Rodrigo Girão Serrão 🐍🚀
@mathspp.com
I'll help you take your Python skills to the next level!
Python deep dive every Monday 🐍🚀 -> https://mathspp.com/insider
Short daily drop of Python knowledge 🐍💧 -> https://mathspp.com/drops
Python deep dive every Monday 🐍🚀 -> https://mathspp.com/insider
Short daily drop of Python knowledge 🐍💧 -> https://mathspp.com/drops
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]}
```
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]}
```
![Diagram showing how to use `json.dumps` to convert data into a JSON string.
Code snippet:
```py
import json
data = {"key1": True, "key2": [73, 42, 10]}
dumped = json.dumps(data)
print(type(dumped), dumped)
# str {"key1": true, "key2": [73, 42, 10]}
```](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:4642ovs4svxe3k3echdm4rks/bafkreigvrh22c65bu5fdn64hw2mibhy5blvzfwx3fntny6sggemyy2flmq@jpeg)
January 20, 2026 at 2:31 PM
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]}
```
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!
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!
January 19, 2026 at 3:26 PM
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!
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.
```
```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.
```
![Diagram showing how `itertools.pairwise` works.
Code snippet:
```py
from itertools import pairwise
queue = ["Harry", "Hermione", "Ron"]
for front, back in pairwise(queue):
print(f"{front} is directly in front of {back}.")
```
Output:
```text
Harry is directly in front of Hermione.
Hermione is directly in front of Ron.
```](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:4642ovs4svxe3k3echdm4rks/bafkreigm5g7lmac2xbmjebc6nooubmunhwwucyh6v22pxpudqkdfslervy@jpeg)
January 18, 2026 at 12:27 PM
`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.
```
```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...
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...
January 17, 2026 at 2:57 PM
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...
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 👇
This method returns a tuple with all of the groups that the pattern contained.
Here's an example 👇
January 16, 2026 at 1:16 PM
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 👇
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?
Right?
Wrong...
```py
x: object = []
hash(x)
```
This code type checks but raises a `TypeError` at runtime...
What's going on here?
January 15, 2026 at 11:03 PM
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?
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!
Useful, for example, after clicking through a definition!
January 14, 2026 at 4:04 PM
Use CTRL + - to jump back to where your cursor was in VS Code.
Useful, for example, after clicking through a definition!
Useful, for example, after clicking through a definition!
This is the correct way to annotate Python methods that return self. 👇
January 14, 2026 at 1:44 PM
This is the correct way to annotate Python methods that return self. 👇
This technique will make sure your data is ALWAYS valid. 👇
January 13, 2026 at 1:33 PM
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!
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!
January 12, 2026 at 3:27 PM
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!
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.
- lists
- dictionaries
- strings
- integers
- floats
- Booleans.
January 12, 2026 at 3:09 PM
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.
- 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 👇
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 👇
January 8, 2026 at 10:48 AM
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 👇
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
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
Join the Python 🐍 Lisbon Meetup Discord Server!
Discord server for the Python Lisbon Meetup community. | 61 members
discord.com
January 5, 2026 at 2:03 PM
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
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!
Organise the @python.berlin meeting on 12 February with a talk by Rodrigo Girão Serrão (@mathspp.com) on the paradox of itertools.tee: www.meetup.com/python-users...
#Python #Berlin
#Python #Berlin
Python User Group (PUB): The paradox of itertools.tee, Thu, Feb 12, 2026, 7:00 PM | Meetup
📆 Agenda
* 19:00 Welcome to the PUB (Python Users Berlin) – setting up
* 19:15 Main talk
* 20:00 Lightning talks
* 20:30 Social gathering
🎙 Main talk by Rodrigo Girão S
www.meetup.com
January 4, 2026 at 9:33 PM
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?
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?
December 20, 2025 at 12:54 PM
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?
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!
I have a couple of new talk ideas that I'd love to get some feedback on!
December 19, 2025 at 7:02 PM
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!
I have a couple of new talk ideas that I'd love to get some feedback on!
Reposted by Rodrigo Girão Serrão 🐍🚀
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...
us.pycon.org/2026/speakin...
Proposal Guidelines
PyCon US 2026
us.pycon.org
December 19, 2025 at 5:44 PM
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...
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?
Start from #0001, and solve all Leetcode problems?
Is that something watchable or am I just being ridiculous?
December 15, 2025 at 3:02 PM
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?
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?
I liked streaming!
What if I wanted to stream more?
What should I stream about?
December 13, 2025 at 4:03 PM
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?
I liked streaming!
What if I wanted to stream more?
What should I stream about?
Reposted by Rodrigo Girão Serrão 🐍🚀
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...
🗳️ @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...
December 13, 2025 at 2:13 PM
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...
🗳️ @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 ✨
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 ✨
December 11, 2025 at 1:51 PM
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 ✨
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?
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?
December 10, 2025 at 1:33 PM
📢 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?
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!
December 10, 2025 at 1:23 PM
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.
Worked on this during yesterday's stream, although the colouring was added off stream.
December 8, 2025 at 4:22 PM
A visualisation of day 7 from Advent of Code.
Worked on this during yesterday's stream, although the colouring was added off stream.
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!
December 7, 2025 at 7:06 PM
7 days of Advent of Code diagrams from my streams and analysis sessions!