Problems for Written

1pets = [['cat', 'henning', 10], ['dog', 'rock', 15], ['dog', 'scud', 90]]

• given an array of pets, return the total weight of dogs in the array

Another problem to solve with the same dataset would be: #

• process the array of pets to return a hash with the count of each species, e.g.

1{ 'cat' => 1, 'dog' => 2 }

shallow vs. deep copy #

 1a1 = [1, 2, 3, [4, 5]]
 2a2 = a1.dup
 3a3 = a1.map do |el|
 4  el.dup
 5end
 6
 7p a1.object_id == a2.object_id
 8
 9a1.each_index do |idx|
10  p a1[idx].object_id == a2[idx].object_id
11end

other notes #

• .equal? compares the object id's of the objects
  Eg: a1.equal?(a2) where a1 and a2 are arrays

• experiment with pairs of operations like iterate + transform on nested/complex data structures

• iterate, transform, select, reduce(#any? and #all? are also reduce operations)