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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。
8 G4 F, ^: Z6 v3 t9 gnetlogo自带的social science--traffic grid这一例子当中,5 ], M0 X" J2 W6 m- j4 @9 [
globals
# Q( O% e% q9 L8 J$ I[9 `0 G/ A0 H$ @7 Q- C
  grid-x-inc               ;; the amount of patches in between two roads in the x direction/ V/ o2 r* ~" T8 h) v
  grid-y-inc               ;; the amount of patches in between two roads in the y direction) |3 F+ [4 D. k& k' I+ Q, B
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
3 J5 c3 J0 Z) x7 f                           ;; it is to accelerate or decelerate7 V/ m; }: f( S1 {
  phase                    ;; keeps track of the phase
1 A/ X+ {; |# ~2 I$ _. p  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure) U7 D& Q" t$ f& N
  current-light            ;; the currently selected light
1 `* ?9 v+ F& ~6 M2 X+ [7 U6 m1 Q  d5 r$ Q' m5 _
  ;; patch agentsets6 S4 {! O$ S. K$ O
  intersections ;; agentset containing the patches that are intersections! q( D6 }7 }: c7 x  q& T+ |
  roads         ;; agentset containing the patches that are roads3 ?, t. K8 @% m0 Q6 w4 Q& D
]
! I" ^" C' t! a( V: V" p* ]0 @% U0 ^$ Y
turtles-own
1 J, ^6 K; U. ~% ~" e[6 B! F8 p+ |1 w* z$ i
  speed     ;; the speed of the turtle0 J' }1 o+ w( d- \% g* R
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right. n  N/ B* H4 u/ M3 X* r
  wait-time ;; the amount of time since the last time a turtle has moved
2 m# c" {# x/ T]5 ^3 H& v* w8 v; [( n  @) ^) p2 B7 _

' d5 J' N  C! O; S' p( i& bpatches-own
8 b( Z# `) d. L. e0 f5 G. q[
) n, S( u8 [( c6 j  intersection?   ;; true if the patch is at the intersection of two roads! o) e5 I  q+ \9 h' q* v! Q; f. M
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
! e& G6 S- H9 l& r( g; ?9 w. }                  ;; false for a non-intersection patches.
3 j9 F5 ]2 D+ j  my-row          ;; the row of the intersection counting from the upper left corner of the
: \8 l, Z% h9 e; i9 d                  ;; world.  -1 for non-intersection patches.
. }$ `* g" l  ~  my-column       ;; the column of the intersection counting from the upper left corner of the
& r, H' _5 U: `1 c                  ;; world.  -1 for non-intersection patches.
; s8 g0 f- R- R  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
/ U6 P' y, m! }5 T, t3 N1 `  auto?           ;; whether or not this intersection will switch automatically.7 P' ]) ^4 [2 o  n5 G+ k! A
                  ;; false for non-intersection patches.
3 _. `& a0 t8 T1 u  z4 X6 Z* i]+ N9 X1 S. ]+ I

! J) r3 V7 A1 N6 R+ c7 _5 Q/ |+ H
  {$ k5 a7 c: J8 @# l. f, t" d;;;;;;;;;;;;;;;;;;;;;;$ W. s6 }- x5 K8 t* M! E
;; Setup Procedures ;;6 P5 R0 [0 }4 E9 T7 @
;;;;;;;;;;;;;;;;;;;;;;
1 L% [+ q8 k8 V
3 d2 J& D. y% j8 t* @1 s9 T* r: d5 x;; Initialize the display by giving the global and patch variables initial values.# i7 @4 I# Y7 {2 c) j" h# H
;; Create num-cars of turtles if there are enough road patches for one turtle to2 R* w0 u- ?) K8 p( C; b% Q) Y" x
;; be created per road patch. Set up the plots.* |$ ~' D; \& j! R! w
to setup5 m! J7 |( ?7 }% u& K0 z3 N: v
  ca
3 O: U7 i% x( |9 _0 O  setup-globals
! h' q4 L; [& J1 Y) R3 M, g6 Z' L+ N+ M; I
  ;; First we ask the patches to draw themselves and set up a few variables$ I, ~' c0 L3 X6 C
  setup-patches2 {% j- W5 s+ H9 d0 @$ U& Z2 j
  make-current one-of intersections- Q. N6 \" c+ Y1 J8 `* l
  label-current  q# S. h" k8 t" V* V

