R - count matches between characters of one string and another, no replacement

Question

I have a keyword (e.g. \'green\') and some text (\"I do not like them Sam I Am!\").

I\'d like to see how many of the characters in the keyword (\'g\', \'r\',

Answer 1

The function pmatch() is great for this. Though it would be instinctual to use length here, length has no na.rm option. So to work around this nuisance, sum(!is.na()) is used.

keyword <- unlist(strsplit('greeen', ''))
text <- unlist(strsplit('idonotlikethemsamiam', ''))

sum(!is.na(pmatch(keyword, text)))

# [1] 3

keyword2 <- unlist(strsplit("red", ''))
sum(!is.na(pmatch(keyword2, text)))

# [1] 2

Answer 2

Perhaps you are looking to find the UNIQUE components of your keyword? Try:

keyword <- unique(strsplit('greeen','')[[1]])