Teach Your Kids To Code: A Parent-friendly Guide to Python Programming

Conditions (What If?) 87

w for x in range(number):
x if shape == 'r': # User selected rosette
y t.circle(100)
z else: # Default to polygon
{ t.forward (150)
| t.left(360/number)

At u, we ask the user for a number of sides (for a polygon) or

circles (for a rosette). At v, we give the user a choice between p for

polygon or r for rosette. Run the program a few times, trying each

option with different numbers of sides/circles, and see how the for

loop at w works.

Notice that x through | are indented, so they are part of the

for loop at w and are executed the number of times the user entered

as the number of lines or circles at u. The if statement at x checks

to see if the user entered r to draw a rosette, and if that’s true, y is

executed and draws a circle at this location as part of the rosette. If

the user entered p or anything other than r, the else statement at z

is selected and draws a line at { by default, to make one side of a

polygon. Finally, at | we turn left by the correct number of degrees

(360 degrees divided by the number of sides or rosettes) and keep

looping from w to | until the shape is finished. See Figure 5-5 for

an example.

Figure 5-5: Our PolygonOrRosette.py program with

user input of 7 sides and r for rosette