創建一個CLI應用程序中的進度條

Question

當使用工具，如bzr，doxygen和scp或wget，我看到他們都有一個不錯的進度條，看上去像這樣：

|=============>---------| 55% ETA 3:30 

我試着寫東西就像我在C++中使用\b這個字符的次數一樣多，就像我之前寫過的東西一樣。輸出閃爍得很厲害，看起來沒有上述工具那麼流暢。

我怎樣才能順利地用Python創建這樣一個進度條（或至少改變顯示的ETA）？

Answer 1

使用「\ r」將光標發送到行首。每秒重複打印不超過2-3次，以避免閃爍。

Answer 2

，這可能是有用的例子：？如何在Python中的文件拷貝進度指示條]

http://code.google.com/p/corey-projects/source/browse/trunk/python2/progress_bar.py

import sys 
import time 


class ProgressBar: 
    def __init__(self, duration): 
     self.duration = duration 
     self.prog_bar = '[]' 
     self.fill_char = '#' 
     self.width = 40 
     self.__update_amount(0) 

    def animate(self): 
     for i in range(self.duration): 
      if sys.platform.lower().startswith('win'): 
       print self, '\r', 
      else: 
       print self, chr(27) + '[A' 
      self.update_time(i + 1) 
      time.sleep(1) 
     print self 

    def update_time(self, elapsed_secs): 
     self.__update_amount((elapsed_secs/float(self.duration)) * 100.0) 
     self.prog_bar += ' %ds/%ss' % (elapsed_secs, self.duration) 

    def __update_amount(self, new_amount): 
     percent_done = int(round((new_amount/100.0) * 100.0)) 
     all_full = self.width - 2 
     num_hashes = int(round((percent_done/100.0) * all_full)) 
     self.prog_bar = '[' + self.fill_char * num_hashes + ' ' * (all_full - num_hashes) + ']' 
     pct_place = (len(self.prog_bar)/2) - len(str(percent_done)) 
     pct_string = '%d%%' % percent_done 
     self.prog_bar = self.prog_bar[0:pct_place] + \ 
      (pct_string + self.prog_bar[pct_place + len(pct_string):]) 

    def __str__(self): 
     return str(self.prog_bar) 


if __name__ == '__main__': 
    """ example usage """ 

    # print a static progress bar 
    # [##########  25%     ] 15s/60s 

    p = ProgressBar(60) 
    p.update_time(15) 
    print 'static progress bar:' 
    print p 


    # print a static progress bar 
    # [=================83%============  ] 25s/30s 

    p = ProgressBar(30) 
    p.fill_char = '=' 
    p.update_time(25) 
    print 'static progress bar:' 
    print p 


    # print a dynamic updating progress bar on one line: 
    # 
    # [################100%##################] 10s/10s 
    # done 

    secs = 10 
    p = ProgressBar(secs) 
    print 'dynamic updating progress bar:' 
    print 'please wait %d seconds...' % secs 

    # spawn asych (threads/processes/etc) code here that runs for secs. 
    # the call to .animate() blocks the main thread. 

    p.animate() 

    print 'done' 

的