In this tutorial, I will explain how to sort a list of tuples by the second element in Python. Recently in a Python webinar, someone asked me how to sort a list of tuples by the second element. In my research and experiment, I found several effective methods to do this task. Let us learn more about this topic today.
Sort a List of Tuples by the Second Element in Python
Let’s say you’re working on a project that involves analyzing sales data from various states in the USA. You have a list of tuples, where each tuple contains the state name and the corresponding sales figure. Your task is to sort this list of tuples based on the sales figures, which are the second elements in each tuple.
For example, consider the following list of tuples:
sales_data = [("California", 25000), ("Texas", 30000), ("New York", 28000), ("Florida", 22000)]Our goal is to sort this list in ascending or descending order based on the sales figures.
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1. Use sort() Method
Python’s built-in sort() method allows us to sort a list in place. We can use this method to sort a list of tuples by the second element. Here’s how we can do it:
sales_data = [("California", 25000), ("Texas", 30000), ("New York", 28000), ("Florida", 22000)]
# Sort the list of tuples by the second element
sales_data.sort(key=lambda x: x[1])
print(sales_data)Output:
[("Florida", 22000), ("California", 25000), ("New York", 28000), ("Texas", 30000)]You can refer to the below screenshot to see the output.
In this example, we use the sort() method with a key parameter. The key parameter takes a function that specifies the sorting criteria. We pass a lambda function lambda x: x[1] which tells the sort() method to sort based on the second element of each tuple.
Sort in Descending Order
To sort the list of tuples in descending order, we can modify the sort() method slightly:
sales_data = [("California", 25000), ("Texas", 30000), ("New York", 28000), ("Florida", 22000)]
# Sort the list of tuples by the second element in descending order
sales_data.sort(key=lambda x: x[1], reverse=True)
print(sales_data)Output:
[("Texas", 30000), ("New York", 28000), ("California", 25000), ("Florida", 22000)]By adding the reverse=True parameter, we tell the sort() method to sort the list in descending order.
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2. Use sorted() Function
Another way to sort a list of tuples by the second element is by using the sorted() function. Unlike the sort() method, sorted() returns a new sorted list without modifying the original list. Here’s an example:
sales_data = [("California", 25000), ("Texas", 30000), ("New York", 28000), ("Florida", 22000)]
# Sort the list of tuples by the second element using sorted()
sorted_sales_data = sorted(sales_data, key=lambda x: x[1])
print(sorted_sales_data)Output:
[("Florida", 22000), ("California", 25000), ("New York", 28000), ("Texas", 30000)]You can refer to the below screenshot to see the output.
The sorted() function takes the list of tuples as the first argument and the key parameter specifying the sorting criteria. It returns a new sorted list, leaving the original list unmodified.
Sort in Descending Order with sorted()
To sort the list of tuples in descending order using sorted(), we can pass the reverse=True parameter:
sales_data = [("California", 25000), ("Texas", 30000), ("New York", 28000), ("Florida", 22000)]
# Sort the list of tuples by the second element in descending order using sorted()
sorted_sales_data = sorted(sales_data, key=lambda x: x[1], reverse=True)
print(sorted_sales_data)Output:
[("Texas", 30000), ("New York", 28000), ("California", 25000), ("Florida", 22000)]Read How to Find the Length of a Tuple in Python?
3. Use Bubble Sort Algorithm
If you prefer to implement your own sorting algorithm, you can use the Bubble Sort algorithm to sort the list of tuples by the second element. Here’s an example:
def bubble_sort(tuples):
n = len(tuples)
for i in range(n - 1):
for j in range(n - i - 1):
if tuples[j][1] > tuples[j + 1][1]:
tuples[j], tuples[j + 1] = tuples[j + 1], tuples[j]
return tuples
sales_data = [("California", 25000), ("Texas", 30000), ("New York", 28000), ("Florida", 22000)]
# Sort the list of tuples by the second element using Bubble Sort
sorted_sales_data = bubble_sort(sales_data)
print(sorted_sales_data)Output:
[("Florida", 22000), ("California", 25000), ("New York", 28000), ("Texas", 30000)]You can refer to the below screenshot to see the output.
The Bubble Sort algorithm compares adjacent elements and swaps them if they are in the wrong order. It repeats this process until the list is sorted.
Read Python Set vs Tuple
Conclusion
In this tutorial, I explained how to sort a list of tuples by the second element in Python. I discussed the sort() method, sorted() function and sorted in descending order by using them, and using the bubble sort algorithm.
You can read:
- How to Iterate Through Tuples in Python?
- How to Convert an Array to a Tuple in Python?
- How to Unpack a Tuple in Python?
I am Bijay Kumar, a Microsoft MVP in SharePoint. Apart from SharePoint, I started working on Python, Machine learning, and artificial intelligence for the last 5 years. During this time I got expertise in various Python libraries also like Tkinter, Pandas, NumPy, Turtle, Django, Matplotlib, Tensorflow, Scipy, Scikit-Learn, etc… for various clients in the United States, Canada, the United Kingdom, Australia, New Zealand, etc. Check out my profile.
