Append a dictionary to a dictionary

17    Asked by LucasJackson in Python , Asked on May 12, 2025

How can you append one dictionary to another in Python? Learn how to merge or update dictionaries using simple methods like the update() function or the ** unpacking operator for clean and efficient code.

Answered by Sally Langdon

Appending one dictionary to another in Python is commonly done when you want to combine or update key-value pairs. While Python dictionaries don’t have a direct “append” method like lists, you can merge them using a few simple approaches.

 Method 1: Using update()

This is the most straightforward way:

dict1 = {'a': 1, 'b': 2}
dict2 = {'c': 3, 'd': 4}
dict1.update(dict2)
print(dict1) # {'a': 1, 'b': 2, 'c': 3, 'd': 4}

  • update() adds all key-value pairs from dict2 to dict1.
  • If any keys are the same, the values in dict1 will be overwritten.

 Method 2: Using ** Unpacking (Python 3.5+)

A more modern and clean approach:

combined = {**dict1, **dict2}
print(combined) # {'a': 1, 'b': 2, 'c': 3, 'd': 4}

  • This creates a new dictionary without modifying the originals.
  • Also handles key overwriting if duplicates exist.

 Method 3: Using a Loop (if more control is needed)

for key, value in dict2.items():
    dict1[key] = value

Useful if you want to apply some condition before adding values.

 Tips:

  • Be careful with overlapping keys—values will be overwritten.
  • Use update() when you’re okay modifying the original dictionary.
  • Use unpacking (**) if you prefer to keep the originals intact.

Combining dictionaries in Python is super easy—and knowing multiple ways helps you choose what fits best for your code!



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