7. Random Flower Field: Let Python Choose

You have placed flowers by choosing the exact position, color, and size yourself. Today you will let Python choose some of those values.

Random values make a program feel different each time it runs. Python's random module can choose numbers and items from a list.

Start With A Turtle File

Save a new file named random_flower_field.py.

Start with this template.

import random
import turtle

screen = turtle.Screen()
screen.setup(600, 800, 0, 0)
t = turtle.Turtle()
t.speed(0)
t.pensize(2)

# Your random flower code goes here.

screen.mainloop()

Run the program. A blank turtle window is fine. Close the turtle window before you change the code again.

Step 1 - Choose One Random Number

Replace the middle comment with this code.

t.speed(0)
t.pensize(2)

x_position = random.randint(-250, 250)
print(x_position)

screen.mainloop()

Run the program a few times.

random.randint(-250, 250) chooses a whole number from -250 through 250. The printed number may be different each time you run the program.

Step 2 - Move To A Random Spot

Add a random y_position.

x_position = random.randint(-250, 250)
y_position = random.randint(-300, 250)

print(x_position, y_position)

screen.mainloop()

Then move the turtle to that spot.

print(x_position, y_position)

t.teleport(x_position, y_position)
t.dot(12)

screen.mainloop()

Run the program a few times. The dot should appear in a new place.

t.teleport(x_position, y_position) jumps to the random spot without drawing a travel line.

Step 3 - Choose A Random Color

Make a list of colors.

y_position = random.randint(-300, 250)

colors = ['purple', 'red', 'orange', 'blue', 'teal']
ink = random.choice(colors)
print(ink)

t.teleport(x_position, y_position)
...

Use the chosen color before drawing the dot.

ink = random.choice(colors)

t.color(ink)
t.teleport(x_position, y_position)
t.dot(12)

Run the program a few times.

Step 4 - Bring Back The Flower Function

Replace the dot with a small flower function.

colors = ['purple', 'red', 'orange', 'blue', 'teal']
ink = random.choice(colors)

def draw_flower(radius, arc_angle):
    for i in range(8):
        t.circle(radius, arc_angle)
        t.left(180 - arc_angle)
        t.circle(radius, arc_angle)
        t.left(180)

t.color(ink)
t.teleport(x_position, y_position)
...

Then call the flower at the bottom.

t.teleport(x_position, y_position)

draw_flower(25, 60)

screen.mainloop()

Run the program. Each run should place one flower somewhere new.

Step 5 - Repeat The Random Flower

Put the random choices inside a loop.

def draw_flower(radius, arc_angle):
    ...

for i in range(10):
    x_position = random.randint(-250, 250)
    y_position = random.randint(-300, 250)
    ink = random.choice(colors)
    t.color(ink)
    t.teleport(x_position, y_position)
    draw_flower(25, 60)

screen.mainloop()

Run the program.

The loop chooses a new position and color before each flower. That is why the field fills with different flowers.

Step 6 - Random Sizes Too

Choose a radius inside the loop.

for i in range(10):
    x_position = random.randint(-250, 250)
    y_position = random.randint(-300, 250)
    ink = random.choice(colors)
    radius = random.randint(12, 35)
    t.color(ink)
    ...
    draw_flower(25, 60)

Use that radius in the call.

for i in range(10):
    ...
    t.teleport(x_position, y_position)
    draw_flower(radius, 60)

Run the program.

Final Project - Random Flower Field

Use this full program to grow a random field.

import random
import turtle

screen = turtle.Screen()
screen.setup(600, 800, 0, 0)
t = turtle.Turtle()
t.speed(0)
t.pensize(2)

colors = ['purple', 'red', 'orange', 'blue', 'teal']

def draw_flower(radius, arc_angle):
    for i in range(8):
        t.circle(radius, arc_angle)
        t.left(180 - arc_angle)
        t.circle(radius, arc_angle)
        t.left(180)

for i in range(18):
    x_position = random.randint(-250, 250)
    y_position = random.randint(-300, 250)
    ink = random.choice(colors)
    radius = random.randint(12, 35)
    t.color(ink)
    t.teleport(x_position, y_position)
    draw_flower(radius, 60)

screen.mainloop()

Run the program more than once. Notice what stays the same and what changes.

Make the field yours by changing one value at a time. Good experiments include the number in range(18), the position ranges, the color list, and the radius range.

Teacher Check

Show your random flower field. Then point to:

• one random.randint(...) line
• one random.choice(...) line
• the loop that repeats the flower
• the function call that uses a random radius

Say this out loud: "The loop repeats the same plan, but random values make each flower different."