19. Dictionary Methods

19.1. Summary of Dictionary Methods

19.1.1. Accessing Items

  • get(): Returns the value for a specified key if it exists, otherwise returns a default value.

  • items(): Returns a view object displaying a list of the dictionary’s key-value pairs.

  • keys(): Returns a view object displaying a list of all the keys in the dictionary.

  • values(): Returns a view object displaying a list of all the values in the dictionary.

19.1.2. Modifying Items

  • update(): Updates the dictionary with elements from another dictionary or an iterable of key-value pairs.

  • setdefault(): Returns the value of a specified key, inserting it with a default value if it doesn’t exist.

  • pop(): Removes the specified key and returns the corresponding value.

  • popitem(): Removes and returns a key-value pair from the dictionary in LIFO order.

19.1.3. Dictionary Operations

  • copy(): Returns a shallow copy of the dictionary.

  • clear(): Removes all items from the dictionary.

  • fromkeys(): Creates a new dictionary with keys from an iterable and values set to a specified value.

19.2. Accessing Items

19.2.1. get()

dict.get(key, default=None)

Returns the value for the specified key if the key is in the dictionary, otherwise returns the default value.

sample_dict = {'a': 1, 'b': 2, 'c': 3}
value = sample_dict.get('a')
print(value)
# Output is 1
value = sample_dict.get('d')
print(value)
# Output is None
value = sample_dict.get('d', 0)
print(value)
# Output is 0
The get method is often used since it avoids error messages that occur when a key doesn’t exist.
The code below uses dictionary key access, which accesses the value associated with a specific key in a dictionary using square brackets as in dict[key].
sample_dict = {'a': 1, 'b': 2, 'c': 3}
value = sample_dict['a']
print(value)
# Output is 1
value = sample_dict['d']
print(value)
# Output is Error message KeyError: 'd'

Tasks

  1. Write code to print the value of ‘y’ in the dictionary coordinates_dict = {‘x’: 10, ‘y’: 20, ‘z’: 30}.

  2. Write code to print the value of ‘banana’ in the dictionary fruits_dict = {‘apple’: ‘green’, ‘banana’: ‘yellow’, ‘cherry’: ‘red’}.

  3. Write code to print the value of ‘blue’ in the dictionary colors_dict = {‘red’: ‘#FF0000’, ‘green’: ‘#00FF00’, ‘blue’: ‘#0000FF’}.

  4. Write code to print the value of ‘dog’ in the dictionary animals_dict = {‘cat’: ‘meow’, ‘dog’: ‘woof’, ‘bird’: ‘tweet’}.

Write code to print the value of ‘y’ in the dictionary coordinates_dict = {‘x’: 10, ‘y’: 20, ‘z’: 30}.

coordinates_dict = {'x': 10, 'y': 20, 'z': 30}
value = coordinates_dict.get('y')
print(value)
# Output is 20

Write code to print the value of ‘banana’ in the dictionary fruits_dict = {‘apple’: ‘green’, ‘banana’: ‘yellow’, ‘cherry’: ‘red’}.

fruits_dict = {'apple': 'green', 'banana': 'yellow', 'cherry': 'red'}
value = fruits_dict.get('banana')
print(value)
# Output is 'yellow'

Write code to print the value of ‘blue’ in the dictionary colors_dict = {‘red’: ‘#FF0000’, ‘green’: ‘#00FF00’, ‘blue’: ‘#0000FF’}.

colors_dict = {'red': '#FF0000', 'green': '#00FF00', 'blue': '#0000FF'}
value = colors_dict.get('blue')
print(value)
# Output is '#0000FF'

Write code to print the value of ‘dog’ in the dictionary animals_dict = {‘cat’: ‘meow’, ‘dog’: ‘woof’, ‘bird’: ‘tweet’}.

animals_dict = {'cat': 'meow', 'dog': 'woof', 'bird': 'tweet'}
value = animals_dict.get('dog')
print(value)
# Output is 'woof'

19.2.2. items()

dict.items()

Returns a view object that displays a list of dictionary’s key-value tuple pairs.

sample_dict = {'a': 1, 'b': 2, 'c': 3}
items = sample_dict.items()
print(items)
# Output is dict_items([('a', 1), ('b', 2), ('c', 3)])

Tasks

  1. Write code to print the key-value tuple pairs in the dictionary coordinates_dict = {‘x’: 10, ‘y’: 20, ‘z’: 30}.

  2. Write code to print the key-value tuple pairs in the dictionary fruits_dict = {‘apple’: ‘green’, ‘banana’: ‘yellow’, ‘cherry’: ‘red’}.

