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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。
8 }# i5 W/ ]- @- t# W0 g3 bnetlogo自带的social science--traffic grid这一例子当中,/ E# N& |8 f  _. c% t( D" C; ^
globals7 b+ U1 l% M* ^# l
[- ~7 ?- B) T8 @/ J- g( m
  grid-x-inc               ;; the amount of patches in between two roads in the x direction# V% [, V& g, c! |. r: S
  grid-y-inc               ;; the amount of patches in between two roads in the y direction5 T/ L5 |8 ~- y( [: I
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if6 o7 I# |( t9 i1 B8 Q
                           ;; it is to accelerate or decelerate
8 b2 W0 [) x3 Z0 H" U# ^  phase                    ;; keeps track of the phase) `* h# }6 W( ?0 w. y
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
9 P7 u6 T$ |3 i* U  current-light            ;; the currently selected light: `/ N0 W0 v* c3 k3 B

% y8 V, I' s0 y' o+ ]  ;; patch agentsets
( @5 u- U5 ]$ _$ o  intersections ;; agentset containing the patches that are intersections
1 E! }4 m7 u! m3 P) j  roads         ;; agentset containing the patches that are roads/ I0 \5 G, A* R1 `
]7 K3 y* P" k& W' b1 b
) J1 u# b# ]- S
turtles-own
  y7 R8 \  h+ Y- J; J+ i* X[' F" O9 a+ N+ B+ o: t6 h
  speed     ;; the speed of the turtle
5 y9 m4 r# o3 V- H* U' j  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
( E, _$ F) B/ s( [  wait-time ;; the amount of time since the last time a turtle has moved
( b- I% k8 H* K( |7 i) O* h]' U- y, z5 a) }  [8 o

$ p3 m* m+ N3 g0 s8 w- C. ~$ D8 V8 Lpatches-own
! L4 P) n2 ?7 h5 y/ \* d, U7 P[" [3 D# A  s: f
  intersection?   ;; true if the patch is at the intersection of two roads6 g2 j9 S. U. s/ }+ O  D
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 C1 |  q1 t8 K5 z0 o0 B! r                  ;; false for a non-intersection patches.8 J. [9 o- c* f/ z' o
  my-row          ;; the row of the intersection counting from the upper left corner of the
* g: L# b5 e) E                  ;; world.  -1 for non-intersection patches.
! P2 b$ T$ h) K5 j; j  X, Q  my-column       ;; the column of the intersection counting from the upper left corner of the
7 y/ U+ \9 q0 f                  ;; world.  -1 for non-intersection patches.% a# o& N4 z/ ?
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.2 \  W2 M, ]0 l7 ^7 s. X& }
  auto?           ;; whether or not this intersection will switch automatically.
% B* @7 X0 C9 t9 E9 p                  ;; false for non-intersection patches.
0 r9 O3 `  d6 n. L]) t" q- ^+ L% K% y3 |

0 Q9 ?6 v  P" D( [
* z+ \+ c: H* e5 R# K;;;;;;;;;;;;;;;;;;;;;;
4 \6 C7 `7 v+ y% _! {;; Setup Procedures ;;
- T: j  u2 K$ F$ [2 V;;;;;;;;;;;;;;;;;;;;;;
# h) p! c( ?1 k% @& `) V6 t3 ?% S5 I5 B2 d$ i
;; Initialize the display by giving the global and patch variables initial values.+ a4 R. @' t1 F7 A( ?
;; Create num-cars of turtles if there are enough road patches for one turtle to
2 B/ x) O" u1 \! R# L$ c* m;; be created per road patch. Set up the plots.- @- `1 ?6 l" J; h2 W8 e# @2 H2 L! Q
to setup4 N1 w7 Q* C5 U$ k6 j7 T
  ca) V5 |& }/ ^" F  {: \5 s, L: v0 s
  setup-globals( S1 k4 l* l$ Z& x4 G

  G, Z* N' @2 J' K5 K* X0 ]  ;; First we ask the patches to draw themselves and set up a few variables; {: W4 w  B# L
  setup-patches0 [: N# V( k( _, X
  make-current one-of intersections" c7 X& L5 i5 j5 S$ `# f
  label-current! S+ E& \% \8 w8 `7 f