4 n' a9 I8 Y  ]! A0 p  E) w  set-default-shape turtles "car"
" r) q/ ?' w' t/ J8 O8 a5 h) Z& o
  if (num-cars > count roads)
' d' Y" f6 h' T9 `6 P  [
/ }4 H9 Y, {+ c( L( A) F    user-message (word "There are too many cars for the amount of "
* K6 I' J) [3 K0 G, W3 j& d                       "road.  Either increase the amount of roads "* v$ p( G2 y  u" I% s
                       "by increasing the GRID-SIZE-X or "4 ~: }/ }9 g8 r4 ^
                       "GRID-SIZE-Y sliders, or decrease the "; I& L; M# T7 ^: o5 b# q2 J, }; y
                       "number of cars by lowering the NUMBER slider.\n"1 u1 Q' K% o! |, R) r) O- T3 X
                       "The setup has stopped.")3 v" w3 l# z, p; M8 r
    stop
8 f* a, M  _+ X  ]
/ Z& P$ s; t7 x3 M* o# L5 z5 h. p! S. g5 N) e* U4 X
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color0 l, P' ?8 r* o6 K# X0 _
  crt num-cars
: J/ d: V- C6 s3 l# F  [2 f* M, B$ S: ]& s( F
    setup-cars1 U! s7 W& O! b: [
    set-car-color0 v# c0 C" d5 {0 ]% {2 R
    record-data
( ?. y) o2 u( _2 t* J" N, a  ]
7 y. L" i* p7 U5 ?% t: X/ h3 F' y7 q- T0 S! I, l
  ;; give the turtles an initial speed
# z3 E3 c' m* m+ \" B& w; q  ask turtles [ set-car-speed ]
+ ~+ t+ h7 c$ ?0 y! x8 s7 ^* t# |- f$ j, a! O4 u: ^
  reset-ticks  R- f3 v2 e  T( t' t5 R
end
9 V4 p- D! ^& P% d7 }7 J7 o7 J
  L5 N8 Q4 o9 L4 p;; Initialize the global variables to appropriate values+ ?2 F; O4 M6 _2 K* U0 K  w% W: e8 x
to setup-globals
5 L) x* |& y1 ]: N2 w. J+ z! y" Q) G  set current-light nobody ;; just for now, since there are no lights yet2 Q7 s3 h: Y. p4 {* u! H
  set phase 0
1 v$ r6 C8 @' G2 O! _  F2 ?+ w- ~  set num-cars-stopped 01 g7 c6 }2 Q' {: v- w9 a
  set grid-x-inc world-width / grid-size-x
) t/ K: e; |7 w  set grid-y-inc world-height / grid-size-y
7 P  Y; |4 F/ G* i$ G; z8 B5 s5 ^+ r9 a1 c( u2 x2 b
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
1 i' H7 v8 b0 i) C3 E" t  set acceleration 0.099
; @6 D4 }* b+ j% D7 C) P9 xend) e% ]( y+ t# x# L7 c; B

; l4 P8 B7 V0 P7 f. h. r;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ h, k$ U9 D7 _5 p3 l" n
;; and initialize the traffic lights to one setting4 F+ }6 f! z  u; o: R- l" A6 q
to setup-patches' y4 W, }5 v. A& Y
  ;; initialize the patch-owned variables and color the patches to a base-color
' e( L- Y6 o- U' O  ask patches( G7 _! N* D8 N9 W9 `
  [# s% I. b3 A6 L
    set intersection? false
, t, q# h  _, W    set auto? false, F$ J5 h. Y7 J7 O) y8 N
    set green-light-up? true) b& _2 M2 K+ p9 Z1 W
    set my-row -12 |- w( ~  f6 y5 s: ?) x6 A$ w9 p3 @
    set my-column -13 V! F' N" V+ b
    set my-phase -19 Z' F4 X& U( \  l+ B7 V
    set pcolor brown + 3
0 k4 `; j# ?' M6 i* l  ]6 ~) Z  U0 v( ]* w+ E/ K. h: a/ r

* Q( g0 Z  r( \4 L" c" T  ;; initialize the global variables that hold patch agentsets
1 `' w7 h; n( a/ m# s# u- c  set roads patches with) N$ c2 _' w0 P7 S' x2 n- N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% t/ ~+ v9 f, |$ O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 Y; ?) j7 S( A6 J" Y; s  set intersections roads with0 b3 f4 z9 L: M5 C9 w2 w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% w; O0 n& f) \$ ?    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 s! G) g6 l# z, w
" J1 K3 T4 {$ P/ q9 `! j
  ask roads [ set pcolor white ]
( ?( G( R2 H. ]& D! F2 m# l" L" I    setup-intersections
+ n! \) [6 t+ H* m8 t' X# nend
; }: O" x9 J* U% s1 g  n8 w' l; D其中定义道路的句子,如下所示,是什么意思啊?! V- g5 p" z! m" r* q
set roads patches with* r; O. p: N% B& l- C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ z2 A+ W+ r5 l3 g- }1 d
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' \; x) w3 c$ s. z# W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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