详解Python中如何写控制台进度条的整理

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*。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”，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<a href="http://www.jobbole.com/members/weiboyes8848" rel="external nofollow" >@*</a> ')]
  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')

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。也希望大家多多支持。