How To Create Dynamic Dictionary In Python

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How can I add new keys to a Python dictionary?

In this short tutorial we are going to explore different ways to add values to a dictionary in Python. Some times you create a dictionary in Python and later on on the code or dynamically it is needed to add values or add keys to that dict.

So let's explore Python dictionary and some examples to append new keys.

Creating an empty dictionary

              data = {} # OR data = dict()

Creating a dictionary with initial values

              data = {'a': 1, 'b': 2, 'c': 3} # OR data = dict(a=1, b=2, c=3) # OR data = {k: v for k, v in (('a', 1), ('b',2), ('c',3))}

Inserting/Updating a single value

              data['a'] = 1  # Updates if 'a' exists, else adds 'a' # OR data.update({'a': 1}) # OR data.update(dict(a=1)) # OR data.update(a=1)

Inserting/Updating multiple values

              data.update({'c':3,'d':4})  # Updates 'c' and adds 'd'

Python 3.9+:

The update operator |= now works for dictionaries:

              data |= {'c':3,'d':4}

Creating a merged dictionary without modifying originals

              data3 = {} data3.update(data)  # Modifies data3, not data data3.update(data2)  # Modifies data3, not data2

Python 3.5+:

This uses a new feature called dictionary unpacking.

              data = {**data1, **data2, **data3}

Python 3.9+:

The merge operator | now works for dictionaries:

              data = data1 | {'c':3,'d':4}

Deleting items in dictionary

              del data[key]  # Removes specific element in a dictionary data.pop(key)  # Removes the key & returns the value data.clear()  # Clears entire dictionary

Check if a key is already in dictionary

              key in data

Iterate through pairs in a dictionary

              for key in data: # Iterates just through the keys, ignoring the values for key, value in d.items(): # Iterates through the pairs for key in d.keys(): # Iterates just through key, ignoring the values for value in d.values(): # Iterates just through value, ignoring the keys

Create a dictionary from two lists

              data = dict(zip(list_with_keys, list_with_values))

Interesting resources:

Get the Book: Python Programming from Scratch

source: https://stackoverflow.com/questions/1024847/how-can-i-add-new-keys-to-a-dictionary