Python显示进度条的方法

本文实例讲述了python/' target='_blank'>python显示进度条的方法，是Python程序设计中非常实用的技巧。分享给大家供大家参考。具体方法如下：

首先，进度条和一般的print区别在哪里呢？

答案就是print会输出一个\n，也就是换行符，这样光标移动到了下一行行首，接着输出，之前已经通过stdout输出的东西依旧保留，而且保证我们在下面看到最新的输出结果。

进度条不然，我们必须再原地输出才能保证他是一个进度条，否则换行了怎么还叫进度条？

最简单的办法就是，再输出完毕后，把光标移动到行首，继续在那里输出更长的进度条即可实现，新的更长的进度条把旧的短覆盖，就形成了动画效果。

可以想到那个转义符了吧，那就是 \r。

转义符\r就可以把光标移动到行首而不换行，转义符\n就把光标移动到行首并且换行。

在python中，输出stdout(标准输出)可以使用sys.stdout.write
例如：

#!/usr/bin/env python# -*- coding=utf-8 -*-#Using GPL v2#Author: ihipop@gmail.com##2010-10-27 22:07"""Usage:Just A Template"""from __future__ import division import sys,timej = '#'if __name__ == '__main__':  for i in range(1,61):    j += '#'    sys.stdout.write(str(int((i/60)*100))+'% ||'+j+'->'+"\r")    sys.stdout.flush()    time.sleep(0.5)print

第二种思路是用转义符\b
转义符\b是退格键，也就是说把输出的光标往回退格子，这样就可以不用+=了，例如：

#!/usr/bin/env python# -*- coding=utf-8 -*-#Using GPL v2#Author: ihipop@gmail.com#2010-10-27 22:07"""Usage:Just A Template"""from __future__ import division import sys,timeif __name__ == '__main__':  for i in range(1,61):    sys.stdout.write('#'+'->'+"\b\b")    sys.stdout.flush()    time.sleep(0.5)print

光标回退2格，写个#再回退，再写，达到增长的目的了

不过写这么多似乎是废话，在耳边常常听到一句话：那就是不要重复造轮子。实际上python有丰富发lib帮你实现这个东西，你完全可以把心思放在逻辑开发上而不用注意这些小细节

下面要介绍的就是这个类“progressbar”(http://code.google.com/p/python-progressbar/)，使用easy_install可以方便的安装这个类库，其实就一个文件，拿过来放到文件同一个目录下面也直接可以import过来

如下图所示：

下面就是基本使用举例：

#!/usr/bin/env python# -*- coding=utf-8 -*-#Using GPL v2#Author: ihipop@gmail.com#2010-10-27 22:53"""Usage:Just A Template"""from __future__ import division import sys,timefrom progressbar import *total = 1000 #基本用法progress = ProgressBar()for i in progress(range(total)): time.sleep(0.01) pbar = ProgressBar().start()for i in range(1,1000):  pbar.update(int((i/(total-1))*100))  time.sleep(0.01)pbar.finish() #高级用法widgets = ['Progress: ', Percentage(), ' ', Bar(marker=RotatingMarker('>-=')),      ' ', ETA(), ' ', FileTransferSpeed()]pbar = ProgressBar(widgets=widgets, maxval=10000000).start()for i in range(1000000): # do something pbar.update(10*i+1) time.sleep(0.0001)pbar.finish()

官方示例:http://code.google.com/p/python-progressbar/source/browse/progressbar/examples.py

