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*。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。