Lets say i have a string and i only want unique words in the sentence as separate elements
a = "an apple is an apple"
word <- function(a){
words<- c(strsplit(a,split = " "))
return(unique(words))
}
word(a)
This returns
[[1]]
[1] "an" "apple" "is" "an" "apple"
and the output im expecting is
'an','apple','is'
what im doing wrong? really appreciate any help
Cheers!
Another possible solution, based on stringr::str_split:
library(tidyverse)
a %>% str_split("\\s+") %>% unlist %>% unique
#> [1] "an" "apple" "is"
The problem is that wrapping strsplit(.) in c(.) does not change the fact that it is still a list, and unique will be operating at the list-level, not the word-level.
c(strsplit(rep(a, 2), "\\s+"))
# [[1]]
# [1] "an" "apple" "is" "an" "apple"
# [[2]]
# [1] "an" "apple" "is" "an" "apple"
unique(c(strsplit(rep(a, 2), "\\s+")))
# [[1]]
# [1] "an" "apple" "is" "an" "apple"
Alternatives:
If length(a) is always 1, then perhaps
unique(strsplit(a, "\\s+")[[1]])
# [1] "an" "apple" "is"
If length(a) can be 2 or more and you want a list of unique words for each sentence, then
a2 <- c("an apple is an apple", "a pear is a pear", "an orange is an orange")
lapply(strsplit(a2, "\\s+"), unique)
# [[1]]
# [1] "an" "apple" "is"
# [[2]]
# [1] "a" "pear" "is"
# [[3]]
# [1] "an" "orange" "is"
(Note: this always returns a list, regardless of the number of sentences in the input.)
if length(a) can be 2 ore more and you want a unique words across all sentences, then
unique(unlist(strsplit(a2, "\\s+")))
# [1] "an" "apple" "is" "a" "pear" "orange"
(Note: this method also works well when length(a) is 1.)