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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。
/ S% z  w6 e: F8 gnetlogo自带的social science--traffic grid这一例子当中,
* J: A; \& t/ D% M2 p) W  |3 rglobals
+ l$ X4 H- o: s, w9 h[2 B5 z5 C' {) r# z
  grid-x-inc               ;; the amount of patches in between two roads in the x direction8 D4 N6 O! q+ I) [0 m
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
. F/ h% x' q9 S) S% v" s+ a  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' n$ |& n: ~/ o# R9 {9 Q                           ;; it is to accelerate or decelerate8 g# I! n) {! R$ h3 y0 a6 P* _& d3 \
  phase                    ;; keeps track of the phase
8 M) g  H7 A- D8 F; F/ |- d  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
$ f. S. h" `1 E3 z& h; i7 P9 B$ Y0 h% e  current-light            ;; the currently selected light
6 b1 ^. k0 b4 b4 y, I
( K, J& M- s( G2 A. ]6 t- T  ;; patch agentsets5 W7 _6 d3 I+ ?5 \# A
  intersections ;; agentset containing the patches that are intersections* [8 }! @; x$ t) }
  roads         ;; agentset containing the patches that are roads( N( H  p3 Y  e* x9 w; o. {
]
! G% H) x+ k# M! y  D2 D! c, M7 R1 v! n$ b2 A" j+ E# x
turtles-own
, I' n! v* l' m" |, [! }4 n% B[
  F# m: O* E6 C  speed     ;; the speed of the turtle1 Q: C* Q2 O. X# e( `: l
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right. \4 z7 N9 m1 i) [8 b9 p/ z( T
  wait-time ;; the amount of time since the last time a turtle has moved
9 i0 t- z, n( s3 X' e9 |( p  C* F]
0 M4 V4 }7 l6 a, _/ P8 u
- k, B" y, L" t* mpatches-own
- \, c/ F% F# w' t4 Q[
$ u1 H' H" c8 {  intersection?   ;; true if the patch is at the intersection of two roads; x1 }1 i! O9 A% q9 v7 P( ]* M
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 d2 {$ ?" S' T& n; F! @
                  ;; false for a non-intersection patches.
/ G/ H+ G! J" n3 e" t0 u5 a  my-row          ;; the row of the intersection counting from the upper left corner of the
5 f; H4 N" ]: I; L" q2 ?                  ;; world.  -1 for non-intersection patches.
+ d+ _4 W$ j) G5 J( f( H, x  my-column       ;; the column of the intersection counting from the upper left corner of the
$ y; H' M, B2 Y- u8 w# D9 n                  ;; world.  -1 for non-intersection patches.3 `6 j' A" z# X
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# S+ T- t/ M7 y( g9 z  c
  auto?           ;; whether or not this intersection will switch automatically.* k1 S) {8 V+ Y; [1 ~
                  ;; false for non-intersection patches.
9 y7 z) O% m; c) W' @! o/ L]! f1 t2 p8 W- u. {! `1 {
3 q8 w: ^$ o# v, i

+ p7 W4 n/ S) p7 W% L  b;;;;;;;;;;;;;;;;;;;;;;  k  V7 V  R1 B! C0 L, l
;; Setup Procedures ;;
$ Q( p$ n+ [8 V; j# l3 b/ Z;;;;;;;;;;;;;;;;;;;;;;
5 ?2 A3 {1 X9 d% d: \! c6 B
4 q1 m' m2 G, A* H3 M  g' s;; Initialize the display by giving the global and patch variables initial values.4 X5 ^* k3 H) f0 b, T4 m  k
;; Create num-cars of turtles if there are enough road patches for one turtle to8 R+ v& {& n- e& P  {
;; be created per road patch. Set up the plots./ F" k9 b+ D& G* r
to setup2 J# |* [- F  O6 M! {% W
  ca8 X: j: ?$ z( L
  setup-globals
! c6 ?1 f2 A0 j% t1 d) m  H( W& b
, E1 W7 V" c2 [% S! Q4 Y  ;; First we ask the patches to draw themselves and set up a few variables% _* x9 Y9 X: U& x* m2 O# _" `! d
  setup-patches1 h6 X3 ]& l6 Y9 ?2 ]
  make-current one-of intersections
7 ~6 k$ B- b, @5 \( [9 n  label-current
' w" B: B8 {! V0 {) @. ^, g, W, C5 s, ^; s  ~
  set-default-shape turtles "car"$ R$ m; l) u' t4 L

