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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。# o3 M8 B- P; S0 f% s. ~3 p- T
netlogo自带的social science--traffic grid这一例子当中,$ A% T0 n1 H2 J
globals7 V1 |! E) Z8 g* [7 o' j5 D
[# x+ s( l0 _$ L% ~
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
" o) R, b  H$ d: S+ J! g  grid-y-inc               ;; the amount of patches in between two roads in the y direction& l& K4 V% h. z7 O8 y
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if8 U; C& L- s" ^+ ?3 C
                           ;; it is to accelerate or decelerate( \9 D# M0 X  c% m" i9 F) n
  phase                    ;; keeps track of the phase
  P1 G6 \4 l& _9 {* c$ `" i  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" }8 Z7 L" f1 v
  current-light            ;; the currently selected light3 c" {: j# h$ ?
, J7 w' E& x- x1 ^  s
  ;; patch agentsets
  M  G# H9 M9 b, T( `  intersections ;; agentset containing the patches that are intersections
  Z4 o8 a: n$ [9 N' [  roads         ;; agentset containing the patches that are roads( N4 H9 v5 u  \' L
]
) \& {* C" o( J2 r: w. l9 {$ u* \; n8 h! }2 e7 s
turtles-own
5 H8 F9 J) O8 G0 z) Z( a[
" _, [5 e) ^' m5 _0 ~1 X0 l) ~  speed     ;; the speed of the turtle
: l. z" u" z7 U  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
3 Q' I) J) c6 E& F+ R0 h& \/ t  wait-time ;; the amount of time since the last time a turtle has moved7 U7 f* F" c2 C( o" g* |
]! m) j" b2 w7 v- b/ D' n- s) U

9 ^/ X- x7 N0 O+ T! |  U: bpatches-own
; U% \' }& T, l[# i/ M3 l, S. x  m9 I" a
  intersection?   ;; true if the patch is at the intersection of two roads/ q/ A3 Q1 D' M6 @; e* \( k7 N
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
, ?$ \4 U+ Z" X                  ;; false for a non-intersection patches.
1 M" h) B! c; U% F  my-row          ;; the row of the intersection counting from the upper left corner of the
* r; n( b6 p2 f/ R; w                  ;; world.  -1 for non-intersection patches.
" G/ G1 [0 B, F0 D1 s  my-column       ;; the column of the intersection counting from the upper left corner of the9 W$ K# l4 c9 R7 C
                  ;; world.  -1 for non-intersection patches.5 n+ f* b1 [5 v% }7 t  b
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.* ?% B$ D1 H$ E$ z( y3 H& n8 S6 R4 l
  auto?           ;; whether or not this intersection will switch automatically., _9 Y0 F) m! p' r1 `' |4 o
                  ;; false for non-intersection patches.
9 F+ D6 Z" N  [5 Z]
7 _; z' }9 m) S3 V$ u2 }  ?
% ~0 `4 ]+ L2 j. a0 j! ~( Y& [# }- f" B* W; p& b$ N
;;;;;;;;;;;;;;;;;;;;;;/ b0 d$ k0 M' W. I) X5 p; {% g% q  G
;; Setup Procedures ;;: Z; p2 J2 X! ~* E
;;;;;;;;;;;;;;;;;;;;;;7 ~3 k( f0 G! u, z$ ~* H: p# U7 R
: h! L) G) Q, R( ?. P0 C9 Q0 A
;; Initialize the display by giving the global and patch variables initial values.
, [/ Y7 p4 u4 U( P# S# g;; Create num-cars of turtles if there are enough road patches for one turtle to' L1 n! _) t1 r, }& ]
;; be created per road patch. Set up the plots.! d+ I& m. V3 y' g  P# h+ W! R
to setup
3 V7 c. {7 E$ O- [/ D  V& b  ca& w5 J" W; R, h! y# s; j" L
  setup-globals& z. o$ C* w$ \

' |5 p& C9 {2 r2 M" f  ;; First we ask the patches to draw themselves and set up a few variables9 i1 l% M' ^6 B. x- S+ I. m
  setup-patches
1 Q1 Z% r( ^1 W* J! C- v  Z/ X  make-current one-of intersections
7 u/ F/ Z, R6 q, y  label-current, K3 Z) p# O2 z* v! h" `
% r$ @5 N4 @7 x! S" d
  set-default-shape turtles "car"
5 ~; M. j, ]! L7 p7 X) c% ~' y. Z. B# S! R+ X) E
  if (num-cars > count roads)0 B! C( h0 x. U2 z0 A) W' a6 ], R
  [6 r/ t" ?2 @1 W1 I6 x) n
    user-message (word "There are too many cars for the amount of "
6 V- C8 S2 B% ~# m                       "road.  Either increase the amount of roads "' ]& R! W# V! F' W
                       "by increasing the GRID-SIZE-X or "
. q; B1 i0 }6 S$ d# y% {                       "GRID-SIZE-Y sliders, or decrease the "
; t4 x/ s2 M7 m& L4 A# m                       "number of cars by lowering the NUMBER slider.\n"0 D+ S4 [% O6 ~6 [+ f( o" D
                       "The setup has stopped.")! A$ P& S9 g0 W7 }- B
    stop
& B& r& G) I# e% q3 V' L# c  ]* {) a1 l; V- b

