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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。
4 `& R; M1 Y% f) v) vnetlogo自带的social science--traffic grid这一例子当中,9 m' n, Q. {* M7 f0 j
globals
: v' q+ a- v# x" e/ Y[
( j% N3 x* c5 A6 W9 V$ R  grid-x-inc               ;; the amount of patches in between two roads in the x direction: e! X* W, N( W# L, H
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
( _% W+ {* T: o+ f' H  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
3 R! Q. U3 x, K6 Y+ V& T                           ;; it is to accelerate or decelerate
3 C& Z; q( i+ a' g1 x4 O  phase                    ;; keeps track of the phase: y5 H. ]" _" X5 x' s% a5 y
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
5 U! G! A' @9 U+ `6 a5 U5 W+ s  current-light            ;; the currently selected light
0 ^- F6 y" J/ S
! O  @5 W# F0 r3 X' G' V% M4 l  ;; patch agentsets1 j' F3 X( c( H% o) n$ p
  intersections ;; agentset containing the patches that are intersections
  }5 w) h5 o0 q  roads         ;; agentset containing the patches that are roads: z! _2 V' Y! ?$ v7 |% T
]4 z5 v" \$ T  c

4 }- [/ j( a" r) t) Sturtles-own
! p( [3 f& {$ m7 G& S[9 g' W1 q) Q' }( C1 K
  speed     ;; the speed of the turtle
! ?- A7 B: y9 U7 k/ N- g  ^$ h5 l  up-car?   ;; true if the turtle moves downwards and false if it moves to the right. M; t0 I/ m; |; j: a: p6 |7 c9 S  ?
  wait-time ;; the amount of time since the last time a turtle has moved
% o* I& A/ q1 V' v% D- A]  F0 h; T$ |9 O

6 u& ]& D9 ]6 S5 A) O1 Q$ t6 ppatches-own
  m" W, Y7 q6 X$ d2 v[: B8 y6 f$ P) w4 y
  intersection?   ;; true if the patch is at the intersection of two roads
3 [, \2 E' ?+ d# S% k  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
+ g2 o, @3 Z( _# Z8 w                  ;; false for a non-intersection patches." V* p. V5 r1 K2 r0 W9 g9 W
  my-row          ;; the row of the intersection counting from the upper left corner of the6 @3 G, ~# ?) d$ z, s* @
                  ;; world.  -1 for non-intersection patches.
% `, ]% L" ^/ T6 V' o- T  my-column       ;; the column of the intersection counting from the upper left corner of the
: T9 f- d; D: [: H0 ~* Y6 }# q                  ;; world.  -1 for non-intersection patches.
- A1 M) q1 E: @  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.. W0 _- A; ^  Y& V4 Z; b8 W
  auto?           ;; whether or not this intersection will switch automatically.
, N/ O& F0 e  A; }9 @                  ;; false for non-intersection patches.
# ?" w4 c* C  S$ \4 m]  i7 `2 x, |# a
4 Q8 G" Y1 Q6 c1 p- {- s
% N5 x- b- G( \6 e1 E6 ?- f
;;;;;;;;;;;;;;;;;;;;;;
! H1 V* ]6 H6 P  V) e;; Setup Procedures ;;" X  d4 [: l; H8 d' d
;;;;;;;;;;;;;;;;;;;;;;
1 o9 }& {7 A" ]8 x) X) R" \+ l/ n7 j2 N3 ?$ y
;; Initialize the display by giving the global and patch variables initial values.9 p7 J( R0 Z7 r2 `4 a$ j
;; Create num-cars of turtles if there are enough road patches for one turtle to
. i+ C/ y  S& z4 N$ l;; be created per road patch. Set up the plots.% r$ {6 X& v) `, W3 A& @
to setup% b. ^( ?) t4 j
  ca
4 q5 W; W! u: z2 ~/ i, f: R" A' t  setup-globals( i% ^2 g0 @/ r  ^" g1 V* `0 `
+ G% B8 V, t8 n; a: T8 h
  ;; First we ask the patches to draw themselves and set up a few variables( L% t# _* q: K/ S) m  ^
  setup-patches
$ O: f  G# Z# J% T( M, A1 l  make-current one-of intersections
  `2 B! S; U* b3 K# |: n6 u  label-current8 z! n2 d+ M3 m. p

