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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。
) _4 a) Y7 \0 {5 i1 Knetlogo自带的social science--traffic grid这一例子当中,
, Y# l  i: d  Q# L0 V1 hglobals0 S1 m, m3 R6 K
[4 o) X) g$ g! _) e
  grid-x-inc               ;; the amount of patches in between two roads in the x direction( d% K. k# x+ ~4 T
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
' W3 R& e& R/ ~/ j! i0 L5 X9 b  acceleration             ;; the constant that controls how much a car speeds up or slows down by if. S6 h& f- f( C& @
                           ;; it is to accelerate or decelerate
% c, u8 ]' @6 p" ^& d+ _  phase                    ;; keeps track of the phase
: w, L, x  `! W! k7 T1 h/ O. U$ Y  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure; U% o5 `+ _2 r: Y* @# X' y
  current-light            ;; the currently selected light1 Z2 r8 M3 a0 j
% M! Q- c3 o7 ^, I0 k1 q+ k
  ;; patch agentsets- s& |! p: u) p3 {( V
  intersections ;; agentset containing the patches that are intersections! _( x, J4 q3 i' Q
  roads         ;; agentset containing the patches that are roads4 C: A4 U1 R; z5 T
]
+ `' s& H7 \+ \% a) L7 M4 `
& U3 M+ n. L, C) A$ yturtles-own
1 d+ N" P5 m6 T8 W[
- u7 _- x+ j/ G, B  speed     ;; the speed of the turtle& H6 M! G; g1 o8 r* f: B7 G
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right' A5 Y9 _* X& K& s2 A
  wait-time ;; the amount of time since the last time a turtle has moved: {, Z7 U- F, k- o8 ]
]
9 W8 {8 p4 a- y, U# d, t. ^) K( ?# z1 l8 h
patches-own
! U. M$ X. \5 d1 Z) e, d) K[8 k2 J9 {& V' p6 z! c, j4 |7 D
  intersection?   ;; true if the patch is at the intersection of two roads7 @# \$ C# H" j) Q
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.1 u1 J4 i  d, n1 Q# ^! r
                  ;; false for a non-intersection patches.6 O* g3 V6 P' b% g
  my-row          ;; the row of the intersection counting from the upper left corner of the# {$ u4 i9 K: a8 @1 s
                  ;; world.  -1 for non-intersection patches.
* ~( g- \# r. e0 _% L3 ^! U  my-column       ;; the column of the intersection counting from the upper left corner of the0 H0 Z! A3 t4 A* [2 P( ^
                  ;; world.  -1 for non-intersection patches.
, w. i2 r+ H, M( @4 g  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches./ A8 R  w7 u3 z! y
  auto?           ;; whether or not this intersection will switch automatically.+ o& }: A0 F8 b( z% V
                  ;; false for non-intersection patches.% ?. ~1 o# o0 L& @; K
]
! P2 B  w, G2 A1 x8 V
; A# {& C* H0 }( n- z
$ H: ^3 r' k) t* G( ];;;;;;;;;;;;;;;;;;;;;;0 Q" ~4 D% a' @6 j7 F4 e4 N
;; Setup Procedures ;;
" \2 |) t' }! c: I4 H9 A9 A;;;;;;;;;;;;;;;;;;;;;;
  P$ ]1 V" ^* s/ m& s! t
- m+ ]7 P+ a0 L1 v, a6 Q' Q;; Initialize the display by giving the global and patch variables initial values.( O& t+ t* T$ X2 b
;; Create num-cars of turtles if there are enough road patches for one turtle to1 I1 e4 j1 ~2 \! Z
;; be created per road patch. Set up the plots.
0 N! Z3 J/ M' ]) @  A+ J5 ?to setup. m: _' |9 c( {" n; j/ ~+ M( n
  ca
, \0 t# }# Q$ y  setup-globals
% C" c, y, D5 |9 A! g# v3 }
  z- _; Y+ k' w7 j9 @5 N  ;; First we ask the patches to draw themselves and set up a few variables
6 z: m- W  w1 e! E1 J  setup-patches
; p0 s9 `# f) u& d& t& X  make-current one-of intersections  k) t! @% I6 s6 t
  label-current
" p8 @- p7 |) b- F+ a
- A" Y/ I* i, c+ w+ e  set-default-shape turtles "car"
: J/ E: Y5 J7 ^8 R# J$ ~1 F$ C' d# N/ F& w  f
  if (num-cars > count roads)7 o5 i# {+ C3 j  [; h2 u* R# x8 H
  [
: z- M: S+ C' F! f1 g" g0 A    user-message (word "There are too many cars for the amount of "! u2 C3 n2 o# s1 h3 _4 A0 R9 ^1 x
                       "road.  Either increase the amount of roads "3 v/ S: L" `* S8 H$ o
                       "by increasing the GRID-SIZE-X or ") K) h1 m9 a" n4 a! Y
                       "GRID-SIZE-Y sliders, or decrease the "0 ?+ x' F7 w" V0 ^% ?( l9 C8 X# r
                       "number of cars by lowering the NUMBER slider.\n"
3 Q  {$ o! `  G; F7 M6 T3 x- j                       "The setup has stopped."); }& \5 D6 I5 G# [6 ]
    stop- }, }/ e6 F* N# v+ [3 H: n6 N
  ]; k  z: W& w# a* l) h

