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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。
, a7 d( q3 U7 O7 b; v; s1 anetlogo自带的social science--traffic grid这一例子当中,9 @, a4 p6 t5 B/ z" y
globals" @0 j+ e7 k0 @' G& F, h! C: D
[7 x/ M  u' J. w1 [( x
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
+ a( m1 c' d; |6 V/ J  grid-y-inc               ;; the amount of patches in between two roads in the y direction( ~; m0 Q% X+ b2 x$ O  X* g
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if- f  U5 ]9 h2 |, M3 v
                           ;; it is to accelerate or decelerate
0 @3 P# ~% a2 S: B( U& B  phase                    ;; keeps track of the phase
* @4 ?0 o: g5 ]! \& [- y$ f  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" j, U0 Y, k3 a+ e
  current-light            ;; the currently selected light0 A5 W# k8 R: ~. k" f
( b' b$ G$ @( i$ T
  ;; patch agentsets
) Y" Y: e) z, o/ j  L  intersections ;; agentset containing the patches that are intersections, {6 I" ~2 _. B6 G+ j+ [. g3 F
  roads         ;; agentset containing the patches that are roads. W: K: D5 C4 L! r
]
9 V; Z* s) D" W3 F' h- C) H" M
- T+ c# h3 _( F& |turtles-own
7 J0 }: J5 a( J, Q[. K. p$ i( z- {1 u7 Y4 C0 f
  speed     ;; the speed of the turtle
" x  d. c9 e6 Z5 V0 E( q  up-car?   ;; true if the turtle moves downwards and false if it moves to the right2 [* T' y0 s9 [0 B
  wait-time ;; the amount of time since the last time a turtle has moved) p, H6 ]5 W  @7 V
]0 p5 A& _1 S/ c5 d

& b) |$ P9 V9 d# ?/ spatches-own  L+ N# g2 ?9 K& ^5 B
[* K! Y3 a8 _/ b: a" R) k
  intersection?   ;; true if the patch is at the intersection of two roads1 O4 b  Y: A- ~# c1 k/ C9 L
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
& I$ b" @% `9 E5 k( g0 G0 J  n                  ;; false for a non-intersection patches.
. Z7 M3 u( v9 L; b  my-row          ;; the row of the intersection counting from the upper left corner of the0 f6 p2 k7 T( W5 T4 z+ a
                  ;; world.  -1 for non-intersection patches.) q2 Z/ F% j3 p/ ]( g4 B$ O
  my-column       ;; the column of the intersection counting from the upper left corner of the
4 ^" \7 }. Z+ ^. h- a/ I                  ;; world.  -1 for non-intersection patches.
- P" X( |; U+ @. Q  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
9 B8 o- U4 n) I* c0 m, G  auto?           ;; whether or not this intersection will switch automatically.; y2 R, d- N6 V; v6 o
                  ;; false for non-intersection patches.9 {( s" I6 ^1 ?* \6 f5 r2 j
]1 b- V. Z( C# l) C2 {4 a
" A$ }' k1 ]: P+ i- f

4 r" }* E4 u! @& I;;;;;;;;;;;;;;;;;;;;;;
: R: Y1 Z( F  h' ?# v* a3 M( Q;; Setup Procedures ;;) `! d3 p7 p* F, b
;;;;;;;;;;;;;;;;;;;;;;4 X7 \) M( \4 c9 h& w. f

