FINALLY had technical issues while delivering a remote talk. Today I got all of it! First, my computer froze and I couldn't even share my screen. Then, at some point my internet connection went POOF and I dropped off the call... 🤦 Hopefully now I'm good again for a dozen more talks.

Catch you there?

Stoked to share that the Steering Council has accepted PEP 814. frozendict is coming to Python 3.15! discuss.python.org/t/pep-814-ad...

Introducing the PSF Community Partner Program! The PSF is very excited to announce this new in-kind offering that expands how we support Python community events and initiatives around the world, now and alongside future community support programs 💝🐍

This list is missing the soft keywords. How many are there, and what are they?

I've written this Python function so many times I should no longer be confused by it... But I never know if it's def clamp(v): return min(max(v, low), high) or def clamp(v): return min(max(v, high), low) Always need to stop and think about it for a minute.

If they had used the built-in `range` this wouldn’t happen.

It's pretty cool how much you can get done in Python with so little code if you leverage the standard library.

One of my students today made this mistake. If you have a project and want to test it, your tests will import your project. So, you need to install pytest as a dependency INSIDE your project. If you install it globally, when you run it, it can't see your own project.

Dump JSON and make it Human-readable.

Parse JSON from a string with a single function call. Don't use this if you have JSON in a file. Use `load` for that. This is for when the data comes in a payload, for example.

When writing CLIs and scripts for the terminal, use `sys.exit` to set the exit code of your program. ✅ An exit code of 0 means success; your program terminated without any issues. ❌ Any other integer exit code means “error”.

“Nothing beats the smiles and thank you’s you get when the conference is over. Plus, it is an amazing feeling to be part of something bigger than yourself.” Check out the interview with @mathspp.com, Programme Team for EuroPython 2025 blog.europython.eu/humans-of-ep... #europython #conference

Day 2 of my intermediate Python course: I didn't forget to start the recording. That's a great start to the day :D

Before being added in Python 3.10, itertools.pairwise was commonly implemented in terms of itertools.tee. Isn't this elegant?

`typing.reveal_type` explained: Runtime vs static type checking time.

Python typing pop quiz. Take a look at the function `choice` shown below. Note how it's being called as `choice(3, "hey!")`. Will this type check or not? If it does, what's the revealed type? The right answer might surprise you! It surprised me. 🤷

This is how you learn to write really good code. In Python, and in any other programming language 👇

Has anyone here, in the data science world, successfully moved from using conda/miniconda/... to using uv?

Python has a flexible mechanism built into `pathlib` to look for files with filenames that follow a given pattern. You can use `[...-...]` to represent character ranges and `*` to match arbitrary text. But note that `glob` does NOT support regex syntax! This is just similar.

These two typing features look similar... But they're very different. Here's how to use NewType and TypeAlias in Python 👇

Pandas 3.0.0 is out now!

In hindsight, if you're seeing this on your phone, the QR code isn't very helpful... Just go to mathspp . com / drops 🤣

Just finished scheduling 3 tips for today, tomorrow and Friday. If you want to get smarter about Python in just 3 min/day, follow the QR code to sign-up.

Convert data to a JSON string without writing to a file: Just use `json.dumps`! (The final S stands for String!) ```py import json data = {"k1": True, "k2": [73, 42, 10]} s = json.dumps(data) print(type(s), s) # <class 'str'> {"k1": true, "k2": [73, 42, 10]} ```

Let me teach you to break a Python law. Iterators can only be traversed once: ```py squares = (x ** 2 for x in range(3)) for sq in squares: print(sq, end=", ") # 0, 1, 4, for sq in squares: print(sq, end=", ") # <no output> ``` The second loop produces no output!

`itertools.pairwise` takes an iterable and produces overlapping pairs of consecutive elements: ```py from itertools import pairwise queue = ["John", "Joe", "Ana"] for f, b in pairwise(queue): print(f"{f}'s ahead of {b}.") # John's ahead of Joe. # Joe's ahead of Ana. ```

This uv cheatsheet lists 40+ of the most and useful uv commands. It groups the commands into 9 sections that correspond to major features/capabilities that uv has. The cheatsheet is free to download and comes in light mode, dark mode, and high-contrast mode. mathspp.gumroad.com/l/cheatsheet...

