Python文件操作

Question

假设我有这样的文件夹

  rootfolder
      | 
     / \ \
    01 02 03 ....
    |
  13_itemname.xml

所以在我的rootfolder下,每个目录代表一个月,如01 02 03,在这些目录下我有他们的创建小时和项目名称的项目,如16_item1.xml,24_item1.xml等,你可能会猜到有几个项目和每个xml每小时创造一次.

现在我想做两件事:

• 我需要生成一个月的项目名称列表,即对于01,我有item1,item2和item3.

• 我需要过滤每个项目,例如item1:我想从01_item1.xml到24_item1.xml中读取每个项目.

我怎样才能以简单的方式在Python中实现这些目标？

Answer 1

这里有两种方法可以满足您的要求(如果我理解的话).一个有正则表达式,一个没有.你选择你喜欢哪一个;)

可能看起来像魔术的一点是"setdefault"线.有关说明,请参阅文档.我把它作为"读者的练习"来理解它是如何工作的;)

from os import listdir
from os.path import join

DATA_ROOT = "testdata"

def folder_items_no_regex(month_name):

   # dict holding the items (assuming ordering is irrelevant)
   items = {}

   # 1. Loop through all filenames in said folder
   for file in listdir( join( DATA_ROOT, month_name ) ):
      date, name = file.split( "_", 1 )

      # skip files that were not possible to split on "_"
      if not date or not name:
         continue

      # ignore non-.xml files
      if not name.endswith(".xml"):
         continue

      # cut off the ".xml" extension
      name = name[0:-4]

      # keep a list of filenames
      items.setdefault( name, set() ).add( file )

   return items

def folder_items_regex(month_name):

   import re

   # The pattern:
   # 1. match the beginnning of line "^"
   # 2. capture 1 or more digits ( \d+ )
   # 3. match the "_"
   # 4. capture any character (as few as possible ): (.*?)
   # 5. match ".xml"
   # 6. match the end of line "$"
   pattern = re.compile( r"^(\d+)_(.*?)\.xml$" )

   # dict holding the items (assuming ordering is irrelevant)
   items = {}

   # 1. Loop through all filenames in said folder
   for file in listdir( join( DATA_ROOT, month_name ) ):

      match = pattern.match( file )
      if not match:
         continue

      date, name = match.groups()

      # keep a list of filenames
      items.setdefault( name, set() ).add( file )

   return items
if __name__ == "__main__":
   from pprint import pprint

   data = folder_items_no_regex( "02" )

   print "--- The dict ---------------"
   pprint( data )

   print "--- The items --------------"
   pprint( sorted( data.keys() ) )

   print "--- The files for item1 ---- "
   pprint( sorted( data["item1"] ) )


   data = folder_items_regex( "02" )

   print "--- The dict ---------------"
   pprint( data )

   print "--- The items --------------"
   pprint( sorted( data.keys() ) )

   print "--- The files for item1 ---- "
   pprint( sorted( data["item1"] ) )