  {  ?* q" S. [$ U  set-default-shape turtles "car"
- k; |' J& G0 a; m7 F7 i
0 Z7 c6 j: ~- p$ p5 {  if (num-cars > count roads)
  {. a( I) Y+ C% g$ z  [' a1 ?! I0 Z, L6 h
    user-message (word "There are too many cars for the amount of "
8 ~) S; A8 Y# r6 q3 |: q                       "road.  Either increase the amount of roads "
% U' J8 P$ K7 p' M                       "by increasing the GRID-SIZE-X or "
3 u' l3 f" h1 @% c4 J6 k. D                       "GRID-SIZE-Y sliders, or decrease the "
& ^# z+ F' e% N$ O/ A/ n                       "number of cars by lowering the NUMBER slider.\n"5 f- I& O: d! `; P# w
                       "The setup has stopped.")
7 i* A3 ]  p+ o% u' p' |% {    stop
% U' f4 D4 v) U  ]
! m, f( f* Y% X; I% K
* p0 b; j3 T9 @; N# N" L. {  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color! `5 {/ ]* R& @  M* K8 [1 A$ }
  crt num-cars
" }' p, d6 k4 L) L; n" W; {  [, h7 d* v1 C" q/ v! y
    setup-cars
5 s& i* A& w( l% d& \6 U/ j% x$ u    set-car-color
, t/ Q# D3 E0 r: G6 t    record-data
! g( ~+ T3 L% J+ ~5 H0 W( u0 D  ]. a0 E! t: T: v& ^) W& p$ g

8 |% R: |( j) x* ~$ Z  ;; give the turtles an initial speed3 y, t8 M- k0 f+ V" d# x
  ask turtles [ set-car-speed ]" y4 c  G, K) [. y7 b
# S8 W7 @" @6 j+ i5 c1 d
  reset-ticks
  U5 h3 h& [5 o; Q7 {: A, o& Iend; u  ?2 u5 t- Z  k. _. x

  \  U' O6 D. p/ n! W# G;; Initialize the global variables to appropriate values, ?* n( u' h% h: z7 Y& i8 e
to setup-globals
5 s' N: a* o* A/ q  set current-light nobody ;; just for now, since there are no lights yet
7 b8 J1 q6 n* E8 N+ M  set phase 0
1 ?/ Q. V7 m6 t  set num-cars-stopped 0: E3 [  S* c5 M- r6 V$ o
  set grid-x-inc world-width / grid-size-x0 x0 y) E2 c# f) S1 V% F
  set grid-y-inc world-height / grid-size-y
4 _0 a  L& s3 `" }' k, x, O- \" _. Y& P! O0 S
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary' c/ P# B; m- q+ s  H% J) D& u
  set acceleration 0.0991 F4 g- d/ ]1 p4 T
end8 O. d* t6 C, r0 t
1 Y3 h7 P2 u- E0 X* K7 |
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,* a8 h2 C- B" |# R, }0 p# l$ ~$ x
;; and initialize the traffic lights to one setting
4 o4 I# d. X' }; P/ e' y+ _' Kto setup-patches4 d6 q# ~! x% y3 i
  ;; initialize the patch-owned variables and color the patches to a base-color
+ A- q6 g! L* K- W! S3 k- D  ask patches$ {' a0 ?7 v! n" ^6 ^
  [/ g4 q1 j+ g$ @
    set intersection? false. w, D* ^. {2 L; _4 ?* I: d% {
    set auto? false
8 W4 t$ e; }7 E& O& E    set green-light-up? true
$ ]# ?4 _* j5 j    set my-row -1! Y  r) V" ^- g% B1 s; S
    set my-column -1
+ f4 R9 O4 H' f; ^) t2 V    set my-phase -1
! J# p  Y& b/ G/ N. E    set pcolor brown + 39 Z: l; h' F, @7 d1 \7 X" r
  ]5 [6 m; m; y( h+ o  r

/ U. [7 D  Q3 ~9 p+ N- {7 |9 q' L7 M  ;; initialize the global variables that hold patch agentsets
4 A$ U$ V! e9 b  set roads patches with
( x7 C: A5 @: \7 T7 C# ?3 ^4 U    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! \! O) D4 n2 h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 N' ~' {% y+ ]. L5 c% u$ O
  set intersections roads with
; B7 Q3 r/ ~, n: s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and8 w6 g, P3 k7 X: H/ v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) V* e% S/ \( e- t0 U$ u/ x! T* g$ I: P) Z1 }7 l
  ask roads [ set pcolor white ]
3 Q4 W2 I# q# d) Z& v! s( U    setup-intersections( Z" Q  U1 H" v8 U/ A
end
5 f5 l" r& s* ?; j7 ^2 u( u2 h: F其中定义道路的句子,如下所示,是什么意思啊?
; r! q' c& @) _3 k set roads patches with% t' S/ y* U+ Q6 v: A) W# D
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  C) u  h, N3 }/ @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. Q$ x, v* ]2 Y2 `8 x
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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