Download For Loop

While loop
 Get names up to five times
count=0
while count< 5:
name=input(‘Guess my name.\n’)
if name==‘kim’:
break
count= count+1
For loop
 Convenient when the number of iterations is known
count=0
while count< 5:
for count in range(5):
name=input(‘Guess my name.\n’) name=input(‘Guess my name.\n’)
if name==‘kim’:
if name==‘kim’:
break
break
count= count+1
FOR loop
 “for i in range(max):”
 “i” is a dummy variable keeping counts in the range
 “i” starts at 0, increments by 1, and ends at (max-1)
 max=4: i=0, 1, 2, 3
 Block of statements (instructions) to be repeats is
indented
 “:” at the end of “for”
General FOR loop
 “for i in range(min, max, interval):”
 “i”
 “i” =
min
min+interval
min+interval+inteval
….
 “inteval” is omitted if interval==1
More about ‘for’ loop
 What will be printed
x=0
for i in range(3):
x=x+1
print(x)
for x in range(0,3):
x=x+1
print(x)
 What will be printed
for i in range(-2,3):
print(i)
for count in range(5,-5,-2):
print(count)
“for” loop
for p in range(min, max, interval):
block
p=min
p >= max
false
Do block
p = p + interval
Out of “for”
true
Importing modules
• Modules are pre-programmed package including
useful tools/resources
• math
• bioPython
• pyGame
turtle module
 Simple graphics programming
 How to use it ?
 Import ‘turtle’ module by including
import turtle
 Need to create a turtle, and NAME it to manipulate
 Say, you named a turtle ‘xxx.’
 xxx = turtle.Turtle() or turtle.Pen()
 Opens up a turtle window
 Can have more than one turtles at a time – tell them apart by
names
turtle module
 >>> import turtle
 >>> myT = turtle.Turtle()
 What is “.” between turtle and Turtle() ?
 turtle => class (generic object referring to turtle module)
 Turtle() => method (action, function, constructor)
 Rough interpretation: get ‘turtle’ type (class) and do ‘Turtle()’
 >>> myT.color(“red”)
 Get ‘myT’ turtle and color it red
 Attribute
 Position, heading (direction), color, tail position
Turtle in Python
 Actions
 With myT





myT.forward(100), myT.backward(100)
myT.right(90), myT.left(45)
myT.goto(-200,90), myT.circle(50), myT.color(“red”)
myT.up(), myT.down()
myT.write(“Hello!”)
 References
 http://www.eg.bucknell.edu/~hyde/Python3/TurtleDirections.html
 Official Python turtle page
 https://docs.python.org/release/3.1.3/library/turtle.html
Figure 1.9
Which methods to use ?
 Suppose ‘myT’ turtle is created





Draw a circle --- myT.circle(100)
Draw a thicker circle – myT.width(5)
Find out the location (x,y) of myT – myT.position()
Move myT to (100,-50) – myT.goto(100,-50)
Stop drawing – myT.up()
 Find out the screen sizes
 screen=myT.getscreen()
 screen.window_width() and screen.window_height()
HW 2: due 9/23 (Fri)
 Draw olympics rings




penup()
Goto a location
pendown()
Draw a circle
 Take the screen shot which includes your python codes
and the drawing to [email protected]