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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。
, w( H+ k9 j. e5 C4 I- O" Q9 [8 r5 K+ znetlogo自带的social science--traffic grid这一例子当中,' d3 ~3 `: U/ v8 U  z' p
globals
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  grid-x-inc               ;; the amount of patches in between two roads in the x direction% ^# M- W- k! k0 n$ G
  grid-y-inc               ;; the amount of patches in between two roads in the y direction4 X6 I( O# S+ E. ^" H* {
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if8 L7 c$ Q3 S+ k2 h* B5 K
                           ;; it is to accelerate or decelerate. t$ o, d) l7 z7 O  @* e6 G
  phase                    ;; keeps track of the phase
% W6 i& K2 y& o  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
5 m  s; c, m2 y' O( o7 ~1 x; V5 m  current-light            ;; the currently selected light7 c8 Q% @4 \# c  j1 h

5 Y3 \/ N- j( L" ?  ;; patch agentsets  [) M5 q. M; A, T
  intersections ;; agentset containing the patches that are intersections9 u) c  i  t6 r3 h1 u
  roads         ;; agentset containing the patches that are roads! E% k/ Y! x3 s5 z9 L0 j
]# P( z5 f9 ?/ T, y; k1 L2 Z2 m" ~
1 v3 o& Y, C/ ^2 f; R! j2 \6 y/ q
turtles-own
( C& \' v$ W( c[
1 V3 W, j: F: L+ D) T  speed     ;; the speed of the turtle0 S% y0 `% s( X1 q9 b# s! w% x
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right( d7 n$ J) ]" `2 {  v
  wait-time ;; the amount of time since the last time a turtle has moved
7 n! f6 E2 u  e; ~8 K]2 R& O) J( a! p$ J

8 s' H+ {! \9 B) p5 u& C7 kpatches-own8 g4 |" i8 V2 ?0 U4 `, @& L
[/ b9 r; a6 Q9 k; o& C
  intersection?   ;; true if the patch is at the intersection of two roads0 q( O1 U5 M  S+ |# [) D; X7 K6 v
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
. h/ G+ I  w) u, e0 S, q                  ;; false for a non-intersection patches.( t/ r& b! F- U. c7 |
  my-row          ;; the row of the intersection counting from the upper left corner of the+ x: v5 e- l$ Q. R4 Y0 ?
                  ;; world.  -1 for non-intersection patches.
. x4 ^# [  \8 L. }% }, y  my-column       ;; the column of the intersection counting from the upper left corner of the1 l" x' ^5 h8 t& W' R
                  ;; world.  -1 for non-intersection patches.3 B8 r3 u; [! X2 [- M9 _
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.; ^3 Q) X" I' s- p
  auto?           ;; whether or not this intersection will switch automatically.
# o$ N0 K7 d8 Z) n                  ;; false for non-intersection patches.3 B* g9 w6 j1 I( x- b5 x4 R' m
]* C4 |% H; r, _0 {- V

9 y/ o5 \- n; b7 X4 i" i# [3 c8 I2 ]
4 `9 ^, O' h  [6 @2 {;;;;;;;;;;;;;;;;;;;;;;
" w+ Z7 a3 O) m+ f2 C5 T;; Setup Procedures ;;
) R" M' w: m; m' e+ r;;;;;;;;;;;;;;;;;;;;;;3 C+ Q0 ~  v/ `- f6 u
, u9 m4 k- B: @# I
;; Initialize the display by giving the global and patch variables initial values.
6 L) b# `+ a3 w2 |4 r$ O2 w" u;; Create num-cars of turtles if there are enough road patches for one turtle to
# y/ \2 K9 [* F! ^;; be created per road patch. Set up the plots.
& h( Y4 f& ?, T- D$ M+ jto setup& K2 C1 c! O2 m% G% _
  ca
4 a) i$ W' L# F6 s7 D  setup-globals' V4 d" @$ S# F8 ?: i  W- K" t1 z

' p3 ]; c# M/ ?( z% y2 R3 y# ]8 G  ;; First we ask the patches to draw themselves and set up a few variables. c- j) b+ U! G7 f4 d
  setup-patches
9 P2 s) n7 ~6 s6 W  make-current one-of intersections) h" W- M( U# g" q
  label-current  k" c! ?4 ]+ i8 f- _1 [

( D3 j8 p. |3 g$ A6 t. C  set-default-shape turtles "car"* K1 L% e- B3 _5 ^1 h8 `