#coding:utf-8import sysimport timefrom progressbar import AnimatedMarker, Bar, BouncingBar, Counter, ETA, \  FileTransferSpeed, FormatLabel, Percentage, \  ProgressBar, ReverseBar, RotatingMarker, \  SimpleProgress, Timerexamples = []def example(fn):  try: name = 'Example %d' % int(fn.__name__[7:])  except: name = fn.__name__  def wrapped():    try:      sys.stdout.write('Running: %s\n' % name)      fn()      sys.stdout.write('\n')    except KeyboardInterrupt:      sys.stdout.write('\nSkipping example.\n\n')  examples.append(wrapped)  return wrapped@exampledef example0():  pbar = ProgressBar(widgets=[Percentage(), Bar()], maxval=300).start()  for i in range(300):    time.sleep(0.01)    pbar.update(i+1)  pbar.finish()@exampledef example1():  widgets = ['Test: ', Percentage(), ' ', Bar(marker=RotatingMarker()),        ' ', ETA(), ' ', FileTransferSpeed()]  pbar = ProgressBar(widgets=widgets, maxval=10000000).start()  for i in range(1000000):    # do something    pbar.update(10*i+1)  pbar.finish()@exampledef example2():  class CrazyFileTransferSpeed(FileTransferSpeed):    """It's bigger between 45 and 80 percent."""    def update(self, pbar):      if 45 < pbar.percentage() < 80:        return 'Bigger Now ' + FileTransferSpeed.update(self,pbar)      else:        return FileTransferSpeed.update(self,pbar)  widgets = [CrazyFileTransferSpeed(),' <<<', Bar(), '>>> ',        Percentage(),' ', ETA()]  pbar = ProgressBar(widgets=widgets, maxval=10000000)  # maybe do something  pbar.start()  for i in range(2000000):    # do something    pbar.update(5*i+1)  pbar.finish()@exampledef example3():  widgets = [Bar('>'), ' ', ETA(), ' ', ReverseBar('<')]  pbar = ProgressBar(widgets=widgets, maxval=10000000).start()  for i in range(1000000):    # do something    pbar.update(10*i+1)  pbar.finish()@exampledef example4():  widgets = ['Test: ', Percentage(), ' ',        Bar(marker='0',left='[',right=']'),        ' ', ETA(), ' ', FileTransferSpeed()]  pbar = ProgressBar(widgets=widgets, maxval=500)  pbar.start()  for i in range(100,500+1,50):    time.sleep(0.2)    pbar.update(i)  pbar.finish()@exampledef example5():  pbar = ProgressBar(widgets=[SimpleProgress()], maxval=17).start()  for i in range(17):    time.sleep(0.2)    pbar.update(i + 1)  pbar.finish()@exampledef example6():  pbar = ProgressBar().start()  for i in range(100):    time.sleep(0.01)    pbar.update(i + 1)  pbar.finish()@exampledef example7():  pbar = ProgressBar() # Progressbar can guess maxval automatically.  for i in pbar(range(80)):    time.sleep(0.01)@exampledef example8():  pbar = ProgressBar(maxval=80) # Progressbar can't guess maxval.  for i in pbar((i for i in range(80))):    time.sleep(0.01)@exampledef example9():  pbar = ProgressBar(widgets=['Working: ', AnimatedMarker()])  for i in pbar((i for i in range(50))):    time.sleep(.08)@exampledef example10():  widgets = ['Processed: ', Counter(), ' lines (', Timer(), ')']  pbar = ProgressBar(widgets=widgets)  for i in pbar((i for i in range(150))):    time.sleep(0.1)@exampledef example11():  widgets = [FormatLabel('Processed: %(value)d lines (in: %(elapsed)s)')]  pbar = ProgressBar(widgets=widgets)  for i in pbar((i for i in range(150))):    time.sleep(0.1)@exampledef example12():  widgets = ['Balloon: ', AnimatedMarker(markers='.oO@* ')]  pbar = ProgressBar(widgets=widgets)  for i in pbar((i for i in range(24))):    time.sleep(0.3)@exampledef example13():  # You may need python 3.x to see this correctly  try:    widgets = ['Arrows: ', AnimatedMarker(markers='←↖↑↗→↘↓↙')]    pbar = ProgressBar(widgets=widgets)    for i in pbar((i for i in range(24))):      time.sleep(0.3)  except UnicodeError: sys.stdout.write('Unicode error: skipping example')@exampledef example14():  # You may need python 3.x to see this correctly  try:    widgets = ['Arrows: ', AnimatedMarker(markers='◢◣◤◥')]    pbar = ProgressBar(widgets=widgets)    for i in pbar((i for i in range(24))):      time.sleep(0.3)  except UnicodeError: sys.stdout.write('Unicode error: skipping example')@exampledef example15():  # You may need python 3.x to see this correctly  try:    widgets = ['Wheels: ', AnimatedMarker(markers='◐◓◑◒')]    pbar = ProgressBar(widgets=widgets)    for i in pbar((i for i in range(24))):      time.sleep(0.3)  except UnicodeError: sys.stdout.write('Unicode error: skipping example')@exampledef example16():  widgets = [FormatLabel('Bouncer: value %(value)d - '), BouncingBar()]  pbar = ProgressBar(widgets=widgets)  for i in pbar((i for i in range(180))):    time.sleep(0.05)@exampledef example17():  widgets = [FormatLabel('Animated Bouncer: value %(value)d - '),        BouncingBar(marker=RotatingMarker())]  pbar = ProgressBar(widgets=widgets)  for i in pbar((i for i in range(180))):    time.sleep(0.05)@exampledef example18():  widgets = [Percentage(),        ' ', Bar(),        ' ', ETA(),        ' ', AdaptiveETA()]  pbar = ProgressBar(widgets=widgets, maxval=500)  pbar.start()  for i in range(500):    time.sleep(0.01 + (i < 100) * 0.01 + (i > 400) * 0.9)    pbar.update(i + 1)  pbar.finish()@exampledef example19(): pbar = ProgressBar() for i in pbar([]):  pass pbar.finish()try:  for example in examples:    example()except KeyboardInterrupt:  sys.stdout('\nQuitting examples.\n')Progress Bar 使用例子

