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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。, C' B) d  W, K' O( R0 h4 M$ X% I
netlogo自带的social science--traffic grid这一例子当中,
9 s- @1 v  y6 r/ H! J  ~& Lglobals
' B. K6 c; l# ^* |[
7 N7 P( ~4 d9 h2 f" l5 Q  grid-x-inc               ;; the amount of patches in between two roads in the x direction! P9 c* y# x  O  x( L! y
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 q# ]- f7 P9 x. P- r* S6 g1 ~) q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if5 w+ ?# P) t% a) {* a: T7 a# Y
                           ;; it is to accelerate or decelerate
3 Z- L5 T+ t5 U$ P' b4 y2 X  phase                    ;; keeps track of the phase
6 I) _2 z6 I0 n) r  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure: F. ?  J$ D9 V) N; L0 q
  current-light            ;; the currently selected light; _$ f  g. i8 I
+ B  x% s0 i; V8 R: i
  ;; patch agentsets9 K# N/ _4 U, A' O5 T7 I# m+ _
  intersections ;; agentset containing the patches that are intersections
; ~) P7 Z+ N" H" ?! ?: ?  roads         ;; agentset containing the patches that are roads" L8 i! [/ x1 r2 W
]
' T5 k( V: }+ @" e
* b: y3 g1 g# T* ?2 }* c- Jturtles-own
* m) L% R( [& D- n[7 v" |3 W: y4 U3 Z1 T/ E
  speed     ;; the speed of the turtle' ?2 X0 @, b+ N, J* T+ _- ]5 u
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 w: E( g7 T9 d  wait-time ;; the amount of time since the last time a turtle has moved+ p, o/ @+ f9 B
]% }1 q" S) \- |6 l; @
& `, K* ?$ s( j5 a
patches-own
* ?0 t$ o" V, N[, T  |; H/ u3 p/ N
  intersection?   ;; true if the patch is at the intersection of two roads
( u3 J: `2 Y3 c3 Y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 N9 K) M  T& y6 ]                  ;; false for a non-intersection patches.
/ ?+ X9 }1 M7 |% m9 L$ g  my-row          ;; the row of the intersection counting from the upper left corner of the
4 [( n, [/ I8 D6 r! Z8 z) G                  ;; world.  -1 for non-intersection patches.
) P" l7 v3 a1 M  V  i  t  my-column       ;; the column of the intersection counting from the upper left corner of the
7 s" Z4 T% P& n; X0 J' L                  ;; world.  -1 for non-intersection patches.
5 H* w- A& n! W, [: J  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.. M$ ~- j/ U# W5 A) m6 d' I8 b
  auto?           ;; whether or not this intersection will switch automatically.9 }0 U" G+ A8 W5 _$ q' D3 R
                  ;; false for non-intersection patches.8 W$ O8 \: ^7 |' r) E
]8 ^! p9 a. W6 @, S' j6 \2 L
0 E) I# l& o2 c
4 a7 [0 j+ m2 t
;;;;;;;;;;;;;;;;;;;;;;2 h& k7 a& I+ C0 B  V! s: }
;; Setup Procedures ;;
' k8 L) Q; i) A$ R& K;;;;;;;;;;;;;;;;;;;;;;
: X' W8 M  u  _& t0 K" _$ B7 H- ~; K: s$ _7 y' A/ |% H9 p
;; Initialize the display by giving the global and patch variables initial values.
0 P& W( P+ @4 _: p9 }4 w: |;; Create num-cars of turtles if there are enough road patches for one turtle to
/ j: o9 Q! ?. d0 B; s! a;; be created per road patch. Set up the plots.
$ f3 B+ s3 o, l5 h' g8 [, u8 nto setup6 a7 W$ ^+ D/ r( ^
  ca/ Z; `- L3 W4 v  ]; f
  setup-globals
! m  `8 b5 K* s# T. h/ M8 B" R8 b/ u# V8 J# k' {. |
  ;; First we ask the patches to draw themselves and set up a few variables$ q, e) Q7 W6 A/ _
  setup-patches/ o; P" U8 h4 u/ ^: U# l
  make-current one-of intersections
2 q9 }) K& g; }, ?- O  label-current
4 x* y" ]& G# Z$ x1 e4 `  H
$ o0 W2 R  Z" \# ~7 l, @0 F: `/ E) k  set-default-shape turtles "car"
, S4 Y7 a1 ?4 U! @' p, b3 o8 c/ I( D  |' x6 I. C# S8 L
  if (num-cars > count roads)
% Q, v3 m3 y: b8 s9 B% W7 J1 D  [
" B' U$ ~' p1 V, U& l: i+ L1 B    user-message (word "There are too many cars for the amount of "
, A  U1 E4 X* U                       "road.  Either increase the amount of roads "9 B2 `. p" d4 S# X; P" ]& y& j0 H! m' k
                       "by increasing the GRID-SIZE-X or "
$ t* h5 X' Y8 f+ u) ]/ ]                       "GRID-SIZE-Y sliders, or decrease the "2 a3 c: b, ]$ }; j, P4 |
                       "number of cars by lowering the NUMBER slider.\n"
% {* X! y8 o% m' _                       "The setup has stopped.")
