有更有效的方法吗？如果没有字符串,我怎么能这样做？
txt <- "I want to extract the words between this and that,this goes with that,this is a long way from that"
library(stringr)
w_start <- "this"
w_end <- "that"
pattern <- paste0(w_start,"(.*?)",w_end)
wordsbetween <- unlist(str_extract_all(txt,pattern))
gsub("^\\s+|\\s+$","",str_sub(wordsbetween,nchar(w_start)+1,-nchar(w_end)-1))
[1] "and" "goes with" "is a long way from"
这是我在qdap中使用的方法：
使用qdap：
library(qdap) genXtract(txt,"this","that") ## > genXtract(txt,"that") ## this : that1 this : that2 this : that3 ## " and " " goes with " " is a long way from "
没有添加包：
regmatches(txt,gregexpr("(?<=this).*?(?=that)",txt,perl=TRUE))
## > regmatches(txt,perl=TRUE))
## [[1]]
## [1] " and " " goes with " " is a long way from "
