Modifying a sequence while iterating over it can cause undesired behavior due to the way the iterator is build. To avoid this problem, a simple solution is to iterate over a copy of the list. For example, you’ll obtain a copy of list_1 by using the slice notation with default values list_1[:]. Because you iterate … Read more
NumPy is a popular Python library for data science. Numpy focuses on array, vector, and matrix computations. If you work with data, you cannot avoid NumPy. So learn it now and learn it well. In this tutorial, you’ll learn how to calculate the Hadamard Product (= element-wise multiplication) of two 1D lists, 1D arrays, or … Read more
Challenge: How to find a given value in a sorted list? Example: Say, you have a sorted list: Your goal is to find the index of the element 103 in the list. Do you have to check all elements to do this? Well, only if you used the … Naive List Search Algorithm A naive … Read more
Problem: Write a function that joins an arbitrary number of string arguments with a given separator. Example: Given the string arguments “A”, “B”, and “C” and the string separator “-“. Join them to the concatenated string “A-B-C”. Solution: The following code creates a Python function concat() that takes an arbitrary number of arguments, packs them … Read more
Challenge: How to find an element in a sorted matrix where row and column values increase monotonically? What is a matrix? A matrix is a table of values consisting of rows and columns. Here, we represent the matrix as a list of integer lists. Hence, we can access matrix values with the indexing and slicing … Read more
The most pythonic way to convert a list of integers fs to a list of floats is to use the one-line fs = [float(x) for x in fs]. It iterates over all the elements in the list fs using list comprehension and converts each element of the list x to an integer value using the … Read more
Python slicing means to access a subsequence of a sequence type using the notation [start:end]. A little-known feature of slicing is that it has robust end indices. Slicing is robust even if the end index is greater than the maximal sequence index. The slice just takes all elements up to the maximal element. If the … Read more
Slicing is one of the most popular Python features. Thus, understanding slicing is key to understand existing code bases. In this tutorial, I’m going to train your slicing skills. Ready? So, let’s go! ? Watch the Video Python Slicing Read About Slicing Slicing is a Python-specific concept for accessing a range of values in sequence … Read more
If you work in a data driven career, odds are you will at some point have to perform sorting on your data. Rather than writing your own sorting algorithm (which will most likely be far less efficient), Python provides a built-in function called sorted(). This function allows you to do basic sorting, such as arranging … Read more
Problem: You’ve just learned about the list.clear() method in Python. You wonder, what’s its purpose? Why not creating a new list and overwriting the variable instead of clearing an existing list? Example: Say, you have the following list. If you clear the list, it becomes empty: However, you could have accomplished the same thing by … Read more
Question: Is it possible to call a function inside a list comprehension statement? Background: List comprehension is a compact way of creating lists. The simple formula is [expression + context]. Expression: What to do with each list element? Context: What elements to select? The context consists of an arbitrary number of for and if statements. … Read more
Do you encounter this stupid error? You’re not alone—thousands of coders like you generate this error in thousands of projects every single month. This short tutorial will show you exactly why this error occurs, how to fix it, and how to never make the same mistake again. So, let’s get started! Python throws the TypeError … Read more