Combine lists while overriding values with same name in R

Question

I have two lists with named elements:

a <- list(a=1, b=2) b <- list(b=3, c=4) 

I want to combine these lists, so that any elements in a that have the same names will be overwritten by the list b, so I get this out:

list(a=1, b=3, c=4) 

I know I could do this in a loop, but is there a more compact way of doing this in R?

Answer 1

R has a built in function to do that modifyList

modifyList(a, b) 

Answer 2

Here's a simple solution:

# create new list newlist <- c(a,b)  # remove list element(s) newlist[!duplicated(names(newlist), fromLast = TRUE)] 

The result:

$a [1] 1  $b [1] 3  $c [1] 4 

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An even simpler solution with setdiff:

c(a[setdiff(names(a), names(b))], b)  $a [1] 1  $b [1] 3  $c [1] 4