We're going to continue working with the
'Heroes and Cowards' model today

and we're going to talk a little bit about
how you might want to extend it

which is a topic we're going to get into 
in a lot more detail in the upcoming units

One of the first things you might ask
after you've been playing around with it

is - what if not everyone is a hero? Or
what if not everyone is a coward?

Right now, the model doesn't allow that.

One way we can fix that is that we can
edit the chooser

to allow 'cowards', 'heroes', and 'mixed'
personality types.

So now, if we go over to the code,

we have to figure out how to address what
happens when the personality type is 'mixed'.

The first thing I would do is find all the
places where I'm using 'personalities',

and the only place I'm actually using it
is just this one spot in the setup,

because after that I set the color, and
the color represents the personality.

So I could then use this one spot to help
me figure out how to set up the personalities.

'if ( personalities = 'mixed' ) ['

And what do I want from a personality of
mixed?

What I want is for some of the people to
be cowards, and some to be heroes,

which essentially means some of them are
red and some of them are blue.

So what I can do is I can say set the
color to <i>one-of</i>...

and here I'm going to create my own list,
which is red and blue:

'[ set color one-of [ red blue ] ]'

so this says set the color of this particular
agent to be one of either red or blue.

So when I click back over and I set the
personalities type to 'mixed',

you'll see I get a mixed group of individuals,
some are red and some are blue.

Now you might ask the question, <i>what's
going to be the outcome?</i>

Well, if I let it run you'll see that you
get some very interesting behaviour,

some of them are on the sides, some
of them are frozen in the middle.

In fact, this is something that really
depends upon where the turtles started,

where they wound up, and which exact
turtles wound up red and blue.

We're explore that in a little more
detail...

when we look at the actual 'Heroes and
Cowards' model that was built for the textbook.

I want to look at one other thing before
I stop extending this model

I want to think about extending it to
visualise who my enemies and friends are.

So let's say you like your model, you like
what it's doing,

but you're not 100% positive that it's
working the way you want it to work.

Let's take this simple example of 'Heroes'

where you're trying to move between two
individuals.

One thing you might want to do is use the
<i>turtle inspectors</i> to debug your model.

So I'm going to inspect one of these
turtles,

we showed this before, and now they have
these properties of 'friend' and 'enemy',

and what I can do is create some
visualisations...

to help me explore whether the model is
actually working the way I want.

So, I'm going to have this focal turtle, 
which is turtle 98...

create a <i>link</i> with its friend,

and I'm going to set the color of that
link to be green.

Now I've created that. Unfortunately, you
can't blow up the turtle window,

so I can't make it any bigger for you to
see.

Now we'll have it create a link with its
enemy,

and have it make the color of that link
red.

So now you can see where this turtle is,

and so we know, from the 'heroes' rule,
that if this is its 'friend'...

and this is its 'enemy', this turtle
should move to roughly this location.

So we can turn the speed down, and see,
does the turtle move there?

Well, first of all as you can see it
turns around right away

and starts to head in that direction

so that's given me pretty good confidence
that it's doing what I want.

Now I can speed it up a little bit

Of course, it needs to keep updating its
own destination

because the friend and the enemy are also
moving under their own set of rules.

And now it's gotten to be half way between

it's just oscillating back and forth

and you can see the friend and the enemy
are moving back and forth as well.

So this is a cool little way I often use
the inspectors to debug my code

to make sure it's doing what it's meant
to.

Of course we can do the same thing with
the cowardly code as well.

So that's a great way to extend your
model in a way that allows you to debug.

You could have all the different turtles
display their friend and enemy links

but that might clutter up the display
quite a bit,

so if you're using it for <i>debugging</i> it's
usually easier to do it for just one.

In the next lecture we're going to talk
about...

some of the things this model can teach
us about documentation..

and random numbers.