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Python – Slice till K dictionary value lists
  • Last Updated : 01 Aug, 2020

Given dictionary with value as lists, slice each list till K.

Input : test_dict = {“Gfg” : [1, 6, 3, 5, 7], “Best” : [5, 4, 2, 8, 9], “is” : [4, 6, 8, 4, 2]}, K = 3
Output : {‘Gfg’: [1, 6, 3], ‘Best’: [5, 4, 2], ‘is’: [4, 6, 8]}
Explanation : The extracted 3 length dictionary value list.

Input : test_dict = {“Gfg” : [1, 6, 3, 5, 7], “Best” : [5, 4, 2, 8, 9], “is” : [4, 6, 8, 4, 2]}, K = 2
Output : {‘Gfg’: [1, 6], ‘Best’: [5, 4], ‘is’: [4, 6]}
Explanation : The extracted 2 length dictionary value list.

Method #1 : Using loop + list slicing  

The combination of above functionalities can be used to solve this problem. In this, we perform task of list slicing using slice operation and loop to iterate through all the keys.



Python3




# Python3 code to demonstrate working of 
# Slice till K dictionary value lists
# Using loop + list slicing 
  
# initializing dictionary
test_dict = {"Gfg" : [1, 6, 3, 5, 7], 
             "Best" : [5, 4, 2, 8, 9],
             "is" : [4, 6, 8, 4, 2]}
  
# printing original dictionary
print("The original dictionary is : " + str(test_dict))
  
# initializing K 
K = 4
  
res = dict()
for sub in test_dict:
      
    # slicing till K and reassigning
    res[sub] = test_dict[sub][:K]
  
# printing result 
print("The dictionary after conversion " + str(res)) 
Output

The original dictionary is : {‘Gfg’: [1, 6, 3, 5, 7], ‘Best’: [5, 4, 2, 8, 9], ‘is’: [4, 6, 8, 4, 2]}
The dictionary after conversion {‘Gfg’: [1, 6, 3, 5], ‘Best’: [5, 4, 2, 8], ‘is’: [4, 6, 8, 4]}

Method #2 : Using dictionary comprehension + list slicing

This is yet another way in which this task can be performed. In this, we perform task of reassigning using dictionary comprehension and provides one liner approach to this problem. 

Python3




# Python3 code to demonstrate working of 
# Slice till K dictionary value lists
# Using dictionary comprehension + list slicing
  
# initializing dictionary
test_dict = {"Gfg" : [1, 6, 3, 5, 7],
             "Best" : [5, 4, 2, 8, 9], 
             "is" : [4, 6, 8, 4, 2]}
  
# printing original dictionary
print("The original dictionary is : " + str(test_dict))
  
# initializing K 
K = 4
  
# one-liner to slice elements of list 
# items() used to get all key-value pair of dictionary
res = {key: val[:K] for key, val in test_dict.items()}
  
# printing result 
print("The dictionary after conversion " + str(res)) 
Output

The original dictionary is : {‘Gfg’: [1, 6, 3, 5, 7], ‘Best’: [5, 4, 2, 8, 9], ‘is’: [4, 6, 8, 4, 2]}
The dictionary after conversion {‘Gfg’: [1, 6, 3, 5], ‘Best’: [5, 4, 2, 8], ‘is’: [4, 6, 8, 4]}

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