How to properly use capture reference in R using grepl function

Asked Jun 20 '16 at 16:49

Active Jun 20 '16 at 16:50

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I'm trying to find all the set of strings with two consecutive repeated words like "the the", "air air". I'm using grepl function in R and my code look like this:

grepl("[a-zA-Z]+\\s+\1", c("the the", "Humbert Humbert", "air water"), perl = TRUE)

[1] FALSE FALSE FALSE

The strings "the the" and "air air" should return TRUE but it returns FALSE which is I don't know why.

Is there anything missing in my code? Please help me.

edited Jun 20 '16 at 16:50

lmo

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asked Jun 20 '16 at 16:49

Devonshire

`grepl("([a-zA-Z]+)\\s+\\1", c("the the", "Humbert Humbert", "air water"))` – r2evans Jun 20 '16 at 16:56
You are close. In R you need to use \\1 instead of \1 (two backslashes). Also you are missing the capturing parentheses. – lmo Jun 20 '16 at 16:56
Thank you so much it works fine. – Devonshire Jun 21 '16 at 02:30

How to properly use capture reference in R using grepl function

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