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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。
* n# K7 H6 I  H* A- E4 r5 Xnetlogo自带的social science--traffic grid这一例子当中,4 N3 g# x4 [" `* y
globals. j% q- C. ?5 n+ U, A3 R5 B0 O
[
, o7 l1 g/ \7 X3 _8 l  grid-x-inc               ;; the amount of patches in between two roads in the x direction% @: z. R, Y2 d
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
  s6 J& q! Y3 t  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
+ C+ U* b% w6 G, g7 e/ [) m                           ;; it is to accelerate or decelerate
: m' d3 V0 H' J3 Q* @: ], I  phase                    ;; keeps track of the phase  p  m+ A) _6 t; ]) f8 P# ~' y
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
3 P8 P9 n5 ^0 k, l4 K6 Q  current-light            ;; the currently selected light
& V: B* j  E7 c5 w1 D/ _
  ]3 W$ Y3 v" M1 T- u  ;; patch agentsets
: `+ i3 S1 h, |  _' [% O) H. B  intersections ;; agentset containing the patches that are intersections
) E  c' d2 D4 E* }  roads         ;; agentset containing the patches that are roads2 k. g: Z* w, J5 i3 j# H" H8 r
]0 P9 H. k0 f6 K, b% s' v/ |: W
7 m, W! j! q2 t) K9 S0 x* O9 l
turtles-own9 F, v) O: q# W' Z7 z
[
6 {* i: M' Z8 b3 n. r  speed     ;; the speed of the turtle0 }& F* n' D! p6 Y
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, Y& I/ R2 Y2 F$ ~1 i  k8 R0 H
  wait-time ;; the amount of time since the last time a turtle has moved
5 j# c7 A% v: `; s5 r, i% o]0 ]1 a. Z) U. q" u/ L! _2 [
, p7 K4 K* n& e5 q- N
patches-own
& b- S4 l8 J7 ]0 G" C; `[  f! c7 y9 ~5 h) e4 q1 o1 h- W
  intersection?   ;; true if the patch is at the intersection of two roads- q( D! \( [# s$ v. G; O( \' P1 O
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 ?# o& @0 g6 c: v' e& O                  ;; false for a non-intersection patches.) R2 h$ b# f# @8 |0 {. k
  my-row          ;; the row of the intersection counting from the upper left corner of the( ~: F) G6 z- P1 n
                  ;; world.  -1 for non-intersection patches.
$ @8 {2 Z' p# B& c+ j: U  my-column       ;; the column of the intersection counting from the upper left corner of the
6 s1 w8 `+ s3 F9 X4 D/ u1 L. J                  ;; world.  -1 for non-intersection patches.2 T' k* ~3 }# y
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
3 ]. _5 r9 [! G& _; a" g! s0 e1 ?! |  auto?           ;; whether or not this intersection will switch automatically.
( a/ V2 u* `& h' x/ d2 t: z7 Q                  ;; false for non-intersection patches.
# i+ `3 a6 Q( [9 ~( Y- g7 C+ k]) U8 d% G) e- O3 H7 \# P3 K! t& E0 C4 Z

  B9 Q8 h: M  ~7 {% e$ ^1 v
  n' r2 D! u0 M  `# B5 Q; S;;;;;;;;;;;;;;;;;;;;;;; r7 L( m8 K% ?* ]
;; Setup Procedures ;;+ a8 h8 A3 P- o5 [+ x
;;;;;;;;;;;;;;;;;;;;;;1 s% I- X+ t# }

- v1 g  e% |' e! J' a7 K7 n;; Initialize the display by giving the global and patch variables initial values." S# H: A3 {3 ^/ n
;; Create num-cars of turtles if there are enough road patches for one turtle to
! e' y1 O: a9 t! X4 G5 K;; be created per road patch. Set up the plots.7 [/ M! r9 s* v; q. v
to setup8 j6 ]! q$ k% @- N8 c& ~( h% J
  ca
" }: S8 z) m( ^$ _, j, `  setup-globals0 D! H0 x& e! {7 a
7 J, t; z, d+ L- n2 f( m$ x
  ;; First we ask the patches to draw themselves and set up a few variables
- w  m1 z" F9 b1 r- H. |1 Q/ D  setup-patches6 G" q( ~4 g. ?1 p
  make-current one-of intersections
. A7 v1 N; u: j& x  O, `4 F3 x  label-current
# u& d3 U- O+ [3 A& H
1 F/ L. U1 I8 U0 e  set-default-shape turtles "car"
( c  l0 v; O+ K- X2 M% Z  h
3 ]" r# P8 S4 S! ], y  if (num-cars > count roads)
& J0 r! @' q4 k3 b  [
$ U% ?, r8 f4 A* F, \" a    user-message (word "There are too many cars for the amount of "% G; e, I6 a* u% U
                       "road.  Either increase the amount of roads "
; M- A$ b8 M1 Z9 h6 M                       "by increasing the GRID-SIZE-X or "
! h+ D# }! `7 O- @                       "GRID-SIZE-Y sliders, or decrease the "
# \4 E% z0 u/ _0 ?. D' k                       "number of cars by lowering the NUMBER slider.\n"" B; G# {2 @2 m  d' g& q
                       "The setup has stopped.")
4 J- Z+ ?0 z* x" w7 P    stop0 A; c8 c( Y3 K$ \/ B+ f
  ]) P5 Q/ A) ?7 @& {+ ]6 o

