Python显示进度条的方法

本文实例讲述了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: [e-mail]
##2010-10-27 22:07
"""
Usage:
Just A Template
"""
from __future__ import division
 
import sys,time
j = '#'
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: [e-mail]
#2010-10-27 22:07
"""
Usage:
Just A Template
"""
from __future__ import division
 
import sys,time
if __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: [e-mail]
#2010-10-27 22:53
"""
Usage:
Just A Template
"""
from __future__ import division
 
import sys,time
from 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-8
import sys
import time
from progressbar import AnimatedMarker, Bar, BouncingBar, Counter, ETA, \
  FileTransferSpeed, FormatLabel, Percentage, \
  ProgressBar, ReverseBar, RotatingMarker, \
  SimpleProgress, Timer

examples = []
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

@example
def example0():
  pbar = ProgressBar(widgets=[Percentage(), Bar()], maxval=300).start()
  for i in range(300):
    time.sleep(0.01)
    pbar.update(i+1)
  pbar.finish()

@example
def 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()

@example
def 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()

@example
def 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()

@example
def 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()

@example
def example5():
  pbar = ProgressBar(widgets=[SimpleProgress()], maxval=17).start()
  for i in range(17):
    time.sleep(0.2)
    pbar.update(i + 1)
  pbar.finish()

@example
def example6():
  pbar = ProgressBar().start()
  for i in range(100):
    time.sleep(0.01)
    pbar.update(i + 1)
  pbar.finish()

@example
def example7():
  pbar = ProgressBar() # Progressbar can guess maxval automatically.
  for i in pbar(range(80)):
    time.sleep(0.01)

@example
def example8():
  pbar = ProgressBar(maxval=80) # Progressbar can't guess maxval.
  for i in pbar((i for i in range(80))):
    time.sleep(0.01)

@example
def example9():
  pbar = ProgressBar(widgets=['Working: ', AnimatedMarker()])
  for i in pbar((i for i in range(50))):
    time.sleep(.08)

@example
def example10():
  widgets = ['Processed: ', Counter(), ' lines (', Timer(), ')']
  pbar = ProgressBar(widgets=widgets)
  for i in pbar((i for i in range(150))):
    time.sleep(0.1)

@example
def 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)

@example
def example12():
  widgets = ['Balloon: ', AnimatedMarker(markers='.oO@* ')]
  pbar = ProgressBar(widgets=widgets)
  for i in pbar((i for i in range(24))):
    time.sleep(0.3)

@example
def 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')

@example
def 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')

@example
def 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')

@example
def 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)

@example
def 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)

@example
def 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()

@example
def 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: [e-mail]
#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 sys
class 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。