How to Use Python’s Join() on a List of Objects (Not Strings)?

The most Pythonic way to concatenate a list of objects is the expression ”.join(str(x) for x in lst) that converts each object to a string using the built-in str(…) function in a generator expression. You can concatenate the resulting list of strings using the join() method on the empty string as a delimiter. The result … Read more

How to Get a List Slice with Arbitrary Indices in Python?

To extract elements with specific indices from a Python list, use slicing list[start:stop:step]. If you cannot use slicing because there’s no pattern in the indices you want to access, use the list comprehension statement [lst[i] for i in indices], assuming your indices are stored in the variable indices. People always want to know the most … Read more

[Python OOP Cheat Sheet] A Simple Overview of Object-Oriented Programming

Q: What’s the object-oriented way to become wealthy? A: Inheritance. ? Your vocabulary determines the reality of your life. In this tutorial, I have compiled the most essential terms and concepts of object-oriented programming in Python. My goal was to create the best Python OOP cheat sheet that shows them in one place. Well — … Read more

How to Join Specific List Elements in Python?

To join specific list elements (e.g., with indices 0, 2, and 4) and return the joined string that’s the concatenation of all those, use the expression ”.join([lst[i] for i in [0, 2, 4]]). The list comprehension statement creates a list consisting of elements lst[0], lst[2], and lst[4]. The ”.join() method concatenates those elements using the … Read more

Introduction to Slicing in Python

Slicing is a concept to carve out a substring from a given string. Use slicing notation s[start:stop:step] to access every step-th element starting from index start (included) and ending in index stop (excluded). All three arguments are optional, so you can skip them to use the default values (start=0, stop=len(lst), step=1). For example, the expression … Read more

Python | Join List as Path

Do you want to join a list of strings to a path in your specific operating system? Remembering the correct path separator can be a real pain. Fortunately, the os.path.join() method comes to the rescue! The os.path.join() method takes one or more path arguments and returns a concatenation of the path arguments with the correct … Read more

String Formatting: Keep It Simple, Stupid!

What is the output of this code snippet? The string format function is a useful feature that is new in Python 3. Use it to programmatically insert variable values into the string. Without the format function, you must break the string into a series of smaller substrings and concatenate them. For example, the last line … Read more

List Indexing

What is the output of this code snippet? This puzzle introduces the simple but powerful list data structure in Python. You have to search very hard to find an algorithm that is not building upon a list. Many famous algorithms such as quicksort are based on only one list as core data structure. Wikipedia defines … Read more