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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。
4 y" ?- P5 N. p0 Ynetlogo自带的social science--traffic grid这一例子当中,
2 t9 ?* h! l7 Y7 O& e5 C* Wglobals
. e) [- @0 y1 L. [[. y. y. O2 _" J6 N) V% \
  grid-x-inc               ;; the amount of patches in between two roads in the x direction3 Z  P* B$ V* z
  grid-y-inc               ;; the amount of patches in between two roads in the y direction, T2 }( {4 H. z" u0 o0 a8 P
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 {. P% s8 q0 e  ?                           ;; it is to accelerate or decelerate
8 o3 M* y) d9 d  phase                    ;; keeps track of the phase
/ \( X: Q9 Y6 i  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
- v1 P% H7 Q: |$ E  current-light            ;; the currently selected light: F  Q0 X/ e* z

' r  k0 T4 N; @6 `  ;; patch agentsets
8 i! W" z7 ?! w  intersections ;; agentset containing the patches that are intersections4 \- N: v4 W8 T( y
  roads         ;; agentset containing the patches that are roads" j9 T. V- S( z1 j8 a" A
]& ]5 V6 v6 t; @4 Q& m) P

: N) y, W8 v8 h0 k; f5 Kturtles-own
2 I/ t. J" b( D9 P- f5 X[4 Q# e5 }* e# a) w1 d+ e/ o
  speed     ;; the speed of the turtle% e  N- O6 K; C
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
0 q) r* Z$ g  V4 f4 h3 X  wait-time ;; the amount of time since the last time a turtle has moved# O7 q* ^2 X! E/ w7 j+ k
]
0 a% {3 `! @2 \' e4 F3 T: |  F: J) V& T9 N
patches-own
" @6 {- l% W! w7 A7 z2 R  M; \[9 }) S; P. x8 I$ G
  intersection?   ;; true if the patch is at the intersection of two roads0 @# [' `: t2 _7 Y( X" D
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.9 N1 T* t: K+ m9 F
                  ;; false for a non-intersection patches.  |+ W7 V9 S' X: }
  my-row          ;; the row of the intersection counting from the upper left corner of the
  U/ o0 A  G( a6 a' K                  ;; world.  -1 for non-intersection patches.! t2 r. ?, v" H+ z
  my-column       ;; the column of the intersection counting from the upper left corner of the: I; y6 @9 O: s
                  ;; world.  -1 for non-intersection patches.
2 S7 J( y4 C, S5 j: m6 w$ w  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 ^' Q3 j) }: u( g/ s: t. }: }, m5 P
  auto?           ;; whether or not this intersection will switch automatically.' O5 E: X$ Q: l
                  ;; false for non-intersection patches.
8 v7 o: ~/ ?6 _4 s]9 @2 x/ ~" G$ c0 k: [- Z, t

5 T2 j6 _  C7 q8 z4 ]) Y
4 _' |" ~2 L, R) e9 `$ Z% U;;;;;;;;;;;;;;;;;;;;;;
( x* T( v6 ~7 X' |6 S;; Setup Procedures ;;% O9 r( Q+ ]. y: k! G
;;;;;;;;;;;;;;;;;;;;;;" ^2 b6 @2 H9 Q

& ?8 V' U7 f) i7 |- g5 n8 W0 b5 G;; Initialize the display by giving the global and patch variables initial values.
+ C6 T2 y! R( w* s/ ~$ t;; Create num-cars of turtles if there are enough road patches for one turtle to5 A( [6 v/ a2 j$ N! h
;; be created per road patch. Set up the plots.7 v" U$ ~; J7 w
to setup1 S2 m/ s0 e+ L% ~- I
  ca
2 n( q; t. F  H  s  setup-globals9 H8 l) R* p0 I6 Z5 o) M
. n7 J) J9 e, h6 |2 t2 j3 M
  ;; First we ask the patches to draw themselves and set up a few variables/ a  E) e; s) _9 O! X7 h
  setup-patches: x. w8 r: e& q8 z# k4 B
  make-current one-of intersections$ j( r) F4 F0 q# H; i: J
  label-current4 e" J6 l- J3 S( R' M. L
) B# x) {9 N) x. x
  set-default-shape turtles "car"" z' F  w5 w5 b/ `
- j* x. ^7 }$ p
  if (num-cars > count roads)4 q# p) U: y3 o+ v
  [* r0 h/ g2 K3 `$ F- r
    user-message (word "There are too many cars for the amount of "
) a6 \  }9 R# ]5 [" U                       "road.  Either increase the amount of roads "3 L1 g1 g8 I( P4 X4 ?
                       "by increasing the GRID-SIZE-X or "
/ t, E' c/ a' D* R                       "GRID-SIZE-Y sliders, or decrease the "
% @. \& Z4 z5 }& s! N4 x                       "number of cars by lowering the NUMBER slider.\n"
! E9 o# p5 r! h: y# L% K                       "The setup has stopped.")! o+ Z8 }& @- f4 N& U/ _
    stop+ ~1 M2 t% {+ r4 f$ @# ]
  ]* G9 ?  Z2 P7 X- J6 }

