debug01.rb

list = {'yvr' => 'Vancouver', 'yba' => 'Banff', 'yyz' => 'Toronto', 'yxx' => 'Abbotsford', 'ybw' => 'Calgary'}

# Why is it returning nil instead of first element of the list above
# p list[0] treats 0 as a key, not an integer index.
# we can call the first element like so, assuming we want the value.

#p list.values[0]

# if we want the key, we can do it like so:

# p list.keys[0]

# but, again assuming we want 'Vancouver' we should probably call
# it by the key instead:

p list['yvr']

debug02.rb

def average(numbers=[])
  sum = 0
  numbers.each do |num|
      sum += num.to_f 
  end
  sum / (numbers.size - numbers.count(nil)) unless numbers.size == 0
end

## TEST HELPER METHOD
def test_average(array=[])
  print "avg of #{array.inspect}: "
  result = average(array)
  p result
end

## TEST CODE
test_average([4,5,6]) # => 5
test_average([15,5,10]) # => 10

# Should treat string like number
test_average([15,'5',10]) # => 10

# Should show decimal value
test_average([10, 5]) # => 7.5 instead of just 7

# Watch out! Even tests can have bugs!
test_average([9, 5, 7]) #=> 7

# Empty set should return nil, not throw an error
test_average([]) # => nil

# Non-existent set should return nil
test_average() # => nil

# BONUS: Should ignore nils in the set
test_average([9,6,nil,3]) # => 6
  

debug03.rb

def sum(list)
  total = 0
  list.each do |ele|
    total += ele
  end
  total
end

list1 = [16,21,31,42,55]
# 1. The following should return 165 instead of an error

# puts sum(list1)

# 2. How would you refactor it using an enumerable method other than each? Examples of enumerables: map, select, inject, reject, detect.
def sum_alt(list)
  list.inject {|sum, i| sum + i}
end

puts sum_alt(list1)

debug04.rb

def char_count(list)
  letters = Hash.new(0)
  list.each do |word|
    word.split('').each { |letter| letters[letter] += 1 }
  end
  letters
end

# Why the long face(error)? 
# 1. This should return count of each letter in the list
# ex: { "a" => 4, "p" => 3, "l" => 1  ...}

puts char_count(['apples', 'oranges', 'hipsters', 'are', 'same'])

# A: caused an error when the letter was not already present as a key.

# 2. What are the improvements you can do to above code?

# A: added default value 0 to prevent error, which has the added benefit
#    of allowing us to check the count of a letter which is not present in
#    the original array and get the correct answer: 0.

error_example.rb

def method1
  method2
end

def method2
  method3
end

def method3(a)
  puts a
end

method1