Python

Question

我想运行每当我的文件夹发生变化时我的功能。这里要做的主要事情是规范化新文件，我们通过比较我的两个文件夹，包含规范化文件的文件夹和我们添加新文件的文件夹以及 return 我们的不匹配文件列表来做到这一点normalize函数会修改并放置在normalized的文件夹中。

这是我的代码:

def normalize(c):
    PATH = path_to_file 
    fileNames = os.listdir(PATH)

    fileNames = c
    for file in fileNames:
        sfm = pd.read_csv(PATH + file, delimiter = ';', parse_dates=[[0, 1]], skiprows = 3)
  # other instructions then rewrite my new dataframe in my normalized folder
sfm.to_csv('.\dirnormalized'+str(file[:-4])+'.csv', sep=';', index=False, header=True)

def comparison():
    PATH = path_to_file 
    PATH_norm = path_to_norm
    fileNames = os.listdir(PATH)
    files = os.listdir(PATH_norm)
    fileNames = [file for file in fileNames if '.csv' in file]
    files = [fl for fl in files if '.csv' in fl]
    diff = [x for x in fileNames if x not in files]
    return diff

def change():

    logging.basicConfig(level=logging.INFO,
                        format='%(asctime)s - %(message)s',
                        datefmt='%Y-%m-%d %H:%M:%S')
# path_to_file and word_file are the same the only difference is that in path_to_file we have a back slash in the end in order to acces the files one by one 
    path = word_file
    event_handler = LoggingEventHandler()
    observer = Observer()
    observer.schedule(event_handler, path, recursive=True)
    observer.start()
    try:
        while True:
            time.sleep(1)
    except KeyboardInterrupt:
        observer.stop()
    observer.join()

def process(): 
    if(change()):
        c = comparison()
        normalize(c)
if __name__ == "__main__":
    import os 
    import time
    import logging
    from watchdog.observers import Observer
    from watchdog.events import LoggingEventHandler

    process()

这里唯一的问题是在我的 process() 函数中 if() 指令似乎没有传递给其他指令，我可以看到何时添加新文件，这意味着何时发生修改但其他指令不会出现，它卡在 if() 上。

Answer 1

process() 的最后一行即 observer.join() 可能会阻塞线程以防止函数返回。

此外，控制让函数返回 None，导致 if 语句永远不会被执行。

Answer 2

查看 this 目录中的更改。

使用 MS ReadDirectoryChanges API，通过 pywin32 win32file 模块公开。

我们这里使用的方式是在阻塞模式下调用ReadDirectoryChangesW。

函数returns 一个二元组列表，每个元组代表一个动作和一个文件名。重命名总是给出一对二元组；其他复合动作也可能给出一个列表。

import os
import win32file
import win32con

ACTIONS = {
  1 : "Created",
  2 : "Deleted",
  3 : "Updated",
  4 : "Renamed from something",
  5 : "Renamed to something"
}
# Thanks to Claudio Grondi for the correct set of numbers
FILE_LIST_DIRECTORY = 0x0001

path_to_watch = "."
hDir = win32file.CreateFile (
  path_to_watch,
  FILE_LIST_DIRECTORY,
  win32con.FILE_SHARE_READ | win32con.FILE_SHARE_WRITE | win32con.FILE_SHARE_DELETE,
  None,
  win32con.OPEN_EXISTING,
  win32con.FILE_FLAG_BACKUP_SEMANTICS,
  None
)
while 1:
  #
  # ReadDirectoryChangesW takes a previously-created
  # handle to a directory, a buffer size for results,
  # a flag to indicate whether to watch subtrees and
  # a filter of what changes to notify.
  #
  # NB Tim Juchcinski reports that he needed to up
  # the buffer size to be sure of picking up all
  # events when a large number of files were
  # deleted at once.
  #
  results = win32file.ReadDirectoryChangesW (
    hDir,
    1024,
    True,
    win32con.FILE_NOTIFY_CHANGE_FILE_NAME |
     win32con.FILE_NOTIFY_CHANGE_DIR_NAME |
     win32con.FILE_NOTIFY_CHANGE_ATTRIBUTES |
     win32con.FILE_NOTIFY_CHANGE_SIZE |
     win32con.FILE_NOTIFY_CHANGE_LAST_WRITE |
     win32con.FILE_NOTIFY_CHANGE_SECURITY,
    None,
    None
  )
  for action, file in results:
    full_filename = os.path.join (path_to_watch, file)
    print full_filename, ACTIONS.get (action, "Unknown")

通过一些编辑，这可以很容易地实现你想要的，因为利用了 winApi，它可能不太容易出错。

谢谢蒂姆·戈登。

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