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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。1 B) V: A. j! C
netlogo自带的social science--traffic grid这一例子当中,
/ g- y+ s, s7 D+ Fglobals
& x% c, y; H9 Q4 c6 h( K0 w5 ?$ [[6 H0 A# O' [6 F5 u: r+ n
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, {: m, x% @' g7 a  grid-y-inc               ;; the amount of patches in between two roads in the y direction
1 w/ n( W9 F( Y. F& p2 J! c  acceleration             ;; the constant that controls how much a car speeds up or slows down by if! t2 A- L- ]2 F: X! }
                           ;; it is to accelerate or decelerate
2 @1 Z+ R' z! n1 J% Y# `/ f# ?( h5 k  phase                    ;; keeps track of the phase0 a( E/ K6 B# q' F4 t/ ~+ H/ {- G
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure$ f9 a" I  C) A2 _
  current-light            ;; the currently selected light2 }  q( e0 t  w1 N, P! F1 P
* E" h& n' p5 a( o! N
  ;; patch agentsets
- g( Y7 k+ y5 x' Q. l! @9 s4 F  intersections ;; agentset containing the patches that are intersections
  i+ Y% Q& C- `% N: o1 D  roads         ;; agentset containing the patches that are roads$ e% @8 G+ P5 c# d  u5 x- U& V
]
: b6 S& ^, X3 q% k- K/ m7 U
6 L2 `9 q; H! I& s# Yturtles-own% T/ v" \  q$ D6 R+ A' ^1 C
[7 d4 k+ B! v! R/ N) u$ m  Q! Z
  speed     ;; the speed of the turtle/ A1 F+ E! x. ~* P+ @5 x
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right/ m1 r* f% U: a: X, M
  wait-time ;; the amount of time since the last time a turtle has moved
' T8 ]2 [- N$ M+ {+ T' v8 E) A]
% p) i* ]+ x* `* O2 O0 M( y% e
/ V- \9 m5 |$ S, i% r+ u8 xpatches-own
# n; n0 z" D2 n[" ]. c9 c7 O* z( |
  intersection?   ;; true if the patch is at the intersection of two roads
& l$ E9 O. W6 t  \6 F  {7 \( T  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.$ Y# @" x$ \; `4 I- `6 o# ]3 \  ]
                  ;; false for a non-intersection patches.6 T! n5 e( C0 D2 u7 E
  my-row          ;; the row of the intersection counting from the upper left corner of the3 q% Y8 {: q) N0 I- `* p
                  ;; world.  -1 for non-intersection patches.; j1 ]: q8 }/ N7 s& K6 k
  my-column       ;; the column of the intersection counting from the upper left corner of the8 o5 A  ]4 z7 M8 j
                  ;; world.  -1 for non-intersection patches.  O3 |0 N" T" O6 }0 L$ k
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.2 J  A& t6 Q4 u% M; n  A5 N
  auto?           ;; whether or not this intersection will switch automatically.3 M+ B$ _9 M1 C0 [  d: _
                  ;; false for non-intersection patches.4 b; A5 V, L  D
]5 a  Y$ V+ g" d! _. ]) }

9 o2 s* h: p" p) n8 T
0 M' q: i2 Z/ g/ v8 W( `;;;;;;;;;;;;;;;;;;;;;;# I" q" O' i$ @
;; Setup Procedures ;;) G' h& n9 x* k/ y- N
;;;;;;;;;;;;;;;;;;;;;;
9 c4 [; h/ Y. D; W
7 s* y* M3 w/ \/ t" `7 P;; Initialize the display by giving the global and patch variables initial values.9 l$ w1 l. D6 C
;; Create num-cars of turtles if there are enough road patches for one turtle to
& ]2 T- g5 g. f: ]4 _. H" E;; be created per road patch. Set up the plots.
( g# I5 Y, A4 b2 Mto setup
, g. i. g' m' r7 U  ca2 Q: q( w$ b7 f3 F5 c" z0 e3 y2 ]
  setup-globals
4 K( f8 W* f* w7 y9 h% }/ d5 B: [! C+ D5 a
  ;; First we ask the patches to draw themselves and set up a few variables
1 z8 f0 g8 ^" L8 a! h/ s$ t  k: \  setup-patches
) z+ i( {9 j% q/ R- R7 i" ]+ ?  make-current one-of intersections! R% X' M) k  M$ |: k: ~! C/ U" d
  label-current; \! U! u1 d8 ^0 O  ?) Y
& w2 j  n* w/ @- E, k* V
  set-default-shape turtles "car"
, i% U  f+ D- X8 V) p) r- S# d
7 x6 J3 m4 ^: h- @& T0 B) p6 y  if (num-cars > count roads)  F. i- d& P" r9 _  ?' F2 R' G
  [% N# h& f" p+ X3 d
    user-message (word "There are too many cars for the amount of "
; L( v$ N% X9 q) _2 m+ a                       "road.  Either increase the amount of roads "
5 D) {# A  ^8 a* _# W* w                       "by increasing the GRID-SIZE-X or "5 `! F% U! U! Y% Y8 a  n4 v
                       "GRID-SIZE-Y sliders, or decrease the "9 ]/ H4 ?% k9 S0 p4 P6 ^- T2 P( W& n
                       "number of cars by lowering the NUMBER slider.\n") z# t$ N' Q2 m: {6 F2 J. X/ t
                       "The setup has stopped.")
( c9 ]: I2 E- P1 X. ~: C7 G4 F    stop0 ~; h$ R+ w4 V5 C. a! N8 b% C
  ]; g& M; n4 p. r# ], F1 d( V, |% u
. F+ b, n' Y( D2 f
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color, u1 g  {, w6 A7 h
  crt num-cars7 T; B0 ?4 C0 m& I# }& |7 `8 Y: ^
  [+ ]! S5 \# p+ H/ G
    setup-cars  u1 n, O4 ~/ g0 w0 t  \2 [
    set-car-color
6 `! ~+ N* }$ j* K    record-data' t5 v, |5 @3 C/ J! n% N
  ]
5 x1 v' o$ S4 Y8 L7 r8 v& P) B  F# f
  ;; give the turtles an initial speed4 ~9 [3 J6 _( B/ Z1 v! N
  ask turtles [ set-car-speed ]+ E: ]0 v) H7 W9 v, i+ Z4 O3 q

