如果列表 object 包含从列表中删除的内容

Question

I have a python script that checks a certain folder for new files and then copies the new files to another directory. The files are in such a format 1234.txt and 1234_status.txt. It should only move 1234.txt and leave the 1234_status.txt unattended.

Here's a little piece of my code in python

    while 1:
#retrieves listdir
        after = dict([(f, None) for f in os.listdir (path_to_watch)])
#if after has more files than before, then it adds the new files to an array "added"
        added = [f for f in after if not f in before]

My idea is that after it fills added, then it checks it for values that have status in it and pops it from the array. Couldn't find a way to do this though: /

Answer 1

If I understand your problem correctly:

while 1:
    for f in os.listdir(path_to_watch):
        if 'status' not in f: # or a more appropriate condition
            move_file_to_another_directory(f)
    # wait

or check pyinotify if using Linux to avoid useless checks.

Answer 2

added = [f for f in after if not f in before and '_status' not in f]

I do however recommend to refrain from long one line statements as they make the code almost impossible to read

Answer 3

files_in_directory = [filename for filename in os.listdir(directory_name)]
files_to_move = filter(lambda filename: '_status' not in filename, files_in_directory)

Answer 4

You can use set logic since order doesn't matter here:

from itertools import filterfalse

def is_status_file(filename):
    return filename.endswith('_status.txt')
# ...
added = set(after) - set(before)
without_status = filterfalse(is_status_file, added)