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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。* Q. [# b: \6 d, h
netlogo自带的social science--traffic grid这一例子当中,
0 F7 x: J& `( ]0 Aglobals
: N9 v2 g% b3 d6 l, S! f& G/ ?[
3 _/ }' P# Q: }6 W* x; G( W  grid-x-inc               ;; the amount of patches in between two roads in the x direction3 s' \0 ?' E7 Y0 h8 E& p" @
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 w: f, o, o, m" d: X  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
& W% \4 B5 C/ v% F/ U4 }                           ;; it is to accelerate or decelerate
0 A9 T% r, S% D. S. Z  phase                    ;; keeps track of the phase5 g$ W3 R$ ~, z$ f: Z7 i
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure9 w" ~4 o5 U4 g$ Q# ~9 v7 y
  current-light            ;; the currently selected light+ s6 E2 V7 E9 \: L& K- l

& Q% E1 Q4 j- L0 V# L  ;; patch agentsets: F$ K5 h6 _+ \3 @0 \/ y- T/ P+ D1 b
  intersections ;; agentset containing the patches that are intersections
( I$ C* Q  p8 G, }8 d  roads         ;; agentset containing the patches that are roads
! f. E$ a; f& v]
. t  V' \2 J: c; G( ~+ z4 w" ~1 @7 S( v9 m. Z# m
turtles-own0 f5 U4 l% O6 A  m
[
  k: X: F1 _( g. `% y/ G  speed     ;; the speed of the turtle
( I" }, _4 [' S) T) r5 Y  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& d2 ]# m* [6 \& ]+ ~$ j  U
  wait-time ;; the amount of time since the last time a turtle has moved
5 f6 Z& W" E1 {- P, s) y1 c+ w; P]* y1 y# z- f3 c( \1 F* L9 E
: Q3 C- T% ?$ c7 S9 t
patches-own
  s7 f6 W% ]$ x* V; P! R: R[
% a5 j, d, o  e2 a  intersection?   ;; true if the patch is at the intersection of two roads# C) E4 g; g' |
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
0 b& X( u; m. H) P                  ;; false for a non-intersection patches.; W5 J: ?$ ?& I8 @* t+ |! Z
  my-row          ;; the row of the intersection counting from the upper left corner of the4 ~* _" t- i) ?( Q( u7 k% ]
                  ;; world.  -1 for non-intersection patches.) X, P" A  j% E
  my-column       ;; the column of the intersection counting from the upper left corner of the
0 x6 e+ S2 q9 n                  ;; world.  -1 for non-intersection patches.
3 J* e9 y2 n$ m1 P: H2 H# l  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
* L. H1 r# m: W- T  auto?           ;; whether or not this intersection will switch automatically.6 I& O* j; P$ [9 }2 T( E; X
                  ;; false for non-intersection patches.
5 {  M) z! B$ n- x]" I8 R* ~  q! b3 K, j
9 S' T" k: C& |2 g& n1 ?
8 Y# ?0 ]; j( I9 Y
;;;;;;;;;;;;;;;;;;;;;;
4 W# M1 V( a8 B8 h;; Setup Procedures ;;
8 J6 T1 ^( B" G# Y. H1 u3 s;;;;;;;;;;;;;;;;;;;;;;
8 r# \6 s, W4 h% e; r. C( K
" m) T: T- c. k( ^3 U;; Initialize the display by giving the global and patch variables initial values.
  r' ~( n# \4 Q- [' o3 r! a;; Create num-cars of turtles if there are enough road patches for one turtle to
* P* O* ~9 J) I, \) ^6 ~9 D;; be created per road patch. Set up the plots.
- V1 f1 @+ @# j' ]- sto setup
' `4 g7 Y, e( d- ~9 v" q  ca
/ M/ @: `/ y5 @6 C4 ?" W+ e* ?/ Z  setup-globals2 n1 S  Q4 T( `5 f  B- V

