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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% W2 m( |$ |* C6 s6 R
netlogo自带的social science--traffic grid这一例子当中,
! x7 ^/ W4 F, _! B" Kglobals
) D) l# `6 O$ B9 ]6 _$ i[
6 i9 ?- J& b" K  grid-x-inc               ;; the amount of patches in between two roads in the x direction
5 E8 Q8 r6 x; B' O; g- o* x# S0 r  grid-y-inc               ;; the amount of patches in between two roads in the y direction5 q0 i6 A8 z! ~5 }6 h
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' v, A! h- Z# I% T1 N" M4 ~- }/ J  O                           ;; it is to accelerate or decelerate: Y. g% B5 L  _
  phase                    ;; keeps track of the phase
3 }; Z% L: {8 C( `& A  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
  \/ B+ Z# F! |% {' ?- t  current-light            ;; the currently selected light. }6 D/ n2 g; K# p
6 x5 E/ u& E/ [. D* @4 e3 v
  ;; patch agentsets
1 s  N2 J- ?# S) ]* B/ y  intersections ;; agentset containing the patches that are intersections
* q: c9 V, U7 {2 n9 b3 T0 L, E  roads         ;; agentset containing the patches that are roads
) H& A3 m- X5 J0 S( k7 r; {- `]
( v' S5 e' X' ^5 [/ y4 B- a. ], S' h' X1 E
turtles-own7 S3 f4 s: \0 v8 C+ n
[4 J6 A* {" D2 J' K" V
  speed     ;; the speed of the turtle
$ C! x3 R. E; J& \; I: ^  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
3 s! q0 t8 a+ Q& c0 W! P6 Q  wait-time ;; the amount of time since the last time a turtle has moved7 ^7 v4 W( `- G1 H. U7 V
]3 V5 n* F7 G0 [& T. h
% B( Z8 t! V7 u/ N
patches-own
. j6 U! X1 R$ s' G# g, `[
0 y2 A' C* x  o$ q  intersection?   ;; true if the patch is at the intersection of two roads/ d- h; M5 w9 \/ R2 S- y  y
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.% z* g7 v9 ^& D7 N/ E: D2 W) C8 U
                  ;; false for a non-intersection patches.3 u* k. O+ I+ w1 n+ \+ |
  my-row          ;; the row of the intersection counting from the upper left corner of the" H0 k! G2 ~; {
                  ;; world.  -1 for non-intersection patches.0 z. t! m. v+ \& r$ f4 T
  my-column       ;; the column of the intersection counting from the upper left corner of the$ _2 l! `- s0 h; `' p! i
                  ;; world.  -1 for non-intersection patches." O( q  n7 d: h0 |( L
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.- Y, q4 B% l* i2 N
  auto?           ;; whether or not this intersection will switch automatically.
! ~5 {( j. {3 Z- X$ {                  ;; false for non-intersection patches.8 h! ]1 [1 k4 `6 I
]- B4 T0 ^5 H4 X3 M0 y2 o

4 l: U$ S/ s* {# l
1 _" l3 Y; U) F: d& l;;;;;;;;;;;;;;;;;;;;;;9 s, l( B9 o& D" d
;; Setup Procedures ;;
; \1 y/ f. Y; t1 P& f;;;;;;;;;;;;;;;;;;;;;;; s- j2 ~1 N' Y
- A* f, n) a& [. c/ F. B
;; Initialize the display by giving the global and patch variables initial values.
! j! g4 p% A; L9 R;; Create num-cars of turtles if there are enough road patches for one turtle to
; F7 W/ @- d0 ]% |;; be created per road patch. Set up the plots.
$ g# d9 e2 p9 J4 L$ Dto setup( Y0 m& d6 [) x+ f
  ca
1 F0 b8 W7 {9 O# o( e  setup-globals0 p% U0 N% d7 V( @! Q6 j- L- F" M

2 V( P1 O: Q, \  ^  ;; First we ask the patches to draw themselves and set up a few variables
  f3 M* B. K: N0 Z7 }  setup-patches
' d+ B+ Q- J7 ]* i+ w  make-current one-of intersections
: U0 k; D5 Y- Y; r) p7 a  label-current3 b: K9 |6 |5 T" d

