How Can I Append Data to an Existing CSV File Using Pandas?

Appending Data to Existing CSV Files with Pandas

In data analysis, you may encounter situations where you need to add new data to an existing CSV file that shares the same structure. Pandas, a popular Python library for data manipulation, offers a convenient way to achieve this using the to_csv() function.

To append data to an existing CSV file using Pandas, you can specify the write mode as 'a' within the to_csv() function:

df.to_csv('my_csv.csv', mode='a', header=False)

The default mode is 'w', which overwrites the existing file. By setting the mode to 'a', you can append new data to the end of the file.

It's important to note that the new data should have the same column structure as the existing CSV file. If the file is initially missing, you can ensure that the header is printed in the first write using the following variation:

output_path='my_csv.csv'
df.to_csv(output_path, mode='a', header=not os.path.exists(output_path))

This ensures that the header is preserved even if the file is empty. By following these instructions, you can easily append new data to existing CSV files using Pandas, streamlining your data handling tasks.

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