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

When working with a list of dictionaries in Python, you often need to check if a particular value exists for a specific key across all dictionaries. This can be efficiently done using list comprehension with the in operator.

Example

Here's how to check if a value is present corresponding to a specific key ?

my_list = [
    {"python": "14", "is": "great", "fun": "1"},
    {"python": "cool", "is": "fun", "best": "81"},
    {"python": "93", "is": "CS", "amazing": "16"}
]

print("The list is:")
print(my_list)

K = "python"
print("The value of K is:")
print(K)

value = "cool"

my_result = value in [index[K] for index in my_list]

print("The result is:")

if my_result:
    print("The value is present with respect to key")
else:
    print("The value isn't present with respect to key")

The list is:
[{'python': '14', 'is': 'great', 'fun': '1'}, {'python': 'cool', 'is': 'fun', 'best': '81'}, {'python': '93', 'is': 'CS', 'amazing': '16'}]
The value of K is:
python
The result is:
The value is present with respect to key

How It Works

The solution uses a list comprehension to extract all values associated with the key K from each dictionary in the list:

# Extract all values for key "python"
values = [index[K] for index in my_list]
print("Values for key 'python':", values)

# Check if our target value exists
result = "cool" in values
print("Is 'cool' present?", result)

Values for key 'python': ['14', 'cool', '93']
Is 'cool' present? True

Alternative Approach Using any()

You can also use the any() function for better performance with large datasets ?

my_list = [
    {"python": "14", "is": "great", "fun": "1"},
    {"python": "cool", "is": "fun", "best": "81"},
    {"python": "93", "is": "CS", "amazing": "16"}
]

K = "python"
value = "cool"

# Using any() - stops at first match
result = any(dictionary[K] == value for dictionary in my_list)

print("Using any():", result)

Using any(): True

Comparison

Conclusion

Use list comprehension with in for simple checks, or any() for better performance with large datasets. Both methods effectively check if a value exists for a specific key across multiple dictionaries.