Given a list of dictionary, the task is to sort the dictionary by date. Let’s see a few methods to solve the task. Method #1: Using naive approach
Python3
# Python code to demonstrate# sort a list of dictionary# where value date is in string# Initialising list of dictionaryini_list = [{'name':'akash', 'd.o.b':'1997-03-02'}, {'name':'manjeet', 'd.o.b':'1997-01-04'}, {'name':'nikhil', 'd.o.b':'1997-09-13'}] # printing initial listprint ("initial list : ", str(ini_list))# code to sort list on dateini_list.sort(key = lambda x:x['d.o.b'])# printing final listprint ("result", str(ini_list)) |
initial list : [{‘name’: ‘akash’, ‘d.o.b’: ‘1997-03-02’}, {‘name’: ‘manjeet’, ‘d.o.b’: ‘1997-01-04’}, {‘name’: ‘nikhil’, ‘d.o.b’: ‘1997-09-13’}] result [{‘name’: ‘manjeet’, ‘d.o.b’: ‘1997-01-04’}, {‘name’: ‘akash’, ‘d.o.b’: ‘1997-03-02’}, {‘name’: ‘nikhil’, ‘d.o.b’: ‘1997-09-13’}]
The time complexity of the above Python code is O(n log n), where ‘n’ is the number of dictionaries in the list.
The auxiliary space complexity of the code is O(1), as it only uses a constant amount of additional space, regardless of the size of the input.
Method #2: Using datetime.strptime and lambda
Python3
# Python code to demonstrate# sort a list of dictionary# where value date is in a stringfrom datetime import datetime# Initialising list of dictionaryini_list = [{'name':'akshat', 'd.o.b':'1997-09-01'}, {'name':'vashu', 'd.o.b':'1997-08-19'}, {'name':'manjeet', 'd.o.b':'1997-01-04'}, {'name':'nikhil', 'd.o.b':'1997-09-13'}] # printing initial listprint ("initial list : ", str(ini_list))# code to sort list on dateini_list.sort(key = lambda x: datetime.strptime(x['d.o.b'], '%Y-%m-%d'))# printing final listprint ("result", str(ini_list)) |
initial list : [{‘d.o.b’: ‘1997-09-01’, ‘name’: ‘akshat’}, {‘d.o.b’: ‘1997-08-19’, ‘name’: ‘vashu’}, {‘d.o.b’: ‘1997-01-04’, ‘name’: ‘manjeet’}, {‘d.o.b’: ‘1997-09-13’, ‘name’: ‘nikhil’}] result [{‘d.o.b’: ‘1997-01-04’, ‘name’: ‘manjeet’}, {‘d.o.b’: ‘1997-08-19’, ‘name’: ‘vashu’}, {‘d.o.b’: ‘1997-09-01’, ‘name’: ‘akshat’}, {‘d.o.b’: ‘1997-09-13’, ‘name’: ‘nikhil’}]
Method #3: Using operator.itemgetter
Python3
# Python code to demonstrate# sort a list of dictionary# where value date is in stringimport operator# Initialising list of dictionaryini_list = [{'name':'akash', 'd.o.b':'1997-03-02'}, {'name':'manjeet', 'd.o.b':'1997-01-04'}, {'name':'nikhil', 'd.o.b':'1997-09-13'}] # printing initial listprint ("initial list : ", str(ini_list))# code to sort list on dateini_list.sort(key = operator.itemgetter('d.o.b'))# printing final listprint ("result", str(ini_list)) |
initial list : [{‘d.o.b’: ‘1997-03-02’, ‘name’: ‘akash’}, {‘d.o.b’: ‘1997-01-04’, ‘name’: ‘manjeet’}, {‘d.o.b’: ‘1997-09-13’, ‘name’: ‘nikhil’}] result [{‘d.o.b’: ‘1997-01-04’, ‘name’: ‘manjeet’}, {‘d.o.b’: ‘1997-03-02’, ‘name’: ‘akash’}, {‘d.o.b’: ‘1997-09-13’, ‘name’: ‘nikhil’}]
