使用 R 从以表达式结尾的句子中提取所有单词

Question

suppose I have the next string:

"palavras a serem encontradas fazer-se encontrar-se, enganar-se"

How can I extract the words "fazer-se" "encontrar-se" "enganar-se"

I'm try o use stringr like

library(stringr)    
sentence <- "palavras a serem encontradas fazer-se encontrar-se, enganar-se"
str_extract_all(sentence, "se$")

I'd like this output:

[1] "fazer-se" "encontrar-se" "enganar-se"

Answer 1

We can specify the word boundary ( \\\\b ) and not the end ( $ ) of the string (there is only one match for that, ie at the end of the string) and we need to get the characters that are not a whitespace before the se substring, so use \\\\S+ ie one or more non-whitespace characters

library(stringr)
str_extract_all(sentence, "\\S+se\\b")[[1]]
#[1] "fazer-se"     "encontrar-se" "enganar-se"  

Answer 2

In base R, we can use gregexpr and regmatches :

regmatches(sentence, gregexpr('\\w+-se', sentence))[[1]]
#[1] "fazer-se"     "encontrar-se" "enganar-se"