  3. Write code to print the key-value tuple pairs in the dictionary colors_dict = {‘red’: ‘#FF0000’, ‘green’: ‘#00FF00’, ‘blue’: ‘#0000FF’}.

  4. Write code to print the key-value tuple pairs in the dictionary animals_dict = {‘cat’: ‘meow’, ‘dog’: ‘woof’, ‘bird’: ‘tweet’}.

Write code to print the key-value tuple pairs in the dictionary coordinates_dict = {‘x’: 10, ‘y’: 20, ‘z’: 30}.

coordinates_dict = {'x': 10, 'y': 20, 'z': 30}
coordinates_items = coordinates_dict.items()
print(coordinates_items)
# Output is dict_items([('x', 10), ('y', 20), ('z', 30)])

Write code to print the key-value tuple pairs in the dictionary fruits_dict = {‘apple’: ‘green’, ‘banana’: ‘yellow’, ‘cherry’: ‘red’}.

fruits_dict = {'apple': 'green', 'banana': 'yellow', 'cherry': 'red'}
fruits_items = fruits_dict.items()
print(fruits_items)
# Output is dict_items([('apple', green), ('banana', yellow), ('cherry', red)])

Write code to print the key-value tuple pairs in the dictionary colors_dict = {‘red’: ‘#FF0000’, ‘green’: ‘#00FF00’, ‘blue’: ‘#0000FF’}.

colors_dict = {'red': '#FF0000', 'green': '#00FF00', 'blue': '#0000FF'}
colors_items = colors_dict.items()
print(colors_items)
# Output is dict_items([('red', '#FF0000'), ('green', '#00FF00'), ('blue', '#0000FF')])

Write code to print the key-value tuple pairs in the dictionary animals_dict = {‘cat’: ‘meow’, ‘dog’: ‘woof’, ‘bird’: ‘tweet’}.

animals_dict = {'cat': 'meow', 'dog': 'woof', 'bird': 'tweet'}
animals_items = animals_dict.items()
print(animals_items)
# Output is dict_items([('cat', 'meow'), ('dog', 'woof'), ('bird', 'tweet')])

19.2.3. keys()

dict.keys()

Returns a view object that displays a list of all the keys in the dictionary.

sample_dict = {'a': 1, 'b': 2, 'c': 3}
keys = sample_dict.keys()
print(keys)
# Output is dict_keys(['a', 'b', 'c'])

Tasks

  1. Write code to print the keys in the dictionary coordinates_dict = {‘x’: 10, ‘y’: 20, ‘z’: 30}.

  2. Write code to print the keys in the dictionary fruits_dict = {‘apple’: ‘green’, ‘banana’: ‘yellow’, ‘cherry’: ‘red’}.

  3. Write code to print the keys in the dictionary colors_dict = {‘red’: ‘#FF0000’, ‘green’: ‘#00FF00’, ‘blue’: ‘#0000FF’}.

  4. Write code to print the keys in the dictionary animals_dict = {‘cat’: ‘meow’, ‘dog’: ‘woof’, ‘bird’: ‘tweet’}.

Write code to print the keys in the dictionary coordinates_dict = {‘x’: 10, ‘y’: 20, ‘z’: 30}.

coordinates_dict = {'x': 10, 'y': 20, 'z': 30}
coordinates_keys = coordinates_dict.keys()
print(coordinates_keys)
# Output is dict_keys(['x', 'y', 'z'])

Write code to print the keys in the dictionary fruits_dict = {‘apple’: ‘green’, ‘banana’: ‘yellow’, ‘cherry’: ‘red’}.

