## Sorting

I’ve been trying to sort a mixed array in Ruby the shortest way. Each element of the array by itself is a mixed array of a number and and a hash:

a = [ [0, {:a=>"31", :b=>"21"}], [1, {:a=>"32", :b=>"11"}], [1, {:a=>"25", :b=>"19"}], [0, {:a=>"12", :b=>"10"}] ] #sort by first item of each row (number) a.sort{|x,y| x[0] y[0]} #sort by the first item in the hash a.sort{|x,y| x[1][:a] y[1][:a]} |

Note: I initially posted this as a question on Stackoverflow and got different but correct answers.

## Finding common elements

To find common elements between a number of arrays, simply add them to a hash and use the `&`

operator, which creates a new array from two existing arrays containing only elements that are common to both arrays, omitting duplication. (See Techtopia)

a1 = [[1, 2, 3], [1, 2, 2], [2, 2, 3], [3, 2, 1]] a2 = [[1, 2, 1], [1, 2, 2], [2, 2, 4], [3, 2, 1], [1, 2, 3]] a3 = [[1, 2, 3], [1, 2, 2], [2, 2, 3], [3, 2, 1], [2, 2, 2]] hash = {i1: a1, i2: a2, i3: a3} common = hash.values.inject{|x, y| x & y} |

What I can do with Ruby in just one line fascinates me.

a1 & a2 & a3 is the better way to do it ruby.