CODEWITHSUNDEEP
r
Alexandros
Alexandros

Reputation: 333

naming elements inside list using lapply

I am learning how to accessing list elements using lapply and others to in complex lists. I need to set object names on certain levels but I am stuck at very beginning. So lets create list:

my_list=vector("list",3)#create empty list of 3 elements 
names(my_list)=c("1st.element","2nd.eleent","3rd.element")#set names(this is easy) 
my_list=lapply(my_list, function(x) x=vector("list",5))#each element is list consisting 5 elements

So now I want to set name each element. I know how to do this using for:

for(i in 1:length(my_list)){names(my_list[[i]])=paste(names(my_list[i]),1:length(my_list[[i]]),sep=".")}

Output of this loop is my desired output. How to achieve it? I tried different approaches with lapply the closest to code above is:

lapply(my_list[[i]],function(i)names(i)=paste(names(my_list[i]),1:length(my_list[[i]]),sep="."))

Please keep in mind I am still learning apply functions.

Upvotes: 4

Views: 1017

Answers (1)

akrun
akrun

Reputation: 886938

We can use Map to loop through the names of 'my_list' and the list itself, then use setNames to name the individual nested list elements

Map(function(x, y) setNames(x, paste0(y, seq_along(x)))
            , my_list,  names(my_list))

A similar option using tidyverse would be

library(purrr)
map2(my_list, names(my_list), ~ set_names(.x, paste0(.y, seq_along(.x))))

Or instead of map2, imap get the names of the list as .y (as @Moody_Mudskipper commented)

imap(my_list, ~ set_names(.x, paste0(.y, seq_along(.x))))

Upvotes: 3

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