迭代目录下文件时的FileNotFoundError

Question

import os
import pandas as pd

FILES = os.listdir("/CADEC/original")

for file in FILES:
    if file.startswith("ARTHROTEC."):
        print(file)

ARTHROTEC.1.ann
ARTHROTEC.10.ann
ARTHROTEC.100.ann
ARTHROTEC.101.ann
ARTHROTEC.102.ann
ARTHROTEC.103.ann
ARTHROTEC.104.ann
ARTHROTEC.105.ann
ARTHROTEC.106.ann
ARTHROTEC.107.ann
ARTHROTEC.108.ann
ARTHROTEC.109.ann
ARTHROTEC.11.ann
ARTHROTEC.110.ann
ARTHROTEC.111.ann
ARTHROTEC.112.ann
ARTHROTEC.113.ann
ARTHROTEC.114.ann
ARTHROTEC.115.ann
...

我想从一个目录下从某些字母开始的所有文件中提取数据。如上所示，当我遍历目录并打印每个符合的文件名时，我得到一列文件名（字符串）。同时，data=pd.read_csv（“/cadec/original/arthrotec.1.ann”,sep='\t',header=none)工作得非常好。但是，运行以下代码只会返回错误。为什么找不到文件？我该怎么做才能解决这个问题？

for file in FILES:
    if file.startswith("ARTHROTEC."):
        data = pd.read_csv(file, sep='\t', header=None)

FileNotFoundError: [Errno 2] File ARTHROTEC.1.ann does not exist: 'ARTHROTEC.1.ann'

Answer 1

• os.listdir只返回目录中的文件名，不返回路径，并且pandas需要文件的路径（或相对路径），除非该文件与代码在同一目录中。
• 学习pathlib模块会更好，该模块将路径视为带有方法的对象，而不是字符串。
  • .glob-生成与模式匹配的对象的生成器
  • Python 3的pathlib模块：驯服文件系统

  import pandas as pd
  from pathlib import Path
  
  # create the path object and get the files with .glob
  files = Path('/CADEC/original').glob('ARTHROTEC*.ann')
  
  # create a list of dataframes, 1 dataframe for each file
  df_list = [pd.read_csv(file, sep='\t', header=None) for file in files]
  
  # alternatively, create a dict of dataframes with the filename as the key
  df_dict = {file.stem: pd.read_csv(file, sep='\t', header=None) for file in files}
  

  Python 3.8.5 (default, Sep  3 2020, 21:29:08) [MSC v.1916 64 bit (AMD64)] on win32
  import os
    ...: from pathlib import Path
    ...: os.listdir('e:/PythonProjects/stack_overflow/t-files')
  Out[2]: 
  ['.ipynb_checkpoints',
   '03900169.txt',
   '142233.0.txt',
   '153431.2.txt',
   '17371271.txt',
   '274301.5.txt',
   '42010316.txt',
   '429237.7.txt',
   '570651.4.txt',
   '65500027.txt',
   '688599.3.txt',
   '740103.5.txt',
   '742537.6.txt',
   '87505504.txt',
   '90950222.txt',
   't1.txt',
   't2.txt',
   't3.txt']
  
  list(Path('e:/PythonProjects/stack_overflow/t-files').glob('*'))
  Out[3]: 
  [WindowsPath('e:/PythonProjects/stack_overflow/t-files/.ipynb_checkpoints'),
   WindowsPath('e:/PythonProjects/stack_overflow/t-files/03900169.txt'),
   WindowsPath('e:/PythonProjects/stack_overflow/t-files/142233.0.txt'),
   WindowsPath('e:/PythonProjects/stack_overflow/t-files/153431.2.txt'),
   WindowsPath('e:/PythonProjects/stack_overflow/t-files/17371271.txt'),
   WindowsPath('e:/PythonProjects/stack_overflow/t-files/274301.5.txt'),
   WindowsPath('e:/PythonProjects/stack_overflow/t-files/42010316.txt'),
   WindowsPath('e:/PythonProjects/stack_overflow/t-files/429237.7.txt'),
   WindowsPath('e:/PythonProjects/stack_overflow/t-files/570651.4.txt'),
   WindowsPath('e:/PythonProjects/stack_overflow/t-files/65500027.txt'),
   WindowsPath('e:/PythonProjects/stack_overflow/t-files/688599.3.txt'),
   WindowsPath('e:/PythonProjects/stack_overflow/t-files/740103.5.txt'),
   WindowsPath('e:/PythonProjects/stack_overflow/t-files/742537.6.txt'),
   WindowsPath('e:/PythonProjects/stack_overflow/t-files/87505504.txt'),
   WindowsPath('e:/PythonProjects/stack_overflow/t-files/90950222.txt'),
   WindowsPath('e:/PythonProjects/stack_overflow/t-files/t1.txt'),
   WindowsPath('e:/PythonProjects/stack_overflow/t-files/t2.txt'),
   WindowsPath('e:/PythonProjects/stack_overflow/t-files/t3.txt')]