Extract first word from a column and insert into new column [duplicate]

问题

This question already has an answer here:

• Remove everything after space in string 4 answers

I have a dataframe below and want to extract the first word and insert it into a new column

Dataframe1:

COL1
Nick K Jones
Dave G Barros
Matt H Smith

Convert it to this:

Dataframe2:
COL1              COL2
Nick K Jones      Nick
Dave G Barros     Dave
Matt H Smith      Matt

回答1:

You can use a regex ("([A-Za-z]+)" or "([[:alpha:]]+)"or "(\\w+)") to grab the first word

Dataframe1$COL2 <- gsub("([A-Za-z]+).*", "\\1", Dataframe1$COL1)

回答2:

We can use function stringr::word:

library(stringr)

Dataframe1$COL2 <- word(Dataframe2$COL1, 1)

回答3:

The function strsplit can be useful

Dataframe1$COL2 <- strsplit(Dataframe1$COL1, " ")[[1]][1]

Then you can change the last bracketed number to select other parts from the string too.

来源：https://stackoverflow.com/questions/31925811/extract-first-word-from-a-column-and-insert-into-new-column