Merge Dictionaries without Overwriting in Python

Merging dictionaries in Python is a common operation. In this article, we will see how we can append two dictionaries so that they don’t overwrite each other in Python.

Append two dictionaries so they don’t Overwrite Each Other

Below are some of the ways by which we can append two dictionaries in Python:

1. Using the update() Method
2. Using the ** Unpacking Operator
3. Using the collections.ChainMap Class
4. Using the dict() Constructor and Unpacking

Append Two Dictionaries Using the update() Method

In this example, two dictionaries, `dict1` and `dict2`, are provided. The update() method is employed to merge the contents of `dict2` into a copy of `dict1`, resulting in `merged_dict`. If there are overlapping keys, values from `dict2` will overwrite corresponding values from `dict1`, and the final merged dictionary is printed.

Python3

# Sample dictionaries
dict1 = {'a': 1, 'b': 2}
dict2 = {'b': 3, 'c': 4}

# Using update() method
merged_dict = dict1.copy()
merged_dict.update(dict2)

print(merged_dict)

Output

{'a': 1, 'b': 3, 'c': 4}

Append Two Dictionaries Using the ** Unpacking Operator

In this example, two dictionaries, dict1 and dict2, are provided. The ** unpacking operator is utilized to merge their contents into a new dictionary named merged_dict. This concise approach combines the key-value pairs from both dictionaries, and if there are overlapping keys, the values from dict2 will overwrite the values from dict1. The final merged dictionary is then printed.

Python3

# Sample dictionaries
dict1 = {'a': 1, 'b': 2}
dict2 = {'b': 3, 'c': 4}

# Using ** unpacking operator
merged_dict = {**dict1, **dict2}

print(merged_dict)

Output

{'a': 1, 'b': 3, 'c': 4}

Append Two Dictionaries Using the collections.ChainMap Class

In this example, the collections module’s ChainMap is utilized to merge two dictionaries, dict1 and dict2. The ChainMap class efficiently combines the dictionaries, creating a view that allows access to the keys and values from both dictionaries as if they were a single dictionary. The resulting merged_dict is then converted into a regular dictionary using dict(), and the combined key-value pairs are printed.

Python3

from collections import ChainMap

# Sample dictionaries
dict1 = {'a': 1, 'e': 2}
dict2 = {'b': 3, 'c': 4}

# Using ChainMap
merged_dict = dict(ChainMap(dict1, dict2))

print(merged_dict)

Output

{'b': 3, 'c': 4, 'a': 1, 'e': 2}

Append Two Dictionaries Using the dict() Constructor and Unpacking

In this example, the dict() constructor and the ** unpacking operator are employed to merge two dictionaries, dict1 and dict2. The resulting merged_dict contains the combined key-value pairs from both dictionaries. If there are overlapping keys, the values from dict2 will overwrite the values from dict1.

Python3

# Sample dictionaries
dict1 = {'a': 1, 'b': 2}
dict2 = {'b': 3, 'c': 4}

# Using dict() constructor and unpacking
merged_dict = dict(dict1, **dict2)

print(merged_dict)

Output

{'a': 1, 'b': 3, 'c': 4}