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Activities/Turtle in a Pond

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Revision as of 15:56, 2 December 2011 by Tonyforster (talk | contribs) (Strategy)

Contents

Turtle in a Pond Activity

Turtle in a Pond is a strategy game. The goal is to surround the turtle before it runs off the screen.

Turtle-in-a-pond.png

How to play Turtle in a Pond

Click on the dots to keep the turtle from escaping.


Did you know that:

  • You can load your own strategy for the turtle by importing Python code you can write with Pippy?


The Toolbars

TurtlePond toolbar-1.png

from left to right
  1. the Activity toolbar button (shown in the open position)
  2. the New-game button
  3. an area for messages
  4. the Load-new-strategy button
  5. the Reload-the-default-strategy button
  6. the Activity stop button

Strategy

Cut and paste these examples into Pippy and save then to your Sugar Journal. Then use the Load-new-strategy button in the Turtle-in-a-Pond Activity to try them.

In this strategy, the turtle moves down regardless of whether the dot is open.

def _turtle_strategy(self, turtle):
    turtle[1] += 1
    return turtle

In this strategy, the turtle moves down until it is blocked (i.e., when the dot type is True).

def _turtle_strategy(self, turtle):
    if not self._dots[self._grid_to_dot((turtle[0], turtle[1]+1))].type:
       turtle[1] += 1
    return turtle

In this strategy, the turtle searches for an open dot, looking clockwise.

def _turtle_strategy(self, turtle):
    dots = self._surrounding_dots(turtle)
    for i in range(6):  # search for an opening
        if not self._dots[dots[i]].type:
            return self._dot_to_grid(dots[i])
    return turtle

In this version, the turtle orientation is set as well.

def _turtle_strategy(self, turtle):
    dots = self._surrounding_dots(turtle)
    for i in range(6):  # search for an opening
        if not self._dots[dots[i]].type:
            self._orientation = i
            return self._dot_to_grid(dots[i])
    return turtle

The turtle choose a random direction and goes there if the dot is open.

def _turtle_strategy(self, turtle):
    dots = self._surrounding_dots(turtle)
    n = int(uniform(0, 6))  # choose a random orientation
    for i in range(6):  # search for an opening
        if not self._dots[dots[(i + n) % 6]].type:
            self._orientation = (i + n) % 6
            return self._dot_to_grid(dots[(i + n) % 6])
    return turtle

In this strategy, the turtle will go off the edge if it can.

def _turtle_strategy(self, turtle):
    dots = self._surrounding_dots(turtle)
    for i in range(6):  # search for an edge
        if self._dots[dots[i]].type is None:
            self._orientation = i
            return self._dot_to_grid(dots[i])

    n = int(uniform(0, 6))  # choose a random orientation
    for i in range(6):  # search for an opening
        if not self._dots[dots[(i + n) % 6]].type:
            self._orientation = (i + n) % 6
            return self._dot_to_grid(dots[(i + n) % 6])
    return turtle

In this version, it looks for a path to the edge in the direction it was already heading.

def _turtle_strategy(self, turtle):
    dots = self._surrounding_dots(turtle)

    for i in range(6):  # search for an edge
        if self._dots[dots[i]].type is None:
            self._orientation = i
            return self._dot_to_grid(dots[i])

    if self._daylight_ahead(turtle):
        return self._dot_to_grid(dots[self._orientation])

    n = int(uniform(0, 6))  # choose a random orientation
    for i in range(6):  # search for an opening
        if not self._dots[dots[(i + n) % 6]].type:
            self._orientation = (i + n) % 6
            return self._dot_to_grid(dots[(i + n) % 6])
    return turtle

In the default strategy, a weighing function is used: preference is given to dots closer to the edges.

def _turtle_strategy(self, turtle):
    dots_ordered_by_weight = self._ordered_weights(turtle)
    if self._dots[dots_ordered_by_weight[0]].type is None:
        return self._dot_to_grid(dots_ordered_by_weight[0])
    elif not self._dots[dots_ordered_by_weight[0]].type:
        return self._dot_to_grid(dots_ordered_by_weight[0])
    else:
        return turtle

The dots are stored in a 13✕13 array. Each dot has an attribute, 'type', that determines it status. The edges have a type=None. Occupied dots have a type=True. Unoccupied dots have a type=False.

Your strategy should start with:

def _turtle_strategy(self, turtle):

The turtle argument is a tuple containing the column and row of the current turtle position. That is, turtle[0] is the horizontal position and turtle[1] is the vertical position.

Your strategy should return a tuple containing the column and row of the new turtle position, e.g.,

return [column, row]

Resources

There are some resources that you can use in your program, including:

self._surrounding_dots((column, row))
returns an array of dots surrounding a given position in the grid
self._daylight_ahead((column, row))
returns True if there is a clear path to the edge heading in the current direction
self._ordered_weights((column, row))
returns an array of surrounding dots ordered by their distance from the edge
self._dots
the array of dots from which you can test the type attribute (self._dots[i].type==None → edge; self._dots[i].type==False → open; self._dots[i].type==True → blocked)
self._orientation
you can set the orientation of your turtle by assigning a number from 0-5 (clockwise beginning with 30 degrees from north)
self._set_label('your message here')
you can write a message on the toolbar if you want to communicate what your turtle is thinking
self._grid_to_dot((column, row))
returns the dot that is at a grid position (column, row)
self._dot_to_grid(dot)
returns an array (column, row) representing the grid position of a dot

Digging deeper

To better understand how to use the above resources, view the program source,

Where to get Turtle in a Pond

The Turtle in a Pond activity is available for download from the Sugar activity portal: Turtle in a Pond

The source code is available on the Sugar Labs Gitorious server.