Rodrigo Girão Serrão 🐍🚀
@mathspp.com
I'll help you take your Python skills to the next level!
Algorithm Mastery Bootcamp 🎯 -> https://mathspp.gumroad.com/l/algorithm-mastery-bootcamp-2025
Get a daily drop of Python knowledge 🐍💧 -> https://mathspp.com/drops
Algorithm Mastery Bootcamp 🎯 -> https://mathspp.gumroad.com/l/algorithm-mastery-bootcamp-2025
Get a daily drop of Python knowledge 🐍💧 -> https://mathspp.com/drops
In today's session of the Algorithm Mastery Bootcamp we talked about linear recurrence relations and how to represent them as matrices.
The next step?
Using fast exponentiation with repeated squaring to compute terms at LIGHTNING FAST speeds ⚡️🤓
The next step?
Using fast exponentiation with repeated squaring to compute terms at LIGHTNING FAST speeds ⚡️🤓
November 26, 2025 at 7:16 PM
In today's session of the Algorithm Mastery Bootcamp we talked about linear recurrence relations and how to represent them as matrices.
The next step?
Using fast exponentiation with repeated squaring to compute terms at LIGHTNING FAST speeds ⚡️🤓
The next step?
Using fast exponentiation with repeated squaring to compute terms at LIGHTNING FAST speeds ⚡️🤓
This December I'll be publicly live-streaming myself solving Advent of Code (in Python) on YouTube, but I never streamed on YouTube.
Does anyone have any tips? :D
Both general streaming tips and specific YT-related ones?
Does anyone have any tips? :D
Both general streaming tips and specific YT-related ones?
November 25, 2025 at 2:42 PM
This December I'll be publicly live-streaming myself solving Advent of Code (in Python) on YouTube, but I never streamed on YouTube.
Does anyone have any tips? :D
Both general streaming tips and specific YT-related ones?
Does anyone have any tips? :D
Both general streaming tips and specific YT-related ones?
Reposted by Rodrigo Girão Serrão 🐍🚀
This post includes Python-related sales from @lernerpython.com, @mkennedy.codes, @stephengruppetta.com, @mathspp.com, and @dataschool.io.
...plus a bonus non-Python sale from @b0rk.jvns.ca because the zines are too good not to mention.
...plus a bonus non-Python sale from @b0rk.jvns.ca because the zines are too good not to mention.
November 24, 2025 at 4:52 PM
This post includes Python-related sales from @lernerpython.com, @mkennedy.codes, @stephengruppetta.com, @mathspp.com, and @dataschool.io.
...plus a bonus non-Python sale from @b0rk.jvns.ca because the zines are too good not to mention.
...plus a bonus non-Python sale from @b0rk.jvns.ca because the zines are too good not to mention.
One of my favourite things to do with Python 🐍 is trying to reimplement (parts of) modules.
I just have fun doing it. 🤷
And I was thinking about `itertools.pairwise` and its generalisation, `nwise`...
And how you could implement `nwise` in different ways.
Here's what I got:
I just have fun doing it. 🤷
And I was thinking about `itertools.pairwise` and its generalisation, `nwise`...
And how you could implement `nwise` in different ways.
Here's what I got:
November 24, 2025 at 8:15 PM
One of my favourite things to do with Python 🐍 is trying to reimplement (parts of) modules.
I just have fun doing it. 🤷
And I was thinking about `itertools.pairwise` and its generalisation, `nwise`...
And how you could implement `nwise` in different ways.
Here's what I got:
I just have fun doing it. 🤷
And I was thinking about `itertools.pairwise` and its generalisation, `nwise`...
And how you could implement `nwise` in different ways.
Here's what I got:
With the Black Friday deal (BF202550 for 50% off all my books), my book Python drops, with 179 Python tips, comes out at ~4 cents per tip...
That's a bit criminal 🤣
After the BF I'll have to increase the price of this book!
mathspp.gumroad.com/l/python-dr...
That's a bit criminal 🤣
After the BF I'll have to increase the price of this book!
mathspp.gumroad.com/l/python-dr...
Python drops book and flashcards
mathspp.gumroad.com
November 24, 2025 at 2:25 PM
With the Black Friday deal (BF202550 for 50% off all my books), my book Python drops, with 179 Python tips, comes out at ~4 cents per tip...
That's a bit criminal 🤣
After the BF I'll have to increase the price of this book!
mathspp.gumroad.com/l/python-dr...
