How to create Python dictionary from JSON input?

You can parse JSON data into a Python dictionary using the json module. This module provides methods to convert JSON strings or files into Python dictionaries, allowing you to work with the data using familiar dictionary operations.

Creating Dictionary from JSON String

The most common approach is using json.loads() to parse a JSON string ?

import json

json_string = '''
{
  "id": "file",
  "value": "File",
  "popup": {
    "menuitem": [
      {"value": "New", "onclick": "CreateNewDoc()"},
      {"value": "Open", "onclick": "OpenDoc()"},
      {"value": "Close", "onclick": "CloseDoc()"}
    ]
  }
}
'''

data = json.loads(json_string)
print(type(data))
print(data)

<class 'dict'>
{'id': 'file', 'value': 'File', 'popup': {'menuitem': [{'value': 'New', 'onclick': 'CreateNewDoc()'}, {'value': 'Open', 'onclick': 'OpenDoc()'}, {'value': 'Close', 'onclick': 'CloseDoc()'}]}}

Accessing Dictionary Values

Once converted to a dictionary, you can access values using standard dictionary methods ?

import json

json_string = '''
{
  "id": "file",
  "value": "File",
  "popup": {
    "menuitem": [
      {"value": "New", "onclick": "CreateNewDoc()"},
      {"value": "Open", "onclick": "OpenDoc()"}
    ]
  }
}
'''

data = json.loads(json_string)

# Access top-level values
print("ID:", data["id"])
print("Value:", data["value"])

# Access nested values
menu_items = data["popup"]["menuitem"]
print("First menu item:", menu_items[0]["value"])

ID: file
Value: File
First menu item: New

Iterating Through Dictionary

You can loop through the dictionary keys and values like any Python dictionary ?

import json

json_string = '{"name": "John", "age": 30, "city": "New York"}'
data = json.loads(json_string)

for key, value in data.items():
    print(f"Key: {key}")
    print(f"Value: {value}")
    print("---")

Key: name
Value: John
---
Key: age
Value: 30
---
Key: city
Value: New York
---

Loading from JSON File

For JSON data stored in files, use json.load() instead of json.loads() ?

import json

# Reading from a JSON file
with open('data.json', 'r') as file:
    data = json.load(file)
    
# Now data is a dictionary
for key, value in data.items():
    print(f"{key}: {value}")

Comparison

Conclusion

Use json.loads() for JSON strings and json.load() for JSON files. Both methods return a Python dictionary that you can manipulate using standard dictionary operations.