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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。
- p; y4 W$ v4 R0 ]0 |netlogo自带的social science--traffic grid这一例子当中,' R! g1 Y1 f2 V2 L4 D: G" j9 y( x
globals
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  grid-x-inc               ;; the amount of patches in between two roads in the x direction
/ v9 D7 x+ o! P  grid-y-inc               ;; the amount of patches in between two roads in the y direction! I$ J( G, l9 |  D4 }" }; D1 H
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if1 c+ G$ E- B) v4 P$ A
                           ;; it is to accelerate or decelerate5 a1 c- C  N9 t( s
  phase                    ;; keeps track of the phase
0 [' T. s+ k+ a6 O& L  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
" D! m% ^: ~4 h2 z  current-light            ;; the currently selected light
3 H: L) E# w& l
+ Q. W3 R" Q9 g8 ~- w9 i+ ^/ _* h' h  ;; patch agentsets! w+ ]: o( R7 \+ `* e6 L- L( |
  intersections ;; agentset containing the patches that are intersections
  H" U/ b, [, t8 a2 G1 g2 M# a  roads         ;; agentset containing the patches that are roads( o; Z2 \2 o" e. D
]
: S4 X$ J0 x+ f* K, F+ ^% M% J1 N  |+ g! |, t9 P/ k9 v! l
turtles-own
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  speed     ;; the speed of the turtle
! w+ o4 d, \2 M/ a6 ?/ Z  w  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
. c7 U! Z* Q9 }+ y) ?# q  wait-time ;; the amount of time since the last time a turtle has moved
# D0 ?* H$ j: N# Z9 U7 `7 v0 w]/ v2 ]8 @3 i1 L

! G& B+ J, z" e1 M6 u" f9 xpatches-own
$ T; c/ [8 e/ x7 Y4 V[: Y, m: |9 s* A
  intersection?   ;; true if the patch is at the intersection of two roads  P. S1 e* s& ~$ ~
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
2 u0 V! a  _! P% ^. X9 f                  ;; false for a non-intersection patches.
) e8 k# g  }6 F- ]: N/ P8 q- X9 C# w  my-row          ;; the row of the intersection counting from the upper left corner of the" @/ B2 K! o0 O; i& B* `, O
                  ;; world.  -1 for non-intersection patches.
& U) x. w$ l6 A4 Z# o: @7 d6 }; T  my-column       ;; the column of the intersection counting from the upper left corner of the! R. Y  o. x, E2 v! M+ q
                  ;; world.  -1 for non-intersection patches.4 r8 m. e) v+ _5 _
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches." O& T( K( Q$ b- k+ A
  auto?           ;; whether or not this intersection will switch automatically.9 G; s/ c" Y! ~  |6 k
                  ;; false for non-intersection patches.
0 O6 ?; j9 }# j3 u]& X. N$ x# ^. u5 V7 ?0 V$ S

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& W1 S( U% G' j7 c6 Y0 \;;;;;;;;;;;;;;;;;;;;;;
2 i( Q/ ^2 S5 ~4 X7 _;; Setup Procedures ;;! t, o, ^; U8 d1 N% D
;;;;;;;;;;;;;;;;;;;;;;
, b6 c! y; K4 _: K0 O+ p3 h5 H" a% {
;; Initialize the display by giving the global and patch variables initial values.
! ~+ C' p) H2 L: u- U% ]8 b* b+ t+ ?;; Create num-cars of turtles if there are enough road patches for one turtle to2 Q2 f8 Q! z+ D, |8 a8 R! @. D/ k+ H
;; be created per road patch. Set up the plots.
( ~$ m5 O9 k4 V( ^: }! s. zto setup! U: K' N( n  }
  ca
# i7 R' t: K4 J, N( r  setup-globals3 y/ J/ I: z6 M6 N0 w

, Q! X% `8 v5 l$ R8 Z( \# s  ;; First we ask the patches to draw themselves and set up a few variables
3 b, y, D/ s1 i5 y/ E  setup-patches8 h! ?( l, O$ k& O# [+ i
  make-current one-of intersections
) K, I& i9 R+ k6 G% u  label-current" [4 S3 P$ ^$ [2 w0 k
! f5 {- J: G! O/ d$ p
  set-default-shape turtles "car"
+ _# G4 |" c% b$ C: T! f' X* o& T* ~: `3 H- u7 j+ o3 F3 N7 k
  if (num-cars > count roads)
5 q' H7 F* Q$ c. j* T( L. ?  [( N. h, m2 `/ a% p) U
    user-message (word "There are too many cars for the amount of "
. l6 b! x3 F% e: I& u# c! Q. z                       "road.  Either increase the amount of roads "2 {1 l  ?. i6 {9 Y! F; r6 b. o3 q
                       "by increasing the GRID-SIZE-X or "0 W, i9 U2 M/ P8 q
                       "GRID-SIZE-Y sliders, or decrease the "
. G# {- r+ t0 g; t                       "number of cars by lowering the NUMBER slider.\n"
' e7 e* H/ ~! O                       "The setup has stopped.")* }. o' L6 t, W. J
    stop
6 D. @; M/ X5 Y: p* {1 k2 w  ]0 A( v# @2 d. g4 C' e

