Combining dictionaries with for loops can be incredibly useful, allowing you to iterate over the keys, values, or both. In this article, we’ll explore Python dictionaries and how to work with them using for loops in Python.
Understanding Python Dictionaries
In this example, a person is a dictionary with three key-value pairs. The keys are “name,” “age,” and “city,” and the corresponding values are “John,” 30, and “New York,” respectively.
Python3
person = {"name": "John", "age": 30, "city": "New York"}print(person) |
Modifying Dictionary Elements While Iterating
Be cautious when modifying dictionary elements while iterating over them, as it can lead to unexpected results. If you need to make changes to the dictionary, consider creating a copy or collecting the changes in a separate list or dictionary.
- Iterating Over Dictionary Keys
- Iterating Over Dictionary Values
- Iterating Over Both Keys and Values
Iterating Over Dictionary Keys
In this code, we use the keys() method to obtain a view of the dictionary’s keys, and then we iterate over these keys using a for loop.
Python3
# Iterating over dictionary keysperson = {"name": "John", "age": 30, "city": "New York"}for key in person.keys(): print(key) |
Output
name
age
city
Iterating Over Dictionary Values
If you want to iterate over the values in a dictionary, you can use the values() method. Here’s how you can do it:
Python3
# Iterating over dictionary valuesperson = {"name": "John", "age": 30, "city": "New York"}for value in person.values(): print(value) |
Output
John
30
New York
Iterating Over Both Keys and Values
Sometimes, you may need to iterate over both the keys and values simultaneously. To do this, you can use the items() method, which returns a list of key-value pairs as tuples.
Python3
# Iterating over dictionary key-value pairsperson = {"name": "John", "age": 30, "city": "New York"}for key, value in person.items(): print(key, ":", value) |
Output
name : John
age : 30
city : New York
