Extract all occurrences of characters that differ between two strings

Question

I have used adist to calculate the number of characters that differ between two strings:

a <- "#IvoryCoast TENNIS US OPEN Clément «Un beau combat» entre Simon et Cilic"
b <- "Clément «Un beau combat» entre Simon et Cilic"
adist(a,b) # result 27

Now I would like to extract all the occurrences of those characters that differ. In my example, I would like to get the string "#IvoryCoast TENNIS US OPEN " .

I tried and used:

paste(Reduce(setdiff, strsplit(c(a, b), split = "")), collapse = "")

But the obtained result is not what I expected!

#IvysTENOP

Answer 1

For this case, you could use gsub.

> a <- "#IvoryCoast TENNIS US OPEN Clément «Un beau combat» entre Simon et Cilic"
> b <- "Clément «Un beau combat» entre Simon et Cilic"
> gsub(b, "", a)
[1] "#IvoryCoast TENNIS US OPEN "

Answer 2

You can do, based on the paste/reduce solution:

paste(Reduce(setdiff, strsplit(c(a, b), split = " ")), collapse = " ")
#[1] "#IvoryCoast TENNIS US OPEN"

Or, if you want to get separated items, with setdiff and strsplit :

setdiff(strsplit(a," ")[[1]],strsplit(b," ")[[1]])
#[1] "#IvoryCoast" "TENNIS"      "US"          "OPEN"