Working with CSV and JSON in Python

Handling data in different formats is a common task in Python programming. Two popular formats for data storage and exchange are CSV (Comma-Separated Values) and JSON (JavaScript Object Notation). In this guide, we’ll explore how to work with CSV and JSON data in Python, covering reading, writing, and manipulating data in these formats.

Reading CSV Files

Python provides the ‘csv’ module to read and write CSV files. To read data from a CSV file, you can use the ‘reader’ object from this module. The ‘reader’ allows you to iterate through the rows of the CSV file as lists or dictionaries.

Example:

Here’s an example of reading data from a CSV file named ‘data.csv’ and printing each row:

import csv

with open('data.csv', 'r') as file:
    csv_reader = csv.reader(file)
    for row in csv_reader:
        print(row)

Writing CSV Files

To write data to a CSV file, you can use the ‘writer’ object from the ‘csv’ module. This object allows you to write rows to a CSV file one at a time.

Example:

Let’s write some data to a CSV file named ‘output.csv’:

import csv

data = [
    ['Name', 'Age', 'City'],
    ['Alice', 25, 'New York'],
    ['Bob', 30, 'Los Angeles'],
    ['Charlie', 22, 'Chicago']
]

with open('output.csv', 'w', newline='') as file:
    csv_writer = csv.writer(file)
    csv_writer.writerows(data)

Working with JSON

Python’s ‘json’ module makes working with JSON data straightforward. You can convert Python data structures to JSON and vice versa. JSON supports key-value pairs, arrays, and nested structures, making it a versatile format for data storage and exchange.

Converting Data to JSON

You can convert a Python dictionary or list to a JSON string using the ‘dumps()’ method of the ‘json’ module. This method serializes the Python data into a JSON format.

Example:

Converting a Python dictionary to a JSON string:

import json

data = {
    'name': 'John',
    'age': 30,
    'city': 'San Francisco'
}

json_string = json.dumps(data)
print(json_string)

Reading JSON Data

To read data from a JSON file, you can use the ‘load()’ method of the ‘json’ module. This method loads JSON data from a file and converts it into Python data structures.

Example:

Here’s an example of reading JSON data from a file named ‘data.json’:

import json

with open('data.json', 'r') as file:
    json_data = json.load(file)
    print(json_data)

Writing JSON Data

To write data to a JSON file, you can use the ‘dump()’ method of the ‘json’ module. This method serializes Python data structures and saves them as JSON in a file.

Example:

Let’s save a Python dictionary as JSON in a file named ‘output.json’:

import json

data = {
    'name': 'Alice',
    'age': 28,
    'city': 'Seattle'
}

with open('output.json', 'w') as file:
    json.dump(data, file)

Manipulating JSON Data

You can work with JSON data just like any other Python data structure. This includes adding, modifying, and deleting elements. JSON’s flexible structure allows for easy manipulation.

Example:

Let’s add a new key-value pair to an existing JSON object:

import json

# Read existing JSON data
with open('data.json', 'r') as file:
    json_data = json.load(file)

# Add a new key-value pair
json_data['email'] = 'alice@example.com'

# Write the updated JSON data back to the file
with open('data.json', 'w') as file:
    json.dump(json_data, file)

Conclusion

Working with CSV and JSON data is a fundamental skill for data manipulation and exchange in Python. These formats are commonly used for storing and sharing structured data. Whether you’re reading data from a CSV file or converting Python data to JSON, understanding how to work with these formats is essential for data-related tasks in Python programming.