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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。0 L3 @0 V3 W; J" u; d
netlogo自带的social science--traffic grid这一例子当中,
- D9 U4 x8 g" W$ _- cglobals3 M0 P# U7 v. P) _; ?" d- k, u* V
[, C/ w7 K+ ?4 Z% y
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% k# F8 E6 w/ W" k3 G6 Z  h* c- r  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 ^( T8 p# h3 I' s9 @5 l  acceleration             ;; the constant that controls how much a car speeds up or slows down by if  c% ^5 s. e; q" M' g* |
                           ;; it is to accelerate or decelerate  F' N6 ]) j; q1 F1 G
  phase                    ;; keeps track of the phase5 s6 f. ^: Y- V* Y  y" G
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
3 |2 Z6 z5 ~/ P6 v: Z  current-light            ;; the currently selected light& h4 g1 u* Q) p' {
5 Q/ W# q- v# F) Q2 Z$ ~' I9 x" [
  ;; patch agentsets$ L1 v. Z5 }  }4 J2 v+ P
  intersections ;; agentset containing the patches that are intersections
- r" ?- \* `+ t% {- H  roads         ;; agentset containing the patches that are roads- p9 N( O6 E4 h9 m
]/ D" ^0 _, j* \% t9 P; ~% h! v
) [. A* ^  p6 M  X' X; G! P+ t
turtles-own: ]: w8 y8 S( d! C; V* G
[; C; t0 m5 x+ a, m9 s9 V) \
  speed     ;; the speed of the turtle2 @* R4 `& p: M
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right9 t7 N7 X' X. E0 y/ Y. c
  wait-time ;; the amount of time since the last time a turtle has moved  B3 t% N3 s" ]3 y: g( E1 y3 O
]
: I: T* l" n0 Q+ f! c; D/ t; u- R6 m& k4 `+ J  c4 U2 a
patches-own
; V) ?, M/ e8 L. T5 ?& Q8 U[/ s. S9 {* }+ T; c% M3 n
  intersection?   ;; true if the patch is at the intersection of two roads
: n) ~0 I8 W" d" A% l  r  O* S: I  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 W, R" e" l/ D3 _! o                  ;; false for a non-intersection patches.
# `( `' H4 i0 Y' u. u" Z: s9 U) ~  my-row          ;; the row of the intersection counting from the upper left corner of the
" m5 c' s/ Z7 z5 B                  ;; world.  -1 for non-intersection patches.% x  c5 ]$ y/ z+ X8 P7 K! d. s# J
  my-column       ;; the column of the intersection counting from the upper left corner of the
. e3 y2 T3 K0 z  G" K                  ;; world.  -1 for non-intersection patches.
* c& {7 O9 ?( a3 m7 r4 r! G3 m  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
5 _, H# f* |; H7 l  auto?           ;; whether or not this intersection will switch automatically.
3 S' {6 x& L7 x' m! ]                  ;; false for non-intersection patches.
" y5 u' H$ S6 x( v3 v- z]
2 S7 ~1 I6 n. J5 r
5 Q" F* T/ q3 C
0 w. a6 s. l' c8 L0 Z;;;;;;;;;;;;;;;;;;;;;;
1 A0 h, T2 C5 s/ }& `& w;; Setup Procedures ;;
" P7 y' a7 T5 x;;;;;;;;;;;;;;;;;;;;;;% p0 y1 x0 y9 w/ l- g- }

: {3 x% n7 `7 d# b;; Initialize the display by giving the global and patch variables initial values.4 G# c* L& S/ P' \
;; Create num-cars of turtles if there are enough road patches for one turtle to
2 I- D: r! ^4 o' k;; be created per road patch. Set up the plots.
8 \# [; t7 l, e- k$ h) Cto setup0 e5 j9 B. d; K$ r- `
  ca# d/ n8 v0 j3 P0 G4 w- r- O5 A
  setup-globals
6 _7 ^4 v, _$ \, V2 Z' N5 m* x2 q7 [1 w3 ^- w& n
  ;; First we ask the patches to draw themselves and set up a few variables, L; P! Z3 ~" G" k4 {' ^
  setup-patches5 m7 I) t1 O2 ~1 R6 c, g" h
  make-current one-of intersections+ W, h+ E" @% C7 Z9 c8 V! Y& h
  label-current1 C& q  S: b3 N
& T  @$ q& Q3 T
  set-default-shape turtles "car"
& ^0 Z6 U& ^. R
5 i* g$ T5 w% g. K, B/ U0 U& M1 T  if (num-cars > count roads)" E2 }7 A" K. c# I+ Z
  [6 a1 ^1 U. J  ?6 S% q
    user-message (word "There are too many cars for the amount of "
4 @- N: \- ?/ i, v, D                       "road.  Either increase the amount of roads "
* E" C( b* ^( i( _# s                       "by increasing the GRID-SIZE-X or "( {0 W4 U# O% K  A5 j# C. [+ g+ x
                       "GRID-SIZE-Y sliders, or decrease the "
, o8 y, B, O2 B  F2 e                       "number of cars by lowering the NUMBER slider.\n"
5 |9 a: u% J* O) i# |. J                       "The setup has stopped.")
2 Y# P: y. M' i4 i- x; Y    stop% F3 D, r+ s% y9 L$ Q; E  j7 p
  ]% h. y5 L% {4 Q* d+ Z, t9 _

