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[求助] 在看例子时有几个问题看不懂

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发表于 2012-6-20 08:59:43 | 显示全部楼层 |阅读模式
新手,在看netlogo自带的例子时,有几行程序看不懂,希望高手能够指点。( b( ], x" Y& e: {
netlogo自带的social science--traffic grid这一例子当中,0 H+ t: Q/ g$ w; P
globals
; k  K, `8 w6 g( j( H9 c) p+ Y[% K- }; [. g% x# f2 L1 y1 i
  grid-x-inc               ;; the amount of patches in between two roads in the x direction, z2 _3 Q  O/ U
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 \# ]# ]3 E+ h( ~, z  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
: r3 M/ k  q  L: b- t$ Y: v6 V                           ;; it is to accelerate or decelerate
3 U- }. q0 J! W' t9 w0 p& g1 V  phase                    ;; keeps track of the phase
; q6 F- C; n5 S9 q% Z4 g  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure- b9 e' @6 N2 k8 q$ x, [6 B
  current-light            ;; the currently selected light: I1 @+ I* j2 |1 a4 s5 ~% [

1 t2 m& F( w0 H' \  ;; patch agentsets+ \' C# C6 Y" z8 P+ u( }% ~9 z
  intersections ;; agentset containing the patches that are intersections# Q% H7 e) l" {1 ^9 q3 H
  roads         ;; agentset containing the patches that are roads8 @; w" B* I' M: q; K" z' l. _
]! L% T  H) O( H- o" M% D' r

! Q& P) e( e: ~5 c  `' Wturtles-own
' s: `6 `6 D( r( Q) ^% c[: B" \2 n6 [: a! v  V5 R$ `$ O: ^
  speed     ;; the speed of the turtle
$ W0 s% ?3 k$ T- c9 |  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
% |1 ]. j: I1 V- s/ c; M, R  wait-time ;; the amount of time since the last time a turtle has moved' r+ w( t4 D* N* U: m
]1 e3 n3 j0 a! k' c; u
' g" e( ^$ A2 w0 `8 r% u# ^5 }
patches-own
' X, R2 g0 }7 w: ~- [* {[
: A! Z! F& j0 Y  E, `, F  intersection?   ;; true if the patch is at the intersection of two roads
" X( h+ D2 r& @9 V  ?* V6 R  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.% R& m+ C" b( |
                  ;; false for a non-intersection patches.
4 n8 R6 b) v( X# D  k/ z( K' F  my-row          ;; the row of the intersection counting from the upper left corner of the4 J1 B" H/ G, ?# ^
                  ;; world.  -1 for non-intersection patches.; P. q8 D& \# ?
  my-column       ;; the column of the intersection counting from the upper left corner of the; t8 D% i2 q& u: x; b, h9 e/ F7 }$ }
                  ;; world.  -1 for non-intersection patches.! Q6 X6 w) g: X% h; o
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
" ~- H2 _: ~* L% z: v  auto?           ;; whether or not this intersection will switch automatically.+ o2 D+ y; r! n( ?1 N
                  ;; false for non-intersection patches.) k8 N/ k% S' D% a4 U
]
- L' M5 s1 a& y3 x" J/ f! u4 j& |2 B- n) d4 \

, f+ t/ c8 m* @6 b$ S;;;;;;;;;;;;;;;;;;;;;;
3 B7 Z- ~: U, P# \;; Setup Procedures ;;
% g* a9 {: o& C; O1 O;;;;;;;;;;;;;;;;;;;;;;+ y9 b0 P4 P8 m, `' ?' N: N

' d& I' t! \% l3 V- U;; Initialize the display by giving the global and patch variables initial values.
$ l6 u# V- ~1 C;; Create num-cars of turtles if there are enough road patches for one turtle to
) o$ e$ x4 B+ d' R;; be created per road patch. Set up the plots.: C. c. r! R0 k) @% V/ _
to setup8 [6 U. y! U4 e' z3 G, W/ m
  ca
4 N+ w3 {9 g: T4 ?  setup-globals5 K9 l8 M1 R- z

+ \, A1 {- V" |# v+ Y: h+ C, J! ?  ;; First we ask the patches to draw themselves and set up a few variables
1 b9 P* P# j" M$ F  G) d5 K: f  setup-patches
" u* q; A$ \$ Q+ E  make-current one-of intersections* |+ j# k8 H" \. L3 J: s4 _  t
  label-current8 e9 c% }  @+ K# s" f
; p* v+ z( j; R3 ~/ E1 \
  set-default-shape turtles "car"
% C# A6 K3 F; f* K- B3 @: _; ?, g  n. |
  if (num-cars > count roads). E+ u! T0 P2 f
  [
6 E; v+ v7 C0 Q. G    user-message (word "There are too many cars for the amount of "/ `- C5 g- G! U
                       "road.  Either increase the amount of roads "$ E8 j9 _8 L/ R8 t: h) k- V
                       "by increasing the GRID-SIZE-X or "3 o$ g# s$ z, o) X$ Z: k
                       "GRID-SIZE-Y sliders, or decrease the "/ b$ [6 D6 ?9 v+ K, P8 T" b
                       "number of cars by lowering the NUMBER slider.\n"
" Y. l" u' H9 d) }$ G* X                       "The setup has stopped.")' [- _4 r" @7 n
    stop
6 m; h* J- \# M( Y/ ~8 Z9 N  ]9 P3 f+ S$ c% D- @% X& a' i8 g

