python os.walk达到一定水平 [英] python os.walk to certain level

问题描述

我想构建一个使用一些基本代码来通读文件夹的程序，并告诉我该文件夹中有多少个文件. 目前，这是我的操作方式:

I want to build a program that uses some basic code to read through a folder and tell me how many files are in the folder. Here is how I do that currently:

import os

folders = ['Y:\\path1', 'Y:\\path2', 'Y:\\path3']
for stuff in folders:
    for root, dirs, files in os.walk(stuff, topdown=True):
        print("there are", len(files), "files in", root)

这很好用，直到主"文件夹中有多个文件夹，因为由于不良的文件夹/文件管理，它可能会返回很长的，混乱的文件列表.因此，我最多只想转到第二级.例如:

This works great until there are multiple folders inside the "main" folder as it can return a long, junky list of files due to poor folder/file management. So I would like to go only to the second level at most. example:

Main Folder
---file_i_want
---file_i_want
---Sub_Folder
------file_i_want <--*
------file_i want <--*
------Sub_Folder_2
---------file_i_dont_want
---------file_i_dont_want

我知道如何仅使用break和del dirs[:]从这篇文章和也是这篇文章.

I know how to go to only the first level with a break and with del dirs[:] taken from this post and also this post.

import os
import pandas as pd

folders = ['Y:\\path1', 'Y:\\path2', 'Y:\\path3']
for stuff in folders:
    for root, dirs, files in os.walk(stuff, topdown=True):
        print("there are", len(files), "files in", root)
        del dirs[:] # or a break here. does the same thing.

但是无论我进行何种搜索，我都无法找到如何深入两层的方法.我可能只是不了解它的其他内容或其他内容?我在想类似del dirs[:2]的方法，但无济于事.有人可以指导我或向我解释如何实现这一目标吗?

But no matter my searching I can't find out how to go two layers deep. I may just not be understanding the other posts on it or something? I was thinking something like del dirs[:2] but to no avail. Can someone guide me or explain to mehow to accomplish this?

推荐答案

您可以这样做:

depth = 2

# [1] abspath() already acts as normpath() to remove trailing os.sep
#, and we need ensures trailing os.sep not exists to make slicing accurate. 
# [2] abspath() also make /../ and ////, "." get resolved even though os.walk can returns it literally.
# [3] expanduser() expands ~
# [4] expandvars() expands $HOME
stuff = os.path.abspath(os.path.expanduser(os.path.expandvars(stuff)))

for root,dirs,files in os.walk(stuff):
    if root[len(stuff):].count(os.sep) < depth:
        for f in files:
            print(os.path.join(root,f))

键是:if root[len(stuff):].count(os.sep) < depth

它从root中删除了stuff，因此结果是相对于stuff的.只需计算文件分隔符的数量即可.

It removes stuff from root, so result is relative to stuff. Just count the number of files separators.

深度操作类似于Linux中的find命令，即-maxdepth 0表示什么都不做，-maxdepth 1仅扫描第一级的文件，并且-maxdepth 2扫描包含在子目录中的文件.

The depth acts like find command found in Linux, i.e. -maxdepth 0 means do nothing, -maxdepth 1 only scan files in first level, and -maxdepth 2 scan files included sub-directory.

当然，它仍然会扫描整个文件结构，但是除非它很深，否则它将起作用.

Of course, it still scans the full file structure, but unless it's very deep that'll work.

另一种解决方案是仅递归地使用os.listdir(带有目录检查)，并具有最大的递归级别，但是如果您不需要它，则会有些棘手.由于不那么困难，因此这里是一个实现:

Another solution would be to only use os.listdir recursively (with directory check) with a maximum recursion level, but that's a little trickier if you don't need it. Since it's not that hard, here's one implementation:

def scanrec(root):
    rval = []

    def do_scan(start_dir,output,depth=0):
        for f in os.listdir(start_dir):
            ff = os.path.join(start_dir,f)
            if os.path.isdir(ff):
                if depth<2:
                    do_scan(ff,output,depth+1)
            else:
                output.append(ff)

    do_scan(root,rval,0)
    return rval

print(scanrec(stuff))  # prints the list of files not below 2 deep

注意:os.listdir和os.path.isfile执行2次stat调用，因此不是最佳选择.在Python 3.5中，使用os.scandir可以避免重复调用.

Note: os.listdir and os.path.isfile perform 2 stat calls so not optimal. In Python 3.5, the use of os.scandir could avoid that double call.

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