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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。" _$ K9 j" g" w/ `- D) w3 h
netlogo自带的social science--traffic grid这一例子当中,
6 T  ^" Z+ \3 y9 r) zglobals; a$ Z0 T0 L  U+ M( y+ [
[
( z8 M  R% [) s, A& S( h+ L  grid-x-inc               ;; the amount of patches in between two roads in the x direction3 j. N3 `) l4 M! d
  grid-y-inc               ;; the amount of patches in between two roads in the y direction& ]: Q7 E. a. e- R9 y7 K, O$ C
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 G% ?; c! Y$ x) i& K& k$ @# Y% |                           ;; it is to accelerate or decelerate
+ Z1 }7 X6 }  I; e4 \$ X  phase                    ;; keeps track of the phase
8 Z3 i: a/ S/ I# J+ f; `$ }  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure9 f+ b6 N2 @% v6 ]
  current-light            ;; the currently selected light
0 ~9 N* V1 e$ t3 g* N/ \1 ]* S: P% Q' c) Z  [' t$ r" t
  ;; patch agentsets3 A4 R. f: l# Q% H. C: `2 o' x# V
  intersections ;; agentset containing the patches that are intersections3 k$ a5 k' q# e  M. M
  roads         ;; agentset containing the patches that are roads
$ u5 D7 @. p! R  r+ w]
$ u9 f5 J2 ^/ Q% l/ F
/ u5 m8 J$ q' W) o) ?$ o/ kturtles-own
1 [/ F5 i4 f( |[
  o; r% u: Z' h/ M. g  speed     ;; the speed of the turtle
0 y5 P0 u: _" }& G4 n6 d0 Q  up-car?   ;; true if the turtle moves downwards and false if it moves to the right4 W2 D6 |$ H( R2 x/ v
  wait-time ;; the amount of time since the last time a turtle has moved
5 C1 u  G2 Y% W7 ]8 _) }) P]: t4 E1 w# [+ W5 e: J

- f3 S' S. a4 s2 kpatches-own
, n3 \7 X2 I2 S5 M1 z' i& d0 x: I[# v5 [; e& N8 v0 |
  intersection?   ;; true if the patch is at the intersection of two roads
0 i; a; d* J, h4 _  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.! o5 t4 ^. X" J/ {8 T
                  ;; false for a non-intersection patches.
: J& O( ]7 P3 J/ @; A4 }  my-row          ;; the row of the intersection counting from the upper left corner of the
, F! x* ~) b; v* ]. {3 F* T6 M                  ;; world.  -1 for non-intersection patches.- A/ |5 k1 E" e3 N) ]
  my-column       ;; the column of the intersection counting from the upper left corner of the
. x  w9 _+ s, U4 @) j4 l                  ;; world.  -1 for non-intersection patches.$ U. F6 _& V' b& d- E
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.! t' |! w6 B9 Q7 a
  auto?           ;; whether or not this intersection will switch automatically.1 p/ b$ d: R2 O9 l$ ^% A! b/ r
                  ;; false for non-intersection patches.
: J5 p2 C4 B4 j( _; [+ g4 P" ^]
9 P- l! _1 m+ v& x# X; N% _$ _) J  m' @. Z9 i+ D; K

  Z1 @2 I7 K0 P" Z- R;;;;;;;;;;;;;;;;;;;;;;
. I- ~$ `3 A9 x;; Setup Procedures ;;, i7 G/ a8 c. Z. T9 `4 u' a) ~
;;;;;;;;;;;;;;;;;;;;;;2 q% ~0 G; D# H$ [  U, r8 x

