Python 3 - 如果目标文件夹中不存在文件，则复制文件

Question

I am attempting to move a couple thousand pdfs from one file location to another. The source folder contains multiple subfolders and I am combining just the pdfs (technical drawings) into one folder to simplify searching for the rest of my team.

The main goal is to only copy over files that do not already exist in the destination folder. I have tried a couple different options, most recently what is shown below, and in all cases, every file is copied every time. Prior to today, any time I attempted a bulk file move, I would received errors if the file existed in the destination folder but I no longer do.

I have verified that some of the files exist in both locations but are still being copied. Is there something I am missing or can modify to correct?

Thanks for the assistance.

import os.path
import shutil

source_folder = os.path.abspath(r'\\source\file\location')

dest_folder = os.path.abspath(r'\\dest\folder\location')

    for folder, subfolders, files in os.walk(source_folder):
        for file in files:
            path_file=os.path.join(folder, file)
            if os.path.exists(file) in os.walk(dest_folder):
                print(file+" exists.")
            if not os.path.exists(file) in os.walk(dest_folder):
                  print(file+' does not exist.')
                  shutil.copy2(path_file, dest_folder)

Answer 1

os.path.exists returns a Boolean value. os.walk creates a generator which produces triples of the form (dirpath, dirnames, filenames) . So, that first conditional will never be true.

Also, even if that conditional were correct, your second conditional has a redundancy since it's merely the negation of the first. You could replace it with else .

What you want is something like

if file in os.listdir(dest_folder):
    ...
else:
    ...