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Python | Sort Python Dictionaries by Key or Value

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  • Difficulty Level : Medium
  • Last Updated : 23 Jan, 2023
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In this article, we will discuss how we sort a dictionary by value and keys in Python.

Need for Sorting in Dictionary

We need sorting of data to reduce the complexity of the data and make queries faster and more efficient. Therefore sorting is very important when we are dealing with a large amount of data. Here, we will use the following approach:

  • First, sort the keys alphabetically using key_value.iterkeys() function.
  • Second, sort the keys alphabetically using the sorted (key_value) function & print the value corresponding to it.
  • Third, sort the values alphabetically using key_value.iteritems(), key = lambda (k, v) : (v, k))

Here are the major tasks that are needed to be performed sort a dictionary by value and keys in Python.

  1. Create a dictionary and display its list-keys alphabetically.
  2. Display both the keys and values sorted in alphabetical order by the key.
  3. Same as part (ii), but sorted in alphabetical order by the value.

Example 1: Sort Dictionary By Key in Python

In this example, we will sort the dictionary by keys and the result type will be a dictionary. 

Input:
{'ravi': 10, 'rajnish': 9, 'sanjeev': 15, 'yash': 2, 'suraj': 32}

Output: 
{'rajnish': 9, 'ravi': 10, 'sanjeev': 15, 'suraj': 32, 'yash': 2}

Python3




myDict = {'ravi': 10, 'rajnish': 9,
        'sanjeev': 15, 'yash': 2, 'suraj': 32}
 
myKeys = list(myDict.keys())
myKeys.sort()
sorted_dict = {i: myDict[i] for i in myKeys}
 
print(sorted_dict)

Output

{'rajnish': 9, 'ravi': 10, 'sanjeev': 15, 'suraj': 32, 'yash': 2}

Example 2: Displaying the Keys in sorted order

In this example, we are trying to sort the dictionary by keys and values in Python. Here, iterkeys() returns an iterator over the dictionary’s keys.

Input:
key_value[2] = '56'       
key_value[1] = '2'
key_value[4] = '12'
key_value[5] = '24'
key_value[6] = '18'
key_value[3] = '323'

Output:
1 2 3 4 5 6 

Python3




# Function calling
def dictionary():
    # Declare hash function
    key_value = {}
 
# Initializing value
    key_value[2] = 56
    key_value[1] = 2
    key_value[5] = 12
    key_value[4] = 24
    key_value[6] = 18
    key_value[3] = 323
 
    print("Task 1:-\n")
 
    print("key_value", key_value)
 
    # iterkeys() returns an iterator over the
    # dictionary’s keys.
    for i in sorted(key_value.keys()):
        print(i, end=" ")
 
 
def main():
    # function calling
    dictionairy()
 
 
# Main function calling
if __name__ == "__main__":
    main()

Output

Task 1:-

key_value {2: 56, 1: 2, 5: 12, 4: 24, 6: 18, 3: 323}
1 2 3 4 5 6 

Example 3: Sort the dictionary by key 

In this example, we will sort in lexicographical order Taking the key’s type as a string.

Input:
key_value['ravi'] = '10'       
key_value['rajnish'] = '9'
key_value['sanjeev'] = '15'
key_value['yash'] = '2'
key_value'suraj'] = '32'

Output:
[('rajnish', '9'), ('ravi', '10'), ('sanjeev', '15'), ('suraj', '32'), ('yash', '2')]

Python3




# Creates a sorted dictionary (sorted by key)
from collections import OrderedDict
 
dict = {'ravi': '10', 'rajnish': '9',
        'sanjeev': '15', 'yash': '2', 'suraj': '32'}
dict1 = OrderedDict(sorted(dict.items()))
print(dict1)

Output

OrderedDict([('rajnish', '9'), ('ravi', '10'), ('sanjeev', '15'), ('suraj', '32'), ('yash', '2')])

Example 4: Sorting the Keys and Values in Alphabetical Order using the Key

In this example, we are trying to sort the dictionary by keys and values in Python. Here we are using an iterator over the Dictionary’s value to sort the keys.