1 T9 x7 F% l; S; m  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
0 b4 Q, H5 R+ a- i7 K  crt num-cars
1 E: H( ~( B6 E' S% e/ h$ e2 k  [, ]9 @- U$ O; X
    setup-cars4 r9 m% j2 p+ m' ^8 l
    set-car-color. `, J1 n" l& }. a( h
    record-data
! `! l+ ^* I3 A4 i  o- O+ ?  ]
- Z9 @% ]/ F! T6 r. I3 Y# S, ^! F2 y( H- n4 p
  ;; give the turtles an initial speed8 A. j# e: I& T
  ask turtles [ set-car-speed ]
$ `/ Z2 I! r) @  |1 J/ H+ W. e/ l' e2 P! z: J/ A" u' I( }( l6 t' x
  reset-ticks+ K, a$ l) A) r0 g9 E% g
end$ \9 i+ v- p1 s. `* G# B

+ P. O5 b5 L; n' b8 U$ D;; Initialize the global variables to appropriate values* e0 f+ e* C* Q6 S8 J8 g5 O
to setup-globals
( ]0 X7 y" T5 T; U  set current-light nobody ;; just for now, since there are no lights yet! n- C& h0 k3 s! p4 U' w4 e- p2 D
  set phase 0; u% n1 x1 L0 s" g3 b9 A6 v
  set num-cars-stopped 0# f) t) r7 ~( p: K+ o# J7 A
  set grid-x-inc world-width / grid-size-x0 c7 h- F8 h1 _. ^
  set grid-y-inc world-height / grid-size-y  @3 k: K4 _6 J( R: W. i

$ s$ b) o/ |1 t3 }; e* s  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary. a5 S2 ?$ o/ X, G* t
  set acceleration 0.0997 i6 y, }+ D+ P" P* [/ m# e- q1 d
end6 d4 d3 m% m* f

( I) m2 h0 a' J6 q9 h+ Q;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
$ T2 x' f: ~) Q8 X4 T;; and initialize the traffic lights to one setting
" G" e1 |  C* ]to setup-patches
# J5 O, }2 W/ }& V( U  ;; initialize the patch-owned variables and color the patches to a base-color! t& _, T1 P  r( s' V
  ask patches
0 H6 g( B( O! L8 i  [) D. O% _4 T' h& @
    set intersection? false
7 c0 @1 `; W1 E    set auto? false
, M/ A8 s* i" O; Z- V    set green-light-up? true
5 f. E- J/ g/ t0 e+ x) t" c    set my-row -1
3 A4 @6 s7 Q/ ~/ m2 V( P    set my-column -1
. {4 U+ m  R, H    set my-phase -1
+ H+ h. n; @6 F# A4 l' S1 w" O    set pcolor brown + 3: w3 C! }5 f* i8 z4 a9 C
  ]
6 n2 X: h$ _, T& Z: S; K/ U* k, t. S3 \! f
  ;; initialize the global variables that hold patch agentsets& ]8 Y8 c# _- Q! P+ w
  set roads patches with
' k: d; J5 M& ?) r& Z) g. m    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 V% \, D2 v& P  D/ J5 i
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* Z' h! o3 n" g+ F% V  M* P( t
  set intersections roads with: ^$ {1 ^6 R5 l' E* z" e
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 E4 E. L8 M5 B. Q0 M9 u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% {5 D. v* B3 b* i$ K
! l& I/ Y+ u% e* T2 N$ S
  ask roads [ set pcolor white ]
$ _& m  F; a& l9 n9 X7 |    setup-intersections6 X$ S4 M) W$ A7 o
end
" d  T! J4 c- U% s, j% Y7 ]其中定义道路的句子,如下所示,是什么意思啊?
& F0 ^  A" L9 [2 B! S7 E5 ^ set roads patches with
0 g: @; J. T+ q+ ?# a: t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 G% `5 D% ~# [2 m$ _    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% N% \7 Y! R& m
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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