Python 3.x Study Notes 8 (OS module and xml modification), python3.x

Python 3.x Study Notes 8 (OS module and xml modification), python3.x

1. OS module operations

OS. getcwd (): # view the current path.

OS. listdir (path): # lists all objects in the directory and returns the list type.

OS. path. abspath (path): # returns the absolute path of path.

OS. path. join (path1, path2,...): # combines paths. If there is an absolute path, the previous path will be deleted.

OS. path. dirname (path): # Return the folder section in path. The result does not contain '\'

OS. path. basename (path): # Return the file name in path.

OS. path. getmtime (path): # The last modification time of the file or folder, from the new era to the access time.

OS. path. getatime (path): # The last access time of the file or folder, from the new era to the access time in seconds.

OS. path. getctime (path): # the time when a file or folder is created, from the new era to the access time.

OS. path. getsize (path): # size of the file or folder. If it is a folder, 0 is returned.

OS. path. exists (path): # Check whether the file or folder exists. True or False is returned.

 

2. Use of xml

Xml Creation

From xml. etree import ElementTree as ETdef build_sitemap (): urlset = ET. element ("urlset") # ET. element creates a root node with the label urlset url = ET. subElement (urlset, "url") # ET. subElement creates the sub-node loc = ET under the root node urlset. subElement (url, "loc", attrib = {"name": "Baidu"}) # attrib creates the attribute loc. text = "http: // www/baidu.com" # loc. time = ET. subElement (url, "time") time. text = "8-8-1-30" change = ET. subElement (url, "change") change. text = "daily" priority = ET. subElement (url, "priority") priority. text = "1.0" tree = ET. elementTree (urlset) tree. write ("set. xml ", 'utf-8') # When writing, you can add 'utf-8' to translate Chinese characters, if _ name _ = '_ main _': build_sitemap ()

Generated xml

<Urlset> <url> <loc name = "Baidu"> http: // www/baidu.com </loc> <time> </time> <change> daily </change> <priority> 1.0 </priority> </url> </urlset>

The files to be modified are as follows:

<?xml version="1.0"?><data>    <country name="Liechtenstein">        <rank>1</rank>        <year>2008</year>        <gdppc>141100</gdppc>        <neighbor name="Austria" direction="E"/>        <neighbor name="Switzerland" direction="W"/>    </country>    <country name="Singapore">        <rank>4</rank>        <year>2011</year>        <gdppc>59900</gdppc>        <neighbor name="Malaysia" direction="N"/>    </country>    <country name="Panama">        <rank>68</rank>        <year>2011</year>        <gdppc>13600</gdppc>        <neighbor name="Costa Rica" direction="W"/>        <neighbor name="Colombia" direction="E"/>    </country></data>

Modify Program

Import xml. etree. elementTree as ETtree = ET. parse ('xmltest. xml ') root = tree. getroot () # modify for node in root. iter ('Year'): new_year = int (node. text) + 1 node. text = str (new_year) node. set ('updated _ by', 'hsj') tree. write ('xmltest2. xml ') # delete for country in root. findall ('country'): rank = int (country. find ('rank '). text) if rank> 50: root. remove (country) tree. write ('xmltest3. xml ')