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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。, I1 l/ k/ ]* o2 _" S5 V& @# W
netlogo自带的social science--traffic grid这一例子当中,
+ j+ ~* W3 S8 b" \4 Hglobals
9 y- ~# s2 z# S& g3 r  z, i: A[  z. [. A: j8 s1 y1 |+ E
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
* J; I0 W& m  W3 b7 ~1 ], i/ h2 h, _  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) b0 N4 q1 E2 O: i* n  acceleration             ;; the constant that controls how much a car speeds up or slows down by if2 }! S  a. d' |+ R- j
                           ;; it is to accelerate or decelerate
  C2 I3 a. C3 r; M) n; b  phase                    ;; keeps track of the phase7 P8 u% l# M8 @8 a/ E( a# |3 L
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
# E" r+ [, d2 U$ i  current-light            ;; the currently selected light
! J% N8 w  d( t  h" m, u
0 @6 I& ?! Q% O, h8 _, Q+ K1 A  ;; patch agentsets4 ?$ s, V8 _6 |0 T
  intersections ;; agentset containing the patches that are intersections
( A' U* B' ~6 Y2 @1 H7 F+ ^  roads         ;; agentset containing the patches that are roads6 Q4 B7 T* f& i- |* ]& E8 I
]
" |0 f! k( o2 x  q8 x+ m2 F1 J4 Y5 G% v! h6 |
turtles-own
& `) @8 w' @! N, A- }. i[
' y8 J5 |; N. ?  speed     ;; the speed of the turtle3 g6 L: r$ B  [& ~2 y
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 m; d" U+ a- U0 k+ x) N' v
  wait-time ;; the amount of time since the last time a turtle has moved
  q4 I, ~6 k! r: m$ N# I]) q/ p6 n( A! P, w

! I5 q1 G5 d/ E( c1 f- d5 wpatches-own
, Y5 e& D3 {, n+ v5 Q! @2 p[
2 p7 F3 i! B$ s% V; w! I  intersection?   ;; true if the patch is at the intersection of two roads
  y$ A/ v; Q. i7 j# t8 D, E7 H; z  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
' O7 R3 D4 g# F& T, A                  ;; false for a non-intersection patches.' k( c7 ?2 X) w
  my-row          ;; the row of the intersection counting from the upper left corner of the
, i+ w0 \9 K% t9 O! [) Z                  ;; world.  -1 for non-intersection patches.
# v% ?% i4 ^3 j  my-column       ;; the column of the intersection counting from the upper left corner of the! B: H  k0 ]+ [, W# g0 T' J
                  ;; world.  -1 for non-intersection patches.- O7 V. m- R/ e- y, P. v  f
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( O: D9 E: s5 s  auto?           ;; whether or not this intersection will switch automatically.
& {, F( n6 X  O8 p                  ;; false for non-intersection patches.
" i6 m# S" C* \7 V" H0 F]
/ j6 r! B" P% U7 R; m) q, L( i6 Y. q! d

8 r/ F7 a+ E; @' f1 S: W;;;;;;;;;;;;;;;;;;;;;;- z0 }( u2 ^% {7 M( x  T
;; Setup Procedures ;;
0 S, x' X* A7 G' Y' {6 V% K) a;;;;;;;;;;;;;;;;;;;;;;$ [% z2 D8 K3 c# f) f

! Q( Y- i& ^, f+ ]/ V;; Initialize the display by giving the global and patch variables initial values.) H! l/ ]) L- l) ?5 J
;; Create num-cars of turtles if there are enough road patches for one turtle to1 q9 u9 ~1 K% ^( j6 z5 X  z
;; be created per road patch. Set up the plots.
# V* P) N' M7 y% e' ?$ \to setup7 v' E0 u+ X9 e1 E3 M% I
  ca
$ G) v2 s* Y0 H2 U2 y# U4 v) y  setup-globals  ~/ A% U0 W9 p! ^

