【Python】os.walk的使用及获取文件夹下所有文件的大小

在说os.walk前，我们先在ipython3中help一下，打印如下

Help on function walk in module os:

walk(top, topdown=True, onerror=None, followlinks=False)
    Directory tree generator.
    
    For each directory in the directory tree rooted at top (including top
    itself, but excluding '.' and '..'), yields a 3-tuple，dirpath, dirnames, filenames
    
    dirpath is a string, the path to the directory.  dirnames is a list of
    the names of the subdirectories in dirpath (excluding '.' and '..').
    filenames is a list of the names of the non-directory files in dirpath.
    Note that the names in the lists are just names, with no path components.
    To get a full path (which begins with top) to a file or directory in
    dirpath, do os.path.join(dirpath, name).
    
    If optional arg 'topdown' is true or not specified, the triple for a
    directory is generated before the triples for any of its subdirectories
    (directories are generated top down).  If topdown is false, the triple
    for a directory is generated after the triples for all of its
    subdirectories (directories are generated bottom up).

函数声明如下
os.walk(top, topdown=True, onerror=None, followlinks=False)

os.walk返回一个生成器，每次遍历返回的对象是一个元组，元组中包含三个元素：
dirpath:当前遍历的文件夹的路径，类型为字符串；
dirname:当前遍历的文件夹下的子文件夹的名字，类型为列表；
filenames:当前遍历的文件夹下的文件的名字，类型为列表；

参数说明：
top:需要遍历的目录
topdown:topdown为True则优先遍历顶层目录，topdown为False则优先遍历子目录
onerror:异常时的回调
followlinks:followlinks如果为真，则会遍历目录下的快捷方式实际所指的目录(默认关闭)

创建一个包含子文件夹和文件的walk文件夹，通过终端tree看一下目录结构：

walk
├── test1
│   ├── test1_1
│   │   ├── test1_1_1
│   │   └── test1_1_a.py
│   ├── test1_2
│   │   └── test1_2_1
│   ├── test1_3
│   ├── test1_a.py
│   └── test1_b.py
├── test2
│   ├── test2_1
│   └── test2_a.py
├── test3
└── test.py

我们通过for循环遍历os.walk()的返回结果

import os
for root, dirs, files in os.walk("/home/python/walk",True):
    print("root:%s"%root)
    print("dirs:%s"%dirs)
    print("files:%s"%files)
    print("-------------------------------")

运行结果如下：

root:/home/python/walk
dirs:['test2', 'test1', 'test3']
files:['test.py']
-------------------------------
root:/home/python/walk/test2
dirs:['test2_1']
files:['test2_a.py']
-------------------------------
root:/home/python/walk/test2/test2_1
dirs:[]
files:[]
-------------------------------
root:/home/python/walk/test1
dirs:['test1_2', 'test1_3', 'test1_1']
files:['test1_a.py', 'test1_b.py']
-------------------------------
root:/home/python/walk/test1/test1_2
dirs:['test1_2_1']
files:[]
-------------------------------
root:/home/python/walk/test1/test1_2/test1_2_1
dirs:[]
files:[]
-------------------------------
root:/home/python/walk/test1/test1_3
dirs:[]
files:[]
-------------------------------
root:/home/python/walk/test1/test1_1
dirs:['test1_1_1']
files:['test1_1_a.py']
-------------------------------
root:/home/python/walk/test1/test1_1/test1_1_1
dirs:[]
files:[]
-------------------------------
root:/home/python/walk/test3
dirs:[]
files:[]
-------------------------------

*注意，如果你传入的需要遍历的路径是一个相对路径的话，那么返回的dirpath即root也将是相对路径

使用os.walk()获取文件夹下的文件大小：

import os
from os.path import join,getsize
def getdirsize(dir):
    size = 0 
    for root,dirs,files in os.walk(dir):
        size += sum([getsize(join(root,name))for name in files])
    return size