python之文件读取

python提供三种扫描当前路径的方法：os.listdir, os.scandir和pathlib

Function	Description
os.listdir()	Returns a list of all files and folders in a directory
os.scandir()	Returns an iterator of all the objects in a directory including file attribute information
pathlib.Path.iterdir()	Returns an iterator of all the objects in a directory including file attribute information

以上三种方法都可以列出当前目录中的所有文件和子路径，但如果当我们需要个性化过滤的时候，就需要到以下操作：

1）仅列出所有文件：

import os

# List all files in a directory using os.listdir
basepath = 'my_directory/'
for entry in os.listdir(basepath):
    if os.path.isfile(os.path.join(basepath, entry)):
        print(entry)

import os

# List all files in a directory using scandir()
basepath = 'my_directory/'
with os.scandir(basepath) as entries:
    for entry in entries:
        if entry.is_file():
            print(entry.name)

from pathlib import Path

basepath = Path('my_directory/')
files_in_basepath = basepath.iterdir()
for item in files_in_basepath:
    if item.is_file():
        print(item.name)

2）仅列出所有子路径

import os

# List all subdirectories using os.listdir
basepath = 'my_directory/'
for entry in os.listdir(basepath):
    if os.path.isdir(os.path.join(basepath, entry)):
        print(entry)


# List all subdirectories using scandir()
basepath = 'my_directory/'
with os.scandir(basepath) as entries:
    for entry in entries:
        if entry.is_dir():
            print(entry.name)


# List all subdirectory using pathlib
basepath = Path('my_directory/')
for entry in basepath.iterdir():
    if entry.is_dir():
        print(entry.name)

3）匹配特定类型文件，如txt

>>> for filename in os.listdir('.'):
...     if fnmatch.fnmatch(filename, 'data_*_backup.txt'):
...         print(filename)

python还提供了从linux到windows的兼容路径查找工具glob，利用glob和Unix系统中“*”，“?"的特殊语法，可以做到递归查找特定类型文件

>>> import glob
>>> for file in glob.iglob('**/*.py', recursive=True):
...     print(file)

pathlib也有类似Unix的操作

>>> from pathlib import Path
>>> p = Path('.')
>>> for name in p.glob('*.p*'):
...     print(name)

其他更多高级操作见参考资料[1]

参考资料：

[1]Working With Files in Python

https://realpython.com/working-with-files-in-python/