Python Generator Expression: An Introduction

Einblick Content Team - December 15th, 2022

One useful but not well-understood Python tip for data science is the use of generator expressions. Generator expressions are similar to list comprehensions, but they are more memory efficient because they do not create a new list object in memory. Instead, they generate each individual value in the expression on-the-fly, which can be especially useful when working with large datasets.

Here is an example of how to use a generator expression in Python. Note the use of parentheses () rather than square brackets [] but the syntax of the expression is otherwise the same:

# create a list of numbers from 1 to 10
numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

# use a generator expression to square each number in the list
squared_numbers = (x**2 for x in numbers)

# print the squared numbers
for num in squared_numbers:

In the code snippet above, we use a generator expression to square each number in the numbers list. This generates a generator object that behaves like any other iterable. In this example, we used it in a for loop to print each perfect square. Using a generator expression in this way is more memory efficient than creating a new list object to store the squared numbers.

Overall, generator expressions are a useful and efficient tool to have in your Python toolkit for data science tasks.


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