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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。$ `& R/ c3 m) T" P
netlogo自带的social science--traffic grid这一例子当中,
3 B9 J1 j0 l* z/ {* O) C4 d8 Gglobals2 n9 A  x. m' @6 M) \9 h* R; ]1 q4 u" k
[
- c0 s' ^' v  E) l  grid-x-inc               ;; the amount of patches in between two roads in the x direction
2 S. u6 {) ]3 E1 T4 |# }  grid-y-inc               ;; the amount of patches in between two roads in the y direction
" I$ l( B' w" c, F6 q& H2 p) u  acceleration             ;; the constant that controls how much a car speeds up or slows down by if  e3 k7 C) \1 z/ B0 u
                           ;; it is to accelerate or decelerate8 w+ Z) G; |% Z1 B& t. D
  phase                    ;; keeps track of the phase0 h9 Q- [7 }1 Z2 }5 s
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
" M% ~* c& g( s  W3 w+ ?! A  current-light            ;; the currently selected light
0 j0 g6 s* M/ I+ P: f5 ?8 H4 i5 H% {. M6 N  Y
  ;; patch agentsets
+ O# Y9 y* v# J! P  intersections ;; agentset containing the patches that are intersections
6 ~6 a3 Y+ h+ Z6 r6 p  roads         ;; agentset containing the patches that are roads
  K9 `' t! Q; M5 u]. ^; K! k) u( E/ x1 ~$ F2 G- b
1 B; D2 g- @$ z0 y3 v# I. Q: P
turtles-own# i: R$ V) P7 |6 e. M  B6 q. L5 h
[
8 x9 Z' d' q, ?8 Q  speed     ;; the speed of the turtle
7 J# G# @- O. d& u* \  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& e4 c* Y4 ^4 k
  wait-time ;; the amount of time since the last time a turtle has moved* H2 a  |; C# c/ y- m
]3 i9 H3 O2 y1 j$ \6 P( C! _# m: c

! C; z8 r( G, Upatches-own( {) U+ D. O9 {  Q1 U
[
! s; z4 X; }, s$ B5 P  intersection?   ;; true if the patch is at the intersection of two roads
& r# B2 t& f, l/ E2 [  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
' x1 d" D9 |+ N, L3 O0 Y( u5 n                  ;; false for a non-intersection patches.5 ?: U( i$ E7 c* z% y- o7 i
  my-row          ;; the row of the intersection counting from the upper left corner of the; p0 Z" o# J. a7 g" K
                  ;; world.  -1 for non-intersection patches.
' @- q  v. v6 m& q  my-column       ;; the column of the intersection counting from the upper left corner of the$ }$ H" ]9 G3 l! n
                  ;; world.  -1 for non-intersection patches.
4 c% a; y+ O( o7 z/ b- l( `  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ m& Y& s/ _$ h
  auto?           ;; whether or not this intersection will switch automatically.
3 E& M! O; @; W" l% f                  ;; false for non-intersection patches.* `9 o0 U) D9 |5 t9 \( U' p2 A
]& h# e" q4 [. Q/ F  {2 w( \" f
  m  \2 j1 [& k" v1 a* R" j

; f, h8 B5 s8 X( B;;;;;;;;;;;;;;;;;;;;;;
( O) z* m/ m# q5 ~7 O0 J;; Setup Procedures ;;2 A0 z& c4 L0 g3 l; P- N+ ^
;;;;;;;;;;;;;;;;;;;;;;
& ~4 y6 }0 B) ?# @+ C# z$ ~
3 e; i3 o; K( I- r;; Initialize the display by giving the global and patch variables initial values.
