Given a dictionary with nested dictionaries as values, extract all the values with of particular key.
Input : test_dict = {‘Gfg’ : {“a” : 7, “b” : 9, “c” : 12}, ‘is’ : {“a” : 15, “b” : 19, “c” : 20}, ‘best’ :{“a” : 5, “b” : 10, “c” : 2}}, temp = “b”
Output : [9, 10, 19]
Explanation : All values of “b” key are extracted.Input : test_dict = {‘Gfg’ : {“a” : 7, “b” : 9, “c” : 12}, ‘is’ : {“a” : 15, “b” : 19, “c” : 20}, ‘best’ :{“a” : 5, “b” : 10, “c” : 2}}, temp = “a”
Output : [7, 15, 5]
Eplanation : All values of “a” key are extracted.
Method #1 : Using list comprehension + items()
This is one of the ways in which this task can be performed. In this, we use list comprehension to perform the task of extracting particular key and items() is used to get all the items().
Python3
# Python3 code to demonstrate working of# Extract values of Particular Key in Nested Values# Using list comprehension# initializing dictionarytest_dict = {'Gfg' : {"a" : 7, "b" : 9, "c" : 12}, 'is' : {"a" : 15, "b" : 19, "c" : 20}, 'best' :{"a" : 5, "b" : 10, "c" : 2}}# printing original dictionaryprint("The original dictionary is : " + str(test_dict))# initializing keytemp = "c"# using item() to extract key value pair as wholeres = [val[temp] for key, val in test_dict.items() if temp in val]# printing resultprint("The extracted values : " + str(res)) |
The original dictionary is : {'Gfg': {'a': 7, 'b': 9, 'c': 12}, 'is': {'a': 15, 'b': 19, 'c': 20}, 'best': {'a': 5, 'b': 10, 'c': 2}}
The extracted values : [12, 20, 2]
Time Complexity: O(n), where n is the number of key-value pairs in the dictionary.
Auxiliary Space: O(m), where m is the number of values that have the key we are looking for.
Method #2 : Using list comprehension + values() + keys()
The combination of above functions can be used to solve this problem. In this, we use values() and keys() to get values and keys separately rather than at once extracted using items().
Python3
# Python3 code to demonstrate working of# Extract values of Particular Key in Nested Values# Using list comprehension + values() + keys()# initializing dictionarytest_dict = {'Gfg' : {"a" : 7, "b" : 9, "c" : 12}, 'is' : {"a" : 15, "b" : 19, "c" : 20}, 'best' :{"a" : 5, "b" : 10, "c" : 2}}# printing original dictionaryprint("The original dictionary is : " + str(test_dict))# initializing keytemp = "c"# using keys() and values() to extract valuesres = [sub[temp] for sub in test_dict.values() if temp in sub.keys()]# printing resultprint("The extracted values : " + str(res)) |
The original dictionary is : {'Gfg': {'a': 7, 'b': 9, 'c': 12}, 'is': {'a': 15, 'b': 19, 'c': 20}, 'best': {'a': 5, 'b': 10, 'c': 2}}
The extracted values : [12, 20, 2]
Time complexity: O(n), where n is the number of values in the dictionary.
Auxiliary space: O(m), where m is the number of values that contain the key ‘c’.
Method 3 : using a for loop and if condition.
Here are the steps:
- Initialize an empty list to store the values of the particular key.
- Iterate over each value in the dictionary using a for loop.
- Check if the particular key exists in the current value using an if condition.
- If the key exists, append its value to the list initialized in step 1.
- Print the list containing the extracted values.
Python3
# initializing dictionarytest_dict = {'Gfg': {'a': 7, 'b': 9, 'c': 12}, 'is': {'a': 15, 'b': 19, 'c': 20}, 'best': {'a': 5, 'b': 10, 'c': 2}}# printing original dictionaryprint("The original dictionary is : " + str(test_dict))# initializing keytemp = "c"# initializing empty listres = []# iterating over each value in dictionaryfor value in test_dict.values(): # checking if key exists in current value if temp in value: # appending value of key to the result list res.append(value[temp])# printing resultprint("The extracted values : " + str(res)) |
The original dictionary is : {'Gfg': {'a': 7, 'b': 9, 'c': 12}, 'is': {'a': 15, 'b': 19, 'c': 20}, 'best': {'a': 5, 'b': 10, 'c': 2}}
The extracted values : [12, 20, 2]
Time Complexity: O(n*m), where n is the number of values in the dictionary and m is the maximum number of keys in a value.
Auxiliary Space: O(k), where k is the number of values in the list ‘res’ containing the extracted values.
