Build and display an animated text-based progress bar in python

README.md

This started out as a fork of the progress bar class which I first hosted on ActiveState Code.

It builds a text progress bar and displays it with the draw() method.

The methods are showcased below:

from progressBar import progressBar

# Initiates the progessBar
prog = progressBar(maxValue = 50)

# Uses appendAmount to set current value (20).
prog.updateAmount(20)
# Draws the progress bar only if it has changed from previous draw() call.
prog.draw()

# Uses appendAmount to increment the current value (20+2).
prog.appendAmount(2)
# Draws the progress bar only if it has changed from previous draw() call.
prog.draw()

# Uses updatePercentage to set the percentage to the given value (74% of 50).
prog.updatePercentage(74)
# Draws the progress bar only if it has changed from previous draw() call.
prog.draw()

A typical usage would be to give progress information on network operations, such as a file copy. The maxValue would be set to the size of the file to transfer, and since the operation is buffered, the length of the buffered would be added to the value using appendAmount(buffer) on each iteration.

progressBar.py

import sys

class progressBar:
    """ Builds and display a text-based progress bar. """

    def __init__(self, minValue = 0, maxValue = 100, totalWidth=75):
        """ Initializes the progress bar. """
        self.progBar = ""   # This holds the progress bar string
        self.oldprogBar = ""
        self.min = minValue
        self.max = maxValue
        self.span = maxValue - minValue
        self.width = totalWidth
        self.amount = 0       # When amount == max, we are 100% done 
        self.updateAmount(0)  # Build progress bar string

    def appendAmount(self, append):
        """ Increases the current amount of the value of append and 
        updates the progress bar to new ammount. """
        self.updateAmount(self.amount + append)
    
    def updatePercentage(self, newPercentage):
        """ Updates the progress bar to the new percentage. """
        self.updateAmount((newPercentage * float(self.max)) / 100.0)

    def updateAmount(self, newAmount = 0):
        """ Update the progress bar with the new amount (with min and max
        values set at initialization; if it is over or under, it takes the
        min or max value as a default. """
        if newAmount < self.min: newAmount = self.min
        if newAmount > self.max: newAmount = self.max
        self.amount = newAmount

        # Figure out the new percent done, round to an integer
        diffFromMin = float(self.amount - self.min)
        percentDone = (diffFromMin / float(self.span)) * 100.0
        percentDone = int(round(percentDone))

        # Figure out how many hash bars the percentage should be
        allFull = self.width - 2
        numHashes = (percentDone / 100.0) * allFull
        numHashes = int(round(numHashes))

        # Build a progress bar with an arrow of equal signs; special cases for
        # empty and full
        if numHashes == 0:
            self.progBar = "[>%s]" % (' '*(allFull-1))
        elif numHashes == allFull:
            self.progBar = "[%s]" % ('='*allFull)
        else:
            self.progBar = "[%s>%s]" % ('='*(numHashes-1), ' '*(allFull-numHashes))

        # figure out where to put the percentage, roughly centered
        percentPlace = (len(self.progBar) / 2) - len(str(percentDone))
        percentString = str(percentDone) + "%"

        # slice the percentage into the bar
        self.progBar = ' '.join([self.progBar, percentString])
    
    def draw(self):
        """ Draws the progress bar if it has changed from it's previous value.  """
        if self.progBar != self.oldprogBar:
            self.oldprogBar = self.progBar
            sys.stdout.write(self.progBar + '\r')
            sys.stdout.flush()      # force updating of screen

    def __str__(self):
        """ Returns the current progress bar. """
        return str(self.progBar)