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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。
* M# U& w  x+ gnetlogo自带的social science--traffic grid这一例子当中,' \. _9 z$ S/ i7 A
globals6 s/ z* w6 V& J0 ^  T& y  j; c
[9 F6 q+ \) O  }$ W
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
  R- d1 b" h" ~! A* p  grid-y-inc               ;; the amount of patches in between two roads in the y direction
9 D4 M* \( V9 a2 j* R1 M" `0 _' S* Y  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
  p* C0 J5 d. f                           ;; it is to accelerate or decelerate+ S: g6 P# f0 I+ e
  phase                    ;; keeps track of the phase
6 ]" Y# z8 t* q: ?$ d/ W* R6 x  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
$ y! n  B  v# |, x  current-light            ;; the currently selected light  j, O( i9 g9 ?1 C6 C; T% F+ T+ r

/ ~! o0 u# u5 q, c  ;; patch agentsets! w) x9 O0 _+ ?% a' u% R
  intersections ;; agentset containing the patches that are intersections) T1 x" U  N& Q# }( k5 b7 y
  roads         ;; agentset containing the patches that are roads
4 h1 P; K: m7 g, b]
0 k, C/ {5 R* F! [# \0 j7 ?% |! F0 G- Y/ O3 Y- n( m
turtles-own: m, S0 |% W* M; P' J8 q% n& y
[5 v' i/ R" w0 X! ]( L
  speed     ;; the speed of the turtle3 ^1 N& J7 O: ~- W
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right" E: W! b0 M7 e/ z
  wait-time ;; the amount of time since the last time a turtle has moved0 m$ \6 ^( K' @: h
]# E, c6 p1 K# Z8 J9 e8 ]: I

( D1 G4 @" U3 n9 @) {, xpatches-own: Z. M6 y; G# r- Z
[. I4 Y) y$ ^; f- |2 M4 {, n2 f
  intersection?   ;; true if the patch is at the intersection of two roads1 P$ g- d1 V# s* C+ q3 f
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% L# C( ~7 I  \% e' K5 [2 p% t                  ;; false for a non-intersection patches.
: M. v$ m& B% H! @  N  k7 _/ ^  my-row          ;; the row of the intersection counting from the upper left corner of the/ a) ]# d' J! Y/ B
                  ;; world.  -1 for non-intersection patches.
! H, \3 l% L& J2 @" P& C! O2 I  my-column       ;; the column of the intersection counting from the upper left corner of the* N$ n: K) L5 M
                  ;; world.  -1 for non-intersection patches.4 S" d4 x. O; ~0 Z4 C
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  {& _* b* X* Z  |8 a" d  auto?           ;; whether or not this intersection will switch automatically.
& Z% s( f& [- i! V: T+ g4 Y                  ;; false for non-intersection patches.# ~+ e' e' H5 `
]3 y1 U9 h3 x6 [: a; X5 L- b

8 k" D5 [5 c1 q6 N( @/ F" w8 S. ^( J3 U
;;;;;;;;;;;;;;;;;;;;;;! C( M5 i* @" `
;; Setup Procedures ;;
# `+ R+ D9 F/ Y2 A* M;;;;;;;;;;;;;;;;;;;;;;
5 [' p4 o) L- u
! W" S7 x  w# S5 g4 s2 |- V;; Initialize the display by giving the global and patch variables initial values.# U# G( W$ M1 E
;; Create num-cars of turtles if there are enough road patches for one turtle to6 o; n1 b+ t0 d5 l: G6 H
;; be created per road patch. Set up the plots.% z( b; ]0 M& A& _( h/ s. p
to setup  |' @4 j3 n1 I7 t5 x- }
  ca
1 v& y) i$ o% G; j6 l  setup-globals
4 b2 V5 R) I% H* Y
' L/ z  I: Q# A; S, B, L  ;; First we ask the patches to draw themselves and set up a few variables! ]( ]" t( D$ K2 ^
  setup-patches
$ Q# I4 J$ z3 T# @! ~& D5 f  make-current one-of intersections
+ `; V! o7 Y) y4 {' ~2 h3 d  label-current; M" W$ z  L; l, L& l/ Q
; T6 Y  f- [$ D- c& A1 C
  set-default-shape turtles "car"
! r9 |/ {, K( h! R6 l' N
$ V9 y' }" f# N: p3 x' w; K* W  if (num-cars > count roads)
" @' [4 b1 c9 n  [. i1 V+ d2 c! s( u% G# u/ q8 i
    user-message (word "There are too many cars for the amount of "
) |/ I  m, N% Q! }, Q                       "road.  Either increase the amount of roads "
- ~5 a1 |( B, I                       "by increasing the GRID-SIZE-X or "9 u6 i) f9 |# |
                       "GRID-SIZE-Y sliders, or decrease the "5 S& L' P: l. c0 n
                       "number of cars by lowering the NUMBER slider.\n". z$ W  N& R8 y4 b
                       "The setup has stopped.")
* ^8 @8 _$ Q- {5 k# o    stop) p1 x  R9 x: [3 s; a  m, L7 U
  ]
' t2 \0 M) X) g8 a( W, @7 k% t! J8 c' n: _: m$ t! b
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
) M4 V; G) {. A* L& H7 _  crt num-cars' N5 x" K8 [# V0 Q& ?/ C2 J& o
  [+ T! {$ C2 j/ g& ~
    setup-cars4 B/ E$ |, w% x. |9 Q9 I2 ?
    set-car-color
( e: S5 i3 i# [0 i& K+ M/ x$ K    record-data. i- _' D6 e7 y9 l3 c2 W. R
  ]) {, o/ `4 a4 Y  }3 C

