Merge pull request realpython#71 from ybrenning/master

Fix typos and add comments to ch09

Author: dbader

ch09-lists-tuples-and-dictionaries/1-tuples-are-immutable-sequences.py

@@ -13,7 +13,7 @@
 
 
 # Exercise 3
-# unpack the tuple into three string and display them
+# Unpack the tuple into three strings and display them
 position1, position2, position3 = cardinal_numbers
 print(position1)
 print(position2)

ch09-lists-tuples-and-dictionaries/4-challenge-list-of-lists.py

@@ -24,7 +24,7 @@ def mean(values):
 def median(values):
  """Return the median value of the list `values`"""
  values.sort()
- # If the number of valus is odd,
+ # If the number of values is odd,
  # return the middle value of the list
  if len(values) % 2 == 1:
  # The value at the center of the list is the value

ch09-lists-tuples-and-dictionaries/7-challenge-capital-city-loop.py

@@ -56,8 +56,11 @@
  "Wyoming": "Cheyenne",
 }
 
+# Pull random state and capital pair from the dict by casting to list of tuples
 state, capital = random.choice(list(capitals_dict.items()))
 
+# Game loop continues until the user inputs "exit"
+# or guesses the correct capital
 while True:
  guess = input(f"What is the capital of '{state}'? ").lower()
  if guess == "exit":

ch09-lists-tuples-and-dictionaries/9a-challenge-cats-with-hats.py

@@ -4,18 +4,30 @@
 
 def get_cats_with_hats(array_of_cats):
  cats_with_hats_on = []
+ # We want to walk around the circle 100 times
  for num in range(1, 100 + 1):
+ # Each time we walk around, we visit 100 cats
  for cat in range(1, 100 + 1):
+ # Determine whether to visit the cat
+ # Use modulo operator to visit every 2nd, 3rd, 4th,... etc.
  if cat % num == 0:
+ # Remove or add hat depending on
+ # whether the cat already has one
  if array_of_cats[cat] is True:
  array_of_cats[cat] = False
  else:
  array_of_cats[cat] = True
+
+ # Add all number of each cat with a hat to list
  for cat in range(1, 100 + 1):
- if cats[cat] is True:
+ if array_of_cats[cat] is True:
  cats_with_hats_on.append(cat)
+
+ # Return the resulting list
  return cats_with_hats_on
 
 
+# Cats contains whether each cat already has a hat on,
+# by default all are set to false since none have been visited
 cats = [False] * (100 + 1)
 print(get_cats_with_hats(cats))

ch09-lists-tuples-and-dictionaries/9c-challenge-cats-with-hats.py

@@ -4,17 +4,24 @@
 
 theCats = {}
 
+# By default, no cats have been visited
+# so we set every cat's number to False
 for i in range(1, 101):
  theCats[i] = False
 
+# Walk around the circle 100 times
 for i in range(1, 101):
+ # Visit all cats each time we do a lap
  for cats, hats in theCats.items():
+ # Determine whether or not we visit a cat
  if cats % i == 0:
+ # Add or remove the hat
  if theCats[cats]:
  theCats[cats] = False
  else:
  theCats[cats] = True
 
+# Print whether each cat has a hat
 for cats, hats in theCats.items():
  if theCats[cats]:
  print(f"Cat {cats} has a hat.")