That's a bit criminal 🤣
After the BF I'll have to increase the price of this book!
mathspp.gumroad.com/l/python-dr...
Inspired by @samwho.dev's brilliant interactive essays, I wrote an interactive explanation of the floodfill algorithm.
(Also in preparation for Advent of Code.)
Give it a read and let me know what you think -> mathspp.com/blog/floodfi...
I tried using PyScript for the interactive demos...
(Also in preparation for Advent of Code.)
Give it a read and let me know what you think -> mathspp.com/blog/floodfi...
I tried using PyScript for the interactive demos...
Floodfill algorithm in Python
Learn how to implement and use the floodfill algorithm in Python.
mathspp.com
November 23, 2025 at 1:45 PM
Inspired by @samwho.dev's brilliant interactive essays, I wrote an interactive explanation of the floodfill algorithm.
(Also in preparation for Advent of Code.)
Give it a read and let me know what you think -> mathspp.com/blog/floodfi...
I tried using PyScript for the interactive demos...
(Also in preparation for Advent of Code.)
Give it a read and let me know what you think -> mathspp.com/blog/floodfi...
I tried using PyScript for the interactive demos...
Ok, so I was writing a Python article about the floodfill algorithm.
It includes some interactive demos I created with PyScript!
I was still developing and testing the demos...
But someone shared it online in a major Python newsletter...
So, I guess the cat's out of the bag !
It includes some interactive demos I created with PyScript!
I was still developing and testing the demos...
But someone shared it online in a major Python newsletter...
So, I guess the cat's out of the bag !
November 20, 2025 at 9:23 PM
Ok, so I was writing a Python article about the floodfill algorithm.
It includes some interactive demos I created with PyScript!
I was still developing and testing the demos...
But someone shared it online in a major Python newsletter...
So, I guess the cat's out of the bag !
It includes some interactive demos I created with PyScript!
I was still developing and testing the demos...
But someone shared it online in a major Python newsletter...
So, I guess the cat's out of the bag !
Here's how to NOT get a file name from a path in Python.
The string method `split` has a counterpart `rsplit` that starts splitting from the end of the string.
This is useful if you only want the final segment(s) of a string.
The string method `split` has a counterpart `rsplit` that starts splitting from the end of the string.
This is useful if you only want the final segment(s) of a string.
![Diagram showing how split and rsplit work. Code:
>>> "This is bananas".split()
['This', 'is', 'bananas']
>>> "This is bananas".rsplit()
['This', 'is', 'bananas']
s = "This is bananas"
first, rest = s.split(maxsplit=1)
print(first) # This
print(rest) # is bananas
s = "This is bananas"
rest, last = s.rsplit(maxsplit=1)
print(last) # bananas
print(rest) # This is](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:4642ovs4svxe3k3echdm4rks/bafkreidmys4u2khyard2usmzqx5bp7s45vjkyoqdm3xeemm5rp5iurkqg4@jpeg)
November 20, 2025 at 3:57 PM
Here's how to NOT get a file name from a path in Python.
The string method `split` has a counterpart `rsplit` that starts splitting from the end of the string.
This is useful if you only want the final segment(s) of a string.
The string method `split` has a counterpart `rsplit` that starts splitting from the end of the string.
This is useful if you only want the final segment(s) of a string.
Who can guess what I'm writing about?
November 19, 2025 at 6:33 PM
Who can guess what I'm writing about?
Do you work in Hollywood or at a publisher?
If you do, I've got the perfect Python string method for you:
`str.title`
Changes the case of any string into title case.
“star wars: the empire strikes back”
becomes
“Star Wars: The Empire Strikes Back”.
Much more professional!
If you do, I've got the perfect Python string method for you:
`str.title`
Changes the case of any string into title case.
“star wars: the empire strikes back”
becomes
“Star Wars: The Empire Strikes Back”.
Much more professional!
November 19, 2025 at 6:22 PM
Do you work in Hollywood or at a publisher?
If you do, I've got the perfect Python string method for you:
`str.title`
Changes the case of any string into title case.
“star wars: the empire strikes back”
becomes
“Star Wars: The Empire Strikes Back”.
Much more professional!
If you do, I've got the perfect Python string method for you:
`str.title`
Changes the case of any string into title case.
“star wars: the empire strikes back”
becomes
“Star Wars: The Empire Strikes Back”.
Much more professional!
Need a temp file in Python?
Maybe you need to test a function that requires a file-like object.
