Ruby Tricks and Oddities

Just looked through Julio Santos’ “Ruby Things” on Speaker Deck and learned some quirkly little things about Ruby.

Creating hashes from arrays. 2 different outcomes:

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Hash[["one", 1], ["two", 2]]
=> {["one", 1]=>["two", 2]}

a=["one", 1], ["two",2]
=> [["one", 1], ["two", 2]]

Hash[a]
=> {"one"=>1, "two"=>2}

The zip method “converts any arguments to arrays, then merges elements of self with corresponding elements from each argument.” For example:

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a = [2, 5, 8]
b = [3, 6, 9]
[1, 4, 7].zip(a, b)
=> [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

Santos demonstrates that you can use zip to create hashes:

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keys = [:one, :two, :three]
values = [1, 2, 3]
zip = keys.zip(values)
=> [[:one, 1], [:two, 2], [:three, 3]]
Hash[zip]
=> {:one=>1, :two=>2, :three=>3}

And yesterday while wishing a collect_with_index method existed, my group discovered that you can combine each_with_index with collect!

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class Array
  def make_list
    self.each_with_index.collect do |german, index|
      "#{index+1}. #{german}"
    end
  end
end

array = ["eins", "zwei", "drei"]
array.make_list
 => ["1. eins", "2. zwei", "3. drei"]