Module: Enumerable

Defined in:
lib/lxa_core_extensions/enumerable.rb

Instance Method Summary collapse

Instance Method Details

#build_hash(hsh_or_action = {}) ⇒ Object

shorthand for the common idiom of using inject to populate a hash from an Enumerable

[[1,2],[3,4],[5,6]].build_hash        #=> {1=>2, 3=>4, 5=>6}
[[1,2],[3,4],[5,6]].build_hash(:last) #=> {2=>[1,2], 4=>[...],...}

[1,2,3].build_hash { |h,k| h[k] = k } #=> {1=>1, 2=>2, 3=>3}

# the last example is identical to:

[1,2,3].inject({}) { |h,k| h[k] = k; h }



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# File 'lib/lxa_core_extensions/enumerable.rb', line 15

def build_hash(hsh_or_action = {})
  if block_given?
    raise ArgumentError if hsh_or_action.is_a?(Symbol)

    inject(hsh_or_action) do |h,*args|
      yield h, *args
      h
    end
  else
    hsh, action = *if hsh_or_action.is_a?(Symbol)
                     [{}, hsh_or_action]
                   else
                     [hsh_or_action, nil]
                   end

    if action
      build_hash(hsh) { |h,v| k = v.send(action); h[k] = v }
    else
      build_hash(hsh) { |h,(k,v)| h[k] = v }
    end
  end
end

#tally ⇒ Object 



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# File 'lib/lxa_core_extensions/enumerable.rb', line 38

def tally
  group_by { |x| x }.map { |k,v| [v.length, k] }
end