Python Open File, Append, Create if Not Exist [Methods + Examples]

Example 1: Append Data to an Existing File

# Open a file in append mode
with open("my_file.txt", "a") as file:
    # Write data to the file
    file.write("This is new data.\n")

Output:

This is new data.
    

Example 2: Create a New File If It Doesn't Exist and Append Data

# Open a file in append mode, create it if it doesn't exist
with open("new_file.txt", "a+") as file:
    # Write data to the file
    file.write("This is new data in a new file.\n")
    # Move the file cursor to the beginning
    file.seek(0)
    # Read and print the file content
    file_content = file.read()
    print("File Content:")
    print(file_content)

Output:

File Content:
This is new data in a new file.
    

Example 3: Append Data to an Existing CSV File

import csv

# Data to append
new_data = ["John", "Doe", "john@example.com"]

# Open a CSV file in append mode
with open("data.csv", "a", newline="") as file:
    csv_writer = csv.writer(file)
    # Append the data as a new row
    csv_writer.writerow(new_data)


    

Output:

John,Doe,john@example.com
    

Example 4: Create a New CSV File If It Doesn't Exist and Append Data

import csv

# Data to append
new_data = ["Alice", "Smith", "alice@example.com"]

# Open a CSV file in append mode, create it if it doesn't exist
with open("new_data.csv", "a+", newline="") as file:
    csv_writer = csv.writer(file)
    # Append the data as a new row
    csv_writer.writerow(new_data)
    # Move the file cursor to the beginning
    file.seek(0)
    # Read and print the file content
    file_content = file.read()
    print("File Content:")
    print(file_content)

    

Output:

File Content:
Alice,Smith,alice@example.com