fruits_dict = {'apple': 'green', 'banana': 'yellow', 'cherry': 'red'}
fruits_keys = fruits_dict.keys()
print(fruits_keys)
# Output is dict_keys(['apple', 'banana', 'cherry'])

Write code to print the keys in the dictionary colors_dict = {‘red’: ‘#FF0000’, ‘green’: ‘#00FF00’, ‘blue’: ‘#0000FF’}.

colors_dict = {'red': '#FF0000', 'green': '#00FF00', 'blue': '#0000FF'}
colors_keys = colors_dict.keys()
print(colors_keys)
# Output is dict_keys(['red', 'green', 'blue'])

Write code to print the keys in the dictionary animals_dict = {‘cat’: ‘meow’, ‘dog’: ‘woof’, ‘bird’: ‘tweet’}.

animals_dict = {'cat': 'meow', 'dog': 'woof', 'bird': 'tweet'}
animals_keys = animals_dict.keys()
print(animals_keys)
# Output is dict_keys(['cat', 'dog', 'bird'])

19.2.4. values()

dict.values()

Returns a view object that displays a list of all the values in the dictionary.

sample_dict = {'a': 1, 'b': 2, 'c': 3}
values = sample_dict.values()
print(values)
# Output is dict_values([1, 2, 3])

Tasks

  1. Write code to print the values in the dictionary coordinates_dict = {‘x’: 10, ‘y’: 20, ‘z’: 30}.

  2. Write code to print the values in the dictionary fruits_dict = {‘apple’: ‘green’, ‘banana’: ‘yellow’, ‘cherry’: ‘red’}.

  3. Write code to print the values in the dictionary colors_dict = {‘red’: ‘#FF0000’, ‘green’: ‘#00FF00’, ‘blue’: ‘#0000FF’}.

  4. Write code to print the values in the dictionary animals_dict = {‘cat’: ‘meow’, ‘dog’: ‘woof’, ‘bird’: ‘tweet’}.

Write code to print the values in the dictionary coordinates_dict = {‘x’: 10, ‘y’: 20, ‘z’: 30}.

coordinates_dict = {'x': 10, 'y': 20, 'z': 30}
coordinates_values = coordinates_dict.values()
print(coordinates_values)
# Output is dict_values([10, 20, 30])

Write code to print the values in the dictionary fruits_dict = {‘apple’: ‘green’, ‘banana’: ‘yellow’, ‘cherry’: ‘red’}.

fruits_dict = {'apple': 'green', 'banana': 'yellow', 'cherry': 'red'}
fruits_values = fruits_dict.values()
print(fruits_values)
# Output is dict_values(['green', 'yellow', 'red'])

Write code to print the values in the dictionary colors_dict = {‘red’: ‘#FF0000’, ‘green’: ‘#00FF00’, ‘blue’: ‘#0000FF’}.

colors_dict = {'red': '#FF0000', 'green': '#00FF00', 'blue': '#0000FF'}
colors_values = colors_dict.values()
print(colors_values)
# Output is dict_values(['#FF0000', '#00FF00', '#0000FF'])

Write code to print the values in the dictionary animals_dict = {‘cat’: ‘meow’, ‘dog’: ‘woof’, ‘bird’: ‘tweet’}.

animals_dict = {'cat': 'meow', 'dog': 'woof', 'bird': 'tweet'}
animals_values = animals_dict.values()
print(animals_values)
# Output is dict_values(['meow', 'woof', 'tweet'])

19.3. Modifying Items

19.3.1. update()

dict.update([other])

Updates the dictionary with elements from another dictionary object or from an iterable of key-value pairs.

The code below updates the dictionary with elements from another dictionary.
sample_dict = {'a': 1, 'b': 2, 'c': 3}
new_dict = {'d': 4, 'e': 5}
sample_dict.update(new_dict)
print(sample_dict)
# Output is {'a': 1, 'b': 2, 'c': 3, 'd': 4, 'e': 5}
The code below updates the dictionary with elements from list of tuples, where each tuple contains a key-value pair
sample_dict = {'a': 1, 'b': 2, 'c': 3}
new_items = [('d', 4), ('e', 5)]
sample_dict.update(new_items)
print(sample_dict)
# Output is {'a': 1, 'b': 2, 'c': 3, 'd': 4, 'e': 5}

Tasks

  1. Write code to update the dictionary coordinates_dict = {‘x’: 10, ‘y’: 20, ‘z’: 30} with a second dictionary {‘a’: 40, ‘b’: 50, ‘c’: 60}. Print the dictionary.

