Python | Initializing multiple lists

Python Methods and Functions

Method # 1: Using the * operator
We can list all the required commas in the list separated by commas, and then initialize them with an empty list and multiply this empty list using the * operator by the number of specified lists .

# Python3 demo code
# to initialize multiple lists
# using the * operator

 
# using * operator
# to initialize multiple lists

list1, list2, list3 , list4 = ([],) * 4

 
# printing lists

print ( "The initialized lists are:" )

print ( " List 1: " + str (list1))

print ( "List 2:" + str (list2))

print ( "List 3:" + str (list3))

print ( "List 4:" + str   (list4))

Output:

 The initialized lists are: List 1: [] List 2: [] List 3: [] List 4: [] 

Method # 2: Using a loop
This method is similar to the method described above, but the only difference is that we use a loop instead of the * operator to perform a multi-assignment task.

# Python3 demo code
# to initialize multiple lists
# using a loop

 
# using a loop
# to initialize multiple lists

list1, list2, list3, list4 = ([ ] for i in range ( 4 ))

 
# print lists

print ( "The initialized lists are:" )

print ( "List 1:" + str (list1))

print ( "List 2:" + str (list2))

print ( " List 3: " + str (list3))

print ( "List 4:" + str (list4))

Exit:

 The initialized lists are: List 1: [] List 2: [] List 3: [] List 4: [] 

Method # 3: Using defaultdict()
This method is different and also has several other usefulness than the two methods discussed above. This creates a dictionary with a specific name, and we have the ability to create any number of keys and perform add operations right away, since they are initialized by a list.

# Python3 demo code
# to initialize multiple lists
# using defaultdict ()

import collections

 
# using defaultdict ()
# to initialize multiple lists
# no need to initialize with empty lists

mul_list_dict = collections.defaultdict ( li st )

mul_list_dict [ 'list1' ]. append ( 1 )

mul_list_dict [ 'list2' ]. append ( 2 )

mul_list_dict [ ' list3' ]. append ( 3 )

mul_list_dict [ 'list4' ]. append ( 4 )

 
# printing lists

print ( "The initialized lists are:" ) < / p>

print ( "List 1:" + str (mul_list_dict [ 'list1 ' ]))

print ( "List 2:" + str (mul_list_dict [ 'list2' ]))

print ( "List 3:" + str (mul_list_dict [ 'list3' ]))

print ( " List 4: " + str (mul_list_dict [ 'list4' ] ))

Exit:

 The initialized lists are: List 1: [1] List 2: [2] List 3: [3] List 4: [4]