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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。
% O6 O- W* }( S" ~3 w* C. xnetlogo自带的social science--traffic grid这一例子当中,
; N5 @2 q, ~$ {. ?5 u9 iglobals" n$ r' P2 S* [/ l
[
4 M- P7 i9 F5 O- J) ]  \2 S$ ]  grid-x-inc               ;; the amount of patches in between two roads in the x direction, \  o3 ~* t/ `/ A
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) z7 D& w* f: S0 q. N  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
8 G3 M0 x" o2 B+ @+ Z  d% u5 I                           ;; it is to accelerate or decelerate; E- y; H( t; U! P
  phase                    ;; keeps track of the phase9 g. \8 p+ Y' `5 x. D2 ]2 ?
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
$ W. H3 O7 f. ]5 w& U  current-light            ;; the currently selected light
+ |5 s# [2 N" |5 v
1 `: ?0 q# L9 B; O% m" {  ;; patch agentsets
% P7 _3 R% q6 @( d: y& S  intersections ;; agentset containing the patches that are intersections2 P1 t+ j! J8 O; c9 G+ n
  roads         ;; agentset containing the patches that are roads6 w# _; h1 i' M$ \2 b
]2 Q9 ]  `2 F  T8 k, v1 o0 b
( m% Y: }! z0 q( y6 ~2 u
turtles-own% }! ^; b) }$ I, b3 p% S. C
[" N: R$ E3 J) H# a3 y) w$ O' N: }. h" S
  speed     ;; the speed of the turtle
( |6 N0 W2 o2 P- f# n  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
6 M( |, u8 F8 g& O6 i! _$ z( \  wait-time ;; the amount of time since the last time a turtle has moved
6 W. s  q4 H& c# ~# N) j]
) O3 N* ^7 I" Y
6 N$ t* V. o6 |4 J6 k  `' ~. Kpatches-own0 y8 p/ E" c1 {- H1 R
[
& p8 y. m0 `( J  intersection?   ;; true if the patch is at the intersection of two roads
9 Y' U0 |" D  P0 r3 i  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.9 K. J' d$ W- ?8 B
                  ;; false for a non-intersection patches.' g" L, H. c" F* a0 p1 R5 Y1 E
  my-row          ;; the row of the intersection counting from the upper left corner of the
' [0 ]1 b% w0 U6 ^+ Q1 e5 p                  ;; world.  -1 for non-intersection patches.
" O# P' e' o- C( S9 n  my-column       ;; the column of the intersection counting from the upper left corner of the* T) O0 A( j: N! G6 H5 e  b
                  ;; world.  -1 for non-intersection patches.+ H8 f7 i) M' V! Z, d
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.- _: M! ^' N4 D: k0 y' l0 \$ C
  auto?           ;; whether or not this intersection will switch automatically.3 ~3 R( y7 `/ ^) o. U, @( V
                  ;; false for non-intersection patches.
; p4 ]0 \. l  `, u. a7 s]6 g, p& T7 @& F* T, a; C8 O
& F* P  q+ f4 w: X$ v, C
" p( y0 q0 g% Y2 e. ?7 T" s- d
;;;;;;;;;;;;;;;;;;;;;;1 C* H$ B4 P& Q" A
;; Setup Procedures ;;
6 Q# |3 @% m: F/ g;;;;;;;;;;;;;;;;;;;;;;9 {" M$ b' z/ b

) i3 a' }2 k% }' @2 h6 f;; Initialize the display by giving the global and patch variables initial values.( H  O# B$ L- a. F) u, b( @
;; Create num-cars of turtles if there are enough road patches for one turtle to
3 ?0 N( R/ M, r3 L. {& ^;; be created per road patch. Set up the plots.: B1 x4 ~9 L. e0 O
to setup) |2 w6 N# P8 R, C$ N1 I' A1 _- j
  ca: P8 ]+ x( h/ \& l9 h" T
  setup-globals& u* e- W2 g6 ?' X* t
; A/ B5 Y. T# |+ L
  ;; First we ask the patches to draw themselves and set up a few variables  D6 b4 q1 T2 P3 z; X0 J; I" ^
  setup-patches
5 ?% O# g7 _8 ], I9 j' n( k6 c  make-current one-of intersections
. N- w& Y! T3 b2 f& t$ K  label-current: M6 I: q# m9 S# y* j/ f
/ h! |0 k) x/ W  T
  set-default-shape turtles "car"
" V3 F3 f) l/ P( j7 a7 L9 m' f. l, L& M
  if (num-cars > count roads)+ E7 A) ?& s4 k8 C0 X7 _5 O* E
  [$ D+ d0 j% Q$ N$ `6 Y9 h* U; j
    user-message (word "There are too many cars for the amount of "
- p  |4 [/ C5 \. B' \3 a1 ]5 F& a                       "road.  Either increase the amount of roads "5 g9 C5 F* u/ G( l# _5 ?' v6 h8 X
                       "by increasing the GRID-SIZE-X or "* y& b! O6 v" g
                       "GRID-SIZE-Y sliders, or decrease the "
4 `5 n$ a( y+ j% k" G# z                       "number of cars by lowering the NUMBER slider.\n"; p) O* Q& M# H8 f& s( ^* m
                       "The setup has stopped.")
