% 
  filter(!str_detect(words, "(?<=[ertkgwmnl])s\\b"))
#     obs        words
# 1   1          angle
# 2   3 angle investor

score 0 · Accepted Answer · answered Aug 01 '20 at 14:22

0

Use word-boundary markers \\b:

x <- c("angel investor", "angel","angels", "try angels")

grep("\\bangel\\b", x, value = T)
[1] "angel investor" "angel"

answered Aug 01 '20 at 14:22

Chris Ruehlemann

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Regex match for singular version BUT NOT plural in R

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