Make every other vowel uppercase in R-CodePudding

Given a lower case string. Ex:

s <- 'abcdefghijklmnopqrstuvwxyz'

The goal is to make every other vowel in the string an uppercase.

Desired output here:

abcdEfghijklmnOpqrstuvwxyz

As you can see, since all vowels where used in order, e and o where uppercase.

There are only lowercase characters in the strings in all cases.

For aieou, the desired output is:

aIeOu

How could I do this?

I tried:

s[unlist(strsplit(s, '')) %in% c('a', 'e', 'i', 'o', 'u')] <- toupper(s[unlist(strsplit(s, '')) %in% c('a', 'e', 'i', 'o', 'u')])

But no avail.

CodePudding user response：

It's not a one-liner, but:

s <- 'abcdefghijklmnopqrstuvwxyz'

as_list <- unlist(strsplit(s, ''))
vowels <- as_list %in% c('a', 'e', 'i', 'o', 'u')
every_other_index <- which(vowels)[c(FALSE, TRUE)]

as_list[every_other_index] <- toupper(as_list[every_other_index])

print(paste(as_list, collapse=''))

gives:

[1] "abcdEfghijklmnOpqrstuvwxyz"

(Use of which taken from this question; use of c(FALSE, TRUE)] from here.)

CodePudding user response：

Using gsub, Replacement

s <- 'abcdefghijklmnopqrstuvwxyz'

gsub('(e|o)', '\\U\\1', s, perl=TRUE)
# [1] "AbcdEfghIjklmnOpqrstUvwxyz"

gsub('(e|o)', '\\U\\1', 'Hello World', perl=TRUE)
# [1] "HEllO WOrld"