In Python source code, you sometimes see a
for loop inside a square bracket, . It is called List comprehension. It is a way to create a new list from an old list. It has the following syntax.
new_list = [ NEW_VALUE for item in YOUR_LIST ]
You should read it as: For each item in YOUR_LIST, assign the new value to NEW_VALUE.
To make it more clear, here is an example that adds 1 to every single integer of the list.
my_list = [ 2, 5, 6 ] new_list = [ item+1 for item in my_list ] print(new_list)
[3, 6, 7]
Here is another example. The list comprehension will to create a new capitalized list of words.
fruits = [ 'banana', 'pineapple', 'guava' ] capitalize_fruits = [ f.capitalize() for f in fruits ] print(capitalize_fruits)
['Banana', 'Pineapple', 'Guava']