. [$ y) s7 m$ X, v6 P# p7 P    stop
5 W3 a' J. r+ @. k+ z  ]
) ?3 y  z7 ]2 }1 L7 q( f5 a$ N4 ]9 s4 B  F2 C, f
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color; e6 G- h/ n8 d$ z7 |( U/ l
  crt num-cars
( I0 o" T, B$ _1 ~+ L/ M- L' N& j- r  [% w4 ?" D1 F; S/ C3 K' S2 N2 W
    setup-cars' }0 @' z$ m8 v- }
    set-car-color
' m: Q$ l6 X- a6 \" I4 t7 B: o    record-data
) q* M) f: [% C' |  ]
: t3 ?# z5 P: c3 l: h) G$ o& v( q3 a$ d6 H
  ;; give the turtles an initial speed
+ ^% o# U! N& @  ask turtles [ set-car-speed ], X: Z8 k/ q! x( x3 B* q- Y" ^

% e9 v7 K7 G7 g% Z3 b6 W  reset-ticks7 z" v$ @+ A! J) J
end; Q# Y) N; r% ~. G

- Q4 ^8 |5 g+ I8 \;; Initialize the global variables to appropriate values& m; u! Y1 N2 W
to setup-globals
. X6 [4 Q) ^3 p# ]9 \  set current-light nobody ;; just for now, since there are no lights yet% u2 l! b. q9 [# R
  set phase 0
+ z1 \' O& k. f' g% X0 b! _  set num-cars-stopped 0
- a, V; R' F3 e/ w8 e  set grid-x-inc world-width / grid-size-x
) T- S0 B( Q$ {0 I8 ^+ i5 D  set grid-y-inc world-height / grid-size-y  U# @) w5 C6 M
; k- M- i9 O2 X7 f' q
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary' B1 D# I6 Q* b9 p
  set acceleration 0.099, _" W2 }: I6 Z
end
4 D6 |5 b4 D0 x4 i% u7 @
  v! O# q7 \/ |' M4 v, b! j& e;; Make the patches have appropriate colors, set up the roads and intersections agentsets,0 z0 u- T: f$ f8 p& f. w
;; and initialize the traffic lights to one setting* I: @" `1 |% [& E
to setup-patches
  D0 ]9 L6 L; b" e/ @  ;; initialize the patch-owned variables and color the patches to a base-color
+ y: B; Y3 w, g6 |9 O/ G  ask patches
" T& N  r* Q, w4 u% b! K( O) v  [
6 k3 g) t" \6 x+ y  J4 b; q: B    set intersection? false
. }/ [" W' }, l    set auto? false
- s- ~6 Y$ _9 _0 f; w    set green-light-up? true$ ^; x# l3 I% F# X, X! b
    set my-row -19 R! K9 k0 h" A: r
    set my-column -1# |$ d2 ^) W4 p! s, V  `
    set my-phase -1: R+ e4 n7 u+ \
    set pcolor brown + 3! \; ?/ G$ k% b: J
  ]) [" F, v* Z# M( K+ r- j
7 n! x5 E, \( [! s' d8 x
  ;; initialize the global variables that hold patch agentsets
" c3 k8 j$ g% m; Q  set roads patches with
" v  f, b& ^5 L6 \    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  c% J! o& |' o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 S. b; W" a* j- ^
  set intersections roads with+ ?0 P0 X$ q5 N$ l% U; K. f
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
/ Z+ t5 H# R% O3 B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 d* w# Y# \; D, @2 j: f' k6 B& h
+ ^( f+ C7 `2 r: c8 q: `9 J  ask roads [ set pcolor white ]& Y, y0 F" x  k& p) u- G$ e+ X5 Q
    setup-intersections& d3 x, N8 p  w/ }- F' o' t
end, `- d' q* q' \! `6 }& B# t
其中定义道路的句子,如下所示,是什么意思啊?% a5 P: U9 E* j; s$ O0 v& ~
set roads patches with1 d) p( A& |8 H; I+ q* u6 u3 a
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& V6 U8 v7 p6 f1 C8 r
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ R! b8 f$ U5 g4 ^0 V! e1 u, 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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