R-taking reverse of substring of strsplit sentence

Question

I have a sentence, ['this', 'is, 'my', house']. After splitting it by using "-"as a as separator,and reversing it to[ house, my, is, this], how do I access the last part of string? and join my and is together with house to form another sentence?

When you say " reverse of the last string" do you mean you want "esuoh"? — G5W, Mar 20 '17 at 23:55
@G5W, Yes, I need reverse of house and 'esuoh' should be the first word of the new sentence — rjrj, Mar 21 '17 at 00:04

score 1 · Answer 1 · answered Mar 21 '17 at 00:08

1

out <- strsplit(sentence, "-")
last <- out[length(out)]
flip <- rev(last)
word <- paste(flip, collapse='')

answered Mar 21 '17 at 00:08

DBD

86
3

@Rich, it is not giving me esuoh but it is giving me 'house' I tried it just now – rjrj Mar 21 '17 at 00:13

score 1 · Accepted Answer · answered Mar 21 '17 at 00:10

sentence <- c("this","is","my","house")
strsplit(sentence[4], split="")[[1]][nchar(sentence[4]):1]

This code might be a bit dense for a beginner to interpret. The [[1]] is necessary because the value of strsplit is always a list, even when it's just one vector of individual characters; the indexing extracts that vector. The indexing after that, [nchar(sentence[4]):1], reorders the letters in that vector backwards, from the last to the first, in this case c(5,4,3,2,1). The split="" argument causes the strsplit function to split the string at every possible point, i.e. between each character.

It worked! Thanks for the explanation too. – rjrj Mar 21 '17 at 00:22 — rjrj, Mar 21 '17 at 00:22

R-taking reverse of substring of strsplit sentence

2 Answers2