6.5. Practice Makes Perfect

Here’s a reminder of the drawing commands we’ve learned so far:

Drawing commands	What does it do?
forward( distance )	Move forward a specified distance
backward( distance )	Move backward a specified distance
left(90)	Turns 90 degrees to the left (you can use any angle, not just 90!)
right(90)	Turns 90 degrees to the right
circle( radius )	Draws a circle with the specified radius
goto( x, y )	Move straight to the position with coordinates (x, y). Note: the center is (0, 0)
up()	Stop leaving a trail
down()	Start drawing a trail
color( c )	Set the color to c (https://trinket.io/docs/colors)
begin_fill()	Starts filling in drawn shapes
end_fill()	Stops filling in drawn shapes
speed(number 0-10)	Determines how quickly the turtle will move through commands

Functions and Loops

Drawing commands	What does it do?
for i in range( n ):	Repeat n times
def function_name():	Creates and defines a new function
function_name()	Calls a function

And here are the new commands we’ll be learning this week!

Command	What does it do?
print( message )	Output the message
variable = value	Stores the value in your variable
variable = input( message )	Takes user input and stores it in your variable

What are variables and user input all about?

Let’s test out how to use variables! Use the code below or python tutor to walk through some examples.

import turtle # our variable 'x' is a container that can hold different values. # any time we say 'x = ...', we're telling our computer what to put in the container. x = 10 print(x) x = 20 print(x) x = input('Enter a value for x') print(x)

How could you use variables and user input to draw different colored circles?

import turtle # start by drawing a regular filled in circle in a color of your choice # then modify your code to get the color from the user

How could you use variables and user input to draw different sized circles? Run the code below to see how you can use variables with turtle commands. Try changing the radius variable to see what it does!

Then try drawing a third cirlce that gets the radius value from the user!

import turtle radius = 50 turtle.circle(radius) radius = 100 turtle.circle(radius)

How could we repeat code as many times as the user wants?

Let’s combine what we know about user input with what we know about loops!

import turtle # start writing a loop that draws three circles # Add a line that asks the user how many times to repeat # Use the input to tell the loop how many times to repeat!

How could you use variables and user input to draw a library?

Every library must have books - could you define a function to draw a book?

Then, could you take user input to set the color of each book?

Give it a try!

import turtle import sys sys.setExecutionLimit(60000) def book(): # define a function that draws one book book() # once you can successfully draw one book, add a loop that draws the books # in your loop, add code that asks the user for a color, then uses their input to set the color

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