/ ?# ]: u5 w$ Y' o3 Z$ m+ J;; Initialize the display by giving the global and patch variables initial values.
7 r4 A! b  g; q# D/ w6 u1 W;; Create num-cars of turtles if there are enough road patches for one turtle to) Q  h# ~' _3 u$ p6 V: B2 o
;; be created per road patch. Set up the plots.
- T7 b% n+ L: Q& |* j7 E' U, Eto setup& ~; X( f; [$ w
  ca- n) c) i" @2 Q5 o" `) L6 W. r
  setup-globals
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# z6 N! I6 |+ i" ]9 x  }  ;; First we ask the patches to draw themselves and set up a few variables8 R+ D1 W; w& T9 @- ?' T4 X+ C
  setup-patches! |( O* E' K6 Z. p
  make-current one-of intersections) [  M: S7 k% R3 f" ^* M( U
  label-current
* x( l" A7 ~3 n5 d5 G  W0 o, R! \
  set-default-shape turtles "car"
* l' p5 [' Q2 w# j  n2 i: K7 v0 b" ?$ H8 M5 P# l
  if (num-cars > count roads)
* R+ l- z% m+ p) n; M  [3 M1 x7 \1 Z+ [5 `# h& ]
    user-message (word "There are too many cars for the amount of "
7 r% g6 I; `# D  f' p( E                       "road.  Either increase the amount of roads ", D1 H" d8 P! D
                       "by increasing the GRID-SIZE-X or ") j+ n) W: s: w' A% q; z9 @6 |3 i
                       "GRID-SIZE-Y sliders, or decrease the "0 K1 V9 |+ n. ~) |/ e8 a' A
                       "number of cars by lowering the NUMBER slider.\n") q0 O, N/ b2 [9 @
                       "The setup has stopped.")
+ D9 k9 ], s' C( R% T$ t' q    stop- a5 e' L0 N/ ^% O. ^
  ]
' P6 a  {# E/ B# J: D+ N* h1 @. t9 m0 g6 u2 j
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color( z# H& y5 o- e
  crt num-cars$ E7 o# _) p. D' e& r9 m& _9 a
  [
. Y% l# |! h8 q9 R; `0 c  w    setup-cars& ^5 _% p  u2 g1 Z
    set-car-color
. O+ H8 @  Z5 l  O5 S! E7 k7 |0 I    record-data
! X( b3 @7 ]- ~( E- u, {  ]
2 ?) M4 o9 o2 b( k1 |* e- |
. f; I$ Z7 g; D8 B- _% [) o( B  ;; give the turtles an initial speed: ~) ], N- r, Y9 D' ^) q& v
  ask turtles [ set-car-speed ]
4 R. X& H4 z3 W9 m: W9 K* I3 x0 n% ]! L( l
  reset-ticks
0 ?+ a! ]1 G9 ^$ tend
2 i- O2 v0 Z$ P! x8 O/ n& s0 ~: u  |; c
;; Initialize the global variables to appropriate values
4 u: s; I$ K8 z6 W% a) ato setup-globals  L1 R4 ^8 P: f% P# _+ A
  set current-light nobody ;; just for now, since there are no lights yet7 U1 P) p& H) n$ m  r
  set phase 0* C/ X9 e. X: M1 k* t) i
  set num-cars-stopped 01 g$ I: Z  ?- t% V' H3 W# x5 T- R
  set grid-x-inc world-width / grid-size-x
: {% J  q  o8 P' K! q# p6 Z  set grid-y-inc world-height / grid-size-y3 O, ^5 F% I  C# J

! |+ e  M; ]6 X; z9 E! ~, G  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 i) b7 g* R3 v0 t
  set acceleration 0.0997 S% R% d+ H5 f0 X  q/ ?$ ]/ F' h
end8 R$ N$ @) h5 i2 B( `" p
* E$ W6 {: h# u
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
( [$ ]( {- z/ ~8 `4 d) x. o+ H;; and initialize the traffic lights to one setting
1 |' ?: q8 v$ P% Pto setup-patches! G4 R" e7 V3 h) e  L7 C( v5 S
  ;; initialize the patch-owned variables and color the patches to a base-color
5 h% e3 j7 I+ |9 P+ W  s; M" m$ s  ask patches' d  k. S1 f1 V* J% ~6 i! y
  [+ L& a( [* K1 a: d
    set intersection? false
1 b+ r4 z( x4 B6 K/ k! t  \    set auto? false, ]' z& r+ N4 t. U! r, T) c  O
    set green-light-up? true
0 D3 ?) h8 e( L" K( j    set my-row -1
. e, q$ S4 e; z' Y+ J    set my-column -1/ h: W* T; `: y- U" \0 F0 D
    set my-phase -1
) @$ x. h$ ^' Z8 I2 t    set pcolor brown + 3
/ X4 x0 G/ n' Z6 J3 H8 {  ]# V. p# R- N% X
% @& R6 z- q" E( `
  ;; initialize the global variables that hold patch agentsets8 |' n% S* ]" B, c# P% Z
  set roads patches with4 T0 M/ Y; u' U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% I: {9 s$ e7 j6 y' l6 Q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) a9 x: }) J: @+ G8 t" \( v  set intersections roads with+ l  u9 Q% t. C2 D! h+ d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
9 o( W5 V2 P6 d& g% |4 o    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( _% q& C1 r; E
/ c. w" S# h0 D# M' }( h! s  _  ask roads [ set pcolor white ]
( @& D; L/ n' i8 |* [    setup-intersections
2 a4 M) k& H& h  M$ k$ Q$ Pend
; T' d, I* J) W! m% j其中定义道路的句子,如下所示,是什么意思啊?2 o$ \* T/ ~% B6 O* G3 ~. q  N
set roads patches with
+ v' q( ?' p( R& u5 H* w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. {! H$ e# h' \$ i0 N6 }
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# F  ?5 I8 ~7 {  N2 |
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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