从 csv 文件中读取数据，同时注意文件夹的更改

Question

I have a code which keeps a watch on a folder for any alterations. It checks for newly added and removed files and promptly displays the name of the file when such cases happen. This is my code:

import os, time
import pandas as pd
import glob
path_to_watch = os.path.abspath('C:/Folder for violation csv/')
before = dict ([(f, None) for f in os.listdir (path_to_watch)])
while 1:
  time.sleep (2)
  after = dict ([(f, None) for f in os.listdir (path_to_watch)])
  added = [f for f in after if not f in before]
  removed = [f for f in before if not f in after]
  if added: print ("Added: ", ", ".join (added))
  if removed: print ("Removed: ", ", ".join (removed))
  before = after

Now I want to include one more thing in this code, I want to read the data in the file which is being added in the folder. I tried it by converting the dictionary into a DataFrame using from_dict and then using pandas to read the csv using read_csv but it doesn't seem to be working. This is my updated code:

import os, time
import pandas as pd
import glob
path_to_watch = os.path.abspath('C:/Folder for violation csv/')
before = dict ([(f, None) for f in os.listdir (path_to_watch)])
while 1:
  time.sleep (2)
  after = dict ([(f, None) for f in os.listdir (path_to_watch)])
  added = [f for f in after if not f in before]
  removed = [f for f in before if not f in after]
  if added: 
    print ("Added: ", ", ".join (added))
  df = pd.DataFrame.from_dict(path_to_watch, orient = 'index')
  df1 = pd.read_csv(df)
  if removed: print ("Removed: ", ", ".join (removed))
  before = after

If you could help me get the desired result, I'd greatly appreciate it.

Answer 1

• To begin with, it is better to use the pathlib package for accessing the file system.
• Use set to collect the file names.

from pathlib import Path

path_to_watch = Path('C:/Folder for violation csv/')
before = set(path_to_watch.glob('**/*'))
while 1:
  time.sleep (2)
  after = set(path_to_watch.glob('**/*')
  added = after - before
  removed = before - after
  for f in added:
     df = pd.read_csv(f)
  before = after

Answer 2

try this,

import os, time
import pandas as pd
import glob
path_to_watch = os.path.abspath('C:/Folder for violation csv/')
before = dict ([(f, None) for f in os.listdir (path_to_watch)])
while 1:
  time.sleep (2)
  after = dict ([(f, None) for f in os.listdir (path_to_watch)])
  added = [f for f in after if not f in before]
  removed = [f for f in before if not f in after]
  if added: 
    print ("Added: ", ", ".join (added))
  for file_ in added:
    df = pd.read_csv(os.path.join(path_to_watch, file_))
  if removed: print ("Removed: ", ", ".join (removed))
  before = after