I need to transform ["a", "b", "c", "d"] to {:a => {:b => {:c => "d" }}} ?
Any ideas ?
Thanks
4 Answers
funny
ruby-1.8.7-p174 > ["a", "b", "c", "d"].reverse.inject{|hash,item| {item.to_sym => hash}}
=> {:a=>{:b=>{:c=>"d"}}}
Comments
I like it:
class Array
def to_weird_hash
length == 1 ? first : { first.to_sym => last(length - 1).to_weird_hash }
end
end
["a", "b", "c", "d"].to_weird_hash
What do you think?
4 Comments
Steve Weet
What version of ruby is this valid for?
Steve Weet
OK. I'm getting undefined method
from in both 1.8.7 and 1.9.2
jordinl
I'm doing it now with irb and it's not working, before I did it in script/console. Apparently the method Array#from doesn't exist... :S
Steve Weet
Sounds like it is a ROR Monkeypatch.
If you need to do it for exactly 4 elements, it's easy enought to just write it out (and quite readable too)
>> A=["a", "b", "c", "d"]
=> ["a", "b", "c", "d"]
>> {A[0].to_sym => {A[1].to_sym => {A[2].to_sym => A[3]}}}
=> {:a=>{:b=>{:c=>"d"}}}
Otherwise, this will work for variable length arrays
>> ["a", "b", "c", "d"].reverse.inject(){|a,e|{e.to_sym => a}}
=> {:a=>{:b=>{:c=>"d"}}}
>> ["a", "b", "c", "d", "e", "f"].reverse.inject(){|a,e|{e.to_sym => a}}
=> {:a=>{:b=>{:c=>{:d=>{:e=>"f"}}}}}
3 Comments
retro
I need it with more than one element.
John La Rooy
@retro, not sure what you mean by more than one element. I added a way to do it with variable length arrays
retro
I meant I have more than one element in input array. Also nice solution.
I figured it out with help on IRC.
x = {}; a[0..-3].inject(x) { |h,k| h[k.to_sym] = {} }[a[-2].to_sym] = a[-1]; x
Second way with recursive (better)
def nest(a)
if a.size == 2
{ a[0] => a[1] }
else
{ a[0] => nest(a[1..-1]) }
end
end
Comments
{:a => {:b => {:c => "d" }}}rather than{:a => :b, :c => :d}?