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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。
  l4 X0 H2 ^# Y, Rnetlogo自带的social science--traffic grid这一例子当中,
4 {( f4 }5 i. o& ?7 w8 sglobals
3 ?! P2 \: k- X# H[0 Q* l. f0 Q( t% r5 U2 t
  grid-x-inc               ;; the amount of patches in between two roads in the x direction* R& z+ o( i$ O& ?' B4 j3 S# j
  grid-y-inc               ;; the amount of patches in between two roads in the y direction5 _  f9 R3 c$ n" W* G7 s2 Y
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
- x$ m4 L+ B& O6 a" H$ B7 R, ^1 x# d3 K                           ;; it is to accelerate or decelerate
: V9 C7 ?8 f" m  phase                    ;; keeps track of the phase
! b3 J* ~, \- h9 z6 n& T6 X  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
: K; R6 h9 c; p% e) t  current-light            ;; the currently selected light
0 D% V" x* T; w3 I. J8 P) H$ x7 c6 Q+ h1 Y* d( D. H
  ;; patch agentsets
. k) [" @0 }: \4 B1 S) Y3 I8 T  intersections ;; agentset containing the patches that are intersections
1 c. f4 Q9 M# k# Y* F  roads         ;; agentset containing the patches that are roads- ~6 h1 a7 y7 T! Q3 p; h
]
& n! S/ O& v* ~* F: x2 F' J" R7 i$ u/ Q* [2 d7 V& p
turtles-own7 i3 E% i" M3 T5 S
[
9 F0 D0 z( x/ M3 I2 [6 K/ c  speed     ;; the speed of the turtle# L6 r5 G0 b2 h/ q( [( a, I
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 Z8 R* K0 g) i
  wait-time ;; the amount of time since the last time a turtle has moved
' u" k! m' d6 E- K) []
, m3 h0 k! @, e8 H2 Y" x' u7 p9 M% q# K7 S2 A
patches-own
% q: S  o7 l/ A& K* S* t5 n& U[2 e7 {6 z  G$ ?2 p5 J0 t/ m
  intersection?   ;; true if the patch is at the intersection of two roads0 d* n+ C4 B( @
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- U# Z4 j/ s# B9 p0 }* q. q2 j, L$ T
                  ;; false for a non-intersection patches.
; |  v) q9 {: R$ ^( V( p/ n  my-row          ;; the row of the intersection counting from the upper left corner of the
) Q' G2 @! ?  U$ G                  ;; world.  -1 for non-intersection patches.8 }1 ]# Y0 |1 L  T
  my-column       ;; the column of the intersection counting from the upper left corner of the
# ~* w2 }7 t, r: S( s) V                  ;; world.  -1 for non-intersection patches.
  z: V( K, Z+ W& y2 R. q+ A  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
8 {- a! n9 W! q: J2 X' R  auto?           ;; whether or not this intersection will switch automatically.& A) V* }4 U9 C5 D  b8 t, ?+ G
                  ;; false for non-intersection patches.$ C2 {! G, J, o" E
]4 H! [  ~- I# f$ t7 c  G

3 [. G2 x2 f2 x7 a" Q9 H3 c$ x$ n$ c7 z( O
;;;;;;;;;;;;;;;;;;;;;;
$ }7 S1 {$ r/ B! S1 x;; Setup Procedures ;;% L% x, X8 H1 Y# D( j
;;;;;;;;;;;;;;;;;;;;;;
& I9 J4 M% `, l( U! f! d- N1 q
% i; t) {1 V8 e( j6 d; {5 i& X;; Initialize the display by giving the global and patch variables initial values.
' m% J# z4 t* w/ }0 D0 n  z; N" o;; Create num-cars of turtles if there are enough road patches for one turtle to% E8 m, s  D" P8 y
;; be created per road patch. Set up the plots.5 q& A1 f8 O& O0 P
to setup9 k1 G& j% O/ t; ?) z8 c; N
  ca
$ q! N: z0 l0 e5 g' x1 P  setup-globals
& a: o& X" S; [# J* d+ g- z" z; K5 w' j
  ;; First we ask the patches to draw themselves and set up a few variables
1 x) f: r% P, i% r  setup-patches
1 k) _  U  Q  C, j( w# x4 j  make-current one-of intersections
$ T+ m/ \# ~. l) C" b1 s4 p  label-current
( \) n/ {+ a7 d% s* c# {) Z( K: c8 F  _, h/ ?
  set-default-shape turtles "car"
& e8 v$ b4 K& q" x" ~' t5 M  G2 v; D' o/ m7 ^! q
  if (num-cars > count roads)
2 n- h# G" O4 t2 i7 G0 n) \  [
/ a7 D$ X$ g$ D6 Y' W7 P* }    user-message (word "There are too many cars for the amount of "# v8 u( C3 e0 H/ Y6 L
                       "road.  Either increase the amount of roads "
+ i$ `- f2 T3 f3 e" ^) @; V% e* |                       "by increasing the GRID-SIZE-X or "8 z: z0 R) c$ J8 }- I+ n7 U' `+ G* f7 R
                       "GRID-SIZE-Y sliders, or decrease the "
- \6 C; ?! f5 l# A% u0 |  z                       "number of cars by lowering the NUMBER slider.\n"
1 W# I, _3 e: K' ?4 H8 v                       "The setup has stopped.")5 Y9 k! Z& R! N; x+ @9 D$ u7 Z
    stop
, X6 k4 ~8 b$ Q# ^  M  ]$ h( F3 E  ]6 c  e$ f

