In Ruby, what is the most expressive way to map an array in such a way that certain elements are modified and the others left untouched?
This is a straight-forward way to do it:
old_a = ["a", "b", "c"] # ["a", "b", "c"]
new_a = old_a.map { |x| (x=="b" ? x+"!" : x) } # ["a", "b!", "c"]
Omitting the "leave-alone" case of course if not enough:
new_a = old_a.map { |x| x+"!" if x=="b" } # [nil, "b!", nil]
What I would like is something like this:
new_a = old_a.map_modifying_only_elements_where (Proc.new {|x| x == "b"})
do |y|
y + "!"
end
# ["a", "b!", "c"]
Is there some nice way to do this in Ruby (or maybe Rails has some kind of convenience method that I haven't found yet)?
CLOSED:
Thanks everybody for replying. While you collectively convinced me that it's best to just use map
with the ternary operator, some of you posted very interesting answers!