Estimated completion date/time in bar_format

[kolayne]

Closes #1051

Adds the possibility to display ETA date and time. Example of basic usage of the feature:

from time import sleep
from random import randint

from tqdm import trange


for i in trange(20, bar_format='{l_bar}{bar}{r_bar} ({eta_dt})'):
    sleep(randint(1, 5) / 10)

How this looks

You can also customize the date format with the directives from the datetime library (see the official documentation):

from time import sleep
from random import randint

from tqdm import trange


for i in trange(20, bar_format='{l_bar}{bar}{r_bar} ({eta_dt:%Y.%m.%d, %H:%M})'):
    sleep(randint(1, 5) / 10)

How this looks

Notes

• Works for Python 2 just in the same way (in the samples above you should wrap randint in float, but no changes to tqdm calls are needed)
• When it's impossible to calculate ETA (i. e. first iteration or no total and length of an iterable is unavailable), eta_dt defaults to the epoch beginning datetime (to not break formatting directives usage)

[codecov-io]

Codecov Report

Merging #1055 into devel will increase coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##            devel    #1055      +/-   ##
==========================================
+ Coverage   86.40%   86.44%   +0.04%     
==========================================
  Files          22       22              
  Lines        1456     1461       +5     
  Branches      247      247              
==========================================
+ Hits         1258     1263       +5     
  Misses        167      167              
  Partials       31       31              

[casperdcl]

Exactly the implementation I was thinking of; thanks

[casperdcl]

made a few changes

• eta_dt => eta
• catch OverflowError => max

Example:

tqdm(..., bar_format='{l_bar}{bar}| {n_fmt}/{total_fmt} [{rate_fmt} ETA:{eta:%y-%m-%d %H:%M}{postfix}]')

[casperdcl]

would likely merge #1052 first before adding a test