The empty slice operator [:] in Python is a powerful and concise way of copying a list. It is shorthand syntax allowing you to create a new list that contains all the elements of the existing list where the operator is used. This operator is represented by one colon wrapped in square brackets [:] with …
When starting out in Python it can be easy to think that the expression list2 = list1 will make list2 contain a copy of list1. But it doesn’t take long to realise that this doesn’t meet expectations of what actually happens in the wild. Take the following code as an example: Huh? Why did list2 …
Why is it when you copy a list in Python doing b_list = a_list that, any changes made to a_list or to b_list modify the other list? If you’ve played with lists in Python you will reach a point where you want to copy a list to make modifications to it without changing the original …
How do you sort a list of lists by the second element using Python? To sort a list of lists by the second element in each list use the key parameter to either the .sort() list function (if modifying the original list) or the sorted() function (if returning a new list). Here’s an example demonstrating …
How do you sort a list of tuples by the first element in each tuple in Python? To sort a list of tuples in Python use the .sort() list method if you want to modify the list to sort or the sorted() function if you want to generate a new list. Use the parameter key …
How do read the contents of a file in Python and insert these lines into a list? Using the built-in function open() and the asterisk operator * a file’s contents can easily be translated into a list with the following one-liner: [*open(‘my_file.txt’)]. What Does open() Function Do? The built-in open() function has one required parameter …
