Little time to learn NumPy? This article shows you the ten most amazing NumPy cheat sheets. Download them, print them, and pin them to your wall — and watch your data science skills grow! ?? All NumPy cheat sheets in this article are 100% free. All links open in a new tab (so feel free … Read more
Problem: Given two lists [1, 2, 2, 4] and [2, 5, 5, 5, 6]. How do you combine those lists to the new list [1, 2, 2, 4, 5, 6] by removing the duplicates in the second list? Note: You want to remove all duplicates in the second list and the elements in the second … Read more
Problem: Say, you’ve got a list of dictionaries: Notice how the first and the last dictionaries carry the same key ‘a’. How do you merge all those dictionaries into a single dictionary to obtain the following one? Notice how the value of the duplicate key ‘a’ is the value of the last and not the … Read more
When teaching the Finxter Python students, I’m often shocked how even intermediate-level coders do not understand the very basic foundations of computer science. In CS, there’s almost nothing as fundamental as a simple, plain byte. (You know, that sequence of 0s and 1s called bits). This tutorial aims to clarify some misconceptions and questions regarding … Read more
To intersect multiple sets, stored in a list l, use the Python one-liner l.pop().intersection(*l) that takes the first set from the list, calls the intersection() method on it, and passes the remaining sets as arguments by unpacking them from the list. A set is a unique collection of unordered elements. The intersection operation creates a … Read more
The most efficient way to join multiple sets (stored in a list of sets), use the Python one-liner set().union(*list) that creates a new set object, calls the union() method on the new object, and unpacks all sets from the list of sets into the union() method’s argument list. A set is a unique collection of … Read more
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
Problem: Given a list of Boolean elements. What’s the best way to join all elements using the logical “OR” and logical “AND” operations? Example: Convert the list [True, True, False] using The logical “AND” operation to True and True and False = False, The logical “OR” operation to True or True or False = True, … 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
The string.join(iterable) method concatenates all the string elements in the iterable (such as a list, string, or tuple) and returns the result as a new string. The string on which you call it is the delimiter string—and it separates the individual elements. For example, ‘-‘.join([‘hello’, ‘world’]) returns the joined string ‘hello-world’. In this ultimate guide, … 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