Want to check whether a Python Pandas series contains another string? Use .str.contains: This returns a boolean series, whose index matches that of df. Keep only those rows containing ‘a’: The post Pandas .str.contains: Finding and filtering rows by substring appeared first on LernerPython.

Keyword-only parameters in a Python function can have a default: Now call it: Remember: parameters with defaults come *after* those without. The post Python keyword-only parameters: Setting default values appeared first on LernerPython.

Any Python function parameters after *args are keyword-only: Want to give k a value? Use a keyword argument: Don’t need *args? Just use *, and k is keyword only: The post Python keyword-only parameters: Using * and *args in def appeared first on LernerPython.

How to annotate *args in Python? Just set the elements’ type; we know it’s a tuple: Normally, tuples contain different types. In args, we assume all values have the same […] The post Type hints for *args in Python: Annotate the element type appeared first on LernerPython.

Classic use of Python’s *args: Invoke it with separate int arguments: and *not* with a list containing ints: The post Python *args: Collecting positional arguments into a tuple appeared first on LernerPython.

Want your Python function to take any number of positional args? Use *args: – Can be any name, but args is traditional– The * is only in the function definition– […] The post Python *args: Accepting any number of positional arguments appeared first on LernerPython.

How are arguments assigned to parameters when calling a Python function? There are two ways: – Positional, based on order– Keyword, i.e., name=value, assigned by name Want to mix and […] The post Positional vs keyword arguments in Python function calls appeared first on LernerPython.

Every import in Python executes the module, from start to finish. Meaning? Big modules slow down your program’s startup time. Coming in Python 3.15 this October: “lazy import”, which delays […] The post Python 3.15 lazy imports: Deferring module load until first use appeared first on LernerPython.

Mutable builtins in Python cannot be dict keys. But your (mutable) classes can! The post Python dict keys: Why custom objects work but lists don’t appeared first on LernerPython.

You can’t use a list as a Python dict key: Why not? Dicts run “hash” on a key to choose a pair’s storage location. To avoid pairs getting lost, mutable […] The post Python dict keys must be hashable: Why lists don’t work appeared first on LernerPython.

TL;DR: If you teach Python, then you should check out course-setup (https://pypi.org/project/course-setup/) at PyPI! I’ve been teaching Python and Pandas for many years. And while I started my teaching career […] The post Do you teach Python? Then check out course-setup appeared first on LernerPytho...

A Python Pandas column contains comma-separated values. How can you get the first of those? First, break each string into a list: Then use .str[0] to grab the first element […] The post Pandas str.split: Get the first item of a comma-separated column appeared first on LernerPython.

Want to check whether a Python Pandas string series only contains digits? Use str.isdigit: This returns a boolean series, with df’s index. You can then convert the digit-containing strings to […] The post Pandas str.isdigit: Checking whether strings contain only digits appeared first on LernerPython...