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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。' t: H/ K  N* ~0 x, C
netlogo自带的social science--traffic grid这一例子当中,# q2 k" S0 x4 j" ^& w: B& A7 F; U% U& w
globals3 O6 c( X  ~! C$ S  d. g7 S
[8 |+ G: W* L. @$ U
  grid-x-inc               ;; the amount of patches in between two roads in the x direction3 j: f2 E8 Q1 Q5 U" F4 ^0 N
  grid-y-inc               ;; the amount of patches in between two roads in the y direction8 }8 a5 S: r! r( U% B( b8 C
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 q& H7 ~9 F. _* D( ^9 l  f7 m) @                           ;; it is to accelerate or decelerate0 G+ k+ p7 s+ U  v0 ^- z1 a- S% J0 C
  phase                    ;; keeps track of the phase' B6 }! ]5 k$ N3 Q% w
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, |2 a* @3 y" ~% n% C
  current-light            ;; the currently selected light
. t/ y4 X) N; c
6 C* O6 |# N' P6 K; L$ E7 J  ;; patch agentsets
5 b, {+ q. I7 ^4 @  intersections ;; agentset containing the patches that are intersections6 I  B1 m6 O! H: ^
  roads         ;; agentset containing the patches that are roads
: o3 |8 E% W: u7 G3 D6 r% c3 ~]
  B$ J( J, I+ a+ |& R3 n4 n6 Y$ K1 X8 m- {2 o
turtles-own& R& w6 C7 I& l+ A
[
0 |* n1 N, B4 W9 F$ n" U; n  speed     ;; the speed of the turtle
  W  [; s( {! H* B4 S, n( M  x  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 h. F; ?1 D" R8 v4 _4 W4 `1 @  wait-time ;; the amount of time since the last time a turtle has moved5 o# K& M4 B, |0 q2 i( v
]
8 S/ d1 P: c: G! D9 {( }* a
  O4 h: J! p( v$ V' D* vpatches-own
6 m& U' c3 O3 y; W% i4 {[
; ]/ H$ T4 ]' E; s  intersection?   ;; true if the patch is at the intersection of two roads/ R$ i' H; Z4 v
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.& t" W; a* B) _% l8 A
                  ;; false for a non-intersection patches.
) o- e) N( H- v& q  my-row          ;; the row of the intersection counting from the upper left corner of the
1 Q( Y- U" K  u( p3 o                  ;; world.  -1 for non-intersection patches.
( E6 S% m+ `1 {. x: n  my-column       ;; the column of the intersection counting from the upper left corner of the
; [, L# `; p( q" G                  ;; world.  -1 for non-intersection patches.; O& X5 _+ e3 u; d
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.. y9 M6 B& R) ~5 v6 P% Q
  auto?           ;; whether or not this intersection will switch automatically.
1 P; n! v0 _, N                  ;; false for non-intersection patches.
# S8 L1 y$ F6 Z5 Q! Q4 `]
4 t' ~' F2 L6 |8 _* m1 n" j6 i+ a8 F2 u
1 a% l! A* r3 v
;;;;;;;;;;;;;;;;;;;;;;
& G5 k/ D/ {$ X8 X;; Setup Procedures ;;# h9 q& [' @, {3 Q$ j: \; L4 X( W
;;;;;;;;;;;;;;;;;;;;;;
7 b* [9 k  N/ Z; x, P2 j2 j- E# r* r& m1 O) z
;; Initialize the display by giving the global and patch variables initial values.
. O$ @. d9 {+ U7 ]2 E6 p;; Create num-cars of turtles if there are enough road patches for one turtle to
3 {: o% {$ g7 @- ]9 S7 {7 g4 C;; be created per road patch. Set up the plots.
" F& K0 p4 E- {: lto setup% {; ]+ W+ R; v! ]1 C
  ca- L+ J2 k& i4 W" @: N8 Z
  setup-globals% A* J+ j6 T/ b
* Z% i" j6 {% m6 w2 y# ?
