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Python实现控制台进度条功能

摘要：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...

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：

Python

#!/usr/bin/env python # -*- coding=utf-8 -*- #Using GPL v2 """ 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：

Python

#!/usr/bin/env python # -*- coding=utf-8 -*- #Using GPL v2 """ Usage: Just A Template """ from __future__ import division import sys,time if __name__ == '__main__': for i in range(1,61): sys.stdout.write('#'+'->'+"bb") 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：

Python实现控制台进度条功能1

下面就是基本使用举例：

Python

#!/usr/bin/env python # -*- coding=utf-8 -*- #Using GPL v2 """ 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

Python

# 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: %sn' % name) fn() sys.stdout.write('n') except KeyboardInterrupt: sys.stdout.write('nSkipping example.nn') 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">@*</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：

Python

#!/usr/bin/env python # -*- coding=utf-8 -*- #Using GPL v2 """ 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：

Python

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 -------------------1n') self.f.write(' 1 2 3 4 5 6 7 8 9 0n') self.f.write('----0----0----0----0----0----0----0----0----0----0n') 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：

Python实现控制台进度条功能2