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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。0 B& U: E; T) a5 c
netlogo自带的social science--traffic grid这一例子当中,
0 ^' ?' N, o  N2 jglobals
' I3 m9 q/ U9 S3 S: A+ J$ V' K7 g- E[  C/ m: M& s9 u9 B8 X0 P& D/ ?* X. n" R
  grid-x-inc               ;; the amount of patches in between two roads in the x direction! `/ w: c: R- C% _8 x3 ~8 U
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 @, @; H3 U  q& `- b/ j  i) B  acceleration             ;; the constant that controls how much a car speeds up or slows down by if, r6 d4 A: Z4 Q2 R! L
                           ;; it is to accelerate or decelerate' P3 t3 v0 G9 q3 R
  phase                    ;; keeps track of the phase
* V% h" Z% W1 Q: t; X$ {) K% C( ^  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ x& S2 }8 H4 d9 X7 j3 `* k0 t  current-light            ;; the currently selected light& s1 _0 j$ z5 d+ ^' _6 y( x

/ D& R! F  ~9 k# R  ;; patch agentsets
& E- H  z2 P+ Q' M* W6 P  P) e  intersections ;; agentset containing the patches that are intersections1 p4 p8 X2 Y  p3 Z1 B
  roads         ;; agentset containing the patches that are roads
# m7 q" j' z/ C1 {+ Y& k* C/ {]
5 P: ^) n- o+ z+ O
! V* _; S  S# f- ~" P% N3 G4 i3 aturtles-own2 e% [$ c4 G+ z, R+ z
[
9 M( Y3 {6 A! a0 T2 b" V  speed     ;; the speed of the turtle
$ ?9 S( Y8 K2 S: T2 P, O" X  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
9 E% i8 X% \+ q6 R4 [  wait-time ;; the amount of time since the last time a turtle has moved) b% R1 v5 I7 M- F6 g5 G. _2 ?) K9 s
]0 r1 D1 z1 l- a( ~- d* |' O/ }

, n8 y/ ]+ o2 `) N2 `: C+ t& jpatches-own
5 a6 F! p' X0 g& ~. G. {0 q[8 n$ o+ x7 e* ]. u
  intersection?   ;; true if the patch is at the intersection of two roads) Q/ H# v# z  Y. l
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
0 @! x# X# H+ F( k* c0 A. {                  ;; false for a non-intersection patches.
* D% a* t, D0 z) L- [  my-row          ;; the row of the intersection counting from the upper left corner of the1 c7 h0 K$ c! B  v; f
                  ;; world.  -1 for non-intersection patches.% q7 B3 g, J& K4 C5 L
  my-column       ;; the column of the intersection counting from the upper left corner of the' o/ i8 ]" t6 ?) S) N0 s0 Z
                  ;; world.  -1 for non-intersection patches.
& i) u: P) Y* `4 j5 k2 e" P  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches., W- P1 n) a- q
  auto?           ;; whether or not this intersection will switch automatically.5 s. Z0 f- [3 I
                  ;; false for non-intersection patches.
! m+ ]/ ^4 _) \: H0 x& ^7 u  E6 T]# A7 M2 a& D) A- s$ W
0 s8 i' f& P: v& [
1 @, q# s% d! A
;;;;;;;;;;;;;;;;;;;;;;
( g  \8 z' w0 e8 b" o. `' Z3 Y) L;; Setup Procedures ;;% Q. Y$ I4 K) O% c$ v4 u9 M& s
;;;;;;;;;;;;;;;;;;;;;;
3 o* p# T& H1 B" C$ Y$ }
% |. o9 T7 d, b- }' J! q7 k;; Initialize the display by giving the global and patch variables initial values.
# L. }% W1 a' C) {  R+ m  ];; Create num-cars of turtles if there are enough road patches for one turtle to
, o* f8 r0 [* k5 Q, W5 R; E;; be created per road patch. Set up the plots.0 K, R) l5 t& I/ c1 A
to setup
$ ^9 m. }% \% P* ]) j9 }3 l  ca
) o+ T& H: A  b6 s! r6 X  setup-globals, `. q7 ]% W3 @6 ?