  ;; First we ask the patches to draw themselves and set up a few variables
2 Q$ }9 t- a- a- y  setup-patches& H; ~# K, ~9 X; S
  make-current one-of intersections- Q: ?; E8 M$ U/ @# Z" d9 G. C2 K
  label-current
! E8 N8 ]2 \# Q/ y. _
( W9 d; d) V7 p2 m# Z6 O  set-default-shape turtles "car"- H9 o. S- b* ^7 P  c
6 O5 M4 g5 B4 ]/ J. I) S: _) [
  if (num-cars > count roads)
4 g- p# M: h8 `1 k6 |! L  [
. y! C3 l" z% q# L7 D( h    user-message (word "There are too many cars for the amount of "
8 y, X1 l! j, P/ ]* _7 C: u                       "road.  Either increase the amount of roads "
; d) u/ G9 e2 D7 k                       "by increasing the GRID-SIZE-X or "
5 i- Z0 D1 o8 Q( E9 }* E8 w1 \                       "GRID-SIZE-Y sliders, or decrease the "4 V  |5 c- ]1 f% L' k
                       "number of cars by lowering the NUMBER slider.\n"+ i' J$ F5 ~5 m" ~: b* y
                       "The setup has stopped."), m' g/ F6 U! ^" `
    stop) v2 b5 Q; ?1 {- P- Q7 |
  ]
$ T& T, ^) H8 m' A/ N+ B& g
, c$ l0 v- {. @+ ~  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color6 L5 G& @; o$ i/ R0 ~! N
  crt num-cars* W& g7 U2 q9 K5 j/ K
  [
8 D) ?+ K$ p0 q5 F4 P    setup-cars1 M4 u6 t: x4 c: ^( i3 q" m
    set-car-color
0 @1 ?0 z% C; D8 [7 S    record-data
4 X5 u+ U8 o: {& R! X  ]
( [. V' M/ k$ O" U/ q7 V9 e
+ [+ F2 t: v$ t, Q' d9 I$ t  ;; give the turtles an initial speed3 H2 M, A9 }& T  o
  ask turtles [ set-car-speed ]
1 d$ ^9 _1 ^7 l1 w" l6 U+ a& _3 z; A9 ^
  reset-ticks
1 I, n) j& u: z3 b2 Nend
) x3 g4 {6 q9 ~
$ \1 R2 g! h: i  q' `;; Initialize the global variables to appropriate values! {  Q- z0 ^8 }  V( b9 W
to setup-globals  q" X# t  e( a9 t$ B
  set current-light nobody ;; just for now, since there are no lights yet) l$ Y6 I3 r( P. l1 j, J
  set phase 0) L  o  d" j% M
  set num-cars-stopped 0: X8 h& k8 {- Z) {- d
  set grid-x-inc world-width / grid-size-x4 {* V& y4 h& V% V" D/ D7 {
  set grid-y-inc world-height / grid-size-y
( B: X# e& x# q+ ?' a
4 a3 A0 M' r$ ^" s% \1 K6 X  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary! `$ n2 l2 d' N2 K- g6 D6 L
  set acceleration 0.099
" x9 G% {3 t4 c. xend
2 s$ y  y% ?+ o! J
. p+ Z, t; ^& r; o8 i4 M;; Make the patches have appropriate colors, set up the roads and intersections agentsets,, F6 ~; c) u3 s' B
;; and initialize the traffic lights to one setting
6 X# |: v5 N& g6 ]4 W6 z- F. sto setup-patches) E+ t' I  |9 q) J/ h5 K5 l
  ;; initialize the patch-owned variables and color the patches to a base-color! E  V6 F% w1 y+ h1 e4 s" C7 C
  ask patches
5 Z/ x5 y  t. i6 i0 i+ p* I' c, Y, u% l  [  q# [4 m' H3 L2 ]6 t8 n
    set intersection? false
! t! v0 g7 D& P& {    set auto? false! f" D. [7 F, A
    set green-light-up? true+ ]1 ~- `& W9 t6 k7 a* J; y/ y8 o
    set my-row -18 q5 g8 a- }1 Z$ L
    set my-column -1: I7 T! k6 l4 `2 l8 w8 a8 K
    set my-phase -1
9 F2 |! L$ ?0 O( k+ K    set pcolor brown + 3
2 `& z/ W! ^3 j" z. i. r; c  ]
2 {. T6 q' q: u: o4 F
) q9 h: Z% X- k4 w  ;; initialize the global variables that hold patch agentsets2 ]8 o) s- m; U! J* m
  set roads patches with
$ B& P4 w0 ^, J2 u5 N1 d6 z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 W1 Z  L/ \& f9 A3 z3 n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% V0 }9 n9 i. Y$ q  set intersections roads with
! m6 K' Q/ M% w9 L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
& M$ c3 B1 L1 s9 q6 W0 q" i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 Y0 O8 U( W+ j# x! `+ ?. c# n( i& ~2 b, W& @' x6 a; K( H! f
  ask roads [ set pcolor white ]: {' g! C' }2 t  L' p: x; I4 g0 R
    setup-intersections' C) x" B. q1 ?, o9 |) f& H
end+ b& v1 H8 p: D) a& T/ x
其中定义道路的句子,如下所示,是什么意思啊?
7 q2 t" o  o% P1 G. y% x set roads patches with$ n0 U  S! `( V; ^/ k- M  n3 I# n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 Y( c) p, l* U0 L2 E1 M" g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; {: L7 {/ N- e
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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