  2. Write code to update the dictionary fruits_dict = {‘apple’: ‘green’, ‘banana’: ‘yellow’, ‘cherry’: ‘red’} with a second dictionary {‘date’: ‘brown’, ‘elderberry’: ‘purple’}. Print the dictionary.

  3. Write code to update the dictionary colors_dict = {‘red’: ‘#FF0000’, ‘green’: ‘#00FF00’, ‘blue’: ‘#0000FF’} with the list of tuples [(‘yellow’, ‘#FFFF00’), (‘purple’, ‘#800080’), (‘orange’, ‘#FFA500’)]. Print the dictionary.

  4. Write code to update the dictionary animals_dict = {‘cat’: ‘meow’, ‘dog’: ‘woof’, ‘bird’: ‘tweet’} with the list of tuples [(‘fish’, ‘blub’), (‘hamster’, ‘squeak’)]. Print the dictionary.

Write code to update the dictionary coordinates_dict = {‘x’: 10, ‘y’: 20, ‘z’: 30} with a second dictionary {‘a’: 40, ‘b’: 50, ‘c’: 60}. Print the dictionary.

coordinates_dict = {'x': 10, 'y': 20, 'z': 30}
new_dict = {'a': 40, 'b': 50, 'c': 60}
coordinates_dict.update(new_dict)
print(coordinates_dict)
# Output is {'x': 10, 'y': 20, 'z': 30, 'a': 40, 'b': 50, 'c': 60}

Write code to update the dictionary fruits_dict = {‘apple’: ‘green’, ‘banana’: ‘yellow’, ‘cherry’: ‘red’} with a second dictionary {‘date’: ‘brown’, ‘elderberry’: ‘purple’}. Print the dictionary.

fruits_dict = {'apple': 'green', 'banana': 'yellow', 'cherry': 'red'}
new_dict = {'date': 'brown', 'elderberry': 'purple'}
fruits_dict.update(new_dict)
print(fruits_dict)
# Output is {'apple': 'green', 'banana': 'yellow', 'cherry': 'red', 'date': 'brown', 'elderberry': 'purple'}

Write code to update the dictionary colors_dict = {‘red’: ‘#FF0000’, ‘green’: ‘#00FF00’, ‘blue’: ‘#0000FF’} with the list of tuples [(‘yellow’, ‘#FFFF00’), (‘purple’, ‘#800080’), (‘orange’, ‘#FFA500’)]. Print the dictionary.

colors_dict = {'red': '#FF0000', 'green': '#00FF00', 'blue': '#0000FF'}
new_items = [('yellow', '#FFFF00'), ('purple', '#800080'), ('orange', '#FFA500')]
colors_dict.update(new_items)
print(colors_dict)
# Output is {'red': '#FF0000', 'green': '#00FF00', 'blue': '#0000FF', 'yellow': '#FFFF00', 'purple': '#800080', 'orange': '#FFA500'}

Write code to update the dictionary animals_dict = {‘cat’: ‘meow’, ‘dog’: ‘woof’, ‘bird’: ‘tweet’} with the list of tuples [(‘fish’, ‘blub’), (‘hamster’, ‘squeak’)]. Print the dictionary.

animals_dict = {'cat': 'meow', 'dog': 'woof', 'bird': 'tweet'}
new_items = [('fish', 4), ('hamster', 5)]
animals_dict.update(new_items)
print(animals_dict)
# Output is {'cat': 'meow', 'dog': 'woof', 'bird': 'tweet', 'fish': 'blub', 'hamster': 'squeak'}

19.3.2. setdefault()

dict.setdefault(key, default=None)

Returns the value of the specified key. If the key does not exist, inserts the key with the specified default value.

sample_dict = {'a': 1, 'b': 2, 'c': 3}
value = sample_dict.setdefault('d', 4)
print(value)
# Output is 4
print(sample_dict)
# sample_dict is now {'a': 1, 'b': 2, 'c': 3, 'd': 4}

Tasks

  1. Write code to find the value of ‘a’ in the dictionary coordinates_dict = {‘x’: 10, ‘y’: 20, ‘z’: 30} setting it to a default value of 40 if it is not in the dictionary. Print value and print the dictionary.