$ O3 ]. B& d% F% w9 f;; Initialize the display by giving the global and patch variables initial values.
- C* u' ~2 j5 x1 |;; Create num-cars of turtles if there are enough road patches for one turtle to
) N9 k: R: |5 |;; be created per road patch. Set up the plots.
- h0 ]: g& |4 E, ?+ wto setup4 j; s" Y" Y- A" @- s
  ca
, G" H6 f0 J. T9 R  setup-globals
/ ?/ g$ Q4 n& y, z( H
) i0 \1 ]2 h0 g# ?' P2 a  ;; First we ask the patches to draw themselves and set up a few variables
. f1 K( ^  Y6 X  setup-patches
" _( T0 ?7 D5 L- r  make-current one-of intersections# H0 P0 ]; L; h! I& W& m
  label-current
$ j) ]! D+ G9 ~1 ~4 J9 c+ @) P$ p' Z' |+ k+ K
  set-default-shape turtles "car"
! S& a* z" E7 ]  d- m
, @' q. c. j/ u6 w  if (num-cars > count roads)% f% y1 E% q5 o  J
  [8 h" _3 h0 j/ N
    user-message (word "There are too many cars for the amount of "
6 ^) ^' {' Y5 J9 @4 s3 l+ x                       "road.  Either increase the amount of roads "' [4 e. x# F# @
                       "by increasing the GRID-SIZE-X or ": `8 K7 z$ e) L( p8 q) q
                       "GRID-SIZE-Y sliders, or decrease the ": e+ _- l  {! \% p% Y  G
                       "number of cars by lowering the NUMBER slider.\n"
& _8 b8 C! i) I! T6 ]4 E                       "The setup has stopped.")9 z9 A: u+ V8 J! @/ a3 D) F
    stop) Y0 I# |0 x7 N! L+ e
  ]
- S; }- X0 S5 a# w- u
/ h/ T: r* q% B  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
5 a0 {  W0 o! P- t( T  crt num-cars
/ s) f3 N/ _! ~3 `  [
3 J: z; K5 r6 S/ E! w    setup-cars
! J, W* V) c+ L! k; W2 ?2 |    set-car-color* ^" W" J; M% R* N$ J+ {0 s, u
    record-data& _2 {/ m9 }; l! o8 @% f
  ]0 `  `, f% X/ ^6 l. X/ i

7 B% V- h  y4 F& e6 s- m  ;; give the turtles an initial speed; X# N* f2 C% y# ^
  ask turtles [ set-car-speed ]( D! l& l& ~* O/ I
) R% B- Q9 K8 R
  reset-ticks
; Y/ w2 q7 h2 K  ^end
7 C- s5 e1 Y5 V, F
' S0 w" D9 c' C8 w- k  m( B  d;; Initialize the global variables to appropriate values
& v1 [$ x! V/ N. B& ?to setup-globals* f$ B; s+ S8 `* Q  b
  set current-light nobody ;; just for now, since there are no lights yet
) D; c) u' R( @5 o# L9 y  set phase 0
# i6 e9 b7 W6 @1 a- x  set num-cars-stopped 0
7 r1 g5 f3 s& J- W  set grid-x-inc world-width / grid-size-x
% |. ~6 P( J5 i7 R; o$ `, N  set grid-y-inc world-height / grid-size-y1 B5 n/ Z6 r; ]0 R/ E: j

% ]  r1 J1 L1 B) b+ ~  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
; A, ~; \+ r/ o" L  set acceleration 0.099
/ `8 U0 U* @: K) M3 gend
+ a. G  |* s7 k5 i5 g2 T+ f
% B+ i2 g% H# m; W;; Make the patches have appropriate colors, set up the roads and intersections agentsets,0 H! m7 ^2 b2 i3 @, B$ {; N
;; and initialize the traffic lights to one setting' s, t' L( N. D7 `
to setup-patches* y. j, D3 J! X
  ;; initialize the patch-owned variables and color the patches to a base-color
3 A" J: o' g. f) U, W7 p  ask patches9 Q/ d& `4 F5 k
  [
, q  @$ l6 a, B+ m$ g- h    set intersection? false
- C' J6 p( Y1 W3 R" ?: E. k    set auto? false+ |, E( Z" `# T
    set green-light-up? true
6 t0 w8 w$ m4 `8 D    set my-row -1
4 [9 q0 s. r% U( ]4 B( t) M) Q7 F    set my-column -1
$ m- A, I) h$ j0 r- w4 A    set my-phase -1
. {& X+ c) S- z) _! e4 s    set pcolor brown + 3
8 _& ~- J  z# S% ]! `  ]
1 V0 ?1 ~) E$ [( V- q
* r6 S- L; F5 v( X/ Z1 A2 h# l  ;; initialize the global variables that hold patch agentsets7 ^6 u. z  h; W+ Y5 z
  set roads patches with3 w2 H! e0 u# b0 G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, ^' y) f: n9 P/ K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( q) u" V- U: @# F3 g  set intersections roads with( Y, v) d' ?6 v% u+ R" D: P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
, U$ r. O. g5 J+ M$ z, x    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 K. d: y4 |" N* a# G: o
* t; H* X# g  H- y3 z  ask roads [ set pcolor white ]
2 P2 r3 C8 D. K) v5 G, a* k  X    setup-intersections
# l7 m: f9 L. N. A& t  Cend
# w8 ~& k' v& ]$ k' Z  w# \' B其中定义道路的句子,如下所示,是什么意思啊?# U: o6 r, _) W+ V  j
set roads patches with9 }; K" V4 q1 }5 o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 j  q; V* R6 M3 U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 V5 O4 o" u7 x  v7 U/ T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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