, F- I: o' G1 U; a( G: z% B! K  ;; First we ask the patches to draw themselves and set up a few variables
$ l+ Z' x6 D7 d# M9 `) k  setup-patches
4 N* d1 {/ D# F9 @9 J* @  }  make-current one-of intersections
5 n" R" u# D, e8 _  label-current
: _" n# d+ i) N/ v$ i
2 N  N( o3 \  l, D  set-default-shape turtles "car"
- V3 `+ c  u# G. p  g% I- I/ ^' E% t: [) m
  if (num-cars > count roads): o  G# r; a' j) F# i6 r$ L
  [  ^8 O/ [' Q# z2 f( z# a1 I
    user-message (word "There are too many cars for the amount of "
9 v) y+ K/ ?6 n7 n4 Z                       "road.  Either increase the amount of roads "
6 m3 O& \; l& ^% C+ q- D* g2 R                       "by increasing the GRID-SIZE-X or "
# J/ O6 L' ?8 Q* {. t* A+ `                       "GRID-SIZE-Y sliders, or decrease the "  ^2 b6 q/ g# l4 ]  ~/ i* J% O
                       "number of cars by lowering the NUMBER slider.\n"
) k  ~  g0 T" ]! A& T5 G3 g0 L4 H$ j                       "The setup has stopped.")" A* y9 W% q$ e
    stop
) h& a0 ^( m$ m5 `- w, p* N6 t1 F5 _  ]
3 v' b& o4 W* b; e1 L8 B
  z/ v: t8 T6 s3 m  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
+ \9 q/ Y7 T9 O$ F0 V% e% M  crt num-cars2 F0 z1 h5 H$ k- o9 N  l0 O# p' Z# P
  [
* a% ^4 m  H2 \    setup-cars7 _) x$ ~3 ~& r7 K* z2 \) V$ n* n
    set-car-color6 D% \1 t6 C5 f) Q/ o( e- b
    record-data+ ~4 g/ v  m- |- L8 U* I
  ]8 K2 D, e! {/ f

% ^, Q5 z- m! r3 C1 ?' A: u9 I: T  ;; give the turtles an initial speed
5 U2 a& C3 X% w7 [0 y2 ^3 q  ask turtles [ set-car-speed ]" H( U# f8 o/ c3 c( {& J( a
5 \! N, }8 g" V: \
  reset-ticks
' G$ N6 k  B: L; t/ o( xend
6 `& `, o/ ~7 y; y% Q; w: w+ |* z
;; Initialize the global variables to appropriate values! ^% v( c" Z" T, D" i
to setup-globals1 {1 r; G/ j$ m
  set current-light nobody ;; just for now, since there are no lights yet4 q* |& x) q5 B( b0 ?
  set phase 06 [, B% H# ?5 G& f9 e
  set num-cars-stopped 0% T2 V- G# s, n4 V6 Y* Z
  set grid-x-inc world-width / grid-size-x  b5 k( Y' m0 a2 {+ X! h: G
  set grid-y-inc world-height / grid-size-y3 H# b% z+ J1 ]( W( H! h' t
7 t. A3 U$ `# c
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary$ L2 V/ {% w; D4 h
  set acceleration 0.099
7 \% j$ N! y) Y7 ]& ?- h. ]7 y$ Rend: \0 }3 I& ~# {. J0 R4 i* A9 @  E

" m  [: w1 i- J3 I* ^0 y& T;; Make the patches have appropriate colors, set up the roads and intersections agentsets,9 B" E. u3 b4 s/ B* l, ^1 m
;; and initialize the traffic lights to one setting
: n5 H: q+ A1 t6 {( yto setup-patches# Z: P# d6 y, i$ q) P8 S# f
  ;; initialize the patch-owned variables and color the patches to a base-color& t7 L( |0 H9 q
  ask patches
/ ^* M& d$ N0 j+ W8 [  [8 b, u$ }2 L. B+ ^3 @2 s1 w
    set intersection? false5 K$ J- ]8 `3 U( Q" V' Z
    set auto? false  h7 D$ f9 o+ I1 q! \) y' e
    set green-light-up? true
( P! `4 t4 Q& W: K8 U    set my-row -1
) ?6 q, `% L. w9 c    set my-column -14 r$ P+ Q6 c+ O' E3 }4 x/ ]
    set my-phase -1
7 r' C6 Z( s1 O, G# Y, @    set pcolor brown + 3: l. d9 ?7 e- w5 Z
  ]% q" |; v/ |% h' O+ v  }
+ w& o: U2 ?  R1 x
  ;; initialize the global variables that hold patch agentsets
  o4 C# k1 R1 j8 u  set roads patches with" W) |8 g5 r+ e7 H
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. E0 P  J$ [( j: N( o    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 r6 z9 y+ k" Y" f, Z" j7 c, c4 w
  set intersections roads with
" }5 D2 d2 O: S' U    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. S9 o+ q* z" I( |- r5 S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ c& `3 q/ v/ z8 g* n
/ z% f! g, R6 }* a7 U  ask roads [ set pcolor white ]2 N# ]" g& ]1 s" [
    setup-intersections
, [: ]0 O. ^3 E" Y8 B, b0 a( [4 |2 F% i( gend
5 x! C) G7 G/ r1 R) M2 h- ^3 g其中定义道路的句子,如下所示,是什么意思啊?
) k, r+ R0 W1 W) x+ c  F set roads patches with
; Q4 e8 _$ n' u: Q' Q, s4 {- z% D    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% z1 b0 e$ z( |3 C$ K% k4 E( k    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! }# ^2 Z/ }" q" 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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