再发一个类：

#!/usr/bin/env python# -*- coding=utf-8 -*-#Using GPL v2#Author: ihipop@gmail.com#2010-10-30 13:59"""Usage:Just A Template"""class progressbarClass:   def __init__(self, finalcount, progresschar=None):    import sys    self.finalcount=finalcount    self.blockcount=0    #    # See if caller passed me a character to use on the    # progress bar (like "*"). If not use the block    # character that makes it look like a real progress    # bar.    #    if not progresschar: self.block=chr(178)    else:        self.block=progresschar    #    # Get pointer to sys.stdout so I can use the write/flush    # methods to display the progress bar.    #    self.f=sys.stdout    #    # If the final count is zero, don't start the progress gauge    #    if not self.finalcount : return    self.f.write('\n------------------- % Progress -------------------\n')    return   def progress(self, count):    #    # Make sure I don't try to go off the end (e.g. >100%)    #    count=min(count, self.finalcount)    #    # If finalcount is zero, I'm done    #    if self.finalcount:      percentcomplete=int(round(100*count/self.finalcount))      if percentcomplete < 1: percentcomplete=1    else:      percentcomplete=100          #print "percentcomplete=",percentcomplete    blockcount=int(percentcomplete/2)    #print "blockcount=",blockcount    if blockcount > self.blockcount:      for i in range(self.blockcount,blockcount):        self.f.write(self.block)        self.f.flush()            if percentcomplete == 100: self.f.write("\n")    self.blockcount=blockcount    return  if __name__ == "__main__":  from time import sleep  pb=progressbarClass(8,"*")  count=0  while count<9:    count+=1    pb.progress(count)    sleep(0.2)

另外，python cookbook中11.1节也提供了一个不错的进度条类，代码如下：

import sysclass progressbar(object):  def __init__(self, finalcount, block_char='.'):    self.finalcount = finalcount    self.blockcount = 0    self.block = block_char    self.f = sys.stdout    if not self.finalcount: return    self.f.write('\n------------------ % Progress -------------------1\n')    self.f.write('  1  2  3  4  5  6  7  8  9  0\n')    self.f.write('----0----0----0----0----0----0----0----0----0----0\n')  def progress(self, count):    count = min(count, self.finalcount)    if self.finalcount:      percentcomplete = int(round(100.0*count/self.finalcount))      if percentcomplete < 1: percentcomplete = 1    else:      percentcomplete=100    blockcount = int(percentcomplete//2)    if blockcount <= self.blockcount:      return    for i in range(self.blockcount, blockcount):      self.f.write(self.block)    self.f.flush()    self.blockcount = blockcount    if percentcomplete == 100:      self.f.write("\n")if __name__ == "__main__":  from time import sleep  pb = progressbar(8, "*")  for count in range(1, 9):    pb.progress(count)    sleep(0.2)  pb = progressbar(100)  pb.progress(20)  sleep(0.3)  pb.progress(47)  sleep(0.3)  pb.progress(90)  sleep(0.3)  pb.progress(100)  print "testing 1:"  pb = progressbar(1)  pb.progress(1)

运行结果如下图所示：

希望本文所述对大家Python程序设计的学习有所帮助。