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.
- Create a dictionary and display its list-keys alphabetically.
- Display both the keys and values sorted in alphabetical order by the key.
- 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) |
{'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 callingdef 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 dictionary()# Main function callingif __name__ == "__main__": main() |
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 OrderedDictdict = {'ravi': '10', 'rajnish': '9', 'sanjeev': '15', 'yash': '2', 'suraj': '32'}dict1 = OrderedDict(sorted(dict.items()))print(dict1) |
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 callingdef 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 a sorted list # of the Dictionary’s keys. for i in sorted(key_value): print((i, key_value[i]), end=" ")def main(): # function calling dictionairy()# main function callingif __name__ == "__main__": main() |
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 callingdef 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 callingif __name__ == "__main__": main() |
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)]
The time complexity for this program is O(n log n), where n is the number of key-value pairs in the dictionary.
The auxiliary space complexity for this program is also O(n), where n is the number of key-value pairs in the dictionary.
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 OrderedDictimport numpy as npdict = {'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}
Time complexity: O(n log n), where n is the number of items in the dictionary.
Auxiliary space: O(n), as we are creating new lists of keys and values, and creating a new dictionary with the same number of entries as the original dictionary.
