Sometimes, while working with Python dictionaries, we can have a problem in which we need to perform a merge of dictionaries in list with similar keys. This kind of problem can come in data optimization domains. Let’s discuss a way in which this task can be performed.
Input : test_list = [{‘a’: 6}, {‘b’: 2}, {‘a’: 9}, {‘b’: 7}]
Output : [{‘b’: 2, ‘a’: 6}, {‘b’: 7, ‘a’: 9}]Input : test_list = [{‘a’: 8}, {‘a’: 2}, {‘a’: 3}]
Output : [{‘a’: 8}, {‘a’: 2}, {‘a’: 3}]
Method : loop + ** operator The combination of above functions can be used to solve this problem. In this, we use brute force to construct a new dictionary and add keys only if that is not added in current. The task of merging dictionaries is by unpacking the initial dictionaries using “**” operator, and then packing again with dictionary with no repeated key and new one, using the usual dictionary initialization construct {}.
Python3
# Python3 code to demonstrate working of # Merge Similar Dictionaries in List# Using loop + "**" operator# initializing listtest_list = [{'gfg' : 1}, {'is' : 2}, {'best' : 3}, {'gfg' : 5}, {'is' : 17}, {'best' : 14}, {'gfg' : 7}, {'is' : 8}, {'best' : 10},]# printing original listprint("The original list is : " + str(test_list))# Merge Similar Dictionaries in List# Using loop + "**" operatorres = [{}]for sub in test_list: if list(sub)[0] not in res[-1]: res[-1] = {**res[-1], **sub} else: res.append(sub)# printing result print("The merged dictionaries : " + str(res)) |
The original list is : [{‘gfg’: 1}, {‘is’: 2}, {‘best’: 3}, {‘gfg’: 5}, {‘is’: 17}, {‘best’: 14}, {‘gfg’: 7}, {‘is’: 8}, {‘best’: 10}] The merged dictionaries : [{‘best’: 3, ‘is’: 2, ‘gfg’: 1}, {‘best’: 14, ‘is’: 17, ‘gfg’: 5}, {‘best’: 10, ‘is’: 8, ‘gfg’: 7}]
Time complexity: O(n^2).
Auxiliary space: O(n).
