Python Partials

Have you ever heard of the concept of currying? If not, I'm about to blow your mind. Let's say that you have a method you want to use and it takes two parameters. The only problem is that you only have one parameter at the moment. You will have the next parameter later. You can create an intermediate method from the other method that takes one parameter and then use that method at the time of your choosing. In Python, this is achieved by using a partial.

Let's say that you ran os.listdir, this method returns the unqualified file names inside of a folder. The only problem is that I want the file names fully qualified with it's entire path. So I should use os.path.join on each of the items.

import os
from functools import partial
folder = "/your/path/to/whatever"
folder_join = partial(os.path.join, folder)
images = [x for x in os.listdir(folder) if x.endswith(".jpg")]
images = list(map(folder_join, images))

If one.jpg, two.jpg, and three.jpg are in our folder, we would get this output => ['/your/path/to/whatever/one.jpg', '/your/path/to/whatever/two.jpg', '/your/path/to/whatever/three.jpg']

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