Count unique string patterns in a row

Question

i have a following example:

dat <- read.table(text="index  string
1      'I have first and second'
2      'I have first, first'
3      'I have second and first and thirdeen'", header=TRUE)


toMatch <-  c('first', 'second', 'third')

dat$count <- stri_count_regex(dat$string, paste0('\\b',toMatch,'\\b', collapse="|"))

dat

index                               string count
1     1              I have first and second     2
2     2                  I have first, first     2
3     3 I have second and first and thirdeen     2

I want to add to the dataframe a column count, which will tell me how many UNIQUE words does each row have. The desired output would in this case be

index                               string count
1     1              I have first and second     2
2     2                  I have first, first     1
3     3 I have second and first and thirdeen     2

Could you please give me a hint how to modify the original formula? Thank you very much

Answer 1

With base R you could do the following:

sapply(dat$string, function(x) 
    {sum(sapply(toMatch, function(y) {grepl(paste0('\\b', y, '\\b'), x)}))})

which returns

[1] 2 1 2

Hope this helps!