Ways to sort list of dictionaries by values in Python Using lambda function (original) (raw)

In Python, sorting a list of dictionaries can be done efficiently using the built-in sorted() function combined with a lambda function. A lambda function is a small anonymous function with any number of arguments and a single expression that is returned.

Syntax:

lambda arguments: expression

**Example:

**Input: [{"name": "Harry", "marks": 85},
{"name": "Robin", "marks": 92},
{"name": "Kevin", "marks": 78}]

**Output: (sorted by marks ascending):
[{'name': 'Kevin', 'marks': 78},
{'name': 'Harry', 'marks': 85},
{'name': 'Robin', 'marks': 92}]

Sort by Single Key

Sort a list of dictionaries using the values of a single key, either in ascending or descending order, to organize data efficiently.

Python `

dic = [ {"name": "Harry", "age": 20}, {"name": "Robin", "age": 20}, {"name": "Kevin", "age": 19} ]

print("Sorted by age:") print(sorted(dic, key=lambda x: x['age']))

`

Output

Sorted by age: [{'name': 'Kevin', 'age': 19}, {'name': 'Harry', 'age': 20}, {'name': 'Robin', 'age': 20}]

**Explanation:

• **sorted(dic, key=lambda x: x['age']): sorts the list of dictionaries in ascending order based on the 'age' value of each dictionary.
• If two items have the same 'age', Python keeps them in the same order as they appeared in the original list.

Sort by Multiple Keys

Sort a list of dictionaries using more than one key, so if the first key is the same, the next key decides the order.

Python `

print("\nSorted by age and name:") print(sorted(dic, key=lambda x: (x['age'], x['name'])))

`

**Output

[{'name': 'Kevin', 'age': 19}, {'name': 'Harry', 'age': 20}, {'name': 'Robin', 'age': 20}]

**Explanation: ****(sorted(dic, key=lambda x: (x['age'], x['name'])):** Sorts the list of dictionaries first by "age" in ascending order and if ages are equal then by "name" in alphabetic order.

Sort by Key in Descending Order

Sort a list of dictionaries by a key in descending order, from largest to smallest.

Python `

print("\nSorted by age (descending):") print(sorted(dic, key=lambda x: x['age'], reverse=True))

`