Or maybe you need a buffer because you're processing an amount of data so large that it doesn't fit into memory...
In these situations, `tempfile.TemporaryFile` can help you out.
Maybe you need to test a function that requires a file-like object.
Or maybe you need a buffer because you're processing an amount of data so large that it doesn't fit into memory...
In these situations, `tempfile.TemporaryFile` can help you out.
November 17, 2025 at 4:28 PM
Need a temp file in Python?
Maybe you need to test a function that requires a file-like object.
Or maybe you need a buffer because you're processing an amount of data so large that it doesn't fit into memory...
In these situations, `tempfile.TemporaryFile` can help you out.
Maybe you need to test a function that requires a file-like object.
Or maybe you need a buffer because you're processing an amount of data so large that it doesn't fit into memory...
In these situations, `tempfile.TemporaryFile` can help you out.
What I share in a Python tip:
You CAN use this data structure for this.
Note how, from a pedagogical standpoint, this is an instructive example.
What the commenters see:
You HAVE to use this code EXACTLY like this and this is the ABSOLUTE BEST solution in EVERY context.
You CAN use this data structure for this.
Note how, from a pedagogical standpoint, this is an instructive example.
What the commenters see:
You HAVE to use this code EXACTLY like this and this is the ABSOLUTE BEST solution in EVERY context.
November 17, 2025 at 11:34 AM
What I share in a Python tip:
You CAN use this data structure for this.
Note how, from a pedagogical standpoint, this is an instructive example.
What the commenters see:
You HAVE to use this code EXACTLY like this and this is the ABSOLUTE BEST solution in EVERY context.
You CAN use this data structure for this.
Note how, from a pedagogical standpoint, this is an instructive example.
What the commenters see:
You HAVE to use this code EXACTLY like this and this is the ABSOLUTE BEST solution in EVERY context.
When doing Advent of Code I always end up needing a stack.
When I do, I create it by inheriting from `list`.
This gives me almost everything I want for free!
When I do, I create it by inheriting from `list`.
This gives me almost everything I want for free!
![Diagram showing how to use the built-in `list` as a base class to create a stack. Code:
class stack(list):
def put(self, value):
self.append(value)
def peek(self):
return self[-1]
s = stack()
s.put(1)
s.put(2)
s.put(3)
print(f"The stack has {len(s)} items.")
# The stack has 3 items.
print(3 in s) # True
popped = s.pop()
print(3 in s) # False
if s:
print(f"{popped} was at the top.")
print(f"Now it's {s.peek()}.")
# 3 was at the top.
# Now it's 2.](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:4642ovs4svxe3k3echdm4rks/bafkreibcs27rx22gopfb6oey74mxvf6yh2itfeleuupi7jub6267bmurrm@jpeg)
November 14, 2025 at 1:27 PM
When doing Advent of Code I always end up needing a stack.
When I do, I create it by inheriting from `list`.
This gives me almost everything I want for free!
When I do, I create it by inheriting from `list`.
This gives me almost everything I want for free!
33 likes on BlueSky? Am I famous now?!
You know what's a pain to implement in Python?
A moving average function.
Manually keeping track of all the values being considered for the window is a pain!
Unless you use `collections.deque`.
Its param `maxlen` makes the window automatically evict the values you don't need.
A moving average function.
Manually keeping track of all the values being considered for the window is a pain!
Unless you use `collections.deque`.
Its param `maxlen` makes the window automatically evict the values you don't need.
![Snippet of code showing a moving average implementation in pure Python. Code:
```py
from collections import deque
from itertools import islice
def moving_average(values, n):
source = iter(values)
window = deque(islice(source, n - 1), maxlen=n)
averages = []
for value in source:
window.append(value)
averages.append(sum(window) / n)
return averages
moving_average([10, 20, 30], 2)
# [15.0, 25.0]
```](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:4642ovs4svxe3k3echdm4rks/bafkreiabfdynxg2fbv7zen54weymktg2yed7jww55knrqs2zdvn4tw6cy4@jpeg)
November 14, 2025 at 11:57 AM
33 likes on BlueSky? Am I famous now?!
I published an article about “everything related to functions”.
It was supposed to be a reference article...
And I forgot to talk about docstrings! 🤦
What's worse is that no one event pointed that out to me!
I've fixed it now: mathspp.com/blog/pydont...
It was supposed to be a reference article...
And I forgot to talk about docstrings! 🤦
What's worse is that no one event pointed that out to me!
