R中的Regmatches不起作用

Question

I am trying to add a column to a data set in R. The column should be the initials from a name column. I am trying to use lapply and passing in a function to get the initials - however, I can't get this regexp to work.

pattern <- "(\b[a-zA-Z])"
str<-"MICHAEL,  JENSON F"
m <- regexpr(pattern,str,perl=TRUE)
regmatches(str,m)

Returns character(0)

How can I have R return a list of matches of a string? I want regmatches to return MJ and F.

Answer 1

There are two problems: \\b must be escaped and you should use gregexpr instead of regexpr because the latter returns only the first match.

pattern <- "(\\b[a-zA-Z])"
str<-"MICHAEL,  JENSON F"
m <- gregexpr(pattern,str,perl=TRUE)
regmatches(str,m)[[1]]
# [1] "M" "J" "F"

Answer 2

只是想出了Stringr库。

str_match_all(str, "(\\b[a-zA-Z])[a-zA-Z]* ?")