Python – Check List elements from Dictionary List

Sometimes, while working with data, we can have a problem in which we need to check for list element presence as a particular key in list of records. This kind of problem can occur in domains in which data are involved like web development and Machine Learning. Lets discuss certain ways in which this task can be solved.

Input : test_list = [{‘Price’: 20, ‘Color’: ‘Orange’}, {‘Price’: 25, ‘Color’: ‘Yellow’}]
Output : [True, False, True, False]

Input : test_list = [{‘Color’: ‘Pink’, ‘Price’: 50}]
Output : [False, False, False, False]

Method #1 : Using loop
This is brute way to solve this problem. In this, we iterate will all the dictionaries for each value from list and compare with the desired key and return True for records that possess it.

# Python3 code to demonstrate working of
# Check List elements from Dictionary List
# Using loop

# helpr_func
def check_ele(ele, test_list):

    for sub in test_list:
        for item in sub.values():
            if ele == item:
                return True
    return False

# initializing list
test_list = [{'Name' : 'Apple', 'Price' : 18, 'Color' : 'Red'},
             {'Name' : 'Mango', 'Price' : 20, 'Color' : 'Yellow'},
             {'Name' : 'Orange', 'Price' : 24, 'Color' : 'Orange'},
             {'Name' : 'Plum', 'Price' : 28, 'Color' : 'Red'}]

# printing original list
print("The original list is : " + str(test_list))

# initializing Values list
val_list = ['Yellow', 'Red', 'Orange', 'Green']

# Check List elements from Dictionary List
# Using loop
res = []
for ele in val_list:
    res.append(check_ele(ele, test_list))

# printing result
print("The Association list in Order : " + str(res))

Output :

The original list is : [{‘Name’: ‘Apple’, ‘Color’: ‘Red’, ‘Price’: 18}, {‘Name’: ‘Mango’, ‘Color’: ‘Yellow’, ‘Price’: 20}, {‘Name’: ‘Orange’, ‘Color’: ‘Orange’, ‘Price’: 24}, {‘Name’: ‘Plum’, ‘Color’: ‘Red’, ‘Price’: 28}]

The Association list in Order : [True, True, True, False]

Method #2 : Using any() + generator expression
The use of any() with integration with generator expression can solve this problem. In this we reduce the lines of code by reducing inner loop, by testing using any().

# Python3 code to demonstrate working of
# Check List elements from Dictionary List
# Using any() + generator expression

# initializing list
test_list = [{'Name' : 'Apple', 'Price' : 18, 'Color' : 'Red'},
             {'Name' : 'Mango', 'Price' : 20, 'Color' : 'Yellow'},
             {'Name' : 'Orange', 'Price' : 24, 'Color' : 'Orange'},
             {'Name' : 'Plum', 'Price' : 28, 'Color' : 'Red'}]

# printing original list
print("The original list is : " + str(test_list))

# initializing Values list
val_list = ['Yellow', 'Red', 'Orange', 'Green']

# initializing Key
key = 'Color'

# Check List elements from Dictionary List
# Using loop
res = [any(clr == sub[key] for sub in test_list) for clr in val_list]

# printing result
print("The Association list in Order : " + str(res))

Output :

The original list is : [{‘Name’: ‘Apple’, ‘Color’: ‘Red’, ‘Price’: 18}, {‘Name’: ‘Mango’, ‘Color’: ‘Yellow’, ‘Price’: 20}, {‘Name’: ‘Orange’, ‘Color’: ‘Orange’, ‘Price’: 24}, {‘Name’: ‘Plum’, ‘Color’: ‘Red’, ‘Price’: 28}]

The Association list in Order : [True, True, True, False]