I've fixed it now: mathspp.com/blog/pydont...
Functions: a complete reference | Pydon't 🐍
This article serves as a complete reference for all the non-trivial things you should know about Python functions.
mathspp.com
November 14, 2025 at 11:19 AM
I published an article about “everything related to functions”.
It was supposed to be a reference article...
And I forgot to talk about docstrings! 🤦
What's worse is that no one event pointed that out to me!
I've fixed it now: mathspp.com/blog/pydont...
It was supposed to be a reference article...
And I forgot to talk about docstrings! 🤦
What's worse is that no one event pointed that out to me!
I've fixed it now: mathspp.com/blog/pydont...
You know what's a pain to implement in Python?
A moving average function.
Manually keeping track of all the values being considered for the window is a pain!
Unless you use `collections.deque`.
Its param `maxlen` makes the window automatically evict the values you don't need.
A moving average function.
Manually keeping track of all the values being considered for the window is a pain!
Unless you use `collections.deque`.
Its param `maxlen` makes the window automatically evict the values you don't need.
November 13, 2025 at 6:19 PM
You know what's a pain to implement in Python?
A moving average function.
Manually keeping track of all the values being considered for the window is a pain!
Unless you use `collections.deque`.
Its param `maxlen` makes the window automatically evict the values you don't need.
A moving average function.
Manually keeping track of all the values being considered for the window is a pain!
Unless you use `collections.deque`.
Its param `maxlen` makes the window automatically evict the values you don't need.
I was going through the OVERWHELMINGLY POSITIVE reviews of my book “Pydon'ts” and I always giggle when I find this 1-star review.
I mean, after 200 ⭐️⭐️⭐️⭐️⭐️ reviews, this anonymous user could think for a second and realise that the issue wasn't mine/the book's...
🤡
I mean, after 200 ⭐️⭐️⭐️⭐️⭐️ reviews, this anonymous user could think for a second and realise that the issue wasn't mine/the book's...
🤡
November 12, 2025 at 2:17 PM
I was going through the OVERWHELMINGLY POSITIVE reviews of my book “Pydon'ts” and I always giggle when I find this 1-star review.
I mean, after 200 ⭐️⭐️⭐️⭐️⭐️ reviews, this anonymous user could think for a second and realise that the issue wasn't mine/the book's...
🤡
I mean, after 200 ⭐️⭐️⭐️⭐️⭐️ reviews, this anonymous user could think for a second and realise that the issue wasn't mine/the book's...
🤡
This GitHub Action dorny/path-filters just saved me hours of work 🥵
I have a folder in a repo with cloudflare workers:
workers/
workerA/**
workerB/**
I want to deploy workers that get changed but not the others!
That's when dorny/path-filters comes in handy! ✨
I have a folder in a repo with cloudflare workers:
workers/
workerA/**
workerB/**
I want to deploy workers that get changed but not the others!
That's when dorny/path-filters comes in handy! ✨
November 12, 2025 at 1:59 PM
This GitHub Action dorny/path-filters just saved me hours of work 🥵
I have a folder in a repo with cloudflare workers:
workers/
workerA/**
workerB/**
I want to deploy workers that get changed but not the others!
That's when dorny/path-filters comes in handy! ✨
I have a folder in a repo with cloudflare workers:
workers/
workerA/**
workerB/**
I want to deploy workers that get changed but not the others!
That's when dorny/path-filters comes in handy! ✨
Your future you will thank you for this:
The keyword `assert` takes an expression to its right.
If the expression evaluates to `True`, or Truthy, everything is fine.
But if it doesn’t, you get an `AssertionError`.
That's a pretty unhelpful/generic error...
Here's the fix:
The keyword `assert` takes an expression to its right.
If the expression evaluates to `True`, or Truthy, everything is fine.
But if it doesn’t, you get an `AssertionError`.
That's a pretty unhelpful/generic error...
Here's the fix:
November 11, 2025 at 2:19 PM
Your future you will thank you for this:
The keyword `assert` takes an expression to its right.
If the expression evaluates to `True`, or Truthy, everything is fine.
But if it doesn’t, you get an `AssertionError`.
That's a pretty unhelpful/generic error...
Here's the fix:
The keyword `assert` takes an expression to its right.
If the expression evaluates to `True`, or Truthy, everything is fine.
But if it doesn’t, you get an `AssertionError`.
That's a pretty unhelpful/generic error...
Here's the fix:
Quick!
