Numbers and Variables: Python Does the Math 45

the power of strings with colorful turtle graphics. Let’s give it a

try! In the following program, we’ll set up turtle graphics just like

in our earlier spirals, but instead of drawing lines or circles on the

screen, we’ll ask the user for their name and then draw it on the

screen in a colorful spiral. Type this into a new window and save it

as SpiralMyName.py.

SpiralMyName.py

# SpiralMyName.py - prints a colorful spiral of the user's name

import turtle # Set up turtle graphics

t = turtle.Pen()

turtle.bgcolor("black")

colors = ["red", "yellow", "blue", "green"]

Ask the user's name using turtle's textinput pop-up window

u your_name = turtle.textinput("Enter your name", "What is your name?")

Draw a spiral of the name on the screen, written 100 times

for x in range(100):
t.pencolor(colors[x%4]) # Rotate through the four colors
v t.penup() # Don't draw the regular spiral lines
w t.forward(x*4) # Just move the turtle on the screen
x t.pendown() # Write the user's name, bigger each time
y t.write(your_name, font = ("Arial", int( (x + 4) / 4), "bold") )
t.left(92) # Turn left, just as in our other spirals

Most of the code in SpiralMyName.py looks just like our earlier

color spirals, but we ask the user their name in a turtle.textinput

pop-up window at u and store the user’s answer in your_name. We’ve

also changed the drawing loop by lifting the turtle’s pen off the

screen at v so when we move the turtle forward at w, it doesn’t

leave a trail or draw the normal spiral line. All we want in the

spiral is the user’s name, so after the turtle moves at w, we tell it

to start drawing again with t.pendown() at x. Then with the write

command at y, we tell the turtle to write your_name on the screen

every time through the loop. The final result is a lovely spiral; my

son Max ran the one shown in Figure 3-8.