CODEWITHSUNDEEP
rlist
Oscar Kjell
Oscar Kjell

Reputation: 1651

R turn each element in a vector into a list of lists

What is an efficient way to turn a list of elements into a list of lists with only one element in each list. See example data below:

#This vector (but with many more elements) I'd like to turn into a list of list with one element in each. 
vector <- c("element1", "element2", "element3")

# It should look like this: 
list_vector <- list("element1", "element2", "element3")

#This is old: and not really how I want it: 
 
 list_vector <- list(list("element1"), list("element1"), list("element1"))

Thanks in advance

Upvotes: 2

Views: 1240

Answers (2)

GKi
GKi

Reputation: 39737

Using as.list will be an efficient way to turn each element of a vector into a list.
As your list_vector is an unnamed list you can use as.list, lapply or sapply to turn each element of a vector into a list with only one element in each.

x <- as.list(vector)
y <- lapply(vector, identity)
z <- unname(sapply(vector,list))

Test for Equality:

identical(x, list_vector)
[1] TRUE
identical(y, list_vector)
[1] TRUE
identical(z, list_vector)
[1] TRUE

Benchmark

x <- c("element1", "element2", "element3")

bench::mark("as.list" = as.list(x)
          , "lapply" = lapply(x, identity)
          , "sapply" = unname(sapply(x, list)))
#  expression     min  median `itr/sec` mem_alloc `gc/sec` n_itr  n_gc total_time
#  <bch:expr> <bch:t> <bch:t>     <dbl> <bch:byt>    <dbl> <int> <dbl>   <bch:tm>
#1 as.list     1.19µs  1.76µs   493963.        0B     98.8  9998     2     20.2ms
#2 lapply      1.78µs  2.02µs   341163.        0B      0   10000     0     29.3ms
#3 sapply       9.6µs 10.94µs    81512.        0B     32.6  9996     4    122.6m```

Upvotes: 5

Daniel O
Daniel O

Reputation: 4358

you could use

lapply(vector,list)

Edit: for new desired output

sapply(vector,list)

Upvotes: 3

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