Input:
key_value[2] = '56'       
key_value[1] = '2'
key_value[4] = '12'
key_value[5] = '24'
key_value[6] = '18'
key_value[3] = '323'

Output:
(1, 2) (2, 56) (3, 323) (4, 24) (5, 12) (6, 18) 

Python3




# function calling
def dictionairy():
 
    # Declaring the hash function
    key_value = {}
 
# Initialize value
    key_value[2] = 56
    key_value[1] = 2
    key_value[5] = 12
    key_value[4] = 24
    key_value[6] = 18
    key_value[3] = 323
     
    print("key_value",key_value)
 
    print("Task 2:-\nKeys and Values sorted in",
          "alphabetical order by the key  ")
     
 
    # sorted(key_value) returns an iterator over the
    # Dictionary’s value sorted in keys.
    for i in sorted(key_value):
        print((i, key_value[i]), end=" ")
 
 
def main():
        # function calling
    dictionairy()
 
 
# main function calling
if __name__ == "__main__":
    main()

Output

key_value {2: 56, 1: 2, 5: 12, 4: 24, 6: 18, 3: 323}
Task 2:-
Keys and Values sorted in alphabetical order by the key  
(1, 2) (2, 56) (3, 323) (4, 24) (5, 12) (6, 18) 

Example 5: Sorting the Keys and Values alphabetically using the value

In this example, we are trying to sort the dictionary by keys and values in Python. Here we are using to sort in lexicographical order.

Input:
key_value[2] = '56'       
key_value[1] = '2'
key_value[4] = '12'
key_value[5] = '24'
key_value[6] = '18'
key_value[3] = '323'

Output:
[(1, 2), (5, 12), (6, 18), (4, 24), (2, 56), (3, 323)]

Python3




# Function calling
def dictionairy():
 
    # Declaring hash function
    key_value = {}
 
# Initializing the value
    key_value[2] = 56
    key_value[1] = 2
    key_value[5] = 12
    key_value[4] = 24
    key_value[6] = 18
    key_value[3] = 323
     
    print("key_value",key_value)
 
    print("Task 3:-\nKeys and Values sorted",
          "in alphabetical order by the value")
 
    # Note that it will sort in lexicographical order
    # For mathematical way, change it to float
    print(sorted(key_value.items(), key=lambda kv:
                 (kv[1], kv[0])))
 
 
def main():
    # function calling
    dictionairy()
 
 
# main function calling
if __name__ == "__main__":
    main()

Output

key_value {2: 56, 1: 2, 5: 12, 4: 24, 6: 18, 3: 323}
Task 3:-
Keys and Values sorted in alphabetical order by the value
[(1, 2), (5, 12), (6, 18), (4, 24), (2, 56), (3, 323)]

Example 6: Sort Dictionary By Value in Python

In this example, we are trying to sort the dictionary by values in Python. Here we are using dictionary comprehension to sort our values.

Input:
key_value['ravi'] = 10       
key_value['rajnish'] = 9
key_value['sanjeev'] = 15
key_value['yash'] = 2
key_value['suraj'] = 32

Output:
{'ravi': 2, 'rajnish': 9, 'sanjeev': 10, 'yash': 15, 'suraj': 32}

Python3




# Creates a sorted dictionary (sorted by key)
from collections import OrderedDict
import numpy as np
 
dict = {'ravi': 10, 'rajnish': 9,
        'sanjeev': 15, 'yash': 2, 'suraj': 32}
print(dict)
 
keys = list(dict.keys())
values = list(dict.values())
sorted_value_index = np.argsort(values)
sorted_dict = {keys[i]: values[i] for i in sorted_value_index}
 
print(sorted_dict)

Output:

{'ravi': 10, 'rajnish': 9, 'sanjeev': 15, 'yash': 2, 'suraj': 32}
{'ravi': 2, 'rajnish': 9, 'sanjeev': 10, 'yash': 15, 'suraj': 32}

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