/ E4 Q+ [/ _/ u3 W' Z  o7 s8 v  ;; give the turtles an initial speed
1 Z( ]. b  ]: Q% z& H  ask turtles [ set-car-speed ]
8 n4 |  }/ r, ~# I$ c/ W4 ?0 R; ?' M  `
  reset-ticks& q) _/ K; b  H: |: v
end
% c; x, ^: E+ X+ o& M) Y
% [: K. K* s$ M4 [9 o$ J- Y;; Initialize the global variables to appropriate values2 }/ w8 t7 a; f. Z1 l$ l
to setup-globals
& ~7 l  c; v3 {' Q5 v3 Y  set current-light nobody ;; just for now, since there are no lights yet
2 V, t! E5 r( A- ]  set phase 0/ ?( M8 w  _6 |7 Q" d0 [/ n* ^8 R6 H4 I
  set num-cars-stopped 0
0 @& D; P- ~# w- i: T# X. B# L  set grid-x-inc world-width / grid-size-x3 r% U4 n1 w0 r1 j4 N: F( ^2 O
  set grid-y-inc world-height / grid-size-y
& P3 \1 ?8 D# K2 K
0 o( j2 W9 B: }: w% h  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary# X$ \9 ?" d4 q0 a, n
  set acceleration 0.099
7 q8 m) X7 h/ j+ H, m# B* P& Hend8 i+ ~0 U0 S% C
) f& l1 j, A7 v3 y! |, L! W
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
- o* x* Y8 E; Q: K: D; A- x4 y% J;; and initialize the traffic lights to one setting
( {) E" w) X0 R6 o0 B8 N9 _! C* Rto setup-patches% x/ D  `& q2 t. Y/ T( X+ b7 H
  ;; initialize the patch-owned variables and color the patches to a base-color* `9 K) q7 V5 B+ T3 h
  ask patches2 c* g4 z0 d# s/ r3 p# b- m/ M6 W
  [- l1 S8 D+ G# B1 \
    set intersection? false
) ~6 _5 S+ Z. Z, `$ N    set auto? false
2 I& A% Z6 A# X5 b  v! H, H    set green-light-up? true
0 ~$ @, x3 i& x    set my-row -12 L! G% B; x, ?* s* n6 S9 `
    set my-column -15 W! G! R( w' p2 Z" _
    set my-phase -1
. K+ l  j+ B' t' C+ P    set pcolor brown + 3
0 }  N9 M) W- r$ S; D  ]2 w7 N1 i- }8 ?9 O
% u. K3 _; [! k& f
  ;; initialize the global variables that hold patch agentsets% X+ s3 I/ p% m
  set roads patches with& o& M; u3 \1 B2 |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 X2 g4 [7 {7 H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 g* T, R0 B0 k: ^2 |  C# q3 d  set intersections roads with. z9 i) J3 X' m6 G" c5 ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and- F3 K7 j, W+ `* T  _
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! p: e- z2 r' }# o. y/ _* V
0 Y8 p- u! G1 J1 U# K9 {, K
  ask roads [ set pcolor white ]
( r1 b5 ]: L8 U    setup-intersections
/ ~# N4 r, V  @7 ^) a" pend5 a; y( i* z) ]9 V, I
其中定义道路的句子,如下所示,是什么意思啊?
  F! L5 v9 O0 t2 e- j/ D! A set roads patches with- d/ B8 C" f( \9 H
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 I! p. s  W  ~+ p! l9 h3 G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ ^# f1 _  P9 ?, q9 T$ a8 V4 n' F
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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