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/envpython
#-*-coding=utf-8-*-
#UsingGPLv2
#Author:ihipop@gmail.com
##2010-10-2722:07
"""
Usage:
JustATemplate
"""
from__future__importdivision

importsys,time
j="#"
if__name__=="__main__":
foriinrange(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/envpython
#-*-coding=utf-8-*-
#UsingGPLv2
#Author:ihipop@gmail.com
#2010-10-2722:07
"""
Usage:
JustATemplate
"""
from__future__importdivision

importsys,time
if__name__=="__main__":
foriinrange(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/envpython
#-*-coding=utf-8-*-
#UsingGPLv2
#Author:ihipop@gmail.com
#2010-10-2722:53
"""
Usage:
JustATemplate
"""
from__future__importdivision

importsys,time
fromprogressbarimport*
total=1000

#基本用法
progress=ProgressBar()
foriinprogress(range(total)):
time.sleep(0.01)

pbar=ProgressBar().start()
foriinrange(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()
foriinrange(1000000):
#dosomething
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
importsys
importtime
fromprogressbarimportAnimatedMarker,Bar,BouncingBar,Counter,ETA,\
FileTransferSpeed,FormatLabel,Percentage,\
ProgressBar,ReverseBar,RotatingMarker,\
SimpleProgress,Timer

examples=[]
defexample(fn):
try:name="Example%d"%int(fn.__name__[7:])
except:name=fn.__name__

defwrapped():
try:
sys.stdout.write("Running:%s\n"%name)
fn()
sys.stdout.write("\n")
exceptKeyboardInterrupt:
sys.stdout.write("\nSkippingexample.\n\n")

examples.append(wrapped)
returnwrapped

@example
defexample0():
pbar=ProgressBar(widgets=[Percentage(),Bar()],maxval=300).start()
foriinrange(300):
time.sleep(0.01)
pbar.update(i+1)
pbar.finish()

@example
defexample1():
widgets=["Test:",Percentage(),"",Bar(marker=RotatingMarker()),
"",ETA(),"",FileTransferSpeed()]
pbar=ProgressBar(widgets=widgets,maxval=10000000).start()
foriinrange(1000000):
#dosomething
pbar.update(10*i+1)
pbar.finish()

@example
defexample2():
classCrazyFileTransferSpeed(FileTransferSpeed):
"""It"sbiggerbetween45and80percent."""
defupdate(self,pbar):
if45<pbar.percentage()<80:
return"BiggerNow"+FileTransferSpeed.update(self,pbar)
else:
returnFileTransferSpeed.update(self,pbar)

widgets=[CrazyFileTransferSpeed(),"<<<",Bar(),">>>",
Percentage(),"",ETA()]
pbar=ProgressBar(widgets=widgets,maxval=10000000)
#maybedosomething
pbar.start()
foriinrange(2000000):
#dosomething
pbar.update(5*i+1)
pbar.finish()

@example
defexample3():
widgets=[Bar(">"),"",ETA(),"",ReverseBar("<")]
pbar=ProgressBar(widgets=widgets,maxval=10000000).start()
foriinrange(1000000):
#dosomething
pbar.update(10*i+1)
pbar.finish()

@example
defexample4():
widgets=["Test:",Percentage(),"",
Bar(marker="0",left="[",right="]"),
"",ETA(),"",FileTransferSpeed()]
pbar=ProgressBar(widgets=widgets,maxval=500)
pbar.start()
foriinrange(100,500+1,50):
time.sleep(0.2)
pbar.update(i)
pbar.finish()

@example
defexample5():
pbar=ProgressBar(widgets=[SimpleProgress()],maxval=17).start()
foriinrange(17):
time.sleep(0.2)
pbar.update(i+1)
pbar.finish()

@example
defexample6():
pbar=ProgressBar().start()
foriinrange(100):
time.sleep(0.01)
pbar.update(i+1)
pbar.finish()

@example
defexample7():
pbar=ProgressBar()#Progressbarcanguessmaxvalautomatically.
foriinpbar(range(80)):
time.sleep(0.01)

@example
defexample8():
pbar=ProgressBar(maxval=80)#Progressbarcan"tguessmaxval.
foriinpbar((iforiinrange(80))):
time.sleep(0.01)

@example
defexample9():
pbar=ProgressBar(widgets=["Working:",AnimatedMarker()])
foriinpbar((iforiinrange(50))):
time.sleep(.08)

@example
defexample10():
widgets=["Processed:",Counter(),"lines(",Timer(),")"]
pbar=ProgressBar(widgets=widgets)
foriinpbar((iforiinrange(150))):
time.sleep(0.1)

@example
defexample11():
widgets=[FormatLabel("Processed:%(value)dlines(in:%(elapsed)s)")]
pbar=ProgressBar(widgets=widgets)
foriinpbar((iforiinrange(150))):
time.sleep(0.1)

@example
defexample12():
widgets=["Balloon:",AnimatedMarker(markers=".oO@*")]
pbar=ProgressBar(widgets=widgets)
foriinpbar((iforiinrange(24))):
time.sleep(0.3)

