Reading JSON from a file in python

Reading JSON from a file in python

To read JSON data from a file in Python, you can use the built-in json module. Here's a step-by-step guide on how to do it:

Suppose you have a JSON file named "data.json" with the following content:

{ "name": "John", "age": 30, "city": "New York" }

You can read this JSON data from the file as follows:

import json # Specify the file path file_path = "data.json" # Open the JSON file for reading with open(file_path, "r") as json_file: # Load the JSON data from the file data = json.load(json_file) # Now 'data' contains the JSON data as a Python dictionary print(data) # Access specific values from the dictionary name = data["name"] age = data["age"] city = data["city"] print(f"Name: {name}") print(f"Age: {age}") print(f"City: {city}")

Here's what the code does:

  1. Import the json module.
  2. Specify the file path of the JSON file you want to read (file_path).
  3. Open the JSON file using a with statement, specifying the file path and mode "r" (read).
  4. Use json.load(json_file) to parse the JSON data from the file. This function reads the JSON data and returns a Python dictionary.
  5. You can then access specific values from the dictionary, just like any other Python dictionary.

After running this code, you'll have the JSON data loaded into the data dictionary, and you can work with it in your Python program.

Examples

  1. Reading JSON from a File in Python

    • This snippet shows how to read JSON data from a local file and convert it into a Python object (like a dictionary or list).
    import json # Load JSON from a file with open("data.json", "r") as file: json_data = json.load(file) print("JSON Data:", json_data)

  2. Handling Errors When Reading JSON from a File in Python

    • This snippet demonstrates how to handle errors (like JSONDecodeError) when reading JSON data from a file.
    import json try: with open("invalid_data.json", "r") as file: json_data = json.load(file) except json.JSONDecodeError as e: print("Error decoding JSON:", e) except FileNotFoundError: print("File not found.")

  3. Reading JSON from a File and Accessing Specific Data

    • This snippet shows how to access specific keys/values from JSON data read from a file.
    import json # Load JSON from a file with open("data.json", "r") as file: json_data = json.load(file) # Access specific keys/values user_name = json_data.get("name", "Unknown") user_age = json_data.get("age", None) print("User Name:", user_name) print("User Age:", user_age)

  4. Reading and Modifying JSON Data from a File in Python

    • This snippet demonstrates how to read JSON data from a file, modify it, and then save it back to the same file.
    import json # Load JSON from a file with open("data.json", "r") as file: json_data = json.load(file) # Modify the JSON data json_data["age"] = 30 # Change age to 30 # Save the modified JSON data back to the file with open("data.json", "w") as file: json.dump(json_data, file) print("JSON Data modified and saved.")

  5. Pretty-Printing JSON Data in Python

    • This snippet demonstrates how to read JSON from a file and then print it in a human-readable format.
    import json # Load JSON from a file with open("data.json", "r") as file: json_data = json.load(file) # Pretty-print the JSON data print("Pretty-Printed JSON:") print(json.dumps(json_data, indent=4, sort_keys=True))

  6. Reading a Large JSON File in Python

    • This snippet shows how to read a large JSON file efficiently using a streaming approach.
    # Install `ijson` if needed !pip install ijson 
    import ijson # Stream JSON data from a large file with open("large_data.json", "r") as file: for item in ijson.items(file, "item"): print("JSON Item:", item) # Process each item

  7. Reading Nested JSON Data from a File in Python

    • This snippet demonstrates how to read JSON data with nested structures and access deeper elements.
    import json # Load JSON from a file with open("nested_data.json", "r") as file: json_data = json.load(file) # Access a nested key user_address = json_data["user"]["address"]["street"] print("User's Street Address:", user_address)

  8. Validating JSON Data from a File in Python

    • This snippet shows how to read JSON from a file and validate its structure against a predefined schema.
    # Install `jsonschema` if needed !pip install jsonschema 
    import json from jsonschema import validate, ValidationError # JSON Schema to validate against json_schema = { "type": "object", "properties": { "name": {"type": "string"}, "age": {"type": "integer"}, }, "required": ["name"], } try: # Load JSON from a file with open("data.json", "r") as file: json_data = json.load(file) # Validate the JSON data validate(instance=json_data, schema=json_schema) print("JSON is valid.") except ValidationError as e: print("JSON Validation Error:", e)

  9. Filtering JSON Data from a File in Python

    • This snippet demonstrates how to read JSON from a file and filter it based on specific criteria.
    import json # Load JSON from a file with open("data.json", "r") as file: json_data = json.load(file) # Filter data where age is greater than 25 filtered_data = [item for item in json_data if item.get("age", 0) > 25] print("Filtered Data:", filtered_data)

  10. Converting JSON to a Pandas DataFrame in Python

    • This snippet demonstrates how to read JSON from a file and convert it into a Pandas DataFrame for further analysis.
    # Install `pandas` if needed !pip install pandas 
    import pandas as pd import json # Load JSON from a file with open("data.json", "r") as file: json_data = json.load(file) # Convert JSON to a Pandas DataFrame df = pd.DataFrame(json_data) print("DataFrame from JSON:") print(df.head())

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