Python Progress Bar

Question

How do I use a progress bar when my script is doing some task that is likely to take time?

For example, a function which takes some time to complete and returns

Answer 1

The code below is a quite general solution and also has a time elapsed and time remaining estimate. You can use any iterable with it. The progress bar has a fixed size of 25 characters but it can show updates in 1% steps using full, half, and quarter block characters. The output looks like this:

 18% |████▌                    | \ [0:00:01, 0:00:06]

Code with example:

import sys, time
from numpy import linspace

def ProgressBar(iterObj):
  def SecToStr(sec):
    m, s = divmod(sec, 60)
    h, m = divmod(m, 60)
    return u'%d:%02d:%02d'%(h, m, s)
  L = len(iterObj)
  steps = {int(x):y for x,y in zip(linspace(0, L, min(100,L), endpoint=False),
                                   linspace(0, 100, min(100,L), endpoint=False))}
  qSteps = ['', u'\u258E', u'\u258C', u'\u258A'] # quarter and half block chars
  startT = time.time()
  timeStr = '   [0:00:00, -:--:--]'
  activity = [' -',' \\',' |',' /']
  for nn,item in enumerate(iterObj):
    if nn in steps:
      done = u'\u2588'*int(steps[nn]/4.0)+qSteps[int(steps[nn]%4)]
      todo = ' '*(25-len(done))
      barStr = u'%4d%% |%s%s|'%(steps[nn], done, todo)
    if nn>0:
      endT = time.time()
      timeStr = ' [%s, %s]'%(SecToStr(endT-startT),
                             SecToStr((endT-startT)*(L/float(nn)-1)))
    sys.stdout.write('\r'+barStr+activity[nn%4]+timeStr); sys.stdout.flush()
    yield item
  barStr = u'%4d%% |%s|'%(100, u'\u2588'*25)
  timeStr = '   [%s, 0:00:00]\n'%(SecToStr(time.time()-startT))
  sys.stdout.write('\r'+barStr+timeStr); sys.stdout.flush()

# Example
s = ''
for c in ProgressBar(list('Disassemble and reassemble this string')):
  time.sleep(0.2)
  s += c
print(s)

Suggestions for improvements or other comments are appreciated. Cheers!