R：在向量列表中查找唯一的向量

Question

I have a list of vectors

list_of_vectors <- list(c("a", "b", "c"), c("a", "c", "b"), c("b", "c", "a"), c("b", "b", "c"), c("c", "c", "b"), c("b", "c", "b"), c("b", "b", "c", "d"), NULL)

For this list I would like to know which vectors are unique in terms of their elements. That is, I would like the following output

[[1]]
[1] "a" "b" "c"

[[2]]
[1] "b" "b" "c"

[[3]]
[1] "c" "c" "b"

[[4]]
[1] "b" "b" "c" "d"

[[5]]
[1] NULL

Is there a function in R for performing this check? Or do I need do a lot of workarounds by writing functions?

My current not so elegant solution:

# Function for turning vectors into strings ordered by alphabet
stringer <- function(vector) {
  if(is.null(vector)) {
    return(NULL)
  } else {
    vector_ordered <- vector[order(vector)]
    vector_string <- paste(vector_ordered, collapse = "")
    return(vector_string)
  }
}

# Identifying unique strings
vector_strings_unique <- unique(lapply(list_of_vectors, function(vector) 
stringer(vector)))
vector_strings_unique 

[[1]]
[1] "abc"

[[2]]
[1] "bbc"

[[3]]
[1] "bcc"

[[4]]
[1] "bbcd"

[[5]]
NULL

# Function for splitting the strings back into vectors 
splitter <- function(string) {
  if(is.null(string)) {
    return(NULL)
  } else {
    vector <- unlist(strsplit(string, split = ""))
    return(vector)
  }
}

# Applying function
lapply(vector_strings_unique, function(string) splitter(string))

[[1]]
[1] "a" "b" "c"

[[2]]
[1] "b" "b" "c"

[[3]]
[1] "c" "c" "b"

[[4]]
[1] "b" "b" "c" "d"

[[5]]
[1] NULL

It does the trick and could be rewritten as a single function, but there must be a more elegant solution.

Answer 1

We can sort the list elements, apply duplicated to get a logical index of unique elements and subset the list based on that

list_of_vectors[!duplicated(lapply(list_of_vectors, sort))]
#[[1]]
#[1] "a" "b" "c"

#[[2]]
#[1] "b" "b" "c"

#[[3]]
#[1] "c" "c" "b"

#[[4]]
#[1] "b" "b" "c" "d"

#[[5]]
#NULL