Flash card challenge
Project
Write a flash card quizzer from scratch.
Goals
- practice breaking down a problem and solving it in Python from scratch
- practice command line option parsing
- practice reading from files
- practice working with dictionaries and for loops
Problem statement
Write a Python script that takes a file as an argument and quizzes the user based on the contents of that file until the user quits the program. Questions should be selected randomly (as opposed to going in order through the file), and the user should type in their guess. The script should say whether or not a guess is correct and provide the correct answer if an incorrect answer is given.
The file will contain flash card challenges in the form:
question,answer question,answer question,answer question,answer ...
For example, a state capitals flash card file might have the form:
Alabama,Montgomery Alaska,Juneau Arizona,Phoenix ...
Running the quizzer script with this file might look like this:
$ python quizzer.py state_capitals.txt Texas? Austin Correct! Nice job. New Mexico? Santa Fe Correct! Nice job. Oregon? Portland Incorrect. The correct answer is Salem. Virginia? Richmond Correct! Nice job. Virginia? Exit Goodbye
Project steps
1. Learn about HSV values
Run the ColorWall effects again with
python run.py -a
The names of the effects are printed to the terminal as they are run. Pay particular attention to the first 4 effects:
- SolidColorTest
- HueTest
- SaturationTest
- ValueTest
In all of these effects, a tuple hsv
containing the hue, saturation, and value describing a color are passed to self.wall.set_pixel
to change the color of a single pixel on the wall.
What are the differences between these tests? Given these difference and how they are expressed visually, how does varying hue, saturation, or value change a color?
Check your understanding: what saturation and value would you guess firetruck red have?
2. Examine Effect
and the interface its subclasses provide
All of the effects inherit from the Effect
class. Examine this class and its __init__
and run
methods.
What is the purpose of the __init__
method?
What is the purpose of the run
method?
Open up run.py
and look at this chunk of code at the bottom of the file:
for effect in effects_to_run: new_effect = effect(wall) print new_effect.__class__.__name__ new_effect.run()
effects.py
exports and Effects
list at the bottom of the file. run.py
goes through every effect in that list, creates a new instance of the effect, and invokes its run
method.
Check your understanding: what would happen if you added an effect to the Effects
list that didn't implement a run
method? (Try it!)
3. Examine the nested for
loop in SolidColorTest
for x in range(self.wall.width): for y in range(self.wall.height): self.wall.set_pixel(x, y, hsv)
This code loops over every pixel in the ColorWall, setting the pixel to a particular hsv
value. After that for
loop is over, self.wall.draw()
updates the display.
Check your understanding: what would happen if you moved the self.wall.draw()
to inside the inner for
loop, just under self.wall.set_pixel(x, y, hsv)
in SaturationTest
? (Try it!)
Tip: you can run individual tests by passing their names as command line arguments to run.py
. For example, if you only wanted to run SaturationTest
, you could:
python run.py SaturationTest
4. Implement a new effect called RainbowTest
It should run for 5 seconds, cycling through the colors in the rainbow, pausing for a moment at each color.
Remember to add your effect to the Effect
list at the bottom of effects.py
!
Test your new effect with
python run.py RainbowTest
5. Play with the randomness in Twinkle
Walk through Twinkle
. Find explanations of the random.randint
and random.uniform
functions in the online documentation at http://docs.python.org/library/random.html.
Experiment with these functions at a Python prompt:
import random random.randint(0, 1) random.randint(0, 5) random.uniform(-1, 1)
Then experiment with the numbers that make up the hue and re-run the effect:
python run.py Twinkle
Challenge: make Twinkle
twinkle with shades of red.
6. Implement a new effect that involves randomness!
Remember to add your effect to the Effect
list at the bottom of effects.py
.
Bonus exercises
Checkerboard
Find and change the colors used in the Checkerboards
effect, and re-run the effect:
python run.py Checkerboards
Then change the line
if (x + y + i) % 2 == 0:
to
if (x + y + i) % 3 == 0:
re-run the effect, and see what changed.
What other patterns can you create by tweaking the math for this effect?
Matrix
Find and change the color of the columns in the Matrix
effect, and re-run the effect:
python run.py Matrix
Each column that we see on the wall corresponds to a Column
object. Add some randomness to the color used by each column (the variable whose value you changed above) using the random.random
function, re-run the effect, and see what happens.
Write more of your own effects!
You have color, time, randomness, letters, and more at your disposal. Go nuts!