CODEWITHSUNDEEP
regexr
SalimK
SalimK

Reputation: 380

How to find the longest string in a text using regex in R

Given a string x, i can count the number of words (length) in this string using gregexpr("[A-Za-z]\w+", x) . 

> x<-"\n\n\n\n\n\nMasters Publics\n\n\n\n\n\n\n\n\n\n\n\n\nMasters Universitaires et Prives au Maroc\n\n\n\n\n\n\n\n\\n\n\n\n\nMasters Par Ville\n\n\n\n\n\n\n\n\n\n\n\n\n"
> sapply(gregexpr("[A-Za-z]\\w+", x), function(x) sum(x > 0))
[1] 11

However, how can i retrieve the number of words in the longest attached string (with space and not \n), using regex under R environnent

in this example it would be "Masters Universitaires et Prives au Maroc" which length is 6 .

Thanks in Advance .

Upvotes: 3

Views: 1796

Answers (2)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 627101

I would solve it with

x <- "\n\n\n\n\n\nMasters Publics\n\n\n\n\n\n\n\n\n\n\n\n\nMasters Universitaires et Prives au Maroc\n\n\n\n\n\n\n\n\\n\n\n\n\nMasters Par Ville\n\n\n\n\n\n\n\n\n\n\n\n\n"
max(nchar(gsub("[^ ]+", "", unlist(strsplit(trimws(x), "\n+"))))) + 1

Split a trimmed string into lines, unlist the result, remove all characters other than a space, get the longest item and add one. The [^ ]+ is a regex that matches one or more (due to the + quantifier) characters other than (as [^...] is a negated character class) a space.

See IDEONE demo.

Upvotes: 2

PereG
PereG

Reputation: 1846

Load the package

library(stringr)

Create a new dataset, extracting and splitting the phrases

data <- unlist(str_split(x, pattern="\n", n = Inf))
index <- lapply(data, nchar)
index <- index !=0
# extract the maximum length of the phrase

max(sapply(gregexpr("\\W+", data[index]), length) + 1)
[1] 6

# just checking
data[index]
[1] "Masters Publics"                          
[2] "Masters Universitaires et Prives au Maroc"
[3] "\\n"                                      
[4] "Masters Par Ville"

Upvotes: 1

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