python文件排序的方法总结

在python环境中提供两种排序方案：用库函数sorted()对字符串排序，它的对象是字符；用函数sort()对数字排序，它的对象是数字，如果读取文件的话，需要进行处理（把文件后缀名‘屏蔽'）。

（1）首先：我测试的文件夹是/img/，里面的文件都是图片，如下图所示：

（2）测试库函数sorted()，直接贴出代码：

import numpy as np
import os
 
img_path='./img/'
 
img_list=sorted(os.listdir(img_path))#文件名按字母排序
img_nums=len(img_list)
for i in range(img_nums):
    img_name=img_path+img_list[i]
    print(img_name)

运行效果如下：

从图片可以清晰的看出，文件名是按字符排序的。

（3）测试函数sort()，代码：

import numpy as np
import os
img_path='./img/'
 
img_list=os.listdir(img_path)
img_list.sort()
img_list.sort(key = lambda x: int(x[:-4])) ##文件名按数字排序
img_nums=len(img_list)
for i in range(img_nums):
    img_name=img_path+img_list[i]
    print(img_name)

运行效果如下：

可以看出，文件名是按数字排序的；顺便提下，sort函数中用到了匿名函数(key = lambda x:int(x[:-4]))，其作用是将后缀名'.jpg'“屏蔽”（因为‘.jpg'是4个字符，所以[:-4]的含义是从文件名开始到倒数第四个字符为止），具体看python的匿名函数和数组取值方式。

实例扩展：

import gzip
import os
from multiprocessing import Process, Queue, Pipe, current_process, freeze_support
from datetime import datetime
def sort_worker(input,output):
 while True:
 lines = input.get().splitlines()
 element_set = {}
 for line in lines:
  if line.strip() == 'STOP':
   return
  try:
   element = line.split(' ')[0]
   if not element_set.get(element): element_set[element] = ''
  except:
   pass
 sorted_element = sorted(element_set)
 #print sorted_element
 output.put('\n'.join(sorted_element))
def write_worker(input, pre):
 os.system('mkdir %s'%pre)
 i = 0
 while True:
  content = input.get()
  if content.strip() == 'STOP':
   return
  write_sorted_bulk(content, '%s/%s'%(pre, i))
  i += 1
def write_sorted_bulk(content, filename):
 f = file(filename, 'w')
 f.write(content)
 f.close()
def split_sort_file(filename, num_sort = 3, buf_size = 65536*64*4):
 t = datetime.now()
 pre, ext = os.path.splitext(filename)
 if ext == '.gz':
  file_file = gzip.open(filename, 'rb')
 else:
  file_file = open(filename)
 bulk_queue = Queue(10)
 sorted_queue = Queue(10)
 NUM_SORT = num_sort
 sort_worker_pool = []
 for i in range(NUM_SORT):
  sort_worker_pool.append( Process(target=sort_worker, args=(bulk_queue, sorted_queue)) )
  sort_worker_pool[i].start()
 NUM_WRITE = 1
 write_worker_pool = []
 for i in range(NUM_WRITE):
  write_worker_pool.append( Process(target=write_worker, args=(sorted_queue, pre)) )
  write_worker_pool[i].start()
 buf = file_file.read(buf_size)
 sorted_count = 0
 while len(buf):
  end_line = buf.rfind('\n')
  #print buf[:end_line+1]
  bulk_queue.put(buf[:end_line+1])
  sorted_count += 1
  if end_line != -1:
   buf = buf[end_line+1:] + file_file.read(buf_size)
  else:
   buf = file_file.read(buf_size)
 for i in range(NUM_SORT):
  bulk_queue.put('STOP')
 for i in range(NUM_SORT):
  sort_worker_pool[i].join()
  
