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Rodrigo 🐍📝

@mathsppblog

8 Sep

Have you ever tried to optimise your Python 🐍 code, but weren't able to tell which alternative implementation was faster?

Let me teach you how to use the `timeit.timeit` method to measure execution time of small code snippets.

A thread 👇🧵

If you have a snippet of code you want to time, you can use the command line to measure its execution time.

For example, how long does it take for Python 🐍 to add up the first 10,000 integers?

Using the command `python -m timeit`, I get that it takes 189 microseconds.

https://twitter.com/mathsppblog/status/1427256481796218880

The execution of `python -m timeit` reports some more info:

“2000 loops, best of 5: ...”

I'll explain what that means, but first let me show you how to use `timeit` in your code.

(Oh, btw, there's a MUCH better way to add consecutive integers! 👇)

https://twitter.com/mathsppblog/status/1427256481796218880

Read 23 tweets

Rodrigo 🐍📝

@mathsppblog

8 Sep

Did you know that Python 🐍 supports keyword argument unpacking?

What's that?

If you have a function that accepts a series of arguments: `arg1`, `arg2`, ...

And if you have a dictionary with keys named `arg1`, `arg2`, ...

Then you can use the dict's values as arguments:

The `**` in front of `kwargs` does the unpacking in the function call.

`my_func(kwargs)` – this calls `my_func` with a single argument, the `kwargs` variable (a dictionary in the image above)

...

`my_func(**kwargs)` – this calls `my_func` with one named argument for each (key, value) pair in the dictionary.

E.g., in the above,

`my_func(**kwargs)` unpacks to `my_func(a=73, b="hey!", c=(1, 10))`.

Read 4 tweets

Rodrigo 🐍📝

@mathsppblog

7 Sep

@svpino

@svpino Hey Santiago! I'd just like to clarify something for the readers of this thread:

The formula

P(A or B or C) = P(A) + P(B) + P(C) - P(A and B and C) is NOT ‼ true in general.

The result works here because the events are mutually exclusive and P(A and B and C) = 0

1/

@svpino

@svpino But the actual general formula is

P(A or B or C) = P(A) + P(B) + P(C) - P(A and B) - P(B and C) - P(A and C) + P(A and B and C)

You can read up on the inclusion-exclusion principle, which explains this: 🔗 en.wikipedia.org/wiki/Inclusion…

This can also be explained visually:

2/

@svpino

@svpino Checking the overlaps below 👇

The ellipsis (representing the events) can overlap all over the place, and we CANNOT overcount the overlaps!

So, we need to remove the pairwise overlaps:

A and B
A and C
B and C

But when we do that, we over-subtract the final intersection,

3/

Read 4 tweets

Rodrigo 🐍📝

@mathsppblog

2 Sep

Have you ever seen anything like this in Python 🐍 loops??

I just saw this being used for the first time, ever, and I decided to figure out what the heck this was...

And so here goes the explanation 👇🧵

1/

Foreword:

Python has many amazing capabilities to deal with `for` loops, among which you can count the `zip` and `enumerate` built-ins.

This little thread assumes you are familiar with both.

Read these if you need:
🔗 mathspp.com/blog/pydonts/e…
🔗 mathspp.com/blog/pydonts/z…

2/

When using `zip` and `enumerate` in your `for` loops, something you do often is to unpack the values you are iterating over.

Unpacking, in and out of itself, is an amazing feature of Python, and you can read about it in the linked article if needed.

mathspp.com/blog/pydonts/d…

3/

Read 10 tweets

Rodrigo 🐍📝

@mathsppblog

31 Aug

https://twitter.com/mathsppblog/status/1431980960858480651

🥇 I challenged you to write a Python 🐍 function `is_pangram`, that checks if a string contains all 26 letters of the English alphabet.

(Original challenge linked below 👇)

I got many amazing suggestions.

Here is a thread 🧵 about different solutions.

https://twitter.com/mathsppblog/status/1431980960858480651

Overall, people tended to follow one of 3 approaches:

1. remove irrelevant chars and see if there are 26 letters left (duplicates excluded);

2. check if each letter of the alphabet appears in the string; and

3. check if the alphabet is fully contained inside the input string.

Then, I saw two major trends in the solutions people shared, regardless of strategy.

Either they did all the work by hand with a `for` loop or they leveraged tools like Python's `set`.

Here's the archetype for a `for` based solution:

Read 17 tweets

Rodrigo 🐍📝

@mathsppblog

24 Aug

Did you know that Python 🐍 has over 240 modules in the standard library?

Here is a MEGA thread 🧵with a super high level overview of those modules...

... but before that, I challenge you to name as many modules by heart as possible! 💬👇

Let's see who gets more!

To help get a sense for the more popular and used modules, leave a like ♥ on the tweets that contain modules you remember using.

Can you guess what module(s) are the most widely used..? 🤔

(P.S. To learn more about all these cool modules, check docs.python.org/3/library/)

Let's kick things off with

👉 Text Processing Services
🔗 docs.python.org/3/library/text…

1️⃣ string — Common string operations

2️⃣ re — Regular expression operations

3️⃣ difflib — Helpers for computing deltas

4️⃣ textwrap — Text wrapping and filling

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