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='◐◓◑◒')]
   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。