 for i in range(NUM_WRITE):
  sorted_queue.put('STOP')
 for i in range(NUM_WRITE):
  write_worker_pool[i].join()
 print 'elasped ', datetime.now() - t
 return sorted_count
from heapq import heappush, heappop
from datetime import datetime
from multiprocessing import Process, Queue, Pipe, current_process, freeze_support
import os
class file_heap:
 def __init__(self, dir, idx = 0, count = 1):
  files = os.listdir(dir)
  self.heap = []
  self.files = {}
  self.bulks = {}
  self.pre_element = None
  for i in range(len(files)):
   file = files[i]
   if hash(file) % count != idx: continue
   input = open(os.path.join(dir, file))
   self.files[i] = input
   self.bulks[i] = ''
   heappush(self.heap, (self.get_next_element_buffered(i), i))
 def get_next_element_buffered(self, i):
  if len(self.bulks[i]) < 256:
   if self.files[i] is not None:
    buf = self.files[i].read(65536)
    if buf:
     self.bulks[i] += buf
    else:
     self.files[i].close()
     self.files[i] = None
  end_line = self.bulks[i].find('\n')
  if end_line == -1:
   end_line = len(self.bulks[i])
  element = self.bulks[i][:end_line]
  self.bulks[i] = self.bulks[i][end_line+1:]
  return element
 def poppush_uniq(self):
  while True:
   element = self.poppush()
   if element is None:
    return None
   if element != self.pre_element:
    self.pre_element = element
    return element
 def poppush(self):
  try:
   element, index = heappop(self.heap)
  except IndexError:
   return None
  new_element = self.get_next_element_buffered(index)
  if new_element:
   heappush(self.heap, (new_element, index))
  return element
def heappoppush(dir, queue, idx = 0, count = 1):
 heap = file_heap(dir, idx, count)
 while True:
  d = heap.poppush_uniq()
  queue.put(d)
  if d is None: return
def heappoppush2(dir, queue, count = 1):
 heap = []
 procs = []
 queues = []
 pre_element = None
 for i in range(count):
  q = Queue(1024)
  q_buf = queue_buffer(q)
  queues.append(q_buf)
  p = Process(target=heappoppush, args=(dir, q_buf, i, count))
  procs.append(p)
  p.start()
 queues = tuple(queues)
 for i in range(count):
  heappush(heap, (queues[i].get(), i))
 while True:
  try:
   d, i= heappop(heap)
  except IndexError:
   queue.put(None)
   for p in procs:
    p.join()
   return
  else:
   if d is not None:
    heappush(heap,(queues[i].get(), i))
    if d != pre_element:
     pre_element = d
     queue.put(d)
def merge_file(dir):
 heap = file_heap( dir )
 os.system('rm -f '+dir+'.merge')
 fmerge = open(dir+'.merge', 'a')
 element = heap.poppush_uniq()
 fmerge.write(element+'\n')
 while element is not None:
  element = heap.poppush_uniq()
  fmerge.write(element+'\n')
class queue_buffer:
 def __init__(self, queue):
  self.q = queue
  self.rbuf = []
  self.wbuf = []
 def get(self):
  if len(self.rbuf) == 0:
   self.rbuf = self.q.get()
  r = self.rbuf[0]
  del self.rbuf[0]
  return r
 def put(self, d):
  self.wbuf.append(d)
  if d is None or len(self.wbuf) > 1024:
   self.q.put(self.wbuf)
   self.wbuf = []
def diff_file(file_old, file_new, file_diff, buf = 268435456):
 print 'buffer size', buf
 from file_split import split_sort_file
 os.system('rm -rf '+ os.path.splitext(file_old)[0] )
 os.system('rm -rf '+ os.path.splitext(file_new)[0] )
 t = datetime.now()
 split_sort_file(file_old,5,buf)
 split_sort_file(file_new,5,buf)
 print 'split elasped ', datetime.now() - t
 os.system('cat %s/* | wc -l'%os.path.splitext(file_old)[0])
 os.system('cat %s/* | wc -l'%os.path.splitext(file_new)[0])
 os.system('rm -f '+file_diff)
 t = datetime.now()
 zdiff = open(file_diff, 'a')
 old_q = Queue(1024)
 new_q = Queue(1024)
 old_queue = queue_buffer(old_q)
 new_queue = queue_buffer(new_q)
 h1 = Process(target=heappoppush2, args=(os.path.splitext(file_old)[0], old_queue, 3))
 h2 = Process(target=heappoppush2, args=(os.path.splitext(file_new)[0], new_queue, 3))
 h1.start(), h2.start()
 old = old_queue.get()
 new = new_queue.get()
 old_count, new_count = 0, 0
 while old is not None or new is not None:
  if old > new or old is None:
   zdiff.write('< '+new+'\n')
   new = new_queue.get()
   new_count +=1
  elif old < new or new is None:
   zdiff.write('> '+old+'\n')
   old = old_queue.get()
   old_count +=1
  else:
   old = old_queue.get()
   new = new_queue.get()
 print 'new_count:', new_count
 print 'old_count:', old_count
 print 'diff elasped ', datetime.now() - t
 h1.join(), h2.join()

到此这篇关于python文件排序的方法总结的文章就介绍到这了,更多相关python文件排序都有哪些方法内容请搜索三水点靠木以前的文章或继续浏览下面的相关文章希望大家以后多多支持三水点靠木！