{"id":4209,"date":"2022-08-06T01:32:33","date_gmt":"2022-08-06T01:32:33","guid":{"rendered":"https:\/\/www.pythontutorial.net\/?page_id=4209"},"modified":"2025-03-30T13:02:52","modified_gmt":"2025-03-30T13:02:52","slug":"python-list-files","status":"publish","type":"page","link":"https:\/\/www.pythontutorial.net\/python-basics\/python-list-files\/","title":{"rendered":"How to List Files from a Directory in Python"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn how to list files in a directory using the Python os.walk()<\/code> function.<\/p>\n\n\n\n

Sometimes, you may want to list all files from a directory for processing. For example, you might want to find all images of a directory and resize each of them. To list all files in a directory, you can use the os.walk()<\/code> function.<\/p>\n\n\n\n

The os.walk()<\/code><\/code> function generates file names in a directory by walking the tree either top-down or bottom-up. The os.walk()<\/code> function yields a tuple with three fields (dirpath<\/code>, dirnames<\/code>, and filenames<\/code>) for each directory in the directory tree.<\/p>\n\n\n\n

Note that the os.walk()<\/code> function examines the whole directory tree. Therefore, you can use it to get all files from all directories and their subdirectories of a root directory.<\/p>\n\n\n\n

Python list file example #<\/a><\/h2>\n\n\n\n

Suppose you have a folder D:\\web<\/code> with the following directories and files:<\/p>\n\n\n

D:\\web\n\u251c\u2500\u2500 assets\n|  \u251c\u2500\u2500 css\n|  |  \u2514\u2500\u2500 style.css\n|  \u2514\u2500\u2500 js\n|     \u2514\u2500\u2500 app.js\n\u251c\u2500\u2500 blog\n|  \u251c\u2500\u2500 read-file.html\n|  \u2514\u2500\u2500 write-file.html\n\u251c\u2500\u2500 about.html\n\u251c\u2500\u2500 contact.html\n\u2514\u2500\u2500 index.html<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The following example shows how to use the os.walk()<\/code> function to list all HTML files from the D:\\web<\/code> directory:<\/p>\n\n\n
import<\/span> os\n\n\npath = 'D:\\\\web'<\/span>\n\nhtml_files = []\n\nfor<\/span> dirpath, dirnames, filenames in<\/span> os.walk(path):\n    for<\/span> filename in<\/span> filenames:\n        if<\/span> filename.endswith('.html'<\/span>):\n            html_files.append(os.path.join(dirpath, filename))\n\nfor<\/span> html_file in<\/span> html_files:\n    print(html_file)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
D:\\web\\about.html\nD:\\web\\contact.html\nD:\\web\\index.html\nD:\\web\\blog\\read-file.html\nD:\\web\\blog\\write-file.html<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
How it works.<\/p>\n\n\n\n
First, initialize a list to store the path to HTML files:<\/p>\n\n\n
html_files = []<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Second, call os.walk()<\/code> function to examine directories of the D:\\web<\/code> folder:<\/p>\n\n\n
for<\/span> dirpath, dirnames, filenames in<\/span> os.walk(path):<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The dirpath<\/code> stores the directory and filenames store files in that directory.<\/p>\n\n\n\n
Third, loop over the filenames and add them to the html_files<\/code> list if their extensions are .html<\/code>:<\/p>\n\n\n
# ...<\/span>\nfor<\/span> filename in<\/span> filenames:\n        if<\/span> filename.endswith('.html'<\/span>):\n            html_files.append(os.path.join(dirpath, filename))<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Note that the os.path.join()<\/code> returns the full path of the filename by joining the dirpath<\/code> with the filename<\/code>.<\/p>\n\n\n\n
Finally, print output the filenames in the html_files<\/code> list:<\/p>\n\n\n
for<\/span> html_file in<\/span> html_files:\n    print(html_file)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Defining a reusable list files function #<\/a><\/h2>\n\n\n\n
By using the os.walk()<\/code> function, we can define a reusable list_files()<\/code> function like this:<\/p>\n\n\n
import<\/span> os\n\n\ndef<\/span> list_files<\/span>(path, extentions=None)<\/span>:<\/span>\n    \"\"\" List all files in a directory specified by path\n    Args:\n        path - the root directory path\n        extensions - a iterator of file extensions to include, pass None to get all files.\n    Returns:\n        A list of files specified by extensions\n    \"\"\"<\/span>\n    filepaths = []\n    for<\/span> root, _, files in<\/span> os.walk(path):\n        for<\/span> file in<\/span> files:\n            if<\/span> extentions is<\/span> None<\/span>:\n                filepaths.append(os.path.join(root, file))\n            else<\/span>:\n                for<\/span> ext in<\/span> extentions:\n                    if<\/span> file.endswith(ext):\n                        filepaths.append(os.path.join(root, file))\n\n    return<\/span> filepaths\n\n\nif<\/span> __name__ == '__main__'<\/span>:\n    filepaths = list_files(r'D:\\web'<\/span>, ('.html'<\/span>, '.css'<\/span>))\n    for<\/span> filepath in<\/span> filepaths:\n        print(filepath)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
D:\\web\\about.html\nD:\\web\\contact.html\nD:\\web\\index.html\nD:\\web\\assets\\css\\style.css\nD:\\web\\blog\\read-file.html\nD:\\web\\blog\\write-file.html<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Make list files function more efficient #<\/a><\/h2>\n\n\n\n
If the number of files is small, the list_files()<\/code> function works fine. However, when the number of files is large, returning a large list of files is not memory efficient. <\/p>\n\n\n\n
To resolve this, you can use a generator<\/a> to yield each file at a time instead of returning a list:<\/p>\n\n\n
import<\/span> os\n\n\ndef<\/span> list_files<\/span>(path, extentions=None)<\/span>:<\/span>\n    \"\"\" List all files in a directory specified by path\n    Args:\n        path - the root directory path\n        extensions - a iterator of file extensions to include, pass None to get all files.\n    Returns:\n        A list of files specified by extensions\n    \"\"\"<\/span>\n    for<\/span> root, _, files in<\/span> os.walk(path):\n        for<\/span> file in<\/span> files:\n            if<\/span> extentions is<\/span> None<\/span>:\n                yield<\/span> os.path.join(root, file)\n            else<\/span>:\n                for<\/span> ext in<\/span> extentions:\n                    if<\/span> file.endswith(ext):\n                        yield<\/span> os.path.join(root, file)\n\n\nif<\/span> __name__ == '__main__'<\/span>:\n    filepaths = list_files(r'D:\\web'<\/span>, ('.html'<\/span>, '.css'<\/span>))\n    for<\/span> filepath in<\/span> filepaths:\n        print(filepath)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Summary #<\/a><\/h2>\n\n\n\n