  2. Write code to find the value of ‘date’ in the dictionary fruits_dict = {‘apple’: ‘green’, ‘banana’: ‘yellow’, ‘cherry’: ‘red’} setting it to a default value of ‘brown’ if it is not in the dictionary. Print value and print the dictionary.

  3. Write code to find the value of ‘yellow’, in the dictionary colors_dict = {‘red’: ‘#FF0000’, ‘green’: ‘#00FF00’, ‘blue’: ‘#0000FF’} setting it to a default value of ‘#FFFF00’ if it is not in the dictionary. Print value and print the dictionary.

  4. Write code to find the value of ‘fish’ in the dictionary animals_dict = {‘cat’: ‘meow’, ‘dog’: ‘woof’, ‘bird’: ‘tweet’} setting it to a default value of ‘blub’ if it is not in the dictionary. Print value and print the dictionary.

Write code to find the value of ‘a’ in the dictionary coordinates_dict = {‘x’: 10, ‘y’: 20, ‘z’: 30} setting it to a default value of 40 if it is not in the dictionary. Print value and print the dictionary.

coordinates_dict = {'x': 10, 'y': 20, 'z': 30}
value = coordinates_dict.setdefault('a', 40)
print(value)
# Output is 40
print(coordinates_dict)
# coordinates_dict is now {'x': 10, 'y': 20, 'z': 30, 'a': 40}

Write code to find the value of ‘date’ in the dictionary fruits_dict = {‘apple’: ‘green’, ‘banana’: ‘yellow’, ‘cherry’: ‘red’} setting it to a default value of ‘brown’ if it is not in the dictionary. Print value and print the dictionary.

fruits_dict = {'apple': 'green', 'banana': 'yellow', 'cherry': 'red'}
value = fruits_dict.setdefault('date', 'brown')
print(value)
# Output is 'brown'
print(fruits_dict)
# fruits_dict is now {'apple': 'green', 'banana': 'yellow', 'cherry': 'red', 'date': 'brown'}

Write code to find the value of ‘yellow’, in the dictionary colors_dict = {‘red’: ‘#FF0000’, ‘green’: ‘#00FF00’, ‘blue’: ‘#0000FF’} setting it to a default value of ‘#FFFF00’ if it is not in the dictionary. Print value and print the dictionary.

colors_dict = {'red': '#FF0000', 'green': '#00FF00', 'blue': '#0000FF'}
value = colors_dict.setdefault('yellow', '#FFFF00')
print(value)
# Output is '#FFFF00'
print(colors_dict)
# colors_dict is now {'red': '#FF0000', 'green': '#00FF00', 'blue': '#0000FF', 'yellow': '#FFFF00'}

Write code to find the value of ‘fish’ in the dictionary animals_dict = {‘cat’: ‘meow’, ‘dog’: ‘woof’, ‘bird’: ‘tweet’} setting it to a default value of ‘blub’ if it is not in the dictionary. Print value and print the dictionary.

animals_dict = {'cat': 'meow', 'dog': 'woof', 'bird': 'tweet'}
value = animals_dict.setdefault('fish', 'blub')
print(value)
# Output is 'blub'
print(animals_dict)
# animals_dict is now {'cat': 'meow', 'dog': 'woof', 'bird': 'tweet', 'fish': 'blub'}

19.3.3. pop()

dict.pop(key, default=None)

Removes the specified key and returns the corresponding value. If the key is not found, the default value is returned if provided, otherwise a KeyError is raised.

sample_dict = {'a': 1, 'b': 2, 'c': 3}
value = sample_dict.pop('a')
print(value)
# Output is 1
print(sample_dict)
# sample_dict is now {'b': 2, 'c': 3}

Tasks

  1. Remove the value of ‘x’ (first position) from the dictionary coordinates_dict = {‘x’: 10, ‘y’: 20, ‘z’: 30, ‘a’: 40} and print its value and print the dictionary.

