Glenn
1/3/2009 4:15:00 AM
[Note: parts of this message were removed to make it a legal post.]
Hi,
Suppose I want to create a hash, which has a couple of elements with strings as the keys and the values of each of the elements were hashes themselves, and they each had a few elements, like this:
trt_hash = Hash.new( {} )
trt_hash['a'] = { :x => 0, :y => 0, :z => 0 }
trt_hash['b'] = { :x => 0, :y => 0, :z => 0 }
If I increment one of the values of the hash within the hash, like this, it works fine:
trt_hash['a'][:z] += 100
puts trt_hash['Hi'][:z] = 10
puts trt_hash.inspect
I get: {"a"=>{:z=>100, :x=>0, :y=>0}, "b"=>{:z=>0, :x=>0, :y=>0}}, which is what I expected.
But if I try to add another key to trt_hash and increment one of the keys of its hash, like this:
trt_hash['c'][:z] += 100
puts trt_hash.inspect
there is no error, but there is also no reference to the 'c' key when I print trt_hash.
Also, if I try this, I get an error:
trt_hash['a'][:w] += 100
puts trt_hash.inspect
The key above is 'a', which exists, but :w in the 'a' hash does not exist, so I get the following error:
undefined method `+' for nil:NilClass (NoMethodError)
I want to put able to add elements to trt_has at will and have them default to an empty hash, and I want to be able to modify the hash within the hash without predefining anything. I feel like this would work if I set up the hash and the hash within the hash with the proper defaults, but I do not know how to do that.
I thought if I defined trt_hash like this:
trt_hash = Hash.new( Hash.new(0))
I would be able to add any key to trt_hash and its value would have a default of an empty hash, and then I'd be able to add any element I wanted to the nested hash, and its default would be 0. But this does not seem to work.
Any suggestions?
Sorry if this email is unclear. If it is, please let me know and I will try to clarify.
Thanks!
Glenn