CODEWITHSUNDEEP
rregexstringstringr
Manu Sharma
Manu Sharma

Reputation: 1739

str_extract: Extracting exactly nth word from a string

I know this question has been asked at several places, but I didnt see a precise answer to this.

So I am trying to extract exactly the 2nd word from a string("trying to") in R with the help of regex. I do not want to use unlist(strsplit) 

sen= "I am trying to substring here something, but I am not able to"

str_extract(sen, "trying to\\W*\\s+((?:\\S+\\s*){2})")

Ideally I want to get "here" as an output, but I am getting "trying to substring here"

Upvotes: 7

Views: 8893

Answers (5)

Nettle
Nettle

Reputation: 3321

str_split is sometimes a popular choice. Call the nth word using [1,2], which returns the second word, [1,3] for the third, and so forth.

library(stringr)

#Data
sen= "I am trying to substring here something, but I am not able to"

#Code
str_split(sen, boundary("word"), simplify = T)[1,2]
#> [1] "am"

Created on 2018-08-16 by the reprex package (v0.2.0).

Upvotes: 1

Sotos
Sotos

Reputation: 51592

Since you also tagged stringr, I will post the word solution,

library(stringr)

word(sub('.*trying to ', '', sen), 2)
#[1] "here"

Upvotes: 5

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626845

You may actually capture the word you need with str_match:

str_match(sen, "trying to\\W+\\S+\\W+(\\S+)")[,2]

Or

str_match(sen, "trying to\\s+\\S+\\s+(\\S+)")[,2]

Here, \S+ matches 1 or more chars other than whitespace, and \W+ matches one or more chars other than word chars, and \s+ matches 1+ whitespaces.

Note that in case your "words" are separated with more than whitespace (punctuation, for example) use \W+. Else, if there is just whitespace, use \s+.

The [,2] will access the first captured value (the part of text matched with the part of the pattern inside the first unescaped pair of parentheses).

Upvotes: 3

akrun
akrun

Reputation: 887118

We can use sub

sub("^.*\\btrying to\\s+\\w+\\s+(\\w+).*", "\\1", sen)
#[1] "here"

Upvotes: 2

d.b
d.b

Reputation: 32548

You could use strsplit. First separate sen into two parts at "trying to " and then extract second word of the second part.

sapply(strsplit(sen, "trying to "), function(x) unlist(strsplit(x[2], " "))[2])
#[1] "here"

Upvotes: 1

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