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# What are List Comprehensions in Python with Syntax and Examples

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In this tutorial we are going to learn about List Comprehensions in Python with Syntax and Examples.

In addition to sequence operations and list methods, Python includes a more advanced operation called a list comprehension.

List comprehensions allow us to build out lists using a different notation. You can think of it as essentially a one line for loop built inside of brackets.

For a simple example:

Example 1:

``````# Grab every letter in string
lst = [x for x in 'word']
# Check
lst

Output-
['w', 'o', 'r', 'd']``````

This is the basic idea of a list comprehension. If you’re familiar with mathematical notation this format should feel familiar for example: x^2 : x in { 0,1,2…10 }

Let’s see a few more examples of list comprehensions in Python:

Example 2:

``````# Square numbers in range and turn into list
lst = [x**2 for x in range(0,11)]
lst

Output-
[0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100]``````

Example 3

Let’s see how to add in if statements:

``````# Check for even numbers in a range
lst = [x for x in range(11) if x % 2 == 0]
lst

Output-
[0, 2, 4, 6, 8, 10]``````

Example 4

Can also do more complicated arithmetic:

``````# Convert Celsius to Fahrenheit
celsius = [0,10,20.1,34.5]
fahrenheit = [((9/5)*temp + 32) for temp in celsius ]
Fahrenheit

Output-
[32.0, 50.0, 68.18, 94.1]``````

Example 5

We can also perform nested list comprehensions, for example:

``````lst = [ x**2 for x in [x**2 for x in range(11)]]
lst
output-
[0, 1, 16, 81, 256, 625, 1296, 2401, 4096, 6561, 10000]``````

After this lecture you should feel comfortable reading and writing basic list comprehensions.