obtaining first word in the string [duplicate]

问题

This question already has answers here:

Extract first word from a column and insert into new column [duplicate] (3 answers)

Closed 2 years ago.

I would like to extract the first string from a vector. For example,

 y<- c('london/hilss', 'newyork/hills', 'paris/jjk')

I want to get the string before the symbol"/" i.e.,

  location 
  london
  newyork
  paris

回答1:

A very simple approach with gsub

gsub("/.*", '', y)
[1] "london"  "newyork" "paris"

回答2:

Your example is simple, for a more general case like

y<- c('london/hilss', 'newyork.hills', 'paris-jjk')

maybe following will do better?

stringr::str_extract(y, '\\w*')

回答3:

stringr::str_extract(a, '\\b*')

回答4:

This regex will also work fine.

Regex: ^[^\/]+

It will start matching from beginning of string until a / is found.

^ outside character class [] is anchor for beginning of string.

While ^ inside character class means negated character class.

Regex101 Demo

来源：https://stackoverflow.com/questions/43900073/obtaining-first-word-in-the-string