0 \( G2 f# E; `! X. R6 K: S6 I5 ?  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color$ U6 L5 T( Y% W- o
  crt num-cars
- ^8 y% g; C0 O; _% j  [
5 q3 p0 _+ v8 |. Y  j7 O: J    setup-cars
$ t- v! }2 x9 s$ o( r  l# B    set-car-color, X7 [! Z, F# M! Y6 L. r; Y, j2 |$ N* o
    record-data( m% I; a, j& b% B
  ]
3 m8 q. o* X2 o/ p4 s
8 G3 p! q, G/ l  ;; give the turtles an initial speed
  ^4 I/ C" i- U  ask turtles [ set-car-speed ]  t; d0 C% e0 `- C; H

- C/ j- A9 Z1 P  reset-ticks
/ u) x* r9 \9 ^4 m; Dend
) R' `" G$ I1 y# J- R: \; w
9 ]- R" n1 N! B0 I+ C;; Initialize the global variables to appropriate values
, M. Z* e0 R9 ]3 c2 h# E- ^to setup-globals
; T$ q9 R9 ]8 K$ `9 }) T- z) \  set current-light nobody ;; just for now, since there are no lights yet
$ I0 N1 f' j# D1 [8 y1 ]  set phase 0
# a' [. N+ n, P, z. [  set num-cars-stopped 0. q" f% t2 c9 t
  set grid-x-inc world-width / grid-size-x7 n1 L3 D, |2 u) W5 l+ `  m3 f
  set grid-y-inc world-height / grid-size-y
+ j3 r2 k2 Q9 F3 K6 o9 {* `( L% d1 h. g- f" x; {
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) J( p( n$ q: _& J, e6 w# \
  set acceleration 0.099
8 G9 u$ p% G7 i8 O9 S$ p  {' send/ K6 k8 e+ q1 q4 h( J

2 _; Q$ _5 ]+ M/ [8 }+ g6 \; c;; Make the patches have appropriate colors, set up the roads and intersections agentsets,9 {4 [+ }5 S2 r* |5 k* a
;; and initialize the traffic lights to one setting, m, t5 d0 S( R7 C
to setup-patches; E- K2 O& }$ c, B
  ;; initialize the patch-owned variables and color the patches to a base-color7 c+ X; Z6 t) n: Y: ]/ w) j' b8 Y
  ask patches
+ s. p) f" n+ ?  [
$ e" r- u7 a, Z1 P    set intersection? false' z% g0 n5 A& z6 O" r7 w1 B
    set auto? false$ Z! X+ x. N6 ?8 A) S) m9 k) O
    set green-light-up? true
1 e5 h  N7 z! @: h2 M% z5 |    set my-row -1) n3 h+ F$ \+ Z
    set my-column -17 j/ d1 D  b6 B6 K
    set my-phase -1) h8 Y+ U+ C, H4 R* Y0 x
    set pcolor brown + 36 ^* B2 s1 q6 @) y: m5 V8 B
  ]- f/ ^! p7 [. r7 w$ I

' n' n3 @$ c& }9 ~7 n# f  ;; initialize the global variables that hold patch agentsets
1 k0 c: K1 [* v0 W; e  set roads patches with
9 x" E7 {1 T! A$ w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% n0 n% ~0 g0 U) l1 z3 x
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. F+ X) Q$ ~  k& l3 ^9 C, P  set intersections roads with
" ?8 m; ?5 B9 c- y3 h) v) Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and4 i8 u' y0 u7 F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 U- R! `" F8 f, P2 i# b
' |% {, U% o8 Q8 o7 O( y
  ask roads [ set pcolor white ]
; t0 S) t5 `8 P    setup-intersections- b9 E0 j5 g7 H: ~3 z
end5 l5 ^: m  |! t
其中定义道路的句子,如下所示,是什么意思啊?
# ?8 F4 t/ {6 C: K  [- J set roads patches with7 T/ b$ `& g' f7 `, R; G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' r$ C1 m9 l; l4 [
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 Y# f5 E8 c6 F
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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