( p. ?$ Q. W2 _; @  if (num-cars > count roads)/ ~# v: U: ?' D* L
  [* k/ U# S/ ]2 r9 U, I( N
    user-message (word "There are too many cars for the amount of "1 v* r$ F7 m+ }1 x# v
                       "road.  Either increase the amount of roads "
1 q2 y5 _0 m+ M2 Z/ G                       "by increasing the GRID-SIZE-X or "# I( v  j) A+ E3 @2 _7 P
                       "GRID-SIZE-Y sliders, or decrease the "
/ x% w0 j3 Q; k) k0 H1 I+ o& d                       "number of cars by lowering the NUMBER slider.\n"1 s7 D+ i. a. s; `* n1 Y+ Z
                       "The setup has stopped.")/ A/ P/ }. ~' T0 A) O5 F
    stop4 T# r) S4 f' z0 \% P; }
  ]1 N& G4 t4 A+ i% ]/ Y: j; e" @& d. k
- T2 k3 F, E' i6 `
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color0 B0 t! ~! h8 q2 h' A9 ~, q$ N/ z
  crt num-cars3 w8 t) W* x+ U8 U2 i9 q" u% _8 i; j
  [
) G! U! i3 L" h, ?: r+ W    setup-cars
6 z/ z/ ]2 p# S* p& |    set-car-color& B, Z1 x; I5 j
    record-data
- O8 ~3 [6 k: T& l  ]
% P- t+ I/ B. R$ S4 ]& [& f; w: c# o  |6 b# Z- `' Z
  ;; give the turtles an initial speed9 y8 N& W: {# f
  ask turtles [ set-car-speed ]
) {0 a- N5 x9 F$ S* ^9 `8 Y5 n/ b7 B8 _% }% E: h
  reset-ticks/ R9 j- d1 B9 j3 ~- S  d2 I
end* {( ]& H' S5 }3 K, @; }. Q) ?
, p4 x1 N! u$ ?7 ~1 w8 u- \
;; Initialize the global variables to appropriate values0 ^! O0 _9 |4 ?/ Z7 J* t& T
to setup-globals; e; `+ W( t4 c6 L: [( U
  set current-light nobody ;; just for now, since there are no lights yet
# W* a. H3 P* v! q. U1 ?7 _  set phase 0
$ }1 W8 J5 W2 t  set num-cars-stopped 0
/ y& |. @+ m( `2 `2 D. P  set grid-x-inc world-width / grid-size-x/ h" V; I: F6 f/ Q/ s9 O: k6 C
  set grid-y-inc world-height / grid-size-y
2 H$ o! ]  \9 @  F) d
/ x% V. X3 x! C  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary% G; X/ T: A. I1 h7 u; J% m& G/ [
  set acceleration 0.099% [$ q2 K& ?9 Y- m; T1 T( G9 H$ j
end6 U9 m$ p  t0 x( j5 ?  C7 E" I6 }

, I, ?. k4 O9 D4 p;; Make the patches have appropriate colors, set up the roads and intersections agentsets,, o; t3 J/ s; V
;; and initialize the traffic lights to one setting& L) E9 N1 Y# R  z
to setup-patches
. Z8 f: E+ U, j& P7 p, [  ;; initialize the patch-owned variables and color the patches to a base-color& _# W) C4 e' G$ E
  ask patches0 F7 T/ w! W; `; a) C9 ]! y
  [$ x6 y* X5 K5 r0 N& q! B
    set intersection? false
% x: O1 D( X2 R2 g9 s    set auto? false) v& W9 N8 E% S: i- ?9 R' ~+ K
    set green-light-up? true: H. \% b/ K4 k1 k$ J" P9 L
    set my-row -1
- t, n3 [- X  O8 V: w5 B, I+ Z2 I    set my-column -1
7 x$ p0 ~# J! b! t: s" m    set my-phase -1) ~5 c( R! c5 S3 z- n% C5 M
    set pcolor brown + 3
4 N# ~  h; A) {( e7 P  ]
& C0 d; L2 x. s8 h- H- e0 f& B2 ]. B( _! l
  ;; initialize the global variables that hold patch agentsets
8 x  ^; {( I) e$ {& C  set roads patches with* M4 k0 T7 q9 v+ G  M5 R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 B# J5 U; c% |* n: F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 J5 G' X2 b1 |( O/ W& ~0 V3 L$ B
  set intersections roads with# }6 Q7 n1 s- n' C' P% g
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
6 z4 \& W/ E( C: j  y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" r# o9 }4 ~( K, Z# u

2 K7 H4 s! C0 s; P7 b2 Z/ A6 }  ask roads [ set pcolor white ]
- C3 O7 [( _  n2 i: G2 A    setup-intersections
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其中定义道路的句子,如下所示,是什么意思啊?
# M! ?- d" }0 X- n; s- a set roads patches with
7 U: s* o' B! G8 j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: {" k6 L9 ?2 f9 G4 Z! p3 {" a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) B2 y2 O/ m( _! }- I
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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