The most Pythonic way to convert a list of floats fs to a list of integers is to use the one-liner fs = [int(x) for x in fs]. It iterates over all elements in the list fs using list comprehension and converts each list element x to an integer value using the int(x) constructor. This … Read more
Overview As a programmer, you might come across scenarios where you have to convert a string into a list. Now, your requirements might vary, depending on the goal of your program. For example: Example 1: Given a string containing words; how to extract each word of the string and store them as individual items in … Read more
Summary: Use the built-in Python method zip() to iterate through two lists in parallel. The zip() method returns an iterator of tuples and the nth item of each iterator can be paired together using the zip() function. Other methods of iterating through lists in parallel include the enumerate() method and the traditional approach of iterating … Read more
Summary: Flattening a list means converting a nested list into a simple single-dimensional list. To flatten a nested list we can use the for loop or the While loop or recursion or the deepflatten() Method. Other techniques include importing numerous external Python libraries and using their built-in functions. Overview Problem: Given a list of lists … Read more
In this article, you’ll learn the ultimate answer to the following question: How To Eliminate All The Whitespace From A String—on Both Ends, and In-Between Words? Summary: Use the string methods join(), split(), strip(), rstrip(), lstrip() and or replace()—in specific combinations—to remove any whitespace in a given string. The simplest way to remove all whitespaces … Read more
Summary: Slicing is a Python concept to extract a subsequence from a string or list—that lies within a start and stop index range. There are two syntactical ways to define a slice. (1) The extended slice notation makes use of a colon : in string_name[start:stop:step]. (2) The slice() constructor defines the index range in string_name[slice(start:stop:step)]. … Read more
Summary: Variables are passed by object reference in Python. Therefore, mutable objects are passed by reference while immutable objects are passed by value in Python. To pass immutable objects by reference you can return and reassign the value to the variable, or pass it inside a dictionary/list, or create a class and use the self … Read more
Summary: One of the following methods can be used to check if a list is empty :- Boolean operator not Explicit check using len() Simple Work Around With [] Using .size() with NumPy Using Exception Handling with iter() method Problem: Given a list; how to check if it is empty? Example: Consider the given list … Read more
Summary: The slice notation list[::-1] with default start and stop indices and negative step size -1 reverses a given list. Problem: Given a list of elements. How to reverse the order of the elements in the list. Example: Say, you’ve got the following list: Your goal is to reverse the elements to obtain the following … Read more
To remove duplicates from a Python list while preserving the order of the elements, use the code list(dict.fromkeys(list)) that goes through two phases: (1) Convert the list to a dict using the dict.fromkeys() function with the list elements as keys and None as dict values. (2) Convert the dictionary back to a list using the … Read more
Problem: Given a list. How to access the last element of this list? Example: You have the list [‘Alice’, ‘Bob’, ‘Liz’] and you want to get the last element ‘Liz’. Quick solution: Use negative indexing -1. To access the last element of a Python list, use the indexing notation list[-1] with negative index -1 which … Read more
Problem: If you assign a list object to a new variable using new_list = old_list, any modification to new_list changes old_list. What’s the reason for this and how can you clone or copy the list to prevent this problem? Example: Let’s consider the following example. Appending an element to the new_list also modifies the original … Read more