( q" @3 C' K7 H- B  ;; First we ask the patches to draw themselves and set up a few variables: u% P, ^% C$ q* _' o$ h
  setup-patches$ I! x7 P9 N) ]2 x
  make-current one-of intersections$ \' U& |  h1 \. \# b7 T
  label-current) Z% Z4 U+ F/ P; a' Y1 q
7 i) A/ Q0 L3 u" x0 ^; C
  set-default-shape turtles "car"7 d3 i6 A0 Y3 w

- }9 @, a" F) j5 d& s  if (num-cars > count roads)
8 g5 ^* t" k& J4 K* ?& n" ]5 l  [
, N7 H  G( r) X9 b    user-message (word "There are too many cars for the amount of "
! c( ~' `8 H: b, Y+ k" B9 D& o; {# Y                       "road.  Either increase the amount of roads "9 W0 x5 R* l# T" c) a
                       "by increasing the GRID-SIZE-X or "
; R4 O6 A% u6 L5 ?9 S& F                       "GRID-SIZE-Y sliders, or decrease the ": \( {, ~9 T; R( |0 M! ?
                       "number of cars by lowering the NUMBER slider.\n"* {) E6 W0 m$ I# I6 }6 k" H9 d- q
                       "The setup has stopped.")4 N( A) M4 P# ?- D( n# z, T
    stop
: ^; H% J! E) u9 g  ]+ E7 ~5 g' b* ]

. X! J1 G7 o, [. n  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
$ Y8 B. q; a  k6 R$ v  crt num-cars" T0 U+ s% ]# h/ ], b' x0 ~! d" ^
  [
8 ]# F: ^$ y* H    setup-cars
3 b: F! V6 O) }- }* |    set-car-color8 Q: n5 U8 Z( u* H
    record-data8 Y) ^& _' S$ X  S
  ]1 N$ _* P  T( D' [+ f: ]
# z! u' ]9 @' h6 W* v
  ;; give the turtles an initial speed
  G  }) D3 N! x# M* ]1 E/ ?7 D+ ^  ask turtles [ set-car-speed ]5 r( n6 Y0 m2 X  L7 u
" L. k' t7 A2 e  _9 _* Z; K
  reset-ticks* `1 G( S1 b) H5 q' \% Y
end# ~8 Y6 C  x# A, Q5 T

- u! c$ R6 ]4 }% ^6 N. w. n;; Initialize the global variables to appropriate values! r$ `+ Q& p, z1 m1 j, b
to setup-globals( r  |. f% y2 B" }: G6 i
  set current-light nobody ;; just for now, since there are no lights yet% h1 w. j3 U- K4 A! Y
  set phase 0/ z6 X2 t8 j8 @" I  V
  set num-cars-stopped 0% ], h( o1 U- K
  set grid-x-inc world-width / grid-size-x, L  O) d  X% K2 I. U" B; ~
  set grid-y-inc world-height / grid-size-y! a' Y3 x1 `8 C0 b  t9 ~

  X& }+ P% m5 `8 i- }0 O  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
- W: K; t+ x. v. @- ^6 Y0 q  set acceleration 0.099
% L* x8 q0 H( W2 aend' K! D9 @4 [9 f5 r" o5 p0 E

  H8 ]% G# q$ \/ j;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
; A8 y6 j% j  L1 S;; and initialize the traffic lights to one setting
( \) S/ _( s3 Ito setup-patches
4 L1 x2 n" v1 ~1 t4 ~  ;; initialize the patch-owned variables and color the patches to a base-color
$ _) X& H' Q# k' B8 r! g3 f/ p  ask patches; x& Y, F2 h0 b9 c
  [
& A8 _$ a. H) h. z) T% o# V    set intersection? false4 Q8 ^/ \# x4 z- K5 K* h
    set auto? false
2 Y1 v. K+ G5 K5 A    set green-light-up? true
" p* r/ L( c5 @& I/ m2 p4 J# h    set my-row -1
0 G$ w. v/ a+ T" ~6 d    set my-column -1/ _+ T3 {$ A" x* u: ^
    set my-phase -1
* O3 W$ _/ I2 V9 O    set pcolor brown + 3
, N% O9 ~& R$ r  ]
2 F6 R0 U( _: D  a, K  J# z% c+ T, O1 P4 b  ?* y& O0 F& Y9 e
  ;; initialize the global variables that hold patch agentsets# ?! v0 @7 ~* v' |- e- Z
  set roads patches with& J, _  k# n# ^# v3 r
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* B" a; V$ ]* k4 r$ c; X9 |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. v/ g) c8 g! L: L
  set intersections roads with+ S# p0 Z' O) y* d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and% n* F+ i' [8 W, P9 q3 m8 R) ]3 i
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% }, u9 K2 w5 D. R

9 {0 X- @7 @  n' _. i' _9 |  ask roads [ set pcolor white ]
( N( {/ E# {# T& ?9 g1 Q! l    setup-intersections* J+ M* C7 p% a- c9 w1 k$ M
end# X) l: j! F  ^1 O* T2 V9 l
其中定义道路的句子,如下所示,是什么意思啊?! A5 G* ^$ z. x; K. S
set roads patches with
! d. _; L& n3 r% \; q4 `5 L  {; j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% q) m; y# x5 \! `, k- R2 c# [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& ~: k# z1 X. u  l! O4 x8 W! c% 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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