Progress bars 📊

A progress bar is a user interface element that indicates the progress of an operation. Progress bar supports two modes to represent progress: determinate, and indeterminate. Showing Progress Bars Sometimes, you have command line scripts that need to process a lot of data, but you want to quickly show the user some progress about how long that will take. Quo supports simple progress bar rendering for that.

The basic usage is very simple: the idea is that you have an iterable that you want to operate on. For each item in the iterable it might take some time to do processing.

Simple progress bar

Creating a new progress bar can be done by calling the ProgressBar

The progress can be displayed for any iterable. This works by wrapping the iterable (like range) with the ProgressBar. This way, the progress bar knows when the next item is consumed by the forloop and when progress happens.

import time

from quo.progress import ProgressBar


with ProgressBar() as pb:
    for i in pb(range(800)):
        time.sleep(.01)

Keep in mind that not all iterables can report their total length. This happens with a typical generator. In that case, you can still pass the total as follows in order to make displaying the progress possible:

def some_iterable():
    yield ...

with ProgressBar() as pb:
    for i in pb(some_iterable, total=1000):
        time.sleep(.01)

Multiple parallel tasks

A quo ProgressBar can display the progress of multiple tasks running in parallel. Each task can run in a separate thread and the ProgressBar user interface runs in its own thread.

Notice that we set the “daemon” flag for both threads that run the tasks. This is because control-c will stop the progress and quit our application. We don’t want the application to wait for the background threads to finish. Whether you want this depends on the application.

import threading
import time

from quo.progress import ProgressBar

with ProgressBar() as pb:
    # Two parallel tasks.
    def task_1():
        for i in pb(range(100)):
            time.sleep(.05)

    def task_2():
        for i in pb(range(150)):
            time.sleep(.08)

    # Start threads.
    t1 = threading.Thread(target=task_1)
    t2 = threading.Thread(target=task_2)
    t1.daemon = True
    t2.daemon = True
    t1.start()
    t2.start()

    # Wait for the threads to finish. We use a timeout for the join() call,
    # because on Windows, join cannot be interrupted by Control-C or any other
    # signal.
    for t in [t1, t2]:
        while t.is_alive():
            t.join(timeout=.5)

Adding a title and label

Each progress bar can have one title, and for each task an individual label.

import time

from quo import print
from quo.progress import ProgressBar

title = print("<style fg='yellow' bg='black'>Downloading 4 files...</style>")
label = print("<red>some file:</red>")

with ProgressBar(title=title) as pb:
    for i in pb(range(800), label=label):
        time.sleep(.01)

Formatting the progress bar

The visualisation of a ProgressBar can be customized by using a different sequence of formatters. The default formatting looks something like this:

from quo.progress.formatters import *

default_formatting = [
    Label(),
    Text(' '),
    SpinningWheel(),
    Percentage(),
    Text(' '),
    Bar(),
    Text(' '),
    Progress(),
    Text(' '),
    Text('time left', style="fg:purple"),
    Text('[', style='fg:green'),
    TimeLeft(),
    Text(']', style='fg:green'),
    Text(' '),
 ]

That sequence of Formatter can be passed to the formatter argument of ProgressBar. So, we could change this and modify the progress bar to look like an apt-get style progress bar:

import time

from quo.progress import ProgressBar, formatters
from quo.styles import Style

style = Style.add({
    'label': 'bg:#ffff00 #000000',
    'percentage': 'bg:#ffff00 #000000',
    'current': '#448844',
    'bar': '',
   })


custom_formatters = [
    formatters.Label(),
    formatters.Text(': [', style='class:percentage'),
    formatters.Percentage(),
    formatters.Text(']', style='class:percentage'),
    formatters.Text(' '),
    formatters.Bar(sym_a='#', sym_b='#', sym_c='.'),
    formatters.Text('  '),
 ]

with ProgressBar(style=style, formatters=custom_formatters) as pb:
    for i in pb(range(1600), label='Installing'):
        time.sleep(.01)

Adding key bindings and toolbar

Like other quo applications, we can add custom key bindings, by passing quo.keys.bind() which is an instance of Bind object

import os
import signal
import time

from quo.keys import bind
from quo.progress import ProgressBar
from quo.text import Text

example = Text(' <b>[f]</b> Print "f" <b>[x]</b> Abort.')

# Create custom key bindings first.
cancel = [False]

@bind.add('f')
def _(event):
    print('You pressed `f`.')

@bind.add('x')
def _(event):
    " Send Abort (control-c) signal. "
    cancel[0] = True
    os.kill(os.getpid(), signal.SIGINT)

 with ProgressBar(bottom_toolbar=example) as pb
        for i in pb(range(800)):
            time.sleep(.01)

               # Stop when the cancel flag has been set.
            if cancel[0]:
                break

when "x" is pressed, we set a cancel flag, which stops the progress.

It would also be possible to send SIGINT to the mean thread, but that’s not always considered a clean way of cancelling something.

In the example above, we also display a toolbar at the bottom which shows the key bindings.

Read more about key bindings

» Check out more examples here