python排序出现的问题以及解决方案

对某个文件夹中的文件重命名的时候，发现有些文件丢失，代码如下：

#coding=gbk  
  
# Findthe every dir, if 01.rm exist in it, then rename it.  
#!/usr/bin/python  
  
''''' 
Utilitiesof file & directories. 
'''  
  
import os 
import re
import string
import time
  
# Get theall files & directories in the specified directory (path).  
def get_recursive_file_list(path):  
    current_files = os.listdir(path)  
    all_files = []  
    for file_name in current_files:  
        full_file_name = os.path.join(path,file_name)  
        all_files.append(full_file_name)  
  
        if os.path.isdir(full_file_name):  
            next_level_files =get_recursive_file_list(full_file_name)  
            all_files.extend(next_level_files)  
  
    return all_files 

def need_rename(filename):  
    if not os.path.isfile(filename):  
        return False  
      
    base_filename = os.path.basename(filename)  
    pattern = re.compile("^[d]{1,3}.jpeg$")  
    if pattern.match(base_filename):  
        #print base_filename  
        return True  
    else:
        print "no"
        return False  
  
def rename(filename):  
    old_filename = filename  
      
    base_filename = os.path.basename(filename)  
    dir_name = os.path.dirname(filename)  
    #print "%s ----------- %s" % (dir_name, base_filename)  
      
    #story_name = os.path.basename(dir_name)  
    #print "story name: ", story_name  
      
    #new_filename = os.path.join(dir_name, story_name[3:] + " " + base_filename)
    AllName = filename.split('/')[-1] 
    digit = AllName.split('.')[0]
    newDigit = string.atoi(digit)-4

    new_filename = dir_name + "/" +str(newDigit)+".jpeg"
    #os.rename(old_filename, new_filename)
    #os.system("mv "+old_filename +" "+ new_filename) 
    time.sleep(3)
    print "%s ==> %s" % (old_filename, new_filename)  
def numeric_compare(x, y):
    xAllName = x.split('/')[-1] 
    xdigit = xAllName.split('.')[0]
    yAllName = y.split('/')[-1] 
    ydigit = yAllName.split('.')[0]
    return string.atoi(xdigit) - string.atoi(ydigit)      
top_dir = "/mnt/tishare/web/pdf/1125"  
all_files = get_recursive_file_list(top_dir)
flag=True
print(sorted(all_files))
#print(sorted(all_files, cmp=numeric_compare))
for file in all_files: 
    if flag:  
        os.chdir(top_dir)  
        flag=False 
    if not need_rename(file):  
        continue  
    rename(file)  

出错的代码标红，打印出发现其列表为：

['/mnt/tishare/web/pdf/1125/10.jpeg', '/mnt/tishare/web/pdf/1125/11.jpeg', '/mnt/tishare/web/pdf/1125/12.jpeg',
'/mnt/tishare/web/pdf/1125/13.jpeg', '/mnt/tishare/web/pdf/1125/14.jpeg', '/mnt/tishare/web/pdf/1125/4.jpeg', 
'/mnt/tishare/web/pdf/1125/5.jpeg', '/mnt/tishare/web/pdf/1125/6.jpeg', '/mnt/tishare/web/pdf/1125/7.jpeg', 
'/mnt/tishare/web/pdf/1125/8.jpeg', '/mnt/tishare/web/pdf/1125/9.jpeg']

也就是说其排序有问题，先输出的/mnt/tishare/web/pdf/1125/10.jpeg，其修改为/mnt/tishare/web/pdf/1125/6.jpeg，发现其已经存在，然后造成/mnt/tishare/web/pdf/1125/6.jpeg文件丢失。自定义排序函数，在python2.x中cmp参数指定的函数用来进行元素间的比较。我们在其上自定义numeric_compare排序函数，并使用之，然后就不会出现问题了：

['/mnt/tishare/web/pdf/1125/4.jpeg', 
'/mnt/tishare/web/pdf/1125/5.jpeg', '/mnt/tishare/web/pdf/1125/6.jpeg', '/mnt/tishare/web/pdf/1125/7.jpeg', 
'/mnt/tishare/web/pdf/1125/8.jpeg', '/mnt/tishare/web/pdf/1125/9.jpeg','/mnt/tishare/web/pdf/1125/10.jpeg', 
'/mnt/tishare/web/pdf/1125/11.jpeg', '/mnt/tishare/web/pdf/1125/12.jpeg',
 '/mnt/tishare/web/pdf/1125/13.jpeg', '/mnt/tishare/web/pdf/1125/14.jpeg']

然后重命名文件就没有问题了。

参考：

http://www.jb51.net/article/57678.htm

http://blog.csdn.net/a_flying_bird/article/details/24116907