Flashcards

The goal of this script is to help you memorize some of the python functions and custom classes and functions used in the upcoming sections of this guide.

You can also create your own flashcard text files to memorize any kinds of material.

You can view or download the code here:

https://github.com/pythonbyexample/PBE/tree/master/code/flashcards.py

To run flashcards, you will also need to download ‘utils.py’:

https://github.com/pythonbyexample/PBE/tree/master/code/

Card

I will need a Card class which is going to store the front and back sides of a card and will be responsible for displaying the card and getting the response to the “did you get it right” question.

The __init__() method parses the card’s front and back text:

def __init__(self, card):
    front, back = card.split(sep, 1)
    self.front  = front.strip()
    self.back   = back.strip()

In the draw() method, we need to print the card front and status, pause for the user, print the back and status again, and finally return True if the user got the card right.

The last part is handled by the special yesno() method of the TextInput object which returns True if the user’s answer is ‘y’.

def draw(self, status_msg):
    print(nl*screensep)
    self.box(self.front)
    print(status_msg)
    textinput.pause.getinput()

    self.box(self.back)
    print(status_msg)
    return textinput.question.yesno(default='y')

In the box() method I’ll use the unicode box border characters stored in the border container to enclose the text, which is centered using the str.center() method.

We also need to use the textwrap.wrap() method to fit long strings inside the box.

def box(self, txt):
    """Center text and display border around it."""
    in_width = width - 2    # inside width
    tpl      = border.vertical + '%s' + border.vertical

    topline  = border.tl + border.horiz * in_width + border.tr
    btmline  = border.bl + border.horiz * in_width + border.br
    padline  = tpl % (space * in_width)

    wrapped  = [line for line in wrap(txt, width - 10)]
    wrapped  = [tpl % l.center(in_width) for l in wrapped]
    lines    = [topline, padline] + wrapped + [padline, btmline]

    print( nl.join(space+l for l in lines) )

Flashcards

The Flashcards class is responsible for loading the cards and running the main loop. The __init__() method goes over each line and passes it to Card to create the flashcard.

def __init__(self, fname):
    self.cards = list()
    with open(fname) as fp:
        for line in fp:
            if line.strip():
                self.cards.append(Card(line))

The run() method does some simple stats reporting and generates a new randomized list of cards every time it runs out of them (using copy.copy() and utils.shuffled() functions), so that you have to go over the entire set of cards without repeating them before you have to start over.

def run(self):
    right = cards = total = 0

    while True:
        cards   = cards or shuffled(copy(self.cards))
        percent = (right/total*100.0) if total else 0
        stat    = status % (right, total, percent)

        right += int( cards.pop().draw(stat) )
        total += 1

This code is not very efficient since it creates two copies of the cards list; it should be fine for this script as you’ll usually have a small number of cards, but you should not that this approach would be too wasteful in the general case.

You can quit at any prompt by using the ‘q’ command.

You can also provide an alternate cards filename at the command line: flashcards.py mycards.txt; otherwise the default cards.txt is used. Filename argument processing is handled using the utils.getitem() function and the sys.argv argument list:

fname = getitem(sys.argv, 1, default=cards_fn)
if not exists(fname):
    print("Error: %s could not be found" % fname)
    sys.exit()

Screenshots

First the script shows you the front of flashcard:

╭────────────────────────────────────────────────────────────────────────────╮
│                                                                            │
│                                 time.sleep                                 │
│                                                                            │
╰────────────────────────────────────────────────────────────────────────────╯

5 right out of 6 (83%)

>

At this point the script waits for the user to try to remember this card and hit Enter, and then to show the back of the card:

╭────────────────────────────────────────────────────────────────────────────╮
│                                                                            │
│      pause the program for a period of time e.g. 0.5 - half a second       │
│                                                                            │
╰────────────────────────────────────────────────────────────────────────────╯

5 right out of 6 (83%)

Did you get it right (Y/n)?