* N& \' ~; |7 `# K7 T, ^# U* a  ;; First we ask the patches to draw themselves and set up a few variables
( \( d! H0 h/ E: A  setup-patches
2 \% v4 u, X: Z. D( {0 w; V( B4 O  make-current one-of intersections0 u/ ~+ i- B  ~) [# e; b
  label-current" z$ h% g! d- O+ B3 r5 q! D
. l* b' F, V) h7 J$ T: W9 G0 i
  set-default-shape turtles "car": J- w: r/ r) v$ O3 j7 l. M" c: K) ~
/ T1 R/ h. S& V( R
  if (num-cars > count roads)- B: o0 c3 A# d2 I
  [
& S1 h/ r$ a7 |) g' a3 t1 m    user-message (word "There are too many cars for the amount of "
- \2 C9 {( V) u6 s9 M* N7 n9 h                       "road.  Either increase the amount of roads "
/ `' r! f8 E  \                       "by increasing the GRID-SIZE-X or "
4 L0 o1 q9 w$ l# u' Y# h                       "GRID-SIZE-Y sliders, or decrease the "
0 B0 |* `7 ]7 J- g8 u+ {$ X$ h& _8 y" Y! D                       "number of cars by lowering the NUMBER slider.\n") Q: N3 @5 p9 H2 p7 ^1 u$ A" v
                       "The setup has stopped.")" ~- B8 I: i+ N% i+ n$ o; y
    stop
' k8 a* v2 D& j% N+ f% x  ]( @; j' m, p7 A/ K
9 F; W  E' w! k
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color8 h6 {8 j! s. s% j! G
  crt num-cars
, _% k9 E/ R, {* l3 b3 x% R  [- Y$ v7 X  _0 v9 y, Y$ F' u
    setup-cars
% X, k/ S* g- q1 f# Z    set-car-color
; e: D$ r( @1 H2 c  c. S    record-data
& Y0 P# F  z' Q; x( I1 y* a, e  ]
6 E: k3 ~) T1 |! G5 {3 r$ s/ `" V5 M. ]* W0 y1 j
  ;; give the turtles an initial speed4 ^$ V/ D( f+ L" n
  ask turtles [ set-car-speed ]
, R2 _4 _, W3 z. Q; `5 h% J- v' m& X& l  z
  reset-ticks2 e1 @' p/ F% o( h9 x& @3 Z
end0 r1 u& g# |* ?% n9 ^& N

: K) g, a' e8 Z6 b$ m;; Initialize the global variables to appropriate values/ w5 q/ h0 h7 V) k
to setup-globals: s! a* z% V6 @  }9 d
  set current-light nobody ;; just for now, since there are no lights yet
, i! Z( F3 _2 J! m  set phase 0' I3 t8 S$ {3 g/ ]" q
  set num-cars-stopped 0
' Q, N4 W- i- |9 \& C4 g. F% |. T  set grid-x-inc world-width / grid-size-x
( b: ]& r9 |( g  set grid-y-inc world-height / grid-size-y( [( t: C  v  B* ^0 e/ c# L

1 [! T; H4 N" m2 q1 [$ \  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary! q0 Z1 `) Z9 i9 M+ f) |6 Y8 A9 Q  g
  set acceleration 0.099
5 ^7 ~2 M# ^' s( d3 ?. gend( _2 I, [  }! d
  w% r! v" e4 ?
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
, B6 n8 y+ b" T* l: }# L;; and initialize the traffic lights to one setting% v( O0 P! d& l' h7 \/ |
to setup-patches
5 V$ q0 d  Q2 p- U, `  a  ;; initialize the patch-owned variables and color the patches to a base-color
" p  r( U, j0 S2 j, o2 n  ask patches% x; Q$ F( F# V
  [4 J5 J  t6 F3 y5 }/ j
    set intersection? false
* D* u* O2 \  Q0 R' f    set auto? false
6 h  ~8 v  A7 ~9 C( w* F8 I* v    set green-light-up? true
7 t% D( J- `+ W* r+ v* l9 E: |    set my-row -1& m; {: h7 n! D
    set my-column -1
# I+ ]! K" @) A" F% @& p    set my-phase -1! u& q1 z! l' i! ^- f- O5 H
    set pcolor brown + 3
& |" t$ s- t6 _) q& y2 P  ]" `9 `; Q2 e6 h

, q1 q+ J, Q$ z  ;; initialize the global variables that hold patch agentsets
! X% O  _6 f0 @+ l1 w  set roads patches with# }8 D, T* m0 w4 I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 G* w, ]1 V, B2 G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- [+ d$ F3 x. b! y  p9 c. u  set intersections roads with: T0 N, V; W/ e9 z- C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ F+ Y% U+ b" `' X8 A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 T2 ]7 R& U* [# q  |
0 e3 R' U+ ~8 B  ask roads [ set pcolor white ]! a% `; `7 Z3 O: F- {6 l) E
    setup-intersections
, c: T" \) H% O* ?% ^, P; K1 P0 Rend
5 C% B3 W) t7 ?% h  E' W% R其中定义道路的句子,如下所示,是什么意思啊?, h3 {/ k. x- j/ D% D6 f3 S
set roads patches with
# R9 A2 G: G! K; E: |& O( I    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( }! T& m& Q$ }2 o! G9 V$ C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; i/ E, [; q9 W- G; K& q
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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