Regular Expressions

In many cases, first we will have to develop a regular expression. We can use http://www.regexr.com to do that.

Lets say we created this regular expression want|develop that will find rows where there is "want" or "develop" words.

We can use regular expressions with grep, grepl, sub, strsplit, regexpr, gregexpr and gsub functions.

grep function

> text <- "We want to develop new regular expression."
> grep("want|develop", text, value=TRUE)

[1] "We want to develop new regular expression."

More about regular expressions in R or here.