3 ~, L5 T5 K& J: k& B. Q7 A# _  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
9 G5 p6 b1 S' h/ b  crt num-cars
; Y/ ?+ e, h' c. M. m( B0 ?, x  [
+ B/ ^! [4 q4 \. f    setup-cars) n, |' {. ?& u* v
    set-car-color
* y: t' u9 f6 [, z  e, L    record-data
) v' e, r* |  V5 L! ^  ]) |+ k7 g! {/ U9 W

$ K8 A9 i+ n: y! Q& K1 Z  ;; give the turtles an initial speed% [% J1 a/ B9 t( H) q3 g
  ask turtles [ set-car-speed ]) p! M, [2 Q2 G, ^
" |6 V& q4 A0 Y" m
  reset-ticks
$ u# v6 [/ d4 Y2 t: tend6 V9 s0 l" [- ?. I2 A  C# L1 k- c

* u& e0 X" \4 E;; Initialize the global variables to appropriate values
" d/ J0 }/ i/ j6 \* w  I/ Nto setup-globals; K6 Y# W! F, z
  set current-light nobody ;; just for now, since there are no lights yet& A8 H1 A4 d4 n# Z5 s0 Q& }
  set phase 0: |: A9 K& ?& B, s: |
  set num-cars-stopped 0
7 S: R- x3 ?& F" g0 t  set grid-x-inc world-width / grid-size-x( t2 I( O* Q; N2 S, y; j
  set grid-y-inc world-height / grid-size-y1 l$ E2 x% r7 {7 T* T2 r
3 Y1 v: w# p" ~! E" W( ?
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% ]+ \' ?, k/ z/ k* S& D  set acceleration 0.099
) y# n/ G6 n. Z8 K9 ?! ~7 T* yend
1 c0 v8 n/ P- k/ _; \! m& L, {
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
5 F# M9 ~4 r. S# V; G& d/ ~;; and initialize the traffic lights to one setting
1 V' N. w5 H0 k$ x# }to setup-patches
- s6 t2 N4 q) o  v$ `. f. T+ F4 T7 B! B  ;; initialize the patch-owned variables and color the patches to a base-color
* U) |# s- k- V! T/ h2 n( b  ask patches
, ^* s. f. t  i( W/ M. |  [! O" J! X! K+ v
    set intersection? false: r1 c9 G  O" ^* a6 m8 p
    set auto? false0 E  C2 f0 w, Y& p% C. S& J
    set green-light-up? true" Z7 B& s+ k+ `: J( F
    set my-row -1- V' o. y6 r4 Q( |8 b- o3 V, `
    set my-column -14 K  F2 K" F: N, G# z3 f
    set my-phase -1: u% c: ?* x9 \6 q, A
    set pcolor brown + 3; D& _, ?4 T: d; |6 P: C
  ]/ `) c* ]* V; b
9 S! K" O5 j8 [( `
  ;; initialize the global variables that hold patch agentsets
2 Z8 l+ S0 L0 i# Z# n  set roads patches with8 O, _6 W7 D2 [% z9 L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 w2 c# o; G4 G! b- h! b- y) ]
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* P# n) P" t0 f8 G
  set intersections roads with; T3 J6 {/ d1 n) H. U, {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and% r/ `+ v: o, A6 M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  i  ~! ]* b) D  E! C9 |

$ ^# u1 ~2 I- A' D6 s# q  ask roads [ set pcolor white ]8 H6 l2 U; }# D4 K  F0 p
    setup-intersections
1 f& |# Y' n; ^% M8 N$ Oend1 h2 M/ S& Z. t  G
其中定义道路的句子,如下所示,是什么意思啊?
9 D/ r! n5 Q2 H/ t set roads patches with4 v2 d& O; t. o/ ^; L/ ]
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ x' c& n: c6 o& e$ Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& y7 g2 j8 U7 F& y7 z
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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