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Groups > comp.lang.ruby > #2722

Re: hash of arrays

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Define hash of hashes this way

#Using a default hash.

foo = Hash.new { |hash, key| hash[key] = Hash.new }

foo["a"][1] = "one"
foo["a"][2] = "a two"
foo["b"][3] = "b three"
foo["a"][4] = "b four"

p foo["a"][1]
p foo["a"][4]
p foo["a"].size
foo["a"].each {|x,y| p "#{x}  #{y}"}

David Sprague wrote:
> I'm wrote this code to bin a list of words by word-length:
>
> dict = Hash.new([])
>
> dict_file.each do |line|
>    line.chomp!()
>    dict[line.length]<<  line
> end
>
> expecting that I could avoid testing each time whether this was a new
> entry in the hash or not by just appending to the default, an empty
> array,
> if it is new.
>
> What happens is that the *same* array is assigned as the default value
> to all new entries so that all the hash entries finish with the same
> array of values.
>
> is there away to void having to write something like:
>
> if dict.key?(line.length)
>   dict[line.length]<<  line
> else
>    dict[line.length] = line
> end
>
> or the ternary equivalent in the inner loop?
>
> thanks,
>
> Dave
>
>    

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hash of arrays David Sprague <david.sprague@gmail.com> - 2011-04-12 20:06 -0500
  Re: hash of arrays Roger Braun <roger@rogerbraun.net> - 2011-04-12 20:27 -0500
    Re: hash of arrays Roger Braun <roger@rogerbraun.net> - 2011-04-12 20:57 -0500
  Re: hash of arrays Tom Reilly <w3gat@nwlagardener.org> - 2011-04-12 20:52 -0500
  Re: hash of arrays jake kaiden <jakekaiden@yahoo.com> - 2011-04-12 22:05 -0500
  Re: hash of arrays botp <botpena@gmail.com> - 2011-04-12 22:05 -0500
  Re: hash of arrays "WJ" <w_a_x_man@yahoo.com> - 2011-04-17 16:37 +0000

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