Mike Driscoll Profile picture
Jul 24, 2022 5 tweets 3 min read Read on X
You need to know the basics of #Python to be able to use it effectively.

So let's talk about how you can slice a list. List slicing is where you use square brackets to "slice" out a subset of the list.

A slice is a portion of a list returned as a new list

🧵👇 Image
Here is an example of slicing a #Python list: Image
You can also use negative values when slicing a #Python list

This example demonstrates using a negative value for the beginning of the slice while ALSO not specifying the end of the slice Image
You don't need to specify the beginning of a #Python list slice either.

In this example, I want to grab all the values starting at index 0 up to but not including index 3. Image
What do you think happens when you don't specify a beginning or an ending in a #Python list slice? Image

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More from @driscollis

Feb 1, 2024
Did you know that #Python supports SQLite in the standard library? That's right. You don't need to install anything! 🐍🚀

Let's talk a little about that!

🧵👇
If you have a pre-existing SQLite database file, you can use #Python's `sqlite3` module to connect to it

Here's how: Image
If you want to create a new SQLite database with #Python, you can use the same syntax that you'd use to connect to a pre-existing one.

Then create a cursor object and create your table, like this: Image
Read 8 tweets
Nov 21, 2023
Today is a great day to talk about #Python lambdas!

Let's learn about them in a thread

🐍🧵👇
A Python lambda is a one-line anonymous function.

Rule #1 is do NOT assign a lambda to a variable.

When you do that, it's no longer an anonymous function. You should just create a regular function at that point Image
If you want to run a lambda in your REPL, wrap it in parentheses, like this: Image
Read 9 tweets
Mar 23, 2023
Want to create a copy of a #Python list? Use Python's `copy()` method!

Note: Watch out if your list contains lists of dictionaries. In those cases, you might be better off using copy.deepcopy()
But be careful! If your list contains a mutable object, like another list or a dictionary, you may encounter some unexpected behavior.

In the following example, you `copy()` the list. Then you modify the nested dictionary in the copy, but that also changes the original list!
You can fix this behavior by using Python's `copy` module. It provides a deepcopy() function that you can use which will make a deep copy of the ENTIRE list!
Read 4 tweets
Mar 22, 2023
#Python generators aren't talked about enough.

So let's talk about them today!

🧵🐍👇
According to the #Python wiki, "Generator functions allow you to declare a function that behaves like an iterator"

One of their best use cases is to chunk through large data sets a piece at a time, which prevents you from running out of memory.

wiki.python.org/moin/Generators
To create a generator in #Python, you need to use the `yield` keyword instead of `return` inside a function.

Generators will continue to yield values until the generator is exhausted.

The following example will continue to yield numbers for as long as you call it: Image
Read 10 tweets
Mar 21, 2023
My 11th #Python book is now available! 🐍🤯

Test your Python skills and knowledge with over 100 PYthon quizzes. Answers are included if you get stuck!

Available on Amazon, Leanpub, and Gumroad (see following tweets)
Get my 11th #Python book, The Python Quiz book on Amazon in the following formats:

🐍 Kindle
🐍 Paperback

amazon.com/dp/B0BVT8DZV1
You can find The Python Quiz Book on @gumroad too in the following formats:

🐍 epub
🐍 PDF

driscollis.gumroad.com/l/pyquiz
Read 4 tweets
Mar 17, 2023
Starting in Python 3.7, the `breakpoint()` built-in function was added

It is defined in PEP 553 and simplifies adding a breakpoint to your code

#python_builtins_by_driscollis

🧵🐍👇
You can read about the `breakpoint()` function for Python here:

python.org/dev/peps/pep-0…
Here is some sample code showing how to use the `breakpoint()` function in your Python code
Read 6 tweets

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