[R] access list component names with lapply

Kjetil Brinchmann Halvorsen kjetilbrinchmannhalvorsen at gmail.com
Wed Apr 19 22:32:10 CEST 2006


Thomas Girke wrote:
> I have a question regarding accessing the names of list
> components when applying a function with lapply.
> 
> Here is an example that demonstrates what I'd like to do.
> 
> I have a list like this one:
> 	
> 	mylist <- list(a=letters[1:10], b=letters[10:1], c=letters[1:3])

This is how I am doing this:
mapply(functuion(x,y)myfun(x, y),x, names(x)))

Kjetil

> 
> Now I would like to append the names of the list components to their
> corresponding vectors with the c() function. I thought this could
> be done like in the following command, but it doesn't:
> 
> 	lapply(mylist, function(x) { c(names(x), x)  } )
> 
> I know how to do this in a for loop, but lapply runs so much faster over
> large lists.
> 	
> Any help on this simple problem will be highly appreciated.
> 
> Thomas
> 
>




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