Python – Initialize dictionary keys with Matrix

Last Updated : 30 Dec, 2020

Sometimes, while working with Python Data, we can have a problem in which we need to construct an empty mesh of dictionaries for further population of data. This problem can have applications in many domains which include data manipulation. Let’s discuss certain ways in which this task can be performed.

Method #1 : Using list comprehension
This is one of the way in which this task can be performed. In this, we initialize the dictionary keys with empty mesh with N by iterating using list comprehension.

# Python3 code to demonstrate working of 
# Initialize dictionary keys with Matrix
# Using list comprehension
  
# initializing N
num = 4
  
# Initialize dictionary keys with Matrix
# Using list comprehension
res = {'gfg': [[] for _ in range(num)], 'best': [[] for _ in range(num)]}
  
# printing result 
print("The Initialized dictionary : " + str(res)) 

Output :

The Initialized dictionary : {'gfg': [[], [], [], []], 'best': [[], [], [], []]}

Method #2 : Using deepcopy()
This task can also be performed using deepcopy(). In this, we perform the task of performing copy of each dictionary key as non referenced key.

# Python3 code to demonstrate working of 
# Initialize dictionary keys with Matrix
# Using deepcopy()
from copy import deepcopy
  
# initializing N
num = 4
  
# Initialize dictionary keys with Matrix
# Using deepcopy()
temp = [[] for idx in range(num)]
res = {'gfg': deepcopy(temp), 'best': deepcopy(temp)}
  
# printing result 
print("The Initialized dictionary : " + str(res)) 

Output :

The Initialized dictionary : {'gfg': [[], [], [], []], 'best': [[], [], [], []]}

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Python – Initialize dictionary keys with Matrix