  2. Remove the value of ‘banana’ from the dictionary fruits_dict = {‘apple’: ‘green’, ‘banana’: ‘yellow’, ‘cherry’: ‘red’, ‘date’: ‘brown’} and print its value and print the dictionary.

  3. Remove the value of ‘blue’ from the dictionary colors_dict = {‘red’: ‘#FF0000’, ‘green’: ‘#00FF00’, ‘blue’: ‘#0000FF’, ‘yellow’: ‘#FFFF00’} and print its value and print the dictionary.

  4. Remove the value of ‘hamster’ from the dictionary animals_dict = {‘cat’: ‘meow’, ‘dog’: ‘woof’, ‘bird’: ‘tweet’, ‘hamster’: ‘squeak’} and print its value and print the dictionary.

Remove the value of ‘x’ (first position) from the dictionary coordinates_dict = {‘x’: 10, ‘y’: 20, ‘z’: 30, ‘a’: 40} and print its value and print the dictionary.

coordinates_dict = {'x': 10, 'y': 20, 'z': 30, 'a': 40}
value = coordinates_dict.pop('x')
print(value)
# Output is 10
print(coordinates_dict)
# coordinates_dict is now {'y': 20, 'z': 30, 'a': 40}

Remove the value of ‘banana’ from the dictionary fruits_dict = {‘apple’: ‘green’, ‘banana’: ‘yellow’, ‘cherry’: ‘red’, ‘date’: ‘brown’} and print its value and print the dictionary.

fruits_dict = {'apple': 'green', 'banana': 'yellow', 'cherry': 'red', 'date': 'brown'}
value = fruits_dict.pop('banana')
print(value)
# Output is 'yellow'
print(fruits_dict)
# fruits_dict is now {'apple': 'green', 'cherry': 'red', 'date': 'brown'}

Remove the value of ‘blue’ from the dictionary colors_dict = {‘red’: ‘#FF0000’, ‘green’: ‘#00FF00’, ‘blue’: ‘#0000FF’, ‘yellow’: ‘#FFFF00’} and print its value and print the dictionary.

colors_dict = {'red': '#FF0000', 'green': '#00FF00', 'blue': '#0000FF', 'yellow': '#FFFF00'}
value = colors_dict.pop('blue')
print(value)
# Output is '#0000FF'
print(colors_dict)
# colors_dict is now {'red': '#FF0000', 'green': '#00FF00', 'yellow': '#FFFF00'}

Remove the value of ‘hamster’ from the dictionary animals_dict = {‘cat’: ‘meow’, ‘dog’: ‘woof’, ‘bird’: ‘tweet’, ‘hamster’: ‘squeak’} and print its value and print the dictionary.

animals_dict = {'cat': 'meow', 'dog': 'woof', 'bird': 'tweet', 'hamster': 'squeak'}
value = animals_dict.pop('hamster')
print(value)
# Output is 'squeak'
print(animals_dict)
# animals_dict is now {'cat': 'meow', 'dog': 'woof', 'bird': 'tweet'}

19.3.4. popitem()

dict.popitem()

Removes and returns a key-value pair from the dictionary. Pairs are returned in LIFO (last-in, first-out) order.

sample_dict = {'a': 1, 'b': 2, 'c': 3}
item = sample_dict.popitem()
print(item)
# Output is ('c', 3)
print(animals_dict)
# sample_dict is now {'a': 1, 'b': 2}

Tasks

  1. Remove the last item from the dictionary coordinates_dict = {‘x’: 10, ‘y’: 20, ‘z’: 30} and print it and print the dictionary.

  2. Remove the last item from the dictionary fruits_dict = {‘apple’: ‘green’, ‘banana’: ‘yellow’, ‘cherry’: ‘red’} and print it and print the dictionary.

