Python | Sort Python Dictionaries by Key or Value
Prerequisite:
Problem Statement – Here are the major tasks that are needed to be performed.
- Create a dictionary and display its 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.
Approach –
Load the Dictionary and perform the following operations:
- First, sort the keys alphabetically using key_value.iterkeys() function.
- Second, sort the keys alphabetically using 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))
Let’s try performing the above-mentioned tasks:
- Displaying the Keys Alphabetically:
Examples:
Input: key_value[2] = '64' key_value[1] = '69' key_value[4] = '23' key_value[5] = '65' key_value[6] = '34' key_value[3] = '76' Output: 1 2 3 4 5 6
- Program:
Python3
# Function callingdef dictionairy(): # 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 ("Keys are") # 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 callingif __name__=="__main__": main() |
Output:
Task 1:- Keys are 1 2 3 4 5 6
- Sorting the Keys and Values in Alphabetical Order using the Key.
Examples:
Input: key_value[2] = '64' key_value[1] = '69' key_value[4] = '23' key_value[5] = '65' key_value[6] = '34' key_value[3] = '76' Output: (1, 69) (2, 64) (3, 76) (4, 23) (5, 65) (6, 34)
- Program:
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 ("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 callingif __name__=="__main__": main() |
Output:
Task 2:- Keys and Values sorted in alphabetical order by the key (1, 2) (2, 56) (3, 323) (4, 24) (5, 12) (6, 18)
- Sorting the Keys and Values in alphabetical using the value
Examples:
Input: key_value[2] = '64' key_value[1] = '69' key_value[4] = '23' key_value[5] = '65' key_value[6] = '34' key_value[3] = '76' Output: (4, 23), (6, 34), (2, 64), (5, 65), (1, 69), (3, 76)
- Program:
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 ("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() |
Output:
Task 3:- Keys and Values sorted in alphabetical order by the value [(1, 2), (5, 12), (6, 18), (4, 24), (2, 56), (3, 323)]
Sort the dictionary by key
Note:it will sort in lexicographical order
Taking key’s type as string
Program:
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) |
Here, Output is Sorted Dictionary using key in Lexicographical order
Lexicographical order:https://en.wikipedia.org/wiki/Lexicographical_order
Learning Outcome:
- How to handle a dictionary.
- Dictionary has O(1) search time complexity whereas List has O(n) time complexity. So it is recommended to use the dictionary where ever possible.
- The best application of dictionary can be seen in Twitter Sentiment Analysis where analysis Twitter sentiments are analysed, using Lexicon approach.
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