) u( h1 E; o  e4 R1 ^  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color! d. ^- x2 Y' i
  crt num-cars
" Q" ^; w6 l1 D+ Y* P8 K6 I8 k  [
; t( T% K* o& N8 g% m# ^    setup-cars& M5 e) `4 R* B% f  ~7 C, w, S
    set-car-color
9 z: g0 z, i0 V" F    record-data
3 U) ^, p' G( t! b& z  ]
. ~4 G7 O8 A4 C5 H8 k, X( j8 n; j* _( A+ T7 }/ @: \
  ;; give the turtles an initial speed
" V$ i' l/ R9 {! \* e( v  ask turtles [ set-car-speed ]7 N3 c# w% O8 \3 M- {$ s. N$ ~
9 ]4 T+ N* B: j  j: Y* B/ b* q0 y
  reset-ticks
& O) U2 a" B$ Dend6 G; j! {5 D) D

+ m/ k$ Q! x; p- R& ~5 b5 V;; Initialize the global variables to appropriate values2 z( f' X' t- F5 h9 O  b4 e7 X
to setup-globals: |8 _5 k8 M) P9 b
  set current-light nobody ;; just for now, since there are no lights yet0 C% l' o7 a# ]/ n1 D" O' |
  set phase 0
2 Y# e  g  @0 D' G( ~; v. |4 F* I  set num-cars-stopped 00 K6 N. `1 Q; F# B. S
  set grid-x-inc world-width / grid-size-x
/ ^% L# M3 i3 L$ |( `9 ^  set grid-y-inc world-height / grid-size-y1 h3 J& j6 H6 W( N: ]3 s
: p2 v% q) E& j
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary7 y) E8 g* |8 o1 e7 X! n( J) ^
  set acceleration 0.099; U, W& p9 g) A( C4 \
end
" z! P. w7 I- [9 x+ B
# K+ {2 G# c7 S, |5 k;; Make the patches have appropriate colors, set up the roads and intersections agentsets,# ^$ w0 z6 b0 b3 F
;; and initialize the traffic lights to one setting. ?* |, _8 L$ k: U- M$ d
to setup-patches8 O6 |: G# j# p* F9 W9 O4 E1 J9 P
  ;; initialize the patch-owned variables and color the patches to a base-color
* Z; D' i3 }& u" _  ask patches
' q+ v9 P6 x, j9 c5 V0 E  [
2 p. e$ w4 T9 Q( X1 Q6 k    set intersection? false3 l) Z) J8 E( y
    set auto? false& g4 x, q8 J+ y" t3 Y6 J/ b) r
    set green-light-up? true/ J5 L: L" Q  W' k$ }  g8 b, m
    set my-row -1
; [* x4 z5 S& W9 b7 U% c    set my-column -1' z: r( ^! |) _7 r# `
    set my-phase -1- u: H2 Q' y1 Z  `" M
    set pcolor brown + 36 j8 ]+ }1 K) l$ b* A
  ], r$ N9 u, R2 O1 x

% U( G4 g$ s' P) k. q, r  ;; initialize the global variables that hold patch agentsets
+ H0 @: c9 J$ s6 f; g4 s  set roads patches with8 P% [+ A2 O8 ^1 K  A" E% z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' e3 Q( t* M* W  X* [# N
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: T# N3 _1 u' [  set intersections roads with
" v! v5 _( ~3 _' J: c    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
4 Q2 ^6 ?% ~, A  H$ F    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 q( p. u& g+ N8 J
& Z9 S# y% P" m2 L
  ask roads [ set pcolor white ]
" r+ J$ K7 _1 c! B- Y( F    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?% e' D; ~: n  [' k+ i" t! l: r+ U
set roads patches with
' ^4 f  {, L5 B& K) |' k' T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. j' l* b( Z3 U  E5 \& }
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! O$ @( }7 H& W6 H
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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