. h0 ?- ]& Z( v2 ~9 l;; Create num-cars of turtles if there are enough road patches for one turtle to
* n* C2 _2 s) m; Z5 a8 v; q;; be created per road patch. Set up the plots.# E# s4 F/ b. s4 L
to setup+ F) `; E1 _- y" S( H) P
  ca# [5 a) i3 i3 Z
  setup-globals
6 }$ o* ~8 Z* X6 G
4 M. m) t4 f/ h0 s3 h% U8 s8 t  ;; First we ask the patches to draw themselves and set up a few variables
2 @( y  W! [& k% L  T" w  setup-patches
3 ?. I, \& x$ \; g# h4 |% G4 O  make-current one-of intersections9 h4 `" M' m& k( C6 a5 u) W/ S
  label-current
& s% e, ?& i2 Z" `
! o  I1 e, \- |" _+ v2 ?  set-default-shape turtles "car"% i$ J! S4 q9 E, t. N
& T5 ]4 I3 _3 Y- \2 q# e' {
  if (num-cars > count roads)3 V; {' S+ C; h9 Z5 N7 V  V
  [- P; J8 P6 z0 y! c
    user-message (word "There are too many cars for the amount of "/ W: X4 h5 V' t4 C4 K6 [8 r
                       "road.  Either increase the amount of roads "
! N! T1 ~" p. M5 }; L                       "by increasing the GRID-SIZE-X or "7 j. H, `$ g* ^8 t
                       "GRID-SIZE-Y sliders, or decrease the "5 k. ^, y, M$ Q5 ?4 _; c& W- ~
                       "number of cars by lowering the NUMBER slider.\n"3 V8 K9 b* P# g* G5 a% d
                       "The setup has stopped."): H7 c5 ~4 [9 Z/ l- t3 h) z. X. e
    stop! w2 K  Z, ]: J% R' f8 {8 r; H
  ]( ?/ G3 ~# A$ r7 u" Z
  M/ K( {3 b( }* G/ {3 m/ O
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
/ Y/ R; J' O3 X2 m" }# e+ n! e  crt num-cars9 b- S! j0 [- u5 O
  [
# _" G( b$ t3 \" i9 v    setup-cars
0 [' a2 L  u  U) }2 A    set-car-color' x5 R  i3 W. i4 {! v" u
    record-data8 n4 f' ^9 L( b6 _
  ]' Q0 C& l  O4 h$ p+ G9 c( |
/ b( ~6 i8 r3 n
  ;; give the turtles an initial speed
! J( v; f5 n1 p7 Y  ask turtles [ set-car-speed ]
8 S! F1 G9 P$ q2 Y
, B% F% X9 k+ a. }; B* G  reset-ticks
& w6 a2 x! z5 L0 qend
* n  _$ J6 s$ Y. n3 x" X7 O) G" Y8 d2 @1 {
;; Initialize the global variables to appropriate values' G/ a+ d& }# q. k) c
to setup-globals  ]" r0 N/ Q- l2 N! m
  set current-light nobody ;; just for now, since there are no lights yet+ H  q* P# m2 J0 x$ G
  set phase 0
/ }7 x2 P7 U, F' P( A  set num-cars-stopped 0& j& j0 v0 U  K$ i1 n: w
  set grid-x-inc world-width / grid-size-x
' a; }% X+ i! ~( S' h  set grid-y-inc world-height / grid-size-y- r7 u& i- \6 }7 E; s
3 K' S4 Y, ^* @# I5 T) R2 I/ |; u
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary. j6 R" J- e4 c) j$ J+ e
  set acceleration 0.099& j0 g, J- Y: G, ]
end
' |/ x) O$ U6 R9 b  k) ^$ F2 X3 |" A  M
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
) B8 |/ n9 R3 E;; and initialize the traffic lights to one setting
& o! }) |- I, ~: Vto setup-patches
8 D6 w; k/ Y2 _, p* o0 L  ;; initialize the patch-owned variables and color the patches to a base-color  W+ ]4 t% ~* x6 e' Q* ^
  ask patches
0 w- I5 n) x( k( T  [
0 \9 P! i5 H( G9 x9 M1 j: W    set intersection? false
, u6 R# W: J; b- V* k& I) l, k% i    set auto? false
! w7 d# x5 E; |4 @# U    set green-light-up? true
, @8 q: v! G( a& |5 N    set my-row -1% o: u2 Q" L! I- ?7 J
    set my-column -17 D" Z( X6 j  c; m" ?- O$ O
    set my-phase -13 G! b  Y( ^! p+ X9 ]* U) W
    set pcolor brown + 3* p' [6 f+ Q/ Z
  ]
& w6 F" W! G" x/ ?) C
  S, u, E$ Y8 z3 }  ;; initialize the global variables that hold patch agentsets
2 U& z# [9 n# l; q* K  set roads patches with  x+ u# W3 M% y* a$ t; V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; R' f* R; K! @) g- t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& z/ y/ z6 G# M5 Q& J# @  set intersections roads with
4 W  [, A! p/ C( J    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and8 |* f7 i& t: t5 `2 w+ w
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- E$ ?2 Y7 G) Q% t  j6 k5 `* q0 ?( X
2 o* _/ H$ I1 ]9 y* a& B
  ask roads [ set pcolor white ]
8 p/ J5 u6 Z& [1 t0 \    setup-intersections" }9 P) Z. {. N/ }* E
end
9 N; }* o0 C  l. H5 ], |其中定义道路的句子,如下所示,是什么意思啊?# }1 S9 G7 t: h9 B2 P' G$ r2 y" a
set roads patches with
$ R, R  k" `5 ~. b5 r3 I    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' I) O: q" p* q, I, ?- ]* ?
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; P/ E; y4 a0 D- z! o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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