  3. Remove the last item from the dictionary colors_dict = {‘red’: ‘#FF0000’, ‘green’: ‘#00FF00’, ‘blue’: ‘#0000FF’} and print it and print the dictionary.

  4. Remove the last item from the dictionary animals_dict = {‘cat’: ‘meow’, ‘dog’: ‘woof’, ‘bird’: ‘tweet’} and print it and print the dictionary.

Remove the last item from the dictionary coordinates_dict = {‘x’: 10, ‘y’: 20, ‘z’: 30} and print it and print the dictionary.

coordinates_dict = {'x': 10, 'y': 20, 'z': 30}
item = coordinates_dict.popitem()
print(item)
# Output is ('z', 30)
print(coordinates_dict)
# coordinates_dict is now {'x': 10, 'y': 20}

Remove the last item from the dictionary fruits_dict = {‘apple’: ‘green’, ‘banana’: ‘yellow’, ‘cherry’: ‘red’} and print it and print the dictionary.

fruits_dict = {'apple': 'green', 'banana': 'yellow', 'cherry': 'red'}
item = fruits_dict.popitem()
print(item)
# Output is ('cherry', 'red')
print(fruits_dict)
# fruits_dict is now {'apple': 'green', 'banana': 'yellow'}

Remove the last item from the dictionary colors_dict = {‘red’: ‘#FF0000’, ‘green’: ‘#00FF00’, ‘blue’: ‘#0000FF’} and print it and print the dictionary.

colors_dict = {'red': '#FF0000', 'green': '#00FF00', 'blue': '#0000FF'}
item = colors_dict.popitem()
print(item)
# Output is ('blue', '#0000FF')
print(colors_dict)
# colors_dict is now {'red': '#FF0000', 'green': '#00FF00'}

Remove the last item from the dictionary animals_dict = {‘cat’: ‘meow’, ‘dog’: ‘woof’, ‘bird’: ‘tweet’} and print it and print the dictionary.

animals_dict = {'cat': 'meow', 'dog': 'woof', 'bird': 'tweet'}
item = animals_dict.popitem()
print(item)
# Output is ('bird', 'tweet')
print(animals_dict)
# animals_dict is now {'cat': 'meow', 'dog': 'woof'}

19.4. Dictionary Operations

19.4.1. copy()

The copy method is fine to use when the values in the dictionary are immutable. i.e. strings, integers, floats, tuples.
dict.copy()
Returns a shallow copy of the dictionary.
Mutable objects (lists, dictionaries) will change in the original dictionary if altered in the new dictionary.
# Original dictionary with various types of values
original_dict = {
    'a': 'string',          # String
    'b': 42,                # Integer
    'c': (1, 2, 3),         # Tuple
    'd': [4, 5, 6],         # List
    'e': {'key': 'value'}   # Dictionary
}

# Create a shallow copy
shallow_copy = original_dict.copy()

# the mutable objects will not change in the original
shallow_copy['a'] = 'new_string'
shallow_copy['b'] = 100
shallow_copy['c'] = (7, 8, 9)
# the mutable objects will change in the original
shallow_copy['d'].append(7)
shallow_copy['e']['key'] = 'new_value'

print("Original Dictionary:", original_dict)
# Output is Original Dictionary: {'a': 'string', 'b': 42, 'c': (1, 2, 3), 'd': [4, 5, 6, 7], 'e': {'key': 'new_value'}}
print("Shallow Copy:", shallow_copy)
# Output is Shallow Copy:  {'a': 'new_string', 'b': 100, 'c': (7, 8, 9), 'd': [4, 5, 6, 7], 'e': {'key': 'new_value'}}

19.4.2. copy.deepcopy()

Deepcopy is part of the copy module.
The deepcopy function is best to use when the values in the dictionary are mutable, i.e. lists, dictionaries, and an independent copy is wanted.
copy.deepcopy(dict)
Returns a deep copy of the dictionary.
All objects are independent of those in the original dictionary
Changing any key: value will not result in changes in the original dictionary.
import copy

