Continuation of John Murphy

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Continuation of John Murphys RePast Tutorial

• Steps 10-18
• Charlie Gieseler
• 8-9-04

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Review from last time

• Start to fill out the CarryDropSpace class
• Constructor to build a space of a given size
• Added CarryDropSpace variable to the model
• Added preparation line in Setup()
• Added creation line in buildModel()

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Step 10 - Initializing the Space Object

• We need to disperse money in the space.
• Define spreadMoney() method in CarryDropSpace.

• Call spreadMoney() while building the model in
  CarryDropModel.

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Step 11 - Extracting reusuable code

• We have now have code to check how much money is
  at a location.
• This could be useful outside of spreadMoney() or
  CarryDropSpace
• Define a new method getMoney(int x, int y)

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Tapping RePasts visualization resources

• We are now at the point we can start to visualize
  our model
• Initial visualization objectives
• See our 2-D grid space
• White background
• Visible money, which squares have cash
• Amount of cash indicated by color shade

• RePast provides classes to build displays
• DisplaySurface basically a window
• ColorMap links numerical values to colors
• Value2DDisplay links value sources from the
  model to colors according to the color map.
  Displays colors for each source in window when
  added to a DisplaySurface.

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Step 12 Using the DisplaySurface

• Import the class
• Create the variable
• Tear down
• Instantiate
• Pass in the model
• Give it a name
• Register the object

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Step 13 A splash of color

• Import the needed classes
• Color is a standard Java class to represent
  color values

• Will need access to the 2D grid of values
• Add access method to CarryDropSpace

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Step 13 cont.

• Create and initialize ColorMap in CarryDropModel
• - Use loop to map values to shades of red
• - Value of 0 (default) maps to white

• Create Value2DDisplay object, displayMoney,
  using in 2D grid of values and our ColorMap
• Add displayMoney to the window, displaySurf.
• displayMoney will tell the display window what
  color (white or a shade of red) to put at each
  location in a 2D grid. It does this according to
  what value cdSpace currently has for each
  location in its grid.

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Step 14 Generating the Display

• Simply add this line to in the begin() method in
  CarryDropModel

• Now run compile everything and
• run CarryDropModel in your favorite IDE.
• When RePast starts, hit the Initialize button.

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Step 15 The Agents

• Start with 4 attributes
• Money
• X position
• Y position
• Lifespan (stepsToLive)

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Step 15 cont. Modifying CarryDropModel for
Agents

• Bounding Agent lifespans
• Define default values
• Define parameter variables

• Add parameter names to allow users to edit
  values through RePast
• Add access methods for parameter vriables

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Step 16 Adding Agents to the model

• Make a container to for all the Agents ArrayList
• Initialize the agentList in setup()

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Step 16 cont.

• Define new method in CarryDropModel for adding
  Agents to the list

• In buildModel(), make the desired number of
  calls to addNewAgent() to add Agents to the list

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Step 17 A Space for Agents

• Want to add agents to CarryDropSpace.
• Space containing agents will be an Object2DGrid
  like moneySpace.

• We need
• Agents to track their location
• Some way to tell if a cell is occupied
• Some way to add an Agent to the space

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Step 17 cont.

• IsCellOccupied() checks if an Agent is already in
  a given cell in the agentSpace object.
• addAgent() attempts to add an Agent in a random
  cell.

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Step 18 Adding Agents to the space

• Add a line in addNewAgent() in the CarryDropModel
  to add a agent to the CarryDropSpace.
• Now whenever the model adds a new agent to the
  list, it will also attempt to add it to the
  simulation space.