Python中如何给任务添加进度条

最近不务正业一下，给自己的程序加个进度条，以解决处理长时间任务时对着黑屏或者只看到print的尴尬。

以文件读取为例，给出了处理文件每一行并显示进度的一个例子：

import sys
import numpy as np

def progress_bar(num_cur, total):
    ratio = float(num_cur) / total
    percentage = int(ratio * 100)
    r = '\r\n[%s%s]%d%%' % (">"*percentage, " "*(100-percentage), percentage )
    sys.stdout.write(r)
    sys.stdout.flush()

with open('D:/233/666.txt', 'r') as f:
    lines = f.readlines()

print 'Total line numbers are: %s' %(len(lines))
cur_ = 1
total_ = len(lines)
for line in lines:
    if cur_ % 3 == 0 or cur_ == total_:
        # your processing code here #
        progress_bar(cur_, total_)
    cur_ += 1