Progress Bar
============


.. toctree::
   :maxdepth: 1


Indices and tables
------------------

* :ref:`genindex`
* :ref:`modindex`
* :ref:`search`



Background
----------

It is beneficial to provide users of your program with status of a long running task. One method to do this is to use a progress bar.

There are likely multiple places to use a progress bar in your program and multiple programs you would likely want to use it in. As a programmer, you should therefore keep re-usability in mind. However, for this exercise, just getting a bar to print and update will be sufficient.

There are packages on the web that you can download from `PyPI <pypi_progress_>`_ that let you do just that. But, this is a course to learn, not to copy, so, don't cheat. ;)


Exercise
--------

There are different levels to this problem. Break the problem up and approach them sequentially:

1) Implement code that draws a progress bar to the screen and updates it along the way.

2) Add code to compute the % complete and draw it at the start or end of the bar.

3) Add additional code so that the progress bar re-draws over itself and does not consume a new line each time it updates.

4) Add additional code so that the bar is a different color than the % complete value.

You should package it as a function in a way that lets you call it standalone or from another program.


Hints
-----

* You will undoubtedly have to loop within your code. Below is some boilerplate for loops::

   # Assuming you want to loop NUM_STEPS times
   for i in range(0, NUM_STEPS+1):
       #
       # Put your code here
       #

* The terminal has crazy functionality most people are not aware of. It is exposed via escape codes, which you can read about `here <wikipedia_escape_codes_>`_. Keep in mind, Jupyter is NOT a terminal, and you won't be able to get it to NOT print a new line for each cycle of the progress bar. Use PyCharm or the interpreter instead.

* Checkout the :py:mod:`time` module for methods to pause execution temporarily.

* You can force the text stream to print to the screen by using the following code::

   # At the top of your source file, bring in the sys package
   import sys

   #
   # ...your code somewhere here...
   #

   # Within your code, to force the standard out text stream to display
   sys.stdout.flush()


Solution
--------

When you are ready to see one possible solution, try :download:`this file <progress_bar.py>`


.. _pypi_progress : https://pypi.python.org/pypi/progress

.. _wikipedia_escape_codes : https://en.wikipedia.org/wiki/ANSI_escape_code