In place sub-string reversal in R

Question

I have a string for example, abcdepzxtru

I want to reverse only a part of the string and I have the beginning and the ending indices of the substring, say 1 and 5, i.e. I need to reverse abcde part of abcedpzxtru and the output should be edcbapzxtru

I am not sure how to do this in R and googling around is not very helpful.

Follow the duplicate link to reverse a string and then you're down to just taking a substring using indices. — Tim Biegeleisen, Aug 29 '17 at 16:46

score 4 · Accepted Answer · answered Aug 29 '17 at 16:46

4

Using stringi...

library(stringi)
s <- "abcdepzxtru"

substr(s,1,5) <- stri_reverse(substr(s,1,5))

s
[1] "edcbapzxtru"

answered Aug 29 '17 at 16:46

Andrew Gustar

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score 2 · Answer 2 · answered Aug 29 '17 at 16:48

2

sapply(strsplit("abcdepzxtru", ""),
       function(x) paste(x[c(5:1, 6:length(x))], collapse = ""))
#[1] "edcbapzxtru"

answered Aug 29 '17 at 16:48

d.b

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score 2 · Answer 3 · answered Aug 29 '17 at 16:49

2

str <- "abcedpzxtru"
init <- 1
end <- 4
paste(c(sapply(end:init, (function(i) substr(str, i, i))), 
      substr(str,(end+1),nchar(str))), collapse = "", sep = "")

# [1] "ecbadpzxtru"

answered Aug 29 '17 at 16:49

Damiano Fantini

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In place sub-string reversal in R

3 Answers3