# Original dictionary with various types of values
original_dict = {
    'a': 'string',          # String
    'b': 42,                # Integer
    'c': (1, 2, 3),         # Tuple
    'd': [4, 5, 6],         # List
    'e': {'key': 'value'}   # Dictionary
}

# Create a deep copy
deep_copy = copy.deepcopy(original_dict)

# Modify the values in the deep copy
deep_copy['a'] = 'new_string'
deep_copy['b'] = 100
deep_copy['c'] = (7, 8, 9)
deep_copy['d'].append(7)
deep_copy['e']['key'] = 'new_value'

print("Original Dictionary:", original_dict)
# Output is Original Dictionary: {'a': 'string', 'b': 42, 'c': (1, 2, 3), 'd': [4, 5, 6], 'e': {'key': 'value'}}
print("Deep Copy:", deep_copy)
# Output is Deep Copy: {'a': 'new_string', 'b': 100, 'c': (7, 8, 9), 'd': [4, 5, 6, 7], 'e': {'key': 'new_value'}}

19.4.3. clear()

dict.clear()

Removes all items from the dictionary.

sample_dict = {'a': 1, 'b': 2, 'c': 3}
sample_dict.clear()
print(sample_dict)
# Output is {}

19.4.4. fromkeys()

dict.fromkeys(iterable, value=None)

Creates a new dictionary with keys from the given iterable and values set to the specified value.

keys = ('a', 'b', 'c')
value = 0
new_dict = dict.fromkeys(keys, value)
print(new_dict)
# Output is {'a': 0, 'b': 0, 'c': 0}

Tasks

  1. Create a dictionary named coordinates_dict with the keys ‘x’, ‘y’, and ‘z’, each having the default value 0. Use the dict.fromkeys() method to achieve this and print the resulting dictionary.

  2. Create a dictionary named fruits_dict with the keys ‘apple’, ‘banana’, and ‘cherry’, each having the default value ‘unknown’. Use the dict.fromkeys() method to achieve this and print the resulting dictionary.

  3. Create a dictionary named colors_dict with the keys ‘red’, ‘green’, and ‘blue’, each having the default value ‘#FFFFFF’. Use the dict.fromkeys() method to achieve this and print the resulting dictionary.

  4. Create a dictionary named animals_dict with the keys ‘cat’, ‘dog’, and ‘bird’, each having the default value ‘sound’. Use the dict.fromkeys() method to achieve this and print the resulting dictionary.

Create a dictionary named coordinates_dict with the keys ‘x’, ‘y’, and ‘z’, each having the default value 0. Use the dict.fromkeys() method to achieve this and print the resulting dictionary.

keys = ('x', 'y', 'z')
value = 0
coordinates_dict = dict.fromkeys(keys, value)
print(coordinates_dict)
# Output is {'x': 0, 'y': 0, 'z': 0}

Create a dictionary named fruits_dict with the keys ‘apple’, ‘banana’, and ‘cherry’, each having the default value ‘unknown’. Use the dict.fromkeys() method to achieve this and print the resulting dictionary.

keys = ('apple', 'banana', 'cherry')
value = 'white'
fruits_dict = dict.fromkeys(keys, value)
print(fruits_dict)
# Output is {'apple': 'white', 'banana': 'white', 'cherry': 'white'}

Create a dictionary named colors_dict with the keys ‘red’, ‘green’, and ‘blue’, each having the default value ‘#FFFFFF’. Use the dict.fromkeys() method to achieve this and print the resulting dictionary.

keys = ('red', 'green', 'blue')
value = '#FFFFFF'
colors_dict = dict.fromkeys(keys, value)
print(colors_dict)
# Output is {'red': '#FFFFFF', 'green': '#FFFFFF', 'blue': '#FFFFFF'}

Create a dictionary named animals_dict with the keys ‘cat’, ‘dog’, and ‘bird’, each having the default value ‘sound’. Use the dict.fromkeys() method to achieve this and print the resulting dictionary.

keys = ('cat', 'dog', 'bird')
value = 'sound'
animals_dict = dict.fromkeys(keys, value)
print(animals_dict)
# Output is {'cat': 'sound', 'dog': 'sound', 'bird': 'sound'}