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Python – Check if particular value is present corresponding to K key

  • Last Updated : 14 Oct, 2020

Given a list of dictionaries, check whether particular key-value pair exists or not.

Input : [{“Gfg” : “4”, “is” : “good”, “best” : “1”}, {“Gfg” : “9”, “is” : “CS”, “best” : “10”}], K = “Gfg”, val = “find”
Output : False
Explanation : No value of “Gfg” is “find”.

Input : [{“Gfg” : “4”, “is” : “good”, “best” : “1”}, {“Gfg” : “9”, “is” : “CS”, “best” : “10”}], K = “Gfg”, val = 4
Output : True
Explanation : 4 present as “Gfg” value.

Method #1 : Using list comprehension

This is one of the ways in which this task can be performed. In this, we extract dictionaries using list comprehension, and then use “in” operator to check if it has any values in it.



Python3




# Python3 code to demonstrate working of 
# Check if particular value is present corrresponding to K key
# Using list comprehension
  
# initializing lists
test_list = [{"Gfg" : "4", "is" : "good", "best" : "1"},
             {"Gfg" : "find", "is" : "better", "best" : "8"},
             {"Gfg" : "9", "is" : "CS", "best" : "10"}]
  
# printing original list
print("The original list : " + str(test_list))
  
# initializing K key 
K = "Gfg"
  
# initializing target value 
val = "find"
  
# extracting values using list comprehension
# using in operator to check for values 
res = val in [sub[K] for sub in test_list]
      
# printing result 
print("Is key-val pair present?  : " + str(res))
Output
The original list : [{'Gfg': '4', 'is': 'good', 'best': '1'}, {'Gfg': 'find', 'is': 'better', 'best': '8'}, {'Gfg': '9', 'is': 'CS', 'best': '10'}]
Is key-val pair present?  : True

Method #2 : Using map() + in operator

This is yet another way in which this task can be performed. In this task of getting values corresponding to particular key is performed using map(), extending function to each dictionary.

Python3




# Python3 code to demonstrate working of 
# Check if particular value is present corrresponding to K key
# Using map() + in operator
  
# initializing lists
test_list = [{"Gfg" : "4", "is" : "good", "best" : "1"},
             {"Gfg" : "find", "is" : "better", "best" : "8"},
             {"Gfg" : "9", "is" : "CS", "best" : "10"}]
  
# printing original list
print("The original list : " + str(test_list))
  
# initializing K key 
K = "Gfg"
  
# initializing target value 
val = "find"
  
# extracting values using map 
# using in operator to check for values 
res = val in list(map(lambda sub : sub[K], test_list))
      
# printing result 
print("Is key-val pair present?  : " + str(res))
Output
The original list : [{'Gfg': '4', 'is': 'good', 'best': '1'}, {'Gfg': 'find', 'is': 'better', 'best': '8'}, {'Gfg': '9', 'is': 'CS', 'best': '10'}]
Is key-val pair present?  : True

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