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Using glob to find all CSV files in a folder and subfolder but return list is empty

What will you learn?

In this tutorial, you will explore how to effectively utilize Python’s glob module to effortlessly locate all CSV files within a designated directory and its subdirectories.

Introduction to the Problem and Solution

When employing the glob.glob() function to identify CSV files, encountering an empty returned list can be frustrating. This issue commonly arises due to inaccuracies in path specification or overlooking case sensitivity variations across different operating systems. To overcome this challenge, it is crucial to ensure precise path definition and account for potential discrepancies in file extensions.

Code

import glob

# Specify the directory where your CSV files are located (update 'path_to_folder' accordingly)
csv_files = glob.glob('path_to_folder/**/*.csv', recursive=True)
print(csv_files)

# Ensure proper path format with raw string notation (r'') for Windows paths
csv_files_windows = glob.glob(r'path_to_folder/**/*.csv', recursive=True)
print(csv_files_windows)

# For case-insensitive search on Windows, use an alternative method:
import os

os.chdir('path_to_folder')
csv_files_ci = [file for file in glob.glob('**/*.csv', recursive=True)]
print(csv_files_ci)  # Ensure the current working directory is set correctly 

# Copyright PHD

(Explore more solutions at PythonHelpDesk.com)

Explanation

  • Importing necessary modules: We import glob along with optional os for directory manipulation.
  • Defining the file path: Specify the directory location using a wildcard pattern (**/*.csv) with glob.glob().
  • Adapting to OS requirements: Utilize raw string notation (r”) for Windows paths and adjust search strategies as needed by changing directories.
    Why am I getting an empty list when using glob?

    An empty list may result from incorrect path specifications or variations in how operating systems handle paths.

    How can I make my search case-insensitive on Windows?

    Achieve case insensitivity by converting filenames to lowercase during comparison.

    Can I search for multiple file types simultaneously with glob?

    Yes, multiple patterns like ‘*.csv’, ‘*.txt’, etc., can be included within a single call to glob.

    Does recursive=True work on all Python versions?

    The recursive option was introduced in Python 3.5; older versions may lack support.

    What should I do if my script cannot find any files despite correct path setup?

    Ensure script permissions include access rights to specified directories/files.

    Are there performance considerations when using glob on large directories?

    For extensive directories, optimize search criteria or consider alternative methods such as indexing tools.

    Can I filter out certain filenames while using glob?

    Custom filters can be applied post obtaining results from glob.

    How does os.chdir() impact script execution flow?

    Changing directories affects relative paths used subsequently unless managed carefully.

    Is there a limit on nested subdirectory levels supported by recursive searches with glob?

    Recursion depth varies based on system limits; exceeding these constraints could trigger errors like “recursion depth exceeded.”

    Conclusion

    To conclude, mastering file search techniques through modules like ‘glob’ enhances flexibility and efficiency when navigating vast quantities of files within intricate directory structures.

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