How to Fix the Append Function Not Adding Rows to Your Pandas DataFrame

Описание: Struggling with the `append` function in your Pandas DataFrame? Learn how to properly append data in Python and solve common issues effectively!
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This video is based on the question https://stackoverflow.com/q/69851555/ asked by the user 'Yves' ( https://stackoverflow.com/u/10468840/ ) and on the answer https://stackoverflow.com/a/69851613/ provided by the user 'Tõnis Piip' ( https://stackoverflow.com/u/5967602/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Fixing the Append Function in Pandas: A Closer Look

When working with dataframes in Pandas, it's common to encounter issues, especially when appending data. One such common problem arises when you attempt to use the append function, only to find that your dataframe remains empty despite your best efforts. If you've found yourself in this frustrating situation, you're not alone! In this post, we'll explore a specific example involving ArcPy and Pandas, and we'll provide a clear solution to ensure that your data is appended correctly.

The Problem

Consider the following piece of code where you are trying to extract the extent of features from a shapefile and append this information into a dataframe. Here's the critical section of the code causing the issue:

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

In this example, df1 is intended to accumulate the extents from each row. However, it always results in an empty dataframe. The reason behind this? The append function does not modify df1 in place; instead, it returns a new dataframe that must be assigned back to a variable.

The Solution: Properly Using Append

To ensure that your dataframe accumulates the data as expected, you need to assign the output of the append method back to df1. Simply add df1 = before the append statement as shown below:

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

Complete Code Example

Here’s how your revised code could look:

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

Key Takeaways

Return Value: Always remember that the append method in Pandas returns a new dataframe. If you don't assign this back to a variable, the changes won't reflect in your original dataframe.

Efficiency: Repeated use of append can be inefficient in large loops. Consider collecting your data into a list and creating a dataframe in one go if performance becomes an issue.

By applying this fix, you should now be able to successfully append data to your df1 dataframe without issues. Happy coding!