CODEWITHSUNDEEP
arraysrlist
user4400727
user4400727

Reputation:

Determing the length from a list in R

I have a list where each element is an array. Example data:

set.seed(24)
data <- list(individual1 = array(rnorm(3 * 3 * 2, 60), 
  dim = c(3, 3, 2), dimnames = list(NULL, NULL, c("rep1", "rep2"))), 
 individual2 = array(rnorm(3 * 3 * 2, 60), dim = c(3, 3, 2), 
   dimnames = list(NULL, NULL, c("rep1", "rep2")) ) )

I would like to find the length of the entire list. However, when I use length, I get 2, whereas I want 4 because there are 4 arrays. Is there another way to determine length for my question? 

>length(data)
2

Upvotes: 2

Views: 1369

Answers (1)

Maurits Evers
Maurits Evers

Reputation: 50668

Like this?

sum(sapply(data, function(x) dim(x)[3]))
#[1] 4

Explanation: Your list in fact only contains 2 elements. The dimension of every list element is 

lapply(data, dim)
#$individual1
#[1] 3 3 2
#
#$individual2
#[1] 3 3 2

In other words, every list elements has 2 3x3 arrays. We can therefore get the total number of 3x3 arrays in the list by summing the number of 3x3 arrays from every list element.

Upvotes: 1

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