R tidyverse substring words

sentences <- c("Jane saw a cat", "Jane sat down")
word(sentences, 1)#> [1] "Jane" "Jane"word(sentences, 2)#> [1] "saw" "sat"word(sentences, -1)#> [1] "cat"  "down"word(sentences, 2, -1)#> [1] "saw a cat" "sat down" 
# Also vectorised over start and end
word(sentences[1], 1:3, -1)#> [1] "Jane saw a cat" "saw a cat"      "a cat"         word(sentences[1], 1, 1:4)#> [1] "Jane"           "Jane saw"       "Jane saw a"     "Jane saw a cat"
# Can define words by other separators
str <- 'abc.def..123.4568.999'
word(str, 1, sep = fixed('..'))#> [1] "abc.def"word(str, 2, sep = fixed('..'))#> [1] "123.4568.999"