5 Z) j* Q: I$ v) L( W- E9 e* h  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
! c3 w8 C! C7 x5 T  C  crt num-cars
* N% l$ ^( [' f0 ?+ j  [& Q1 c, H0 I4 u" O  [) R
    setup-cars
6 G9 P8 [! p3 t$ W) P3 Z3 u    set-car-color1 o! d" F! K7 K4 J2 Y( Z
    record-data0 Q2 Y& i# q( ]$ J6 w/ X7 B8 R9 ~
  ]6 g- O1 Y1 r( l+ d- W2 ~  ?

2 C! r7 @+ \9 M+ R+ @  ;; give the turtles an initial speed
& _, u" e1 @& Z! R; {  ask turtles [ set-car-speed ]+ a) y2 J3 W* C! A

. M# Z( e4 K8 i$ ~' c2 m/ w  reset-ticks/ \3 h; _  Q7 @& `: L& @
end
- m9 u, @; ~* O2 P3 J* X+ W: }. q
' _6 m  q, _4 R$ @/ u* T9 e;; Initialize the global variables to appropriate values
5 k0 `& A+ a& oto setup-globals) M7 F) a) u. d
  set current-light nobody ;; just for now, since there are no lights yet/ d, A& C( ?$ U
  set phase 0/ G; o) M5 c/ x8 \
  set num-cars-stopped 08 k( V' ^+ H8 ^- m+ [# o
  set grid-x-inc world-width / grid-size-x
8 |' ?# R4 B; |8 `# U1 P- Q  set grid-y-inc world-height / grid-size-y& l8 L6 N9 v& |
/ I6 ~& `; d; U* G% c" H
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
  J. j0 j/ s( v' S! u1 m; E9 o  set acceleration 0.099
( ^5 L+ C% T1 s0 \! V9 tend! k: e  d6 P! w( T

/ x$ t; V7 U4 {/ O;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
2 X# m# e. [% v! ^;; and initialize the traffic lights to one setting  A3 `2 |/ q' p
to setup-patches
& i9 _( z9 q9 E0 T" `" o0 N3 i  ;; initialize the patch-owned variables and color the patches to a base-color, j, U. [' w# x' G( u
  ask patches" ?3 I* f3 `3 F+ ~% z
  [  K- ?' t* m% }0 I8 J2 C5 J4 s7 ]
    set intersection? false( C* Q( E+ I7 ?# D4 P) D
    set auto? false
( p- p. {. \2 _& S  p; ~+ m    set green-light-up? true
/ f2 S1 }& }) |( G    set my-row -1
" }. h: g+ k; H& G, S! r3 k    set my-column -17 u* d& S; U$ s7 i/ U
    set my-phase -1
) f& r7 Y, ]% y9 Z+ g( `    set pcolor brown + 39 h, Q( B% ~# y" V
  ]
. _" Z9 h% X4 Y8 h, ]) }5 Q7 G/ v* \# F9 ?
  ;; initialize the global variables that hold patch agentsets
" `5 L- s5 U  f$ f( _# A  set roads patches with6 {& Q  O9 M2 d/ D$ U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% V) H2 V  R" P6 g8 P- F    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 M: D' y; }$ [: N7 X5 |- o7 x2 P  set intersections roads with3 z% L6 d+ _& e# t# r$ q' o. i
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and: @, o7 Q% e1 G* p7 |( z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ T5 w6 e% P8 i0 q- S9 a
7 E. C9 J# {% ^. Z  I0 T) a# B4 `
  ask roads [ set pcolor white ]
& l  U+ o7 Z1 d' o" d    setup-intersections
9 L) j; X3 E5 \' G+ E. {6 J/ ?1 gend8 S# S5 N+ A! p1 R* b7 }! F
其中定义道路的句子,如下所示,是什么意思啊?5 s/ j% D. q, z1 ?+ w- ]
set roads patches with8 C; x& d' d* p! R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 F9 ~1 J- U: \, `. a5 V2 Q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! d/ K; K! h( N0 H6 O% l谁能帮我解释一下[(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0)是什么意思吗?
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