$ i2 s" {* ]1 K) G  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
, p& n  {( L2 o/ \  crt num-cars
. q) r, R0 L+ N4 T; K  [
6 Q7 |2 Q8 n! d+ e0 i    setup-cars
  t) N7 o/ J$ Z# z5 }+ ^    set-car-color
2 e) F! R" i/ j% H    record-data
4 Y" s* |% G1 o$ R& h  ]) z2 h; J' Q9 t2 W) T* B1 }
1 d3 ^# u  j- S% D  _! f8 i: b
  ;; give the turtles an initial speed
) Y  {7 `# r5 l. i$ C; p! H" B  ask turtles [ set-car-speed ]
3 N) ^7 P4 ?* a2 b# T, ]$ l4 H6 D& \( M0 @- z
  reset-ticks9 \% d* x  I5 @# S# |6 ^2 N0 t
end
2 u& i/ k( |% i4 `: v
/ U7 a6 _) A) y( x/ w% ~;; Initialize the global variables to appropriate values
/ }& f/ ~$ F7 A% [to setup-globals
3 u6 ~9 X( Q1 X* @  set current-light nobody ;; just for now, since there are no lights yet
5 ?  B! w' e( T+ ]6 |2 l5 H2 A  set phase 0
) `0 I2 |. X2 U/ W  set num-cars-stopped 0
' m' h7 W( E3 J  set grid-x-inc world-width / grid-size-x
  |$ X! g0 q- b* O5 I. ]# J; ^7 M( U  set grid-y-inc world-height / grid-size-y
( |& ?) ]) F* O6 C3 j/ k$ `- I! Z# D6 ]* I  o2 ?
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary: d4 A6 V+ D" i4 T9 q! }1 R
  set acceleration 0.099) U* C/ A. u- f! t" |
end3 o1 V0 b! b9 i0 ~, Z) ~

. [7 q5 \* v& D4 }; p0 X# k1 O;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
/ i% a# r9 f! _; e% X& ^" b* L. `;; and initialize the traffic lights to one setting7 y* M) c3 K, o4 G: G: P/ D
to setup-patches; ?5 O' X8 G/ b' E7 s4 g* x, K
  ;; initialize the patch-owned variables and color the patches to a base-color
" h) `1 S( k- o* l  ask patches
  _9 R! X( w* Y0 q0 L  [. q* |4 [- S+ M
    set intersection? false; m1 d% F$ ~. U$ b  h
    set auto? false
$ }% T( m- z/ t& K* ?6 i# T, E/ n6 C    set green-light-up? true
( m% M( v$ ~" c/ b! v( O1 W% \    set my-row -1
8 @9 M" y9 W$ q& k    set my-column -1
/ \# s$ |6 C( F/ D1 p    set my-phase -1
% t$ z& T+ e+ `8 ]; u. L0 [    set pcolor brown + 3( W" d. [; v. v6 d
  ]% L1 K' A, R$ c

6 ]- n  m2 D  R+ ~4 j1 I  ;; initialize the global variables that hold patch agentsets1 a& n: m" f  w( {6 m7 }
  set roads patches with& p. o7 v. R. C0 b7 @* \
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 O' ^' j' _1 o& D
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* k8 P8 T7 [, p  k
  set intersections roads with0 ]8 E* S. H  z" z& Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and1 g, l* D7 D& j3 x$ b3 R! _, F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 e$ ~/ s* }6 L- X8 \8 @5 Y
, r- G3 {+ Q+ ~# ]/ U9 @  ask roads [ set pcolor white ]9 d2 l7 U" q$ L
    setup-intersections* ?5 k3 J% f" i, Y& L; T* [5 p
end
: n/ M. P5 C, a# Z8 N" D  Y其中定义道路的句子,如下所示,是什么意思啊?& M3 l" r5 M1 A
set roads patches with5 d, T! a7 G. [, r
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% k. Q' j' F+ @: u
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 ?' P% i  o7 @+ S1 w; G- B
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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