, g( x0 B* ?* S5 z  if (num-cars > count roads)
* `0 p0 I( X' Y2 U  [; O1 `' x3 j( l; S7 C
    user-message (word "There are too many cars for the amount of "
0 [; j$ u& @! h6 I                       "road.  Either increase the amount of roads "4 g3 c: c1 Q2 B8 U7 v
                       "by increasing the GRID-SIZE-X or "
. W/ n& _1 y5 ]5 `                       "GRID-SIZE-Y sliders, or decrease the "
( r: M- q3 \0 n1 `                       "number of cars by lowering the NUMBER slider.\n"
& |& P7 H, a/ Q% N# z3 j2 b                       "The setup has stopped.")
( F1 I0 E" @; T  C/ {    stop6 ^+ t5 |* }! \% B
  ]. N$ ]* B, J9 |. U: ]
$ T3 r3 t  [3 z1 _# @: N* ?. s6 x& G
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
2 h: a# T  I. a; m& ?2 ]6 N% O  crt num-cars# d5 ^- @# x3 u7 g: u$ Q
  [
! S# S, Q: ^9 U0 Z    setup-cars7 V+ d+ C$ i4 {
    set-car-color0 D5 Y* d9 Z0 f! [, U
    record-data0 A. W8 |$ D& V5 d5 S
  ]4 o5 B' p' k7 z+ u2 ]  F* h9 J
9 N* E4 f' N$ C5 K8 \3 C
  ;; give the turtles an initial speed
& E5 j5 \4 @& P6 ^  ask turtles [ set-car-speed ]
# G4 Z* u; q, x% ^# J. h; I+ u0 U7 s/ A# u# }6 ^7 N, m
  reset-ticks
$ h7 J5 a. s$ t; s* v' s+ x0 B# k% ^end
+ c$ t, B6 G7 J) ?1 R) p* \9 I* j' d! d5 g+ W0 C/ a
;; Initialize the global variables to appropriate values
7 ?7 U5 y8 O: r+ ~! Z7 eto setup-globals! h4 G; x/ j( u; w
  set current-light nobody ;; just for now, since there are no lights yet5 F5 _) c2 l! E; e
  set phase 0; x4 R; P) k4 f& W7 g$ ?: K
  set num-cars-stopped 0
! v1 G, g# P+ Q( V! E, L4 I, v, R  set grid-x-inc world-width / grid-size-x
; l) a" B/ P9 C8 C  set grid-y-inc world-height / grid-size-y. W8 z2 j7 C; `

1 K; [, B& ~! S; D! A  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 J7 z$ m% C# H1 Z  set acceleration 0.099- w% A; B# k7 @* Q: v
end
( I& \* k3 {7 B  ~* s
+ z( o- @& s# w6 W7 {6 w;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 l# O1 }2 J. Y! x2 F* i& z5 \
;; and initialize the traffic lights to one setting
; o" q4 X: }: Qto setup-patches/ W! |; K7 C9 e( o+ k( _' n
  ;; initialize the patch-owned variables and color the patches to a base-color
) X+ O# t& |# r+ e  ask patches
' r: a% Y  X+ h/ k% ]5 Z! Y' t  [2 o( o3 Q# D& g6 Z/ d  d
    set intersection? false' u" z( {/ p9 e# ~( }6 f
    set auto? false4 i4 G) o. c( ]7 N
    set green-light-up? true  m- z! i/ s0 O; L- i
    set my-row -1
( a9 Y9 {& _6 P* F+ Y    set my-column -17 [! P; r" Y. b9 i. J3 {( D
    set my-phase -14 a7 S1 x8 W4 d" T9 ]& o  N
    set pcolor brown + 3# f. D$ I9 z: S3 |' v" Q; }
  ]
6 r4 j5 b" p) J) w$ P, J4 K# H7 k; \5 N6 z3 v+ H% @
  ;; initialize the global variables that hold patch agentsets: t  D6 P3 B0 J8 l4 K! |5 w0 ~
  set roads patches with
- r- t5 M) |' R5 f8 w, i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: n9 a! f$ Y( D2 R) s1 H# k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# d& ^8 v4 B: d) v  set intersections roads with
. L) V/ U# I  a# {# e! e" |    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ H, v% d, q  A# I& C1 `  Z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) E6 f6 W+ N4 M% U4 B, ?1 @  E" e$ l/ m
  ask roads [ set pcolor white ]$ J9 Y7 U$ J+ [" N- o
    setup-intersections
* h8 E1 Q) x/ J5 i* }+ @end
# L1 n" Z! w- ~) O其中定义道路的句子,如下所示,是什么意思啊?+ D; O0 q: w4 w0 |# [# u
set roads patches with7 Q1 q9 _( x; q3 U7 {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 V, V) R. W; u8 ?9 \: D$ o    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& L$ v5 `: j: [' K2 a
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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