+ ?6 N9 M" f0 r  reset-ticks1 ~% b6 P4 |; W" h
end
* r6 y8 _& r9 W) i' `2 {3 q/ u
9 Y* Y7 \: @; [, Q. o;; Initialize the global variables to appropriate values9 S1 F; s' V$ U, _7 B& N
to setup-globals  W  z8 b1 @3 }1 V0 M
  set current-light nobody ;; just for now, since there are no lights yet
$ ]) \  @7 t1 g# }$ X+ b  set phase 0! b  @6 m. ]1 j9 \+ F* G  M3 v# x1 R
  set num-cars-stopped 0' @* t3 C  q; @- t2 B8 f$ w" B
  set grid-x-inc world-width / grid-size-x
6 f. }+ b2 H& B( ]1 w& B. I: O  set grid-y-inc world-height / grid-size-y0 p( w, y3 t3 j. `+ r& y  S6 @  V
* D% l( g+ I& u& l5 D  D( u
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary7 l3 R; r% e9 K9 r1 h0 u2 F. F  p
  set acceleration 0.099
, x& s  _8 _3 m) ?' b; t/ n/ Cend1 ^! n/ j' o7 S+ |

- N. J. U6 S5 ^1 w4 B* |;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
7 ~( ?" v6 _2 k5 ?* @! [* c; Z! h1 D;; and initialize the traffic lights to one setting
5 q, r" w) |* yto setup-patches
6 S( I6 a5 o. v+ h! f; J8 G  ;; initialize the patch-owned variables and color the patches to a base-color
$ |9 f0 e) V3 N1 v  ask patches' Q1 H% b! d* Q* A
  [& y$ d' u( B6 O6 y: w4 ^/ X$ c0 o
    set intersection? false! |6 z8 T, N+ _6 r( _" r
    set auto? false/ l9 J' Y8 h  [
    set green-light-up? true
& C" H& _: W# X. D    set my-row -1
! y1 s; M0 O! {" {, u    set my-column -1
3 Z) u1 u0 g6 O/ Y0 v    set my-phase -1( g9 |( o9 w4 N- @
    set pcolor brown + 3
& j" B1 ?7 R0 p$ ~9 |  ]# J4 c& m! z7 X
" ^6 y6 H4 j0 ^2 \0 ]' Y, }  g0 e
  ;; initialize the global variables that hold patch agentsets
: o# i8 `- B: J  set roads patches with- e1 O% D' F, R" C" U/ |5 u  \( ~
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  {! G- s0 u# p. X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 s* ^" f# }. s& \% k# i
  set intersections roads with
  r. G- v1 q2 u$ L3 B    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ l$ Y. ^6 o8 x* H( G9 ]) V+ I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: _/ h% ^# B% f4 w0 T
. T7 D1 I" o: E6 D4 Y
  ask roads [ set pcolor white ]
; N4 {2 P$ X+ z8 \, N3 o    setup-intersections
# w+ }' ?+ \5 C% iend$ z. o2 [# M9 ^2 a+ Z. R
其中定义道路的句子,如下所示,是什么意思啊?
* o- j& C/ q6 Q, d3 r set roads patches with0 q: H) W) ^7 |! V/ e# g# ]9 ]
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 c2 U# v! k9 ?    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. K# _5 ?. _5 C7 X/ G8 S
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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