( M" u7 D1 N: T% O5 W    stop
, s  ], o( D7 ~: B) u  ]
# a+ O9 S! q, V, ^% D  e- _! E$ z" i% n& q
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color+ Y# l8 `; i/ o% P
  crt num-cars
7 y! ~+ N8 E1 g7 @& o+ F  [& W( ^: L/ X) t' P, G' Q. f/ W) T
    setup-cars
# J# i5 y+ u( f6 U: s" D    set-car-color, j4 P* U) h) C
    record-data
  _6 x5 O+ c5 `, O& v4 C! W  ]
6 [! C7 j! v: Q
* }* Y3 E' E, E. H8 _  e" v0 h" B  ;; give the turtles an initial speed- m: P3 n) ?, U* q- o
  ask turtles [ set-car-speed ]
. A) l& u' B( `; `+ l9 l* D9 g8 G2 h- B* d
  reset-ticks
4 B" k/ l) H, q  L0 tend' k9 r& ~2 ]2 f3 }% h. Y; w: V
$ W1 r, |3 P; t2 N( p
;; Initialize the global variables to appropriate values
# u. z/ n$ k4 K4 U" b9 Oto setup-globals% J& o; U4 d9 K) P1 V
  set current-light nobody ;; just for now, since there are no lights yet
- A2 L! u4 X- Y  set phase 0# u; _* c8 p0 X) d# B$ K
  set num-cars-stopped 07 M% E& a9 R3 y- j; G- M) @
  set grid-x-inc world-width / grid-size-x
3 Q5 h* E$ \! l4 n6 E7 |  set grid-y-inc world-height / grid-size-y
/ `4 ~* N+ U4 w0 C3 B  R
, v" i+ u1 D/ C6 c- X. [/ q1 B  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, @) e+ R! D9 u6 l% J8 b7 M
  set acceleration 0.099
# v) N; l' N! u  ?9 Y/ ^" wend
' o6 Z, M1 Z  t: S1 ~$ A) C; {9 ~7 z9 U
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,' ~. X9 I9 i- _8 f8 _$ Q
;; and initialize the traffic lights to one setting1 J' S* B. U- ?; {$ t0 _1 N
to setup-patches
, r5 t& C# w! B  ;; initialize the patch-owned variables and color the patches to a base-color! P9 K* h; c& P8 Z- H
  ask patches3 l8 c: l( }, a" ~; Q, |: W+ s+ {; S
  [1 r1 z8 s. ~8 N% q6 U
    set intersection? false
$ `* D7 c3 v9 ^" K: ~    set auto? false/ n" p. J9 f* F4 ~8 h
    set green-light-up? true0 h' y3 V6 k5 l3 L9 s! [' A% U
    set my-row -12 h. a# ?4 d( Y7 L1 ~4 {
    set my-column -1
: Q& C0 l9 W% C0 [( r( }$ F    set my-phase -1
; K# N' u! R' h; u/ `" T- D    set pcolor brown + 3, |3 q$ t- C; Y+ M* D! ?
  ]
7 E: y* h6 I% h+ C) n6 @( a; X* i7 r! _- E1 M
  ;; initialize the global variables that hold patch agentsets
/ R6 r. `) x( t! o7 A+ K  set roads patches with5 V" L0 v9 j5 Z8 Y8 }1 S
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 M* @/ M, X4 w/ w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. B( Y: [" e7 w" Q4 P1 {  set intersections roads with( E' _( r) i3 e) V! q2 s7 c' n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
# D3 c9 q2 ]1 Z- ?7 l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" I7 ^" s  ~- n  r; y( g9 c( Y6 `
. z9 V* O+ X- B/ E8 T0 b  ask roads [ set pcolor white ]' E  j0 R0 J5 H. o, u4 c4 ]- I
    setup-intersections" \% P9 v8 H7 w9 o: a# g
end
: e2 z) L! Y* y* V  y! q' }9 L) M其中定义道路的句子,如下所示,是什么意思啊?/ ?( \! i$ Q& w' v! `, `( B
set roads patches with
* o) H3 j" A! L0 W' h" Y. ^+ M    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 D! f. o- E2 I/ B8 Q, T- Q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 L' R* n( |; P8 k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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