@example
defexample13():
#Youmayneedpython3.xtoseethiscorrectly
try:
widgets=["Arrows:",AnimatedMarker(markers="←?↑?→?↓?")]
pbar=ProgressBar(widgets=widgets)
foriinpbar((iforiinrange(24))):
time.sleep(0.3)
exceptUnicodeError:sys.stdout.write("Unicodeerror:skippingexample")

@example
defexample14():
#Youmayneedpython3.xtoseethiscorrectly
try:
widgets=["Arrows:",AnimatedMarker(markers="????")]
pbar=ProgressBar(widgets=widgets)
foriinpbar((iforiinrange(24))):
time.sleep(0.3)
exceptUnicodeError:sys.stdout.write("Unicodeerror:skippingexample")

@example
defexample15():
#Youmayneedpython3.xtoseethiscorrectly
try:
widgets=["Wheels:",AnimatedMarker(markers="◐◓◑◒")]
pbar=ProgressBar(widgets=widgets)
foriinpbar((iforiinrange(24))):
time.sleep(0.3)
exceptUnicodeError:sys.stdout.write("Unicodeerror:skippingexample")

@example
defexample16():
widgets=[FormatLabel("Bouncer:value%(value)d-"),BouncingBar()]
pbar=ProgressBar(widgets=widgets)
foriinpbar((iforiinrange(180))):
time.sleep(0.05)

@example
defexample17():
widgets=[FormatLabel("AnimatedBouncer:value%(value)d-"),
BouncingBar(marker=RotatingMarker())]

pbar=ProgressBar(widgets=widgets)
foriinpbar((iforiinrange(180))):
time.sleep(0.05)

@example
defexample18():
widgets=[Percentage(),
"",Bar(),
"",ETA(),
"",AdaptiveETA()]
pbar=ProgressBar(widgets=widgets,maxval=500)
pbar.start()
foriinrange(500):
time.sleep(0.01+(i<100)*0.01+(i>400)*0.9)
pbar.update(i+1)
pbar.finish()

@example
defexample19():
pbar=ProgressBar()
foriinpbar([]):
pass
pbar.finish()

try:
forexampleinexamples:
example()
exceptKeyboardInterrupt:
sys.stdout("\nQuittingexamples.\n")

ProgressBar使用例子

再发一个类：

#!/usr/bin/envpython
#-*-coding=utf-8-*-
#UsingGPLv2
#Author:ihipop@gmail.com
#2010-10-3013:59
"""
Usage:
JustATemplate
"""
classprogressbarClass:
def__init__(self,finalcount,progresschar=None):
importsys
self.finalcount=finalcount
self.blockcount=0
#
#Seeifcallerpassedmeacharactertouseonthe
#progressbar(like"*").Ifnotusetheblock
#characterthatmakesitlooklikearealprogress
#bar.
#
ifnotprogresschar:self.block=chr(178)
else:self.block=progresschar
#
#Getpointertosys.stdoutsoIcanusethewrite/flush
#methodstodisplaytheprogressbar.
#
self.f=sys.stdout
#
#Ifthefinalcountiszero,don"tstarttheprogressgauge
#
ifnotself.finalcount:return
self.f.write("\n-------------------%Progress-------------------\n")
return

defprogress(self,count):
#
#MakesureIdon"ttrytogoofftheend(e.g.>100%)
#
count=min(count,self.finalcount)
#
#Iffinalcountiszero,I"mdone
#
ifself.finalcount:
percentcomplete=int(round(100*count/self.finalcount))
ifpercentcomplete<1:percentcomplete=1
else:
percentcomplete=100

#print"percentcomplete=",percentcomplete
blockcount=int(percentcomplete/2)
#print"blockcount=",blockcount
ifblockcount>self.blockcount:
foriinrange(self.blockcount,blockcount):
self.f.write(self.block)
self.f.flush()

ifpercentcomplete==100:self.f.write("\n")
self.blockcount=blockcount
return

if__name__=="__main__":
fromtimeimportsleep
pb=progressbarClass(8,"*")
count=0
whilecount<9:
count+=1
pb.progress(count)
sleep(0.2)

另外，pythoncookbook中11.1节也提供了一个不错的进度条类，代码如下：

importsys
classprogressbar(object):
def__init__(self,finalcount,block_char="."):
self.finalcount=finalcount
self.blockcount=0
self.block=block_char
self.f=sys.stdout
ifnotself.finalcount:return
self.f.write("\n------------------%Progress-------------------1\n")
self.f.write("1234567890\n")
self.f.write("----0----0----0----0----0----0----0----0----0----0\n")
defprogress(self,count):
count=min(count,self.finalcount)
ifself.finalcount:
percentcomplete=int(round(100.0*count/self.finalcount))
ifpercentcomplete<1:percentcomplete=1
else:
percentcomplete=100
blockcount=int(percentcomplete//2)
ifblockcount<=self.blockcount:
return
foriinrange(self.blockcount,blockcount):
self.f.write(self.block)
self.f.flush()
self.blockcount=blockcount
ifpercentcomplete==100:
self.f.write("\n")

if__name__=="__main__":
fromtimeimportsleep
pb=progressbar(8,"*")
forcountinrange(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"testing1:"
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。