Cookbooks

Cookbooks

Practical recipes for real-world Python programming tasks.

1. How to Convert a String to an Integer in Python

   Convert strings to integers using int() with error handling for invalid input.

   python ·conversion ·numbers
2. How to Join a List into a String in Python

   Learn how to convert a list to a string in Python using str.join, with examples for strings, numbers, custom separators, and edge cases.

   python ·strings ·lists
3. How to count occurrences of an item in a list in Python

   Count how many times an element appears in a list using list.count(), Counter, or a manual loop.

   python ·lists ·counting
4. How to Generate a Random Number in Python

   Generate random numbers using the random module — integers, floats, and within ranges.

   python ·random ·numbers
5. How to find the maximum value in a list in Python

   Find the maximum value in a list using max(), sorted(), or a loop. Includes handling empty lists and custom objects.

   python ·lists ·beginner
6. How to flatten a nested list in Python

   Flatten a nested list using list comprehension, itertools, or recursion.

   python ·lists ·nested
7. How to read a file line by line in Python

   Read a file line by line using for loops, readlines(), or iter(). Compare memory efficiency and use cases.

   python ·files ·io
8. How to merge two dictionaries in Python

   Merge dictionaries using the | operator, ** unpacking, or .update(). The | operator is the cleanest for Python 3.9+.

   python ·dict ·dictionaries
9. How to get the current date and time in Python

   Get the current date and time using datetime.now() or timezone-aware datetime with zoneinfo. Also covers date only and time only.

   python ·datetime ·time
10. How to check if a key exists in a dictionary in Python

    Check if a dictionary key exists using in, .get(), or catching KeyError. The in operator is the most Pythonic.

    python ·dict ·dictionaries
11. How to remove duplicates from a list in Python

    Remove duplicates while preserving order using dict.fromkeys() or a loop. The simplest solution is list(dict.fromkeys(items)).

    python ·lists ·deduplication
12. How to reverse a string in Python

    Reverse a string using slicing or reversed(). The fastest method is slicing with [::-1].

    python ·strings ·slicing
13. How to write to a file in Python

    Write text or binary data to files using Python built-in open function with different modes.

    python ·files ·io
14. How to Swap Two Variables in Python

    Swap two variables in Python using tuple unpacking or a temporary variable. Tuple unpacking is the most Pythonic way.

    python ·variables ·basics
15. How to sort a list by a key in Python

    Sort lists by custom criteria using the key parameter in sorted() and list.sort().

    python ·lists ·sorting
16. How to total a CSV column with csv.DictReader

    Read a CSV file with csv.DictReader and total one column in Python with a simple loop.

    python ·csv ·dictreader