Lab 04 Finite State Machine - Non-Deterministic Cat

% Properties of cell arrays
>> letters = {'a', 'b', 'c', 'd', 'e'};
>> whos letters
% Name Size Bytes Class
% letters 1x5 310 cell array
%Grand total is 10 elements using 310 bytes
>> x = letters(2)
%x = 'b'
>> whos x
% Name Size Bytes Class
% x 1x1 62 cell array
%Grand total is 2 elements using 62 bytes
>> y = letters{2}
%y = b
>> whos y
% Name Size Bytes Class
% y 1x1 2 char array
%Grand total is 1 element using 2 bytes

%Construct a cell array piece by piece
>> t{1,1} = 'upper left';
>> t{1,2} = 'upper right';
>> t{2,1} = 'lower left';
>> t{2,2} = 'lower right';
>> t
%t =
% 'upper left' 'upper right'
% 'lower left' 'lower right'
>> t{2,1}
%ans = lower left
>> [rows, cols] = size(t)
%rows = 2
%cols = 2
>> t(1,:)
%ans = 'upper left' 'upper right'

select.m
function selection = select(array)
%SELECT - take a cell array, and randomly take
%one element from the cell arrray to output.
%random index
index = floor(1 + rand*(length(array)));
%eliminate the case when rand is one
if (index == length(array) +1) index = length(array);
end
selection = array(index);
>> letters = {'a', 'b', 'c', 'd', 'e'};
path(path, 'U:\lab04\');
for i = 1:10 x(i) = select(letters);end
>> x
%x =
% Columns 1 through 7
% 'b' 'd' 'c' 'e' 'd' 'c' 'a'
% Columns 8 through 10
% 'e' 'c' 'd'

chooserow.m
function row = chooserow(array)
%CHOOOSEROW - Chooses one of the rows and returns
% the cell array of the chosen row.
[n, m] = size(array);
%random index
index = floor(1 + rand*(n));
%eliminate the case when rand is one
if (index == n +1) index = n;
end
%grab the row of the index
row = array(index,:);
>>t{1,1} = 'upper left';
t{1,2} = 'upper right';
t{2,1} = 'lower left';
t{2,2} = 'lower right';
>> chooserow(t)
%ans =
% 'lower left' 'lower right'
>> chooserow(t)
%ans =
% 'upper left' 'upper right'
>> chooserow(t)
%ans =
% 'lower left' 'lower right'

catlab4.m
%CATLAB4 - the cat for lab 4
%initialize state
state = 'happy';
%infinite loop
while 1
%prompt user for input
str = input('Enter absent, pet, feed, or time passes: ','s');
%quit if 'quit' or 'exit'
if strcmp(str,'quit') break; end
if strcmp(str,'exit') break; end
%call possibleUpdate
result = possibleUpdate(state, str);
state = result{1};
%print output
disp(result{2})
%quit if the cat dies
if strcmp(state, 'dead') break; end
end

possibleUpdate.m
function result = possibleUpdate( state, input )
%initialize the result, a stuttering output
result = {state, 'absent'};
switch (state)
case 'happy'
switch(input)
case 'pet'
result = {state, 'purrs'};
case 'feed'
result = {state, 'throws up'};
case 'time passes'
result = {'hungry', 'rubs'};
end
case 'hungry'
switch(input)
case 'pet'
result = {state, 'bites'};
case 'feed'
result = {'happy', 'purrs'};
case 'time passes'
result = {'dead', 'dies'};
end
case 'dead'
result = {state, 'dies'};
end

>> catlab4
Enter absent, pet, feed, or time passes: absent
absent
Enter absent, pet, feed, or time passes: pet
purrs
Enter absent, pet, feed, or time passes: feed
throws up
Enter absent, pet, feed, or time passes: time passes
rubs
Enter absent, pet, feed, or time passes: pet
bites
Enter absent, pet, feed, or time passes: feed
purrs
Enter absent, pet, feed, or time passes: time passes
rubs
Enter absent, pet, feed, or time passes: time passes
dies

% the one-line-change to catchooselab4.m to make the
% state machine non-deterministic
result = chooserow(possibleUpdate(state, str));

% the one-line-change to possibleUpdate.m to make the
% state machine non-deterministic
case 'feed'
result = {'happy', 'purrs';...
'hungry', 'rubs'};

>> catchooselab4
Enter absent, pet, feed, or time passes: time passes
rubs
Enter absent, pet, feed, or time passes: feed
purrs
Enter absent, pet, feed, or time passes: time passes
rubs
Enter absent, pet, feed, or time passes: feed
rubs
Enter absent, pet, feed, or time passes: quit

feedCat.m
%FEEDCAT - cat state machine cascaded with the feeder
%initialize
feederState = 'happy';
catState = 'happy';
for i=1:10,
[feederState,input] = feeder(feederState, '1');
result = chooserow(possibleChooseUpdate(catState, input));
catState = result{1};
disp(result{2})
end

feeder.m
function [nextState, output] = feeder (state, input)
%feed when 1 or time passes
if ~(strcmp(input, 'absent'))
switch(state)
case 'happy'
output = 'time passes';
nextState = 'hungry';
otherwise
output = 'feed';
nextState = 'happy';
end
else
nextState = state;
output = 'absent';
end

>> feedCat
rubs
purrs
rubs
purrs
rubs
purrs
rubs
rubs
dies
dies




catImmortal.m
%CATIMMORTAL - run the virtual cat finite state machine with a
%feedback loop to ensure the cat does not die
%initialize
driverState = 'happy';
catState = 'happy';
for i=1:10
%feed or time passes base on the state
in = feeder(driverState);
%what the cat decided to do with feed or time passes
catOut = chooserow(possibleChooseUpdate(catState, in));
catState = catOut{1};
out = catOut{2};
%driver state should be the same as the cat state
driverState = catState;
driverOut = feedbackUpdate(driverState, out);
driverState = driverOut{1};
disp(out)
end

feeder.m
%FEEDER - the output of the non-deterministic cat
%(just like my cat at home)
function out = feeder (state)
switch(state)
case 'hungry'
out = 'feed';
otherwise
out = 'time passes';
end

feedbackUpdate.m
%FEEDBACKUPDATE - the output of the update function is a pair of 1x2 cell array
%with format [state, output]
function out = feedbackUpdate(state,in)
%initialize to a stuttering output
out = {state, 'absent'};
if ~strcmp(in, 'absent')
switch(state)
case 'happy'
if strcmp(in, 'purrs')
out = {'happy', 'time passes'};
else
out = {'hungry', 'time passes'};
end
otherwise
if strcmp(in, 'purrs')
out = {'happy', 'feed'};
else
out = {'hungry', 'feed'};
end
end
end

>> catImmortal
rubs
purrs
rubs
rubs
rubs
purrs
rubs
purrs
rubs
purrs