EECS 110: Recitation #1:

Ionut Trestian

Northwestern University

http://cs.northwestern.edu/~akuzma/classes/EECS110-s09/

If statements (1)

2

name = raw_input('Hi... what is your name? ')

if name == 'Ionut': # is it Ionut? print 'x1' else: # in all other cases... print 'x2'

print 'x3'

hw0pr1.py Homework 0, problem 1

If statements (2)

3

name = raw_input('Hi... what is your name? ')

if name == 'Ionut‘: print 'x1' else: print 'x2'

print 'x3'

If statements (3)

4

name = raw_input('Hi... what is your name? ')

if name == 'Ionut': # is it Ionut? print 'x1'

elif name == 'Aleksandar': print 'x2'

else: # in all other cases... print 'x3'

print 'x4'

hw0pr1.py Homework 0, problem 1

If statements (4)

5

name = raw_input('Hi... what is your name? ')

if name == 'Ionut': print 'x1'

elif name == 'Aleksandar': print 'x2'

else: print 'x3'

print 'x4'

If statements (5)

6

name = raw_input('Hi... what is your name? ')

if name == 'Ionut': # is it Ionut? print 'x1'

elif name == 'Aleksandar': print 'x2'

elif name == 'Lisa': print 'x3'

else: # in all other cases... print 'x4'

print 'x5'

hw0pr1.py Homework 0, problem 1

If statements (6)

7

name = raw_input('Hi... what is your name? ')

if name == 'Ionut‘: print 'x1'

elif name == 'Aleksandar’: print 'x2'

elif name == 'Lisa': print 'x3'

else: print 'x4'

print 'x5'

Homework problems 3 and 4

8

Picobot

area not covered

(yet!)

Picobotwalls

area already covered

Goal: whole-environment coverage with only local sensing…

inspiration?

Picobot

9

area not covered

(yet!)

Goal: whole-environment coverage with only local sensing…

area already covered

Picobotwalls

iRobot's Roomba vacuum

inspiration!

Surroundings

10

N

W E

S

Picobot can only sense things directly to the N, E, W, and S

For example, here its surroundings are

NxWxN E W S

Surroundings are always in NEWS order.

How many distinct surroundings are there?

N

EW

S

xxxx Nxxx xExx xxWx xxxS NExx NxWx NxxS

xEWx xExS xxWS NEWx NExS NxWS xEWS NEWS(won’t happen)

== 16 possible …24

Surroundings

State

Picobot's memory is a single number, called its state.

State is the internal context of computation.

State and surroundings represent everything the robot knows about the world

Picobot always starts in state 0.

I am in state 0. My surroundings

are xxWS.

Rules

Picobot moves according to a set of rules:

state

I am in state 0. My surroundings

are xxWS.

surroundings

0 xxWS 0N

direction new state

If I'm in state 0 seeing xxWS,

Then I move North, and change to state 0.

Aha!I should move N.

I should enter state 0.

Wildcards

Asterisks * are wild cards. They match walls or empty space:

0 x*** 0N

state surroundings direction new state

here, EWS may be wall or empty space

I am in state 0. My surroundings

are xxWS.Aha! This matches x***

What will this set of rules do to Picobot?

0 x*** 0N

0 N*** 1X

1 ***x 1S

1 ***S 0X

state surroundings direction new state

Picobot checks its rules from the top each time.

Only one rule is allowed per state and surroundings.

When it finds a matching rule, that rule runs.

->

->

->

->

To do Write rules that will always cover these two rooms.(separate sets of rules are encouraged…)

but your rules should work regardless of Picobot's starting location

hw0, Problem #3 hw0, Problem #4 (Extra)

Alter these "up & down" rules so that Picobot will traverse the empty room…

the empty room

Ideas for the maze?

the maze

Hold on to one wall !!