Filling a list with for loop or Lapply - r

Question

This is my list:
mylist=dput(mylist)
list(list(
c(30, 50, 35, 25, 45),
c(40, 35, 35, 50, 45),
c(40, 20, 40, 50, 25),
),
list(
c(50, 50, 25, 40, 45, 40, 35, 40, 45, 20),
c(40, 35, 40, 40, 45, 30, 20, 50, 35, 25),
c(20, 30, 50, 35, 45, 40, 25, 50, 35, 50),
),
list(
c(45, 50, 25, 25, 30, 25, 35, 35, 35, 30, 50, 50, 30, 30, 20),
c(40, 20, 35, 35, 50, 20, 25, 30, 35, 20, 40, 20, 45, 30, 20),
c(50, 20, 25, 35, 35, 30, 50, 25, 40, 35, 45, 45, 35, 45, 25),
),
list(
c(50, 50, 50, 40, 20, 25, 50, 40, 50, 50, 45, 40, 30, 50, 35, 45, 50, 30,
35, 45),
c(45, 20, 25, 20, 25, 30, 20, 30, 45, 25, 50, 30, 30, 25, 50, 45, 20, 45, 45, 50),
c(20, 40, 50, 25, 40, 45, 25, 30, 20, 20, 35, 45, 20, 40, 50, 45, 40, 40, 45, 35),
),
list(
c(35, 25, 45, 20, 25, 30, 30, 35, 30, 40, 30, 20, 20, 30, 45, 40, 35, 35, 35, 35, 25, 45, 35, 20, 50),
c(50, 35, 30, 30, 35, 45, 45, 50, 25, 25, 40, 25, 50, 45, 25, 30, 30, 25, 45, 45, 30, 20, 50, 30, 30),
c(35, 40, 50, 25, 40, 45, 30, 25, 50, 25, 35, 50, 50, 50, 25, 50, 20, 50, 40, 25, 25, 35, 20, 20, 50),
)
)
)
mylist=dput(mylist)
list
(
list( c(30, 50, 35, 25, 45),
c(40, 35, 35, 50, 45),
c(40, 20, 40, 50, 25),
),
list(
c(50, 50, 25, 40, 45, 40, 35, 40, 45, 20),
c(40, 35, 40, 40, 45, 30, 20, 50, 35, 25),
c(20, 30, 50, 35, 45, 40, 25, 50, 35, 50),
), list(
c(45, 50, 25, 25, 30, 25, 35, 35, 35, 30, 50, 50, 30, 30, 20),
c(40, 20, 35, 35, 50, 20, 25, 30, 35, 20, 40, 20, 45, 30, 20),
c(50, 20, 25, 35, 35, 30, 50, 25, 40, 35, 45, 45, 35, 45, 25),
),
list(
c(50, 50,50, 40, 20, 25, 50, 40, 50, 50, 45, 40, 30, 50, 35, 45, 50, 30, 35, 45),
c(45, 20, 25, 20, 25, 30, 20, 30, 45, 25, 50, 30, 30, 25, 50, 45, 20, 45, 45, 50),
c(20, 40, 50, 25, 40, 45, 25, 30, 20, 20, 35, 45, 20, 40, 50, 45, 40, 40, 45, 35),
),
list(
c(35, 25, 45, 20, 25, 30, 30, 35, 30, 40, 30, 20, 20, 30, 45, 40, 35, 35, 35, 35, 25, 45, 35, 20, 50),
c(50, 35, 30, 30, 35, 45, 45, 50, 25, 25, 40, 25, 50, 45, 25, 30, 30, 25, 45, 45, 30, 20, 50, 30, 30),
c(35, 40, 50, 25, 40, 45, 30, 25, 50, 25, 35, 50, 50, 50, 25, 50, 20, 50, 40, 25, 25, 35, 20, 20, 50),
)))
I am facing two problems:
First: I can´t run this For Loop below:
resultlist<-vector(mode = "list", 5)
for (i in 1:6) {
for(k in 1:5) {
resultlist[[k]][[i]]<-mean(mylist[[k]][[i]])
}
}
It sends the message: Error in mylist[[k]][[i]] : subscript out of bounds
The second problem is actually a sugestion: My original for is much bigger (for example my i goes until 4828), to run a for with this 2 indexes (k and i) there are others functions that would let my code be more simple/efficient or in this situation the best to do is to keep with the for loop?

Answer 1

You are getting that error because the fourth element of mylist has only 5 sublists.
You could also do:
resultlist <- lapply(mylist, function(x) lapply(x, function(y) rep(mean(y), length(y))))
to get what you want.

Answer 2

In your case , your mylist[[4]] only have 5 element, so the error occur because you call the sixth element of it which does not exist.
If all the list elements are equal length, you can use expand.grid to find the all combination, and use sapply to execute the loop which is little bit faster than for
Try this :
list_len=length(mylist)
sub_list_len=6
combination<-expand.grid(1:sub_list_len,1:list_len)
temp_output<-apply(combination,1,function(x) mean( mylist[[x[2]]][[x[1]]] ))
resultlist<-split(temp_output,rep(1:list_len,each=sub_list_len)) %>% lapply(.,function(x) split(x,1:length(x)))
resultlist