How many string methods that change the case of a string can you name?
I'll give you a hint:
I thought there were only 5 but I was wrong.
How many string methods that change the case of a string can you name?
I'll give you a hint:
I thought there were only 5 but I was wrong.
November 10, 2025 at 2:42 PM
Quick!
How many string methods that change the case of a string can you name?
I'll give you a hint:
I thought there were only 5 but I was wrong.
How many string methods that change the case of a string can you name?
I'll give you a hint:
I thought there were only 5 but I was wrong.
All Python objects have a Truthy/Falsy value.
This is the value of an object when used in a Boolean context.
For example, when used in the condition of an `if` statement.
Most objects are Truthy, with a few exceptions.
For most types, the “nothing” or “empty” value is Falsy.
This is the value of an object when used in a Boolean context.
For example, when used in the condition of an `if` statement.
Most objects are Truthy, with a few exceptions.
For most types, the “nothing” or “empty” value is Falsy.
November 10, 2025 at 10:54 AM
All Python objects have a Truthy/Falsy value.
This is the value of an object when used in a Boolean context.
For example, when used in the condition of an `if` statement.
Most objects are Truthy, with a few exceptions.
For most types, the “nothing” or “empty” value is Falsy.
This is the value of an object when used in a Boolean context.
For example, when used in the condition of an `if` statement.
Most objects are Truthy, with a few exceptions.
For most types, the “nothing” or “empty” value is Falsy.
It just hit me that programming is like chess.
Everyone can play.
But not everyone plays beautifully…
It requires practice and calculated moves.
Moves that look like arbitrary choices…
But if you know, you’ll see how each decision builds towards a readable codebase.
Everyone can play.
But not everyone plays beautifully…
It requires practice and calculated moves.
Moves that look like arbitrary choices…
But if you know, you’ll see how each decision builds towards a readable codebase.
November 9, 2025 at 5:48 PM
It just hit me that programming is like chess.
Everyone can play.
But not everyone plays beautifully…
It requires practice and calculated moves.
Moves that look like arbitrary choices…
But if you know, you’ll see how each decision builds towards a readable codebase.
Everyone can play.
But not everyone plays beautifully…
It requires practice and calculated moves.
Moves that look like arbitrary choices…
But if you know, you’ll see how each decision builds towards a readable codebase.
Just published a new article about the new Python 3.14 module `compression`.
This module offers a neat way to access the 5 compression modules we have in Python:
👉 bz2
👉 gzip
👉 lzma
👉 zlib
👉 zstd
The first four were already available as standalone modules...
This module offers a neat way to access the 5 compression modules we have in Python:
👉 bz2
👉 gzip
👉 lzma
👉 zlib
👉 zstd
The first four were already available as standalone modules...
November 8, 2025 at 12:02 AM
Just published a new article about the new Python 3.14 module `compression`.
This module offers a neat way to access the 5 compression modules we have in Python:
👉 bz2
👉 gzip
👉 lzma
👉 zlib
👉 zstd
The first four were already available as standalone modules...
This module offers a neat way to access the 5 compression modules we have in Python:
👉 bz2
👉 gzip
👉 lzma
👉 zlib
👉 zstd
The first four were already available as standalone modules...
When building complex readable strings, consider building them out of smaller fragments.
The function `oxford_comma`, shown below, demonstrates this technique.
What's the point of the smaller fragments?
The function `oxford_comma`, shown below, demonstrates this technique.
What's the point of the smaller fragments?
November 7, 2025 at 2:25 PM
When building complex readable strings, consider building them out of smaller fragments.
The function `oxford_comma`, shown below, demonstrates this technique.
What's the point of the smaller fragments?
The function `oxford_comma`, shown below, demonstrates this technique.
What's the point of the smaller fragments?
Python has a very well-known naming convention:
Names that start with a leading underscore are “private”.
This means the outside world has no business using them.
E.g., attributes and methods starting with `_` in a class mean they're for that class only.
Names that start with a leading underscore are “private”.
This means the outside world has no business using them.
E.g., attributes and methods starting with `_` in a class mean they're for that class only.
November 6, 2025 at 12:03 PM
Python has a very well-known naming convention:
Names that start with a leading underscore are “private”.
This means the outside world has no business using them.
E.g., attributes and methods starting with `_` in a class mean they're for that class only.
Names that start with a leading underscore are “private”.
This means the outside world has no business using them.
E.g., attributes and methods starting with `_` in a class mean they're for that class only.