NetLogo羊吃草模型步骤代码说明

1）setup按钮代码，代码功能含义为生成100个主体（代表羊），并让它们随机分布于窗体上，完整代码为（点击代码可复制）：

        to setup 
            clear-all 
            ask patches [ set pcolor green ]
            create-turtles 100 
            ask turtles [ setxy random-xcor random-ycor ] 
        end

2）go按钮代码，在编辑对话框里勾选“forever（持续执行）”，代码功能为让每个主体每次都按照顺时针转的随机角度前进一格，完整代码为（点击代码可复制）：

        to setup 
           clear-all 
           ask patches [ set pcolor green ]
           create-turtles 100 
           ask turtles [ setxy random-xcor random-ycor ] 
        end

        to go 
           move-turtles 
        end

        to move-turtles 
           ask turtles [ 
           right random 360 
           forward 1 
           ] 
        end

3）目前各只羊在可以随意移动但什么都不做。现在可以让羊吃“草”（绿色瓦片），并增加能量，但是在移动时会损失能量，完整代码为（点击代码可复制）：

        turtles-own [energy]

        to setup 
           clear-all 
           ask patches [ set pcolor green ]
           create-turtles 100 
           ask turtles [ setxy random-xcor random-ycor ] 
        end

        to go 
           move-turtles 
           eat-grass 
        end

        to move-turtles 
           ask turtles [ 
           right random 360 
           forward 1 
           set energy energy - 1 
           ] 
        end

        to eat-grass 
           ask turtles [ 
           if pcolor = green [ 
             set pcolor black 
             set energy (energy + 10) 
           ] 
           ] 
        end

4）进一步增加功能，实现羊群的繁殖和死亡，草被吃掉后可以逐渐恢复，完整代码为（点击代码可复制）：

        turtles-own [energy]

        to setup 
           clear-all 
           ask patches [ set pcolor green ]
           create-turtles 100 
           ask turtles [ setxy random-xcor random-ycor ] 
        end

        to go 
           move-turtles 
           eat-grass
           reproduce 
           check-death 
           regrow-grass
        end

        to move-turtles 
           ask turtles [ 
           right random 360 
           forward 1 
           set energy energy - 1 
           ] 
        end

        to eat-grass 
           ask turtles [ 
           if pcolor = green [ 
             set pcolor black 
             set energy (energy + 10) 
           ] 
           ] 
        end

        to reproduce 
           ask turtles [ 
           if energy > 50 [ 
             set energy energy - 50 
             hatch 1 [ set energy 50 ] 
           ] 
           ] 
        end 

        to check-death 
           ask turtles [ 
           if energy <= 0 [ die ] 
           ] 
        end
 
        to regrow-grass 
           ask patches [ 
           if random 100 < 3 [ set pcolor green ] 
           ] 
        end

5）进一步增加功能，新建滑钮，表示动态的羊群数量，并用于初始羊群生成，完整代码为（点击代码可复制）：

        turtles-own [energy]

        to setup 
           clear-all 
           ask patches [ set pcolor green ]
           create-turtles number
           ask turtles [ setxy random-xcor random-ycor ] 
        end

        to go 
           move-turtles 
           eat-grass
           reproduce 
           check-death 
           regrow-grass
        end

        to move-turtles 
           ask turtles [ 
           right random 360 
           forward 1 
           set energy energy - 1 
           ] 
        end

        to eat-grass 
           ask turtles [ 
           if pcolor = green [ 
             set pcolor black 
             set energy (energy + 10) 
           ] 
           ] 
        end

        to reproduce 
           ask turtles [ 
           if energy > 50 [ 
           set energy energy - 50 
           hatch 1 [ set energy 50 ] 
           ] 
           ] 
        end 

        to check-death 
           ask turtles [ 
           if energy <= 0 [ die ] 
           ] 
        end
 
        to regrow-grass 
           ask patches [ 
           if random 100 < 3 [ set pcolor green ] 
           ] 
        end