I don't really know if the title is correct, but the question is quite simple:
I have a value and a key.
The key is as follows:
"one.two.three"
Now, how can I set this hash:
params['one']['two']['three'] = value
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This is definitely a duplicate; look hard on the site and you'll find more answers.Phrogz– Phrogz2012-01-26 11:59:55 +00:00Commented Jan 26, 2012 at 11:59
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3Your comment would be useful if it included a link.Misha Moroshko– Misha Moroshko2012-01-27 02:19:32 +00:00Commented Jan 27, 2012 at 2:19
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3 Answers
You can try to do it with this code:
keys = "one.two.three".split '.' # => ["one", "two", "three"]
params = {}; value = 1; i = 0; # i is an index of processed keys array element
keys.reduce(params) { |hash, key|
hash[key] = if (i += 1) == keys.length
value # assign value to the last key in keys array
else
hash[key] || {} # initialize hash if it is not initialized yet (won't loose already initialized hashes)
end
}
puts params # {"one"=>{"two"=>{"three"=>1}}}
answered Jan 26, 2012 at 9:37
Aliaksei Kliuchnikau
13.7k4 gold badges63 silver badges74 bronze badges
Use recursion:
def make_hash(keys)
keys.empty? ? 1 : { keys.shift => make_hash(keys) }
end
puts make_hash("one.two.three".split '.')
# => {"one"=>{"two"=>{"three"=>1}}}
1 Comment
tokland
this is ok to create a new hash, but I thought the OP wanted to update an existing hash...
You can use the inject method:
key = "one.two.three"
value = 5
arr = key.split(".").reverse
arr[1..-1].inject({arr[0] => value}){ |memo, i| {i => memo} }
# => {"one"=>{"two"=>{"three"=>5}}}
5 Comments
Tim Baas
So can I make this a one liner like so:
hash = key.split(".").reverse[1..-1].inject({arr[0] => value}){ |memo, i| {i => memo}} ?
DNNX
+Tim,
arr is not defined in your one linerDNNX
"one.two.three".split('.').reverse.inject(5) { |x, y| { y => x } } outputs => {"one"=>{"two"=>{"three"=>5}}}Tim Baas
That looks very nice, but how can I do it on an existing hash ?
BooVeMan
This is so elegant, it should be the accepted answer!