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Running pip install from a requirements txt file takes one command: activate your virtual environment in the project folder, then run pip install -r requirements.txt. pip reads every line and installs those packages and versions: Every command here really ran on Python 3.12.5 in Windows Command Prompt, installing two small packages from PyPI into a … Read more >>
Need to make a directory in Python? Use os.mkdir(“name”) for a single folder, or Path(“a/b/c”).mkdir(parents=True, exist_ok=True) to create nested folders without errors if they already exist: Each folder in these examples was created for real by Python 3.12.5 on Windows, and the screenshots show the Command Prompt output. I’ll cover os.mkdir(), os.makedirs(), pathlib, dated and … Read more >>
There are three main types of errors in Python: syntax errors, which stop the code from running at all; runtime errors (exceptions), which crash it partway through; and logical errors, which run fine but give the wrong answer. All the error messages below are copied from Python 3.12.5 running in a Windows Command Prompt, so … Read more >>
Most Ubuntu Linux systems already include Python 3, so installing Python on Ubuntu often just means adding pip and venv. Open a terminal and run: Which version you get depends on your Ubuntu release. I checked packages.ubuntu.com in October 2026, and the screenshots are real captures of that page and the deadsnakes PPA. This guide … Read more >>
Scraping web data with Python comes down to two steps: download the page with requests, then pull out the parts you need with Beautiful Soup. Here’s the whole idea in four lines: Together we’ll build a small scraper for books.toscrape.com, a fake bookstore made for practice, on Python 3.12.5, requests 2.34.2 and beautifulsoup4 4.15.0. The … Read more >>
Want to copy a list in Python? Call new = old.copy(), or use the slice old[:]. Both give you a separate list, so changing one won’t touch the other. For lists that contain other lists, use copy.deepcopy(): Screenshots come straight from Python 3.12.5 in Command Prompt, with the output text pasted under each code block. … Read more >>
You can install Python on Mac OS X (now macOS) in a few minutes: download the macOS installer from python.org, run it, then type python3 –version in Terminal. Homebrew users can do it in one command instead: As of October 2026, python.org lists Python 3.14.8 as the latest release, and Homebrew’s python@3.14 formula is on … Read more >>
The best Python libraries for web scraping are Requests and Beautiful Soup for simple pages, lxml for speed, Scrapy for large crawls, and Selenium or Playwright for sites that build their content with JavaScript. Most projects start with the first two: My examples scrape quotes.toscrape.com and books.toscrape.com, two sandbox sites built for practice, using Python … Read more >>
with open(“file.txt”) as file: is how Python opens a file safely. The with block gives you the file object as file, and Python closes it automatically when the block ends, even if an error happens inside: You’ll see real output from Python 3.12.5 on Windows 11 in every Command Prompt screenshot below. I’ll cover reading … Read more >>
Principal component analysis in Python takes three lines with scikit-learn: scale your features, create PCA(n_components=2), and call fit_transform(). You get a smaller set of new columns that keep most of the information: I tested this on Python 3.12.5 with scikit-learn 1.9.1, using the wine and iris datasets that ship with scikit-learn, so you won’t need … Read more >>