{"id":118106,"date":"2020-09-17T07:51:03","date_gmt":"2020-09-17T07:51:03","guid":{"rendered":"https:\/\/blog.finxter.com\/?p=13194"},"modified":"2020-09-17T07:51:03","modified_gmt":"2020-09-17T07:51:03","slug":"python-one-line-generator","status":"publish","type":"post","link":"https:\/\/sickgaming.net\/blog\/2020\/09\/17\/python-one-line-generator\/","title":{"rendered":"Python One Line Generator"},"content":{"rendered":"

A generator function is a Pythonic way to create an iterable without explicitly storing it in memory.<\/em><\/strong> This reduces memory usage of your code without incurring any additional costs.<\/p>\n

The following code shows a function get_numbers(n)<\/code> that returns a list <\/a>of n<\/code> random <\/a>numbers. <\/p>\n

import random # NOT A GENERATOR!\n# Create and return a list of numbers\ndef get_numbers(n): numbers = [] for i in range(n): numbers.append(random.random()) # List of n elements exists in memory return numbers # Sum up 1000 random numbers\ns = 0\nfor x in get_numbers(1000): s += x\nprint(s)<\/pre>\n
However, this is not very efficient code because you create a list in advance without need. What if you had 1,000,000,000 numbers? Your memory would quickly fill up! <\/p>\n
A better way is to use a generator function with the yield<\/code> keyword that creates the random numbers dynamically as they are iterated over:<\/p>\n
import random # GENERATOR\n# Generate numbers one by one\ndef generate_numbers(n): for i in range(n): yield random.random() # Sum up 1000 random numbers\ns = 0\nfor x in generate_numbers(1000): s += x\nprint(s)<\/pre>\n
There are two big advantages to using a generator: <\/p>\n