The most Pythonic way to convert a list of tuples to a string is to use the built-in method str(…). If you want to customize the delimiter string, the most Pythonic way is to concatenate the join() method and the map() function ‘\n’.join(map(str, lst)) to convert all tuples to strings and gluing those together with … Read more
The ‘_’.join(list) method on the underscore string ‘_’ glues together all strings in the list using the underscore string as a delimiter—and returns a new string. For example, the expression ‘_’.join([‘a’, ‘b’, ‘c’]) returns the new string ‘a_b_c’. Definition and Usage The string.join(iterable) method joins the string elements in the iterable to a new string … Read more
Short answer: To flatten your list of list lst, use the nested list comprehension [x for l in lst for x in l] to iterate over all nested lists (for l in lst) and over all their elements (for x in l). Each element x, you just place in the outer list, unchanged. When browsing … Read more
In Python, there are always multiple ways to accomplish the same thing—but with subtle differences in the side effects. A great coder will always choose the most effective way for the problem at hand. This tutorial shows you six different ways to add elements to a list in Python. In a nutshell, the different ways … Read more
To check your version in your Python script—for example, to make sure that a user of your Python app uses the correct version—you can use the following commands. To achieve this, simply import the sys module and print the sys.version attribute to your Python shell: Try them in our interactive browser-based Python shell: Exercise: execute … Read more
What are the coolest Python tricks? I’ve compiled this list of the best Python tricks—in reverse order. Without further ado, let’s dive into those crazy one-liner Python features, tricks, and functions: 18. Modifying Iterable Elements 1/2 The function map(func, iter) executes the function func on all elements of the iterable iter. Related article: Which is … Read more
Want to create your own webserver in a single line of Python code? No problem, just use this command in your shell: The terminal will tell you: To shut down your webserver, kill the Python program with CTRL+c. This works if you’ve Python 3 installed on your system. To check your version, use the command … Read more
To add an element to a given Python list, you can use either of the three following methods: Use the list insert method list.insert(index, element). Use slice assignment lst[index:index] = [element] to overwrite the empty slice with a list of one element. Use list concatenation with slicing lst[:2] + [‘Alice’] + lst[2:] to create a … Read more
Short answer: To find the minimal list in a list of lists, you need to make two lists comparable. How? With the key argument of the min() function. The key argument is a function that takes one input (a list) and returns one output (a numerical value). The list with the smallest numerical value is … Read more
Short answer: To find the maximal list in a list of lists, you need to make two lists comparable. How? With the key argument of the max() function. The key argument is a function that takes one input (a list) and returns one output (a numerical value). The list with the largest numerical value is … Read more
Short answer: To filter a list of lists for a condition on the inner lists, use the list comprehension statement [x for x in list if condition(x)] and replace condition(x) with your filtering condition that returns True to include inner list x, and False otherwise. Lists belong to the most important data structures in Python—every … Read more
Problem: Given a list of lists representing a data matrix with n rows and m columns. How to sum over the rows of this matrix? In this article, you’re going to learn different ways to accomplish this in Python. Let’s ensure that you’re on the same page. Here’s a graphical representation of the list of … Read more