In Python, a dictionary is a collection of key-value pairs. Dictionaries are unordered, meaning the items have no index and are stored in an arbitrary order. However, dictionaries are very efficient for certain operations, such as retrieving a value based on its key.

There are several ways to get values from a dictionary in Python. The most common way is to use the square brackets [] to access the value by its key. For example, if you have a dictionary called “colors” with keys “red”, “green”, and “blue” and corresponding values “#ff0000”, “#00ff00”, and “#0000ff”, respectively, you can access the value of the “red” key like this:

				
					colors = {"red": "#ff0000", "green": "#00ff00", "blue": "#0000ff"}
red_value = colors["red"]
print(red_value) # Output: "#ff0000"

Another way to get a value from a dictionary is by using the get() method. The get() method takes a single argument, which is the key of the value you want to retrieve.

If the key exists in the dictionary, the get() method will return the corresponding value. If the key does not exist, the get() method will return None by default, or a value of your choice if you pass a second argument to the method. For example:

				
					colors = {"red": "#ff0000", "green": "#00ff00", "blue": "#0000ff"}
green_value = colors.get("green")
print(green_value) # Output: "#00ff00"

default_value = colors.get("purple", "Unknown color")
print(default_value) # Output: "Unknown color"

You can also use the items() method to get all the key-value pairs in a dictionary as a list of tuples. Each tuple contains a key-value pair. For example:

				
					colors = {"red": "#ff0000", "green": "#00ff00", "blue": "#0000ff"}
items = colors.items()
print(items) # Output: [("red", "#ff0000"), ("green", "#00ff00"), ("blue", "#0000ff")]

The keys() method returns a list of all the keys in a dictionary, and the values() method returns a list of all the values in a dictionary. For example:

				
					colors = {"red": "#ff0000", "green": "#00ff00", "blue": "#0000ff"}
keys = colors.keys()
values = colors.values()
print(keys) # Output: ["red", "green", "blue"]
print(values) # Output: ["#ff0000", "#00ff00", "#0000ff"]

Additionally, in python 3.7 and later versions, dictionaries have the pop() method which is used to remove a key-value pair from a dictionary and returns the value of the key passed as the argument. If the key is not present in the dictionary, the method raises a KeyError. You can also provide a second argument as the default value in case the key is not present in the dictionary.

				
					colors = {"red": "#ff0000", "green": "#00ff00", "blue": "#0000ff"}
color_removed = colors.pop("green", None)
print(color_removed) # Output: "#00ff00"
print(colors) # Output: {"red": "#ff0000", "blue": "#0000ff"}

It is important to note that when using the square brackets [] or the pop() method to access a value by its key, if the key is not present in the dictionary, a KeyError will be raised. To avoid this, you can use the get() method or the in keyword to check if a key exists in the dictionary before trying to access its value.

For example, you can use the in keyword to check if a key exists in the dictionary before using the square brackets to access its value:

				
					colors = {"red": "#ff0000", "green": "#00ff00", "blue": "#0000ff"}
if "purple" in colors:
    purple_value = colors["purple"]
    print(purple_value)
else:
    print("Key not found")

You can also use a try-except block to catch the KeyError and handle it gracefully:

				
					colors = {"red": "#ff0000", "green": "#00ff00", "blue": "#0000ff"}
try:
    purple_value = colors["purple"]
    print(purple_value)
except KeyError:
    print("Key not found")

Wrap up

Python dictionaries are a powerful data structure that allows you to efficiently store and retrieve data based on keys.

You can use the square brackets [] or the get() method to access a value by its key, the items() method to get all the key-value pairs in a dictionary, the keys() method to get all the keys in a dictionary, the values() method to get all the values in a dictionary, and the in keyword and try-except block to check if a key exists in the dictionary before trying to access its value.


Thanks for reading. Happy coding!