. H  s5 f  v. t& `9 U6 `  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color3 ]# n5 K: b% c9 y1 q9 s) x
  crt num-cars3 Z# X' W1 z# ?2 q/ p
  [; h, V/ E* g4 ?* `* `& E0 ?8 [$ t
    setup-cars
( y$ y3 b" i9 [% a+ U    set-car-color' r# l+ C8 R$ z$ {8 H
    record-data- A# R) o3 a. u5 p
  ]
, O, {+ p* L# I# Z$ |0 |+ o1 M8 k" v; `9 @! t, y% [
  ;; give the turtles an initial speed
) [3 _# k& W+ ~& V! r  ask turtles [ set-car-speed ]- T+ X( [/ C2 v" H/ J) c% e

) V4 r/ m! v7 g5 p3 ^4 d, n  reset-ticks! ^" u% z# O& S
end
- L4 r8 u/ j  \% n  ]0 Q
2 T+ w* l4 _3 l, @1 ~;; Initialize the global variables to appropriate values
/ U' O# d/ s; J! g! J) x; l, f0 Fto setup-globals
8 A0 h/ G& K, N% b* @. n! ?3 g  set current-light nobody ;; just for now, since there are no lights yet9 G1 `: ~* f( _; H# K
  set phase 0
9 |# t% G/ T+ p3 H6 A( R$ r  set num-cars-stopped 08 T' H; U, ?' l  G
  set grid-x-inc world-width / grid-size-x& ]2 F6 w( J* \; e
  set grid-y-inc world-height / grid-size-y
) s/ ]- ]# w; g3 Q; y+ X
( m4 E6 C. V+ l$ Z  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
3 e# U6 j( J5 |: u  set acceleration 0.099
2 u) F1 a0 v, t- t- Fend0 B1 R0 H. K# D8 ]

9 ]4 N+ B- \% t3 F! y;; Make the patches have appropriate colors, set up the roads and intersections agentsets,: T- h& }+ w) f: u
;; and initialize the traffic lights to one setting6 a6 @8 P7 W% P% X
to setup-patches
+ L; r$ C) J' D! U/ N  ;; initialize the patch-owned variables and color the patches to a base-color
- O8 g3 a- {1 x  f  ask patches
/ A1 g) Q* r" t* \& P( G1 ?2 D  [7 l& C7 d8 p$ L: M) Y" f/ D! u, w/ W
    set intersection? false6 f. H7 b3 Z' a8 V/ c6 @
    set auto? false8 S5 k; V1 [. s, `
    set green-light-up? true
$ b) j: t, m/ Z2 I    set my-row -13 A2 s1 s; c/ I/ w0 _# i5 |: `
    set my-column -1" k3 p$ m( |# H# I, f
    set my-phase -1
7 U  ]* u+ g% T6 E. @+ F& y% k4 C    set pcolor brown + 3
, h. M. d5 e1 v) H: t: e  ]7 T% B) g7 l" C5 K7 Z% t
! t' v$ H, H5 ~: F" ?$ S
  ;; initialize the global variables that hold patch agentsets* L% T& n3 u* m
  set roads patches with0 n7 k, L# }" ?! M3 g& n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' T: [1 _4 N9 J0 Q* Z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. W8 P- S5 i6 W: A: Z
  set intersections roads with
$ G- f3 _  `# f! Q: B; w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ `9 g. w- `7 c7 R# K% S4 v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 Z5 H( [) \. c& n1 K2 l1 |$ \* y/ f3 C1 |
  ask roads [ set pcolor white ]
. I& C& B9 k6 F6 s7 c1 @) g8 D9 g    setup-intersections6 x% e9 o( e/ c0 X! p
end+ u" g6 q/ h+ j  v4 J; z
其中定义道路的句子,如下所示,是什么意思啊?8 @+ `1 k' c: j
set roads patches with
4 S0 d6 d4 U$ g7 D; B5 m    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* b8 m6 m1 @4 ?, Q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( M9 H" w1 g+ j+ ?8 i
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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