First, let’s define what a dictionary is. In simple terms, a dictionary is a collection of key-value pairs, where each key is unique and is associated with a specific value. Dictionaries are denoted using curly braces ({}) and the key-value pairs are separated by commas. Here’s an example of a simple Python dictionary:
# Create a dictionary of sports teams
teams = {
"basketball": "Boston Celtics",
"football": "New England Patriots",
"hockey": "Boston Bruins"
}
# Create a dictionary of breakfast foods
breakfast = {
"cereal": "Lucky Charms",
"eggs": "scrambled",
"fruit": "strawberry"
}
# Create a mixed dictionary of sports teams and breakfast foods
mixed = {
"basketball": "Boston Celtics",
"cereal": "Lucky Charms",
"eggs": "scrambled",
"football": "New England Patriots",
"fruit": "strawberry",
"hockey": "Boston Bruins"
}
Now that you know what a Python dictionary is, let’s look at some of the common operations that you can perform on dictionaries.
One of the most basic operations is to access the value associated with a specific key in a dictionary. This is done using the square bracket notation, with the key inside the brackets. Here’s an example of accessing values in a dictionary:
# Access the value associated with the key "basketball" teams["basketball"] # Output: "Boston Celtics" # Access the value associated with the key "eggs" breakfast["eggs"] # Output: "scrambled" # Access the value associated with the key "fruit" mixed["fruit"] # Output: "strawberry"
Another common operation is to add a new key-value pair to a dictionary. This is done using the square bracket notation, with the new key inside the brackets and the = operator to assign a value to the key. Here’s an example:
# Add a new key-value pair to the teams dictionary teams["baseball"] = "Boston Red Sox" # The dictionary now contains the key-value pair "baseball": "Boston Red Sox"
You can also update the value associated with an existing key using the same square bracket notation. Here’s an example:
# Update the value associated with the key "hockey" teams["hockey"] = "Montreal Canadiens" # The value associated with the key "hockey" has been updated to "Montreal Canadiens"
Now that you know how to create and manipulate dictionaries in Python. Hope this helps!