Скачать или смотреть How to Fix Python writerows Error When Writing CSV Files

Learn how to resolve the `AttributeError` in Python when using `csv.DictWriter` to write lists to a CSV file. Discover simple steps and practical solutions to avoid common pitfalls.
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Understanding the Python writerows Error When Writing CSV Files

When working with CSV writing in Python, encountering errors can be frustrating, particularly when you're unsure of what went wrong. This guide addresses a common issue that arises when using the csv.DictWriter class to write a list of lists to a CSV file. We will breakdown the problem and explore the solution step-by-step.

The Problem: AttributeError in writerows

In a scenario where you're trying to write data to a CSV file, you might run into the error shown below:

[[See Video to Reveal this Text or Code Snippet]]

This error occurs when you use the csv.DictWriter with writerows, which expects a dictionary format rather than a list format. In the case of your code, you are passing it a list of lists directly, which is not what the method is designed to handle.

Code Example Causing the Error

[[See Video to Reveal this Text or Code Snippet]]

The Solution: Using a Dictionary Format

To correctly write the CSV, you should use a dictionary for each row instead of a list. Here’s how to modify your initial approach to avoid the error:

Step-by-Step Instructions

Define Your Data Structure: The first step remains the same. Prepare your list of lists properly, ensuring the first sub-list serves as headers.

Open a CSV File: Instead of using StringIO, directly open a CSV file for writing.

Create a DictWriter Object: Pass the headers to DictWriter just like before.

Write Rows as Dictionaries: Use a loop to convert each row from a list to a dictionary format, mapping the header names to their corresponding values.

Updated Code Example

Here’s the revised code that avoids the error:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By ensuring that you are passing a dictionary with key-value pairs that match your headers, you can resolve the AttributeError and successfully write to your CSV file. Adhering to the structure expected by csv.DictWriter will save you time and help you avoid common pitfalls in CSV file handling with Python.

With these steps in mind, you should be well-equipped to tackle CSV file writing securely and efficiently. Happy coding!