A regex match has the method `groups`. This method returns a tuple with all of the groups that the pattern contained. Here's an example 👇

If your code type checks and you don't have `Any` or `# type: ignore` then you won't get type errors at runtime. Right? Wrong... ```py x: object = [] hash(x) ``` This code type checks but raises a `TypeError` at runtime... What's going on here?

Use CTRL + - to jump back to where your cursor was in VS Code. Useful, for example, after clicking through a definition!

This is the correct way to annotate Python methods that return self. 👇

This technique will make sure your data is ALWAYS valid. 👇

There's a fundamental rule of Python... That `itertools.tee` breaks! In a couple of hours, I'm sending a deep dive to 11,000+ email subscribers to help them understand how `tee` is able to do what it does! Check the link in my profile to subscribe and to get the deep dive too!

You can use the module `json` to read and write data in the JSON format, which is very suitable to represent the most common Python built-in types: - lists - dictionaries - strings - integers - floats - Booleans.

With the new year comes a new cycle of conferences! What do you want to know about attending/organising/speaking at Python conferences? Drop your Qs below and I’ll address them the best I can 👇

If you're in Lisbon, join us for the Python Lisbon Meetup. It's this Thursday, 8th of January, at 7pm at Instituto Superior Técnico. Find us on www.meetup.com/python-lisb... or on Discord discord.gg/DCNEYDKw9s for the full details! We'll have 1 talk + ?? lightning talks + chat

This is going to be a fun one, I can promise you that!

I had an AMAZING idea for what would easily be my best blog article, ever. But I might be a bit out of touch 😅 Help me figure this out: Have you ever heard of the “P vs NP” problem? Ok, and if you have, what about “NP-completeness”? Have you heard of this term? Could you explain it back to me?

Do you folks know any meetups that would be happy to host a remote talk? I have a couple of new talk ideas that I'd love to get some feedback on!

If you only remember to do one thing today, it should be proposing a talk for #PyConUS 2026. CFP closes today! us.pycon.org/2026/speakin...

What if... I started streaming regularly (weekly?) on a quest to CONQUER Leetcode? Start from #0001, and solve all Leetcode problems? Is that something watchable or am I just being ridiculous?

Advent of Code is over (only 12 days this year) and I'm kind of sad I don't have a reason to stream today. I liked streaming! What if I wanted to stream more? What should I stream about?

Congratulations to the new #Python #SteeringCouncil! 🗳️ @pumpichank.bsky.social 🗳️ @corona10.bsky.social 🗳️ @pablogsal.com 🗳️ @savannah.dev 🗳️ @yhg1s.bsky.social discuss.python.org/t/steering-c... Welcome Savannah & thank you to @gpshead.bsky.social for your service! hugovk.github.io/python-steer...

It's so ANNOYING to break out of nested loops. Auxiliary variables, conditional statements, non-linear paths through your code... It's a mess! But if you extract the looping logic to a generator, you get: - less indentation ✨ - a flat loop you can easily break out of ✨

📢 Public service announcement: Don't buy from me: Don't buy my books. Don't sign-up for my courses. Don't attend my cohorts. Apparently, I'm a scammer. 🤷 At least, that's my interpretation of this comment from a subscriber... Should I delete them from my mailing list?

After yesterday's flop, today I'm live streaming to solve day 10 of Advent of Code and hopefully go back to day 9 part 2 to make progress on finishing it!

A visualisation of day 7 from Advent of Code. Worked on this during yesterday's stream, although the colouring was added off stream.

7 days of Advent of Code diagrams from my streams and analysis sessions!

Today was a fun Advent of Code problem! Join me at 5pm UTC (in ~2h40min) as I livestream my solution and a visualisation for today's part 2. We'll be implementing a very efficient Python solution with sets and counters! Here's the link for later: youtube.com/@mathsppblog...