How to Fix the Error: missing value where TRUE/FALSE needed When Removing Empty Files in R

A step-by-step guide to troubleshoot and fix the "missing value where TRUE/FALSE needed" error in R when dealing with empty files.
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This video is based on the question https://stackoverflow.com/q/65670901/ asked by the user 'VLG' ( https://stackoverflow.com/u/14605831/ ) and on the answer https://stackoverflow.com/a/65672465/ provided by the user 'r2evans' ( https://stackoverflow.com/u/3358272/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Fix the Error: missing value where TRUE/FALSE needed When Removing Empty Files in R

If you’ve ever faced the frustrating error in R: missing value where TRUE/FALSE needed, while trying to check file sizes during your data analysis, you’re not alone. This common hiccup happens when you attempt to load files but run into empty or non-existing files. In this guide, we’ll walk you through how to address this issue effectively with some simple adjustments to your code.

Understanding the Problem

You're trying to load a series of files from a directory while skipping empty ones using a custom function. However, when the function encounters a non-existing file, it returns NA, which leads to the error in your conditional check. Let’s break down how you can resolve this problem into two main parts.

Solution Breakdown

1. Ensure Full File Paths

When listing files using the list.files() function, it’s crucial to get the full paths of each file. The default behavior of list.files returns only the names of the files located in a specified directory and doesn’t include their complete paths, which is necessary for reading them.

Fix

To get the full file paths, modify your list.files call by adding the full.names = TRUE argument:

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This ensures that you are pointing to the correct files during your operations.

2. Check File Existence and Size Properly

Your current conditional statement if (!file.size(x) == 0) fails when a file doesn’t exist, returning NA. Instead, you need to check whether the file actually exists before checking its size.

Fix

Here’s an adjusted version of your lapply function that properly checks for file existence and its size before attempting to read it:

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3. Additional Assurance

To guard against any assumptions about your file paths being correct, it's a good practice to implement a quick check of the files’ existence before proceeding with data loading. You can do this with stopifnot() as follows:

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Conclusion

By implementing these simple fixes, you can effectively skip over any empty or missing files without encountering the dreaded missing value where TRUE/FALSE needed error. Being meticulous about checking both the existence and size of your files will save you time and frustration in your R programming endeavors. Happy coding!

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