+ d' @# ]0 F- E; h  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 U' h* @/ n+ \* v
  crt num-cars% ?) n( x/ x6 I6 t: c
  [6 W3 o5 T& @) Z2 a/ j
    setup-cars
2 p/ ]  }9 l. |, T    set-car-color/ k$ t6 J3 v7 P# {6 b  d& S
    record-data
5 L6 E) e" H9 ?$ A& P, c& ^  ]
+ T" P$ f5 c" I4 D3 v9 Y  W3 q4 m, Q8 Q
  ;; give the turtles an initial speed
5 Q- M' i$ l5 v, F  ask turtles [ set-car-speed ]. t' x  F2 M8 Q0 f/ O" T  a7 b# T. d
$ W7 T  X3 c" E* I! L5 N( d
  reset-ticks
, ]" v2 p" [& A, M6 G1 _end3 M0 B- z5 ]; e. ]0 p9 c5 v

+ Z$ B  D, m3 p* M9 c6 j$ Y" A# D;; Initialize the global variables to appropriate values
5 X, Q# S, E6 h3 ~! vto setup-globals/ S. ]3 Y( q1 |7 _* E- z/ \) _( _
  set current-light nobody ;; just for now, since there are no lights yet
! k7 k5 |  A+ _& [: c$ @; l  set phase 0
7 R: r* E2 W2 `. n  set num-cars-stopped 0. \( w$ ^+ R( `" m  t1 F7 X0 X
  set grid-x-inc world-width / grid-size-x
5 y9 P$ }. _( Y- M6 b/ i& z  set grid-y-inc world-height / grid-size-y3 Q# z+ r6 a. R" k! X2 s5 n
; J+ g% v: O/ K5 L
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary4 G5 ^" ^7 I4 P  s" \* @
  set acceleration 0.099; ^) \5 V  k/ g& e8 u
end
/ W  R3 g' ^; ?/ T: P5 x) M+ @* z& W0 S' @; d& g0 P
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,2 a# N3 [* ?# L- n3 F( A: ]/ x
;; and initialize the traffic lights to one setting/ ~5 C; `8 s% N9 l- {$ f
to setup-patches  k# ~5 Q6 H( X4 l+ V, Q
  ;; initialize the patch-owned variables and color the patches to a base-color- v. i( u, N+ I) Q  F7 G
  ask patches6 k; S! @9 k0 f
  [
, H/ b% _0 V) H7 d4 |2 O    set intersection? false! Y, F0 W6 J* _2 c% o
    set auto? false- f" e  b5 v9 _4 m
    set green-light-up? true
7 v9 U' s/ K) L1 f4 w, A  Q* F    set my-row -17 m0 w$ V1 ]4 o5 s4 `3 T1 i0 k& I
    set my-column -1
+ i* Z! J7 u0 \) ]    set my-phase -19 ?! S% n  t8 c- z9 }
    set pcolor brown + 3
3 P3 @0 L6 ^& I  ]2 q' c/ a! t& G
& [8 W& j# P- `
  ;; initialize the global variables that hold patch agentsets+ P$ R# v# D3 R+ U
  set roads patches with" d, Y9 a' Z. \& q0 j6 C2 l
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 M: Z; P1 E8 l/ m5 l3 y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 k+ \( l, ?8 a
  set intersections roads with6 A/ x# f# E$ Q3 S% a; N- N$ W0 R3 q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
; i/ D5 k0 _" Z; a+ Z# ?+ d+ h* i- ]+ G    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 `: q7 q- v/ I$ T3 U8 Q7 b$ L2 g4 h4 l7 b( d5 m
  ask roads [ set pcolor white ]
, a  g. k& x* e# h  }    setup-intersections  z+ j; a  l: w8 M
end+ c  h- [! r9 o3 ~, I3 Z
其中定义道路的句子,如下所示,是什么意思啊?7 ~8 A0 s- ]+ [! W- w  o/ O
set roads patches with' S- a) T6 h! v' A5 u8 Y+ B; g0 w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 X% m3 S% `2 h0 H7 ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* S( b5 k! z/ z7 x, S; [* h2 d# R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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