& g3 \" R7 P1 [  q; j6 e  set-default-shape turtles "car"# o4 s) r: R6 u6 S8 Y

7 l' z5 T9 L3 q( ]1 Y  if (num-cars > count roads)6 i1 z7 a, k1 q1 \  E, m$ f# j
  [
9 H4 R8 [2 |- Z& c4 }6 ]    user-message (word "There are too many cars for the amount of "  \6 [+ V1 B0 w
                       "road.  Either increase the amount of roads "" c5 m, ~* g5 R, G/ a: D: H
                       "by increasing the GRID-SIZE-X or "
8 M1 _; m" ~' v% V                       "GRID-SIZE-Y sliders, or decrease the "
$ Y  I. `7 N( P                       "number of cars by lowering the NUMBER slider.\n": A0 s! y3 ~% j  z  G
                       "The setup has stopped."): e4 C; T2 D. Z4 l- L
    stop! o3 K4 m3 [8 ~7 Y5 b5 {
  ]
5 {2 ?, x( w& ^& O% R
2 F1 Q- f8 v( }2 a  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
$ E1 l6 X+ ~0 f7 L% R7 u  crt num-cars
" {3 w, T1 q) S1 b  [4 A7 H/ J4 p# ?& h% R' p
    setup-cars
- |0 s2 W! `" o9 w" e) N0 f    set-car-color
8 U8 {6 Y' r& G3 ^$ G& }: D    record-data
# E* ]( s7 T. v2 p& b  p  ]
& U, L& s* w! i7 E4 Q% t, u* h& R; J1 q) g! N: l' |/ f  N5 f- r) Z6 I
  ;; give the turtles an initial speed8 c/ J  Y; [  [
  ask turtles [ set-car-speed ]! D  P, R9 t, b3 M' g; S0 x
, f7 N- ]/ z' i8 h% j+ q- E# z. C
  reset-ticks9 d9 ?& l" a1 q, A
end% K$ o' s2 i( t" |0 N2 U

7 @8 L# b0 K" h;; Initialize the global variables to appropriate values
) }; j4 c4 M' n2 g! _to setup-globals; M: e" ]& E! D3 k% I
  set current-light nobody ;; just for now, since there are no lights yet4 Y5 L4 g6 g& m% t6 H( V& L
  set phase 0# O6 M7 v2 S+ A
  set num-cars-stopped 0* w9 `/ W2 |: o" t) |" E
  set grid-x-inc world-width / grid-size-x% e8 i" g: E& S5 [' I. q- b
  set grid-y-inc world-height / grid-size-y$ E3 v% C7 ?+ \; C/ R
3 ?& P' P2 A  z/ |5 k8 M( h3 l
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
2 d$ X5 v. s3 `) a( C! t3 V  set acceleration 0.0998 |. n- u) F5 P" c
end7 S% k9 T9 X# }' C

1 D1 d0 C6 j0 ~$ e; l! }3 \;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
; U, g: E+ `) {% z; w6 f" p;; and initialize the traffic lights to one setting
& H% F! T6 C6 B4 B* Uto setup-patches! z3 @$ o; k8 V: ]0 G
  ;; initialize the patch-owned variables and color the patches to a base-color- k- E+ h* ^2 z+ ], S
  ask patches8 }" D% x/ B( ?- ^$ w, L
  [+ p# }/ P1 X0 {3 m
    set intersection? false- I' B! R- K1 r6 |7 |% R
    set auto? false; o/ T" g6 y, u( ^6 W, S7 g) M% T( g
    set green-light-up? true' @6 a2 g& x+ V, V0 Y+ S
    set my-row -1% x3 u' K$ X. H- X' T7 Q
    set my-column -1- q: ?6 b: Q$ \/ _
    set my-phase -1
2 v. N3 A( s7 \2 _    set pcolor brown + 3( l0 o2 w" J  d; L; d) e1 ?+ S0 v
  ]2 C" h# E& v0 P+ a2 {4 l/ U

! I6 Z, @* F& K  ;; initialize the global variables that hold patch agentsets) p2 b8 `3 N2 D. }2 }  V! X$ O# j
  set roads patches with8 m9 P8 x  d' i9 X. G' S
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: R: j1 B! i5 @& M6 J& T
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  S4 P5 |0 H( e, z, Z( U, y+ s  set intersections roads with
4 p( g2 x2 X, t. o, A9 @  b, n    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. i# z, e, J8 i& P- P- b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 B/ Z8 B( k3 y5 F2 F; p# }
) r% K9 ~+ v7 A6 w0 D& w
  ask roads [ set pcolor white ]
6 K9 l2 D' [6 _/ p( \/ V    setup-intersections
1 E) R5 y) ]! {. R% Lend( ]! g5 j) t4 Z
其中定义道路的句子,如下所示,是什么意思啊?) v$ a: W. V  I! J, G
set roads patches with
5 q4 W* M7 r' L! V# X# j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ h8 ~0 k8 L1 g9 A# B0 a% M# z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. h6 ]) y/ P& \+ J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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