  F9 \. `8 n, t9 r  set-default-shape turtles "car"! R  r# [, y) X+ Q5 m
9 d1 m# T! d$ X/ V7 d7 }
  if (num-cars > count roads)
$ [  g: o3 G& a2 D2 \  ^5 r  [
9 _' y. v2 ?# R9 b: o- `: \* D+ H% W    user-message (word "There are too many cars for the amount of "5 G5 U0 D, x) q2 K+ r5 l& ?: H
                       "road.  Either increase the amount of roads "/ [5 E, ~7 F8 ~8 B0 @9 o6 q: C
                       "by increasing the GRID-SIZE-X or "" d; Q8 f- y; h9 ?7 `
                       "GRID-SIZE-Y sliders, or decrease the "
* ^# P  f8 u3 [* t% J+ s% X                       "number of cars by lowering the NUMBER slider.\n"
8 O+ ]9 ^# a# o/ ^& Y                       "The setup has stopped.")! D0 q5 d( }5 k: n6 y; M6 E
    stop  W+ T& [# k: ~: E
  ]
0 Q0 P! `! F( r9 e1 f: {% \( F/ X! i1 ?. X
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color5 \3 X* x: O3 C: x8 o
  crt num-cars
8 f& Q/ `! j, w7 D- A0 g1 t% Y  [
! P4 k$ m: Y1 `6 e+ S' z    setup-cars
* Q# f5 ?1 k% u1 n" Y    set-car-color
: K) m% y9 Y1 ?+ M3 {. i    record-data
5 u  \* _& Z9 t& Z  ]
1 P  u5 F1 q+ `& ~! ]" B* k# T/ d- I' j: |7 G* [
  ;; give the turtles an initial speed
1 U8 v4 T3 W* V+ Q8 M  ask turtles [ set-car-speed ]
- J6 Q, z  ^5 x& j" Z3 v9 _: D
: r  }. W2 @: Z0 }, W+ ]/ S# e- l  reset-ticks, I, c! d7 j8 k+ y' `+ K1 q
end
* h; b5 n: U7 D: b9 [' [/ P9 `/ P$ U" Y- c& R
;; Initialize the global variables to appropriate values& D9 h8 S3 [6 u+ m% S8 k3 k% F' W# x
to setup-globals% R  E* Q0 K1 \; {  P  D% i
  set current-light nobody ;; just for now, since there are no lights yet* T+ g* G" }: {9 X. _9 ^& l
  set phase 0
+ x/ U  b/ X( ~0 [5 ?  set num-cars-stopped 0
1 |/ R& v6 g! P7 ]  set grid-x-inc world-width / grid-size-x
1 k; p6 g1 a9 U. L0 ~& u  set grid-y-inc world-height / grid-size-y
, h1 p- N4 D( N& y5 L) O' U. C' P; `3 {# y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
3 C! A& Q9 B  Z, v' e* [( ~. r6 P  set acceleration 0.099. V" x  @. V; r& g: }
end
/ T" q. }8 N! Z: r; B+ ~2 G/ ]$ b4 A( v7 ?$ \; N3 D. f) o$ Q
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,6 F  k" \: [& s5 G8 f0 a
;; and initialize the traffic lights to one setting% c* F/ I5 c1 V, S' m
to setup-patches5 V/ n6 A1 S, j6 U- n, @) T5 H
  ;; initialize the patch-owned variables and color the patches to a base-color
' ]$ k! L1 g6 s+ H  ask patches
8 a- i+ X+ t( {! P  [! s. N: R7 d) U. M
    set intersection? false
* m4 L/ r2 x8 v9 _/ l% [8 P    set auto? false* Z- [5 F) z* J2 i; _
    set green-light-up? true! [: _! P/ H/ @; D  k
    set my-row -13 ]' _* c$ N7 d, b! b9 \$ c
    set my-column -1
' Z! F* l! S7 C1 A' j" H' K1 E    set my-phase -1% S* K* |  O. k3 h0 W
    set pcolor brown + 3# m# _4 @. I# h- W6 ~( R8 b
  ]
/ u2 d- e) R! b! @1 `: q9 p* V/ H/ }- Q; u& {. Q' G
  ;; initialize the global variables that hold patch agentsets
$ X* U# s1 d, Y  set roads patches with4 o; \, O2 I2 k! m  t3 u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" j5 f5 J/ r  }- ]9 ?
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. o, \. {' ^) y: \  d# L2 S7 y: {
  set intersections roads with
( L/ M7 c; i3 m8 J( v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and. ]; h" w5 `4 x) Y0 R" G7 h1 T5 ^
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  ~' R* K& M; `" W0 x2 L( v7 V  T+ Z4 \) i! `+ ?3 E* P. h
  ask roads [ set pcolor white ]- c" z* {% _' C! {, J  d/ U
    setup-intersections' C9 f! E0 ]! [: E
end
0 P. G6 \* e# g8 w$ M1 l  Y其中定义道路的句子,如下所示,是什么意思啊?
2 u! q! U. Z7 p4 k+ r5 ?$ J# V7 j set roads patches with2 H  B/ o- _# _1 j$ t  o) `) O
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# R* J' Y1 j* `  ]3 w. A3 `
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" ^6 k. L" Z- ^: O, p( 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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