用Python基本库实现进度条

用Python基本库实现进度条效果
几个要点：
1. \r，重置光标
2. time.perf_counter,计算运行时间
3. 用format控制输出格式

 1 #progress bar2
 2 #The sytle of prgress bar will be shown as below
 3 ##16%[********->------------------------------------------]0.86s
 4 #It will be divided into three part:ratio,progress bar,duration time
 5 # \r, first use \r to force cursor goto beginng of a line every time
 6 #
 7 import time
 8 scale = 50 #define the scope of char shown as progress bar
 9 print('Getting Start'.center(scale//2,'-'))
10
11 start = time.perf_counter()
12
13 for i in range(scale + 1):
14     ratio = i/scale
15     star = '*' * i
16     hyphen = '-' * (scale - i)
17     dur = time.perf_counter() - start
18     print('\r{:>4.0%}[{}->{}]{:.2f}s'.format(ratio,star,hyphen,dur),end='')
19     time.sleep(0.1)