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: ihipop@gmail.com

##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: ihipop@gmail.com

#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: ihipop@gmail.com

#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='&#9680;&#9683;&#9681;&#9682;')]

    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: 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 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。