The PYTHON programming assignment for this unit has two functions.

1. Use these two functions as models for the functions you are to write. You will be removing code from main() and putting it in several separate functions. The behavior of the program will not change throughout the exercise, so you can always tell if your program is correct.

2. Use the non-fruitful function drawRect as a model. Write another non-fruitful function that moves a turtle forward without drawing a line. The function is defined as

3. def skipForward(t, len): """ Moves the turtle t forward len units without drawing anything. """ and called with a statement like skipForward(alex, 20) The contents of the function are to lift the pen, move the turtle, then lower the pen.

4. Write another non-fruitful function skipTo, which is defined as

5. def skipTo(t, x, y): """ Moves the turtle t to coordinates (x,y) without drawing anything. """ and is called with skipTo(alex, xpos, ypos) Make sure to use the parameters x and y in the body of this function. Next, you'll work with fruitful functions. Look at the function to calculate the next y-position for drawing a set of shapes. This function is called near the bottom of the program: ypos = next_y_position(ypos, width)

6. Using this function as a model, add a fruitful function to calculate the perimeter of a rectangle. The function is defined with def perimeter(len,wid): """ Returns the perimeter of rectangle with sides len and wid. """ and it is called with the statement p = perimeter(length, width) Make sure you use the parameters len and wid in the body of the function.

7. Again, using this function as a model, add a fruitful function to calculate the value math.sqrt(length*width/math.pi) which appears near the end of the program. The function should be defined as def circ_rad(len, wid): """ Returns the radius of a circle with an area of len * wid """ Mimic the call from what you did in the previous step.

8. Make sure that your main function is calling each of the non-fruitful functions at least twice.

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# Draws 3 sets of shapes of varying lengths

# Draw a rectangle

# Draw a line the length of the rectangle's perimeter

# Draw a circle with the same area as the rectangle

import turtle

import math

def next_y_position(y,ht):

""" Returns the next y-position, given current position y and height

ht """

next = y + ht + 30

return next

def drawRect(t, len, wid):

""" Draws a rectangle using turtle t with sides len and wid """

for side in [len, wid, len, wid]:

t.forward(side)

t.left(90)

def main():

# named constants

screen_size = 500

screen_startx = 60 # x coordinate of the left edge of the graphics

window

# Set up the window and its attributes

wn = turtle.Screen()

wn.bgcolor("lightblue")

wn.setup(screen_size, screen_size, screen_startx, 0)

alex = turtle.Turtle()

# Initial turtle position near left edge, toward the bottom

xpos = -screen_size/2 + 20

ypos = -screen_size/2 + 50

alex.up()

alex.goto(xpos,ypos)

alex.down()

# y-dimension of each rectangle

width = 50

# draw three sets of shapes - same width(y-dimension) but different

lengths

for length in [25, 50, 75]:

# Draw the rectangle

drawRect(alex, length, width)

# Move a little to the right of the rectangle

alex.up()

alex.forward(length)

alex.forward(10)

alex.down()

# Draw the line the same length as the perimeter of the rectangle

per = 2 * (length + width)

alex.forward(per)

# Move a little to the right of the line

alex.up()

alex.forward(20)

alex.down()

# Draw a circle with the same area as the rectangle

alex.begin_fill()

rad = math.sqrt(length*width/math.pi)

alex.circle(rad)

alex.end_fill()

# Next vertical position for a set of shapes

ypos = next_y_position(ypos, width)

# Put turtle to left side of screen at correct height

alex.up()

alex.goto(xpos,ypos)

alex.down()

# Run the main function. This should be the last statement in the file.

main()