Short answer: To find the minimal list in a list of lists, you need to make two lists comparable. How? With the key argument of the min() function. The key argument is a function that takes one input (a list) and returns one output (a numerical value). The list with the smallest numerical value is returned as the minimum of the list of lists.
Problem: Say you have a list of lists (nested list) and you want to find the minimum of this list. It’s not trivial to compare lists—what’s the minimum among lists after all? To define the minimum among the inner lists, you may want to consider different objectives.
- The first element of each inner list.
- The i-th element of each inner list.
- The sum of inner list elements.
- The maximum of inner list elements.
- The minimum of inner list elements.
Example: Given list of lists [[1, 1, 1], [0, 2, 0], [3, 3, -1]]. Which is the minimum element?
- The first element of each inner list. The minimum is
[0, 2, 0]. - The i-th element of each inner list (
i = 2). The minimum is[.3, 3, -1] - The sum of inner list elements. The minimum is
[.0, 2, 0] - The maximum of inner list elements. The minimum is
[1, 1, 1]. - The minimum of inner list elements. The minimum is
[3, 3, -1].
So how do you accomplish this?
Solution: Use the min() function with key argument.
Syntax: The min() function is a built-in function in Python (Python versions 2.x and 3.x). Here’s the syntax:
min(iterable, key=None)
Arguments:
| Argument | Description |
|---|---|
iterable | The values among which you want to find the minimum. In our case, it’s a list of lists. |
key | (Optional. Default None.) Pass a function that takes a single argument and returns a comparable value. The function is then applied to each element in the list. Then, the method find the minimum based on the key function results rather than the elements themselves. |
Let’s study the solution code for our different versions of calculating the minimal “list” of a list of lists (nested list).
Try it yourself in our interactive code shell:
lst = [[1, 1, 1], [0, 2, 0], [3, 3, -1]] # Minimum using first element print(min(lst, key=lambda x: x[0])) # [0, 2, 0] # Minimum using third element print(min(lst, key=lambda x: x[2])) # [3, 3, -1] # Minimum using sum() print(min(lst, key=sum)) # [0, 2, 0] # Minimum using max print(min(lst, key=max)) # [1, 1, 1] # Minimum using min print(min(lst, key=min)) # [3, 3, -1]
Related Video:
Related articles:
- How to Find the Max of List of Lists in Python?
- Python List Methods [Overview]
- Python List sort() – The Ultimate Guide
- Python Lists – Everything You Need to Know to Get Started
- Key with Maximum Value in Dict
- Key with Minimum Value in Dict
Where to Go From Here?
Enough theory. Let’s get some practice!
Coders get paid six figures and more because they can solve problems more effectively using machine intelligence and automation.
To become more successful in coding, solve more real problems for real people. That’s how you polish the skills you really need in practice. After all, what’s the use of learning theory that nobody ever needs?
You build high-value coding skills by working on practical coding projects!
Do you want to stop learning with toy projects and focus on practical code projects that earn you money and solve real problems for people?
🚀 If your answer is YES!, consider becoming a Python freelance developer! It’s the best way of approaching the task of improving your Python skills—even if you are a complete beginner.
If you just want to learn about the freelancing opportunity, feel free to watch my free webinar “How to Build Your High-Income Skill Python” and learn how I grew my coding business online and how you can, too—from the comfort of your own home.