R - 用模式提取单词并将其替换为反向顺序的单词

Question

I have the following string vector of phrases.

x <- c("I ate apples 100 already. No apples 50 uhmm" , "He has apples 20 yeah")

And I expect the result to be:

"I ate 100 apples already. No 50 apples uhmm" , "He has 20 apples yeah"

I want to replace de following pattern "apples \\\\d{1,4}" by the reverse order of the found words, in each element of the vector.

Any suggestions?

Answer 1

We can do this with gsub to capture words as a group ( \\\\w+ ) followed by space and then capture the numbers as another group, replace it with the backreference in reverse order

gsub("(\\w+)\\s+(\\d+)", "\\2 \\1", x)
#[1] "I ate 100 apples already. No 50 apples uhmm" "He has 20 apples yeah"