How to delete all files in folder except CSV?

import os
directory = "/path/to/directory/with/files"
files_in_directory = os.listdir(directory)
filtered_files = [file for file in files_in_directory if not file.endswith(".csv")]
for file in filtered_files:
    path_to_file = os.path.join(directory, file)
    os.remove(path_to_file)

first, you list all files in directory. Then, you only keep in list those, which don't end with .csv. And then, you remove all files that are left.

Try iterating over the files in the directory, and then os.remove only those files that do not end with .csv.

import os
dir_path = "path/to/the/directory/containing/files"
dir_list = os.listdir(dir_path)
for item in dir_list:
    if not item.endswith(".csv"):
        os.remove(os.path.join(dir_path, item))

You can also have fun with list comprehension for doing this:

import os

dir_path = 'output/'

[os.remove(os.path.join(dir_path, item)) for item in os.listdir(dir_path) if not item.endswith('.csv')]

I would recommended to use pathlib (Python >= 3.4) and the in-build type set() to substract all csv filenames from the list of all files. I would argument this is easy to read, fast to process and a good pythonic solution.

>>> from pathlib import Path
>>> p = Path('/path/to/directory/with/files')
>>> # Get all file names
>>> # https://stackoverflow.com/a/65025567/4865723
>>> set_all_files = set(filter(Path.is_file, p.glob('**/*')))
>>> # Get all csv filenames (BUT ONLY with lower case suffix!)
>>> set_csv_files = set(filter(Path.is_file, p.glob('**/*.csv')))
>>> # Create a file list without csv files
>>> set_files_to_delete = set_all_files - set_csv_files
>>> # Iteratore on that list and delete the file
>>> for file_name in set_files_to_delete:
...     Path(file_name).unlink()

for (root,dirs,files) in os.walk('Test', topdown=true):
    for name in files:
        fp = os.path.join(root, name)
        if name.endswith(".csv"):
            pass
        else:
             os.remove(fp)

What the advandtage of os.walk?, it reads all the subdirectory in particular directory mentioned.