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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。
$ X3 Q9 k# h3 l0 U- ]netlogo自带的social science--traffic grid这一例子当中,
9 W) y* z: X( g- f. Gglobals
5 P( g$ g: Q' [: W* z1 y) M2 Z+ l3 j[3 [0 `' B4 t8 I& V! T
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
! |( @7 D/ z$ _' y! N2 H( V  grid-y-inc               ;; the amount of patches in between two roads in the y direction$ k6 d" E- B2 @
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if# K1 y0 t" c6 t2 z
                           ;; it is to accelerate or decelerate: S5 k9 O' k- r6 L
  phase                    ;; keeps track of the phase- d& C4 I# H- B( \: b
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
8 `4 D3 x, `# e4 f. N  current-light            ;; the currently selected light
+ X* J' M# r9 {/ A0 O: _
+ R3 f3 C* S1 l! n; a/ A  ;; patch agentsets5 r( N' `) b, [4 ~, Q2 t
  intersections ;; agentset containing the patches that are intersections
. O6 x* ]: E" t8 H. K4 V$ x  roads         ;; agentset containing the patches that are roads
1 s: R; K. x4 u]$ d3 G" O4 o+ F$ B; {9 L
" x8 E; Y9 _5 [
turtles-own
) c" e* U4 G0 W8 ^3 L8 w[7 R4 O) U5 H) ?- Q0 I1 s9 I
  speed     ;; the speed of the turtle9 b: V2 \/ I' ^2 ~
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
; p, N% D7 O; N% M) x0 P  wait-time ;; the amount of time since the last time a turtle has moved- s1 P3 v7 T$ a$ g9 p
]: a/ K% K1 Y7 }; E
' j6 N' ?3 @1 W9 O/ M/ b. h& s
patches-own( V# j2 u% t: _, @2 p  p2 P
[
  g  g( Z6 |- z1 d  k) S* U9 E  intersection?   ;; true if the patch is at the intersection of two roads
  y3 T8 K, J+ r  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
0 I4 D" p8 U4 ?  ]& B' g                  ;; false for a non-intersection patches.
6 ~; f" P  g  H' L8 O  F5 P  my-row          ;; the row of the intersection counting from the upper left corner of the( i5 l! H* I7 F5 C$ O/ j
                  ;; world.  -1 for non-intersection patches.
5 \/ F1 B  W; |( {2 |6 ^% R" X  my-column       ;; the column of the intersection counting from the upper left corner of the" V9 P- ?+ K7 _5 L% l
                  ;; world.  -1 for non-intersection patches.2 W; _/ h; x4 z6 G# F1 T
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( [; i2 T6 a; K& N( |  i  auto?           ;; whether or not this intersection will switch automatically.# V( s, x# e* r6 D
                  ;; false for non-intersection patches.
3 u2 L4 e1 V  H' R+ P( |; x]9 t1 ~" q, N* m6 h8 S

$ i0 V8 G/ c2 R# E" H! u5 e7 G% X7 N3 ]: d
;;;;;;;;;;;;;;;;;;;;;;
( p: G. ~$ F4 X& I: z9 e, k) |;; Setup Procedures ;;+ r3 m; c/ x/ k& X, ]. R( g
;;;;;;;;;;;;;;;;;;;;;;1 J# n3 p( R9 }: J1 i; K

; \8 I5 J$ a( Q9 L;; Initialize the display by giving the global and patch variables initial values.
. H& G% @) r& {% \; y( s4 [4 \0 a7 D;; Create num-cars of turtles if there are enough road patches for one turtle to1 }: B, C& e. |4 b! f9 X4 J( `
;; be created per road patch. Set up the plots.
' b( J5 x6 ^# g* A8 w. @to setup6 r, b+ v" Y9 P, ]& @' H
  ca# q  x* _* b# E/ {3 A
  setup-globals; w, `* U  r1 W7 y9 I

. w0 E( b- r  b1 Q# v8 P% a$ e; N. J  ;; First we ask the patches to draw themselves and set up a few variables
0 Z: M8 Z) T; S* L: Q, C' V6 H  setup-patches
: D( D# k  n' Y% E4 ?5 Q  make-current one-of intersections
# f4 I; Y0 x% Z# S  label-current
  c! W' h+ c; y7 Q
( j2 ~& c, _4 Y4 h( @' T) X% R7 D2 z3 o  set-default-shape turtles "car"( R& g! w7 r2 V
$ o* p( C: l) F6 T5 d0 g* ]
  if (num-cars > count roads)
) m1 B+ M. i6 T3 X& q  [
4 K2 P' _! C1 J: ~" s* J0 d8 d    user-message (word "There are too many cars for the amount of "6 S( F- |8 Z* l' q( l3 L: H  q
                       "road.  Either increase the amount of roads "/ p$ M9