Tag: pythonic

Python: List Comprehension

On By Ben Larson Ph.D.In Python, Python: Learn Python Course4 Comments

List comprehensions are a method for taking a list of elements and performing a transformation on each element.

In our first example, we want to take numbers 0-9, square them, and have the result end up in a list.

ln[5] shows how you would perform this task using for a loop to iterate.

ln[1] does the same thing, but it does it in one line.

 

pythonListcomp

Try your code in our online Python console:  

As you can see, the list comprehension basically crunches the for loop into one line. The syntax is simple enough:

S            =  [x**2 for x in range(10)]

Assign a variable = [operation for loop]

Find even numbers in a list:

Here we add an if statement inside the iteration. (x%2 is modulus, meaning it returns remainder. So 4%2 returns a remainder of 0 and 5%2 returns are remainder of 1)

pythonListcomp1.jpg

You can use list comprehensions with more complex formulas:

pythonListcomp3

You can even use functions from within a list comprehension

pythonListcomp4.jpg

Try your code in our online Python console:  

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