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Python List: sort() Method

sort() Method

The sort() method is used to sort the items of a given list.

Visual Explanation:

Python List: sort() method

Syntax:

list.sort(*, key=None, reverse=False)

Parameter:

  • Key: Optional. A function that specifies the sorting criteria.
  • reverse - Default value of reverse is False. False sort the list in ascending order and True sort the list in descending order.

Return Value:

The sort() method doesn't return any value. Rather, it modifies the original list.

Example 1: Sort a list in ascending/descending order 


colors = ['Red', 'Green', 'Orange', 'Pink']
print("Original List:")
print(colors)
colors.sort()
print('\nSort the said list in ascending order:')
print(colors)
print('\nSort the said list in descending order:')
colors.sort(reverse=True)
print(colors)

Output:

Original List:
['Red', 'Green', 'Orange', 'Pink']

Sort the said list in ascending order:
['Green', 'Orange', 'Pink', 'Red']

Sort the said list in descending order:
['Red', 'Pink', 'Orange', 'Green']

Example 3: Sort the list using key


def test(data):
  return data['Math']
students = [
  {'V': 'Jenny Vang', 'Math': 99},
  {'V': 'Allan Barker', 'Math': 100},
  {'V': 'Bradley Whitney', 'Math': 97},
  {'V': 'Ellie Ross', 'Math': 98},
  {'V': 'Antoine Booker', 'Math': 99}
]
print("Original students list:")
print(students)
students.sort(key=test)
print("\nStudents list after sorting on Math marks:")
print(students)

Output:

Original students list:
[{'V': 'Jenny Vang', 'Math': 99}, {'V': 'Allan Barker', 'Math': 100}, {'V': 'Bradley Whitney', 'Math': 97}, {'V': 'Ellie Ross', 'Math': 98}, {'V': 'Antoine Booker', 'Math': 99}]

Students list after sorting on Math marks:
[{'V': 'Bradley Whitney', 'Math': 97}, {'V': 'Ellie Ross', 'Math': 98}, {'V': 'Jenny Vang', 'Math': 99}, {'V': 'Antoine Booker', 'Math': 99}, {'V': 'Allan Barker', 'Math': 100}]

Python Code Editor:

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Python: Tips of the Day

Kwargs:

**kwargs and *args are function arguments that can be very useful.

They are quite underused and often under-understood as well.

Let's try to explain what kwargs are and how to use them.

  • While *args are used to pass arguments at an unknown amount to functions, **kwargs are used to do the same but with named arguments.
  • So, if *args is a list being passed as an argument, you can think of **kwargs as a dictionary that's being passed as an argument to a function.
  • You can use arguments as you wish as long as you follow the correct order which is: arg1, arg2, *args, **kwargs. It's okay to use only one of those but you can't mix the order, for instance, you can't have: function(**kwargs, arg1), that'd be a major faux pas in Python.
  • Another example: You can do function(*args,**kwargs) since it follows the correct order.
  • Here is an example. Let's say satelites are given with their names and weight in tons in dictionary format. Code prints their weight as kilograms along with their names.
def payloads(**kwargs):
    for key, value in kwargs.items():
        print( key+" |||", float(value)*100)
payloads(NavSat1 = '2.5', BaysatG2 = '4')

Output:

NavSat1 ||| 250.0
BaysatG2 ||| 400.0

Since the function above would work for any number of dictionary keys, **kwargs makes perfect sense rather than passing arguments with a fixed amount.

def payloads(**kwargs):
    for key, value in kwargs.items():
        print( key+" |||", float(value)*100)

sats={"Tx211":"3", "V1":"0.50"}
payloads(**sats)

Output:

Tx211 ||| 300.0
V1 ||| 50.0