Exploring Python Dictionaries

What is a dictionary in Python?

• A dictionary in Python is a single value.

• A dictionary in Python is a type of list.

• A dictionary in Python is a collection of functions.

• A dictionary in Python is a collection of key-value pairs.

Answer explanation

A dictionary in Python is a collection of key-value pairs, allowing for efficient data retrieval. Each key is unique and maps to a specific value, making it distinct from lists and other data types.

How do you create a dictionary with key-value pairs?

• Use curly braces and colons to define key-value pairs, e.g., {'key': 'value'}.

• Use square brackets to define key-value pairs, e.g., ['key': 'value']

• Create a list of key-value pairs using parentheses, e.g., ('key', 'value')

• Define key-value pairs with angle brackets, e.g.,

Answer explanation

The correct way to create a dictionary in Python is by using curly braces and colons to define key-value pairs, such as {'key': 'value'}. Other options provided are incorrect syntax for creating dictionaries.

What method can you use to retrieve a value from a dictionary safely?

• Use the keys() method to find the value.

• Access the value directly using the key.

• Use the pop() method of the dictionary.

• Use the get() method of the dictionary.

Answer explanation

The get() method allows you to retrieve a value from a dictionary safely. If the key does not exist, it returns None (or a specified default), preventing KeyError exceptions that occur with direct access.

How do you add a new key-value pair to an existing dictionary?

• Assign a new value with 'dict[key] := value'.

• Use 'dict.add(key, value)' to insert a new pair.

• Use 'dict[key] = value' to add a new key-value pair.

• Use 'dict.insert(key, value)' to add a new entry.

Answer explanation

To add a new key-value pair to an existing dictionary in Python, you use the syntax 'dict[key] = value'. This directly assigns the value to the specified key, creating a new entry if the key does not already exist.

What is the syntax to update an existing value in a dictionary?

• dict.update(key, new_value)

• dict.add(key, new_value)

• dict[key] := new_value

• dict[key] = new_value

Answer explanation

The correct syntax to update a value in a dictionary is 'dict[key] = new_value'. This assigns 'new_value' to the specified 'key', effectively updating the existing value.

How can you remove a key-value pair from a dictionary using the del keyword?

• my_dict.delete('key')

• my_dict.pop('key')

• remove my_dict['key']

• del my_dict['key']

Answer explanation

The correct way to remove a key-value pair from a dictionary in Python is using the 'del' keyword. Thus, 'del my_dict['key']' effectively deletes the specified key from the dictionary.

What method would you use to remove a key and return its value?

• Use the remove() method.

• Use the discard() method.

• Use the pop() method.

• Use the delete() method.

Answer explanation

The pop() method is used to remove a key from a dictionary and return its associated value. Unlike remove() or discard(), which do not return values, pop() specifically provides the value of the removed key.

How do you iterate through all the keys in a dictionary?

• for each key in my_dict

• my_dict.keys()

• for key in my_dict:

• iterate over my_dict with a loop

Answer explanation

The correct way to iterate through all the keys in a dictionary is using 'for key in my_dict:'. This syntax directly accesses each key in the dictionary, making it the most efficient and Pythonic method.

What method would you use to get all the values from a dictionary?

• Use the `items()` method.

• Use the `get()` method.

• Use the `keys()` method.

• Use the `values()` method.

Answer explanation

To retrieve all values from a dictionary, the correct method is `values()`. This method returns a view object that displays a list of all the values in the dictionary, unlike `items()` which returns key-value pairs.

How can you loop through both keys and values in a dictionary?

• Use 'for item in my_dict:' to loop through items without unpacking.

• Use 'for key in my_dict.keys():' to loop through keys only.

• Use 'for key, value in my_dict.items():' to loop through keys and values.

• Use 'for value in my_dict:' to loop through values only.

Answer explanation

The correct way to loop through both keys and values in a dictionary is by using 'for key, value in my_dict.items():'. This method allows you to access each key-value pair directly.