One-Liners

How can you create a list with identical elements in it with Python? There are two ways to create a list with identical elements in Python. One method is fairly straightforward and easy to remember, whereas the other involves the itertools library. The one I apply the most in my Python coding is the method that uses the asterisk operator to a list containing the item I want to replicate. The other method uses the resources and techniques of a library with a function that is difficult to forget: itertools.repeat() ...

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 and several optional parameters. The required parameter is the location of the file. If the file is located in the current folder where the Python script is run you can insert the name of the file, for example, test.txt. ...

How do you convert a list of strings to a list of integers in Python? And can you do it with one line of code? To convert a list of strings to a list of integers use the built-in map() function if you know the contents of the original list will all convert to integers, otherwise use a lambda function in your map(), or use a list comprehension with conditions. ...

How do you remove the file extension from a path in Python? And can you do it using just one line of code? The file extension is generally the last set of characters after the final period in a path string. Removing the file extension helps with trying to either rename the file name or with renaming the file extension. For example, if my full path string to a particular file on my computer is /usr/ryan/Documents/file.csv the file extension string is .csv. ...

How do you capitalize the first letter of each word in a string using Python? To capitalize the first letter of every word in Python using one line of code enter the following: " ".join([x.capitalize() for x in my_string.split()]). Here is an example demonstrating how the code works in the Python REPL: 1 2 3 >>> my_string = "How long is a piece of string?" >>> " ".join([x.capitalize() for x in my_string.split()]) 'How Long Is A Piece Of String?' As you can see from the above example the output produces a string with each character capitalized. ...

How do you split a string into two equal halves using Python? To tackle this exercise you need to know how you’re going to operate on odd numbered string lengths. For example, how would you like your code to operate on the string halve. As it has 5 characters you’re going to have 5 possible solutions: hal and ve OR ha and lve ha, l and ve halve OR None The first solution just placed the middle character to either side giving the extra character to the first half or second half. ...

How do you find all the duplicates from a list in Python? To find all the duplicate elements from a list using Python, use the following list comprehension: 1 [x for idx, x in enumerate(original_list) if x in original_list[idx+1:] and x not in original_list[:idx]] The result from the above code will be a list of unique elements representing all the duplicate elements from the original list. Here’s an example of how this looks in your Python console: 1 2 3 >>> my_list = [1, 1, 2, 3, 3, 3] >>> [x for idx, x in enumerate(my_list) if x in my_list[idx+1:] and x not in my_list[:idx]] [1, 3] Get List Of Duplicates What if you want a list of all the duplicate entries? ...

How do you remove duplicates from a list using Python? To remove duplicate elements from a list in Python use a list comprehension to create a new list with no duplicates with this code: [x for idx, x in enumerate(original_list) if x not in original_list[idx+1:]] Here is an example demonstrating how this code works: 1 2 3 4 >>> original_list = [1, 2, 1, 3, 1, 2, 3] >>> [x for idx, x in enumerate(original_list) if x not in original_list[idx+1:]] [1, 2, 3] As you can see from the example above the result from the list comprehension produces a unique list from the original. ...

What is the syntax for writing a for loop on one line in Python? This syntax is known as a list comprehension and enables the user to write a for loop on one lin To write a for loop on one line in Python, known more commonly as the list comprehension, wrap the for loop in a list like so: [elem for elem in my_loop]. Here is an example demonstrating how this code works: ...

It can be easy to sort a list, whether a list of strings or even a list of dictionaries, but can you sort a dictionary? One way to sort a dictionary by the values of each key : value pair in Python is to use a dictionary comprehension. Dictionary comprehensions are very similar to list comprehensions and have the following schema: 1 new_dict = { key: value for (key, value) in original_dict.items()} The first expression within the dictionary comprehension, the key: value portion, is the basic structure for setting any key and value pair within a dictionary. The second expression is familiar as the one-liner for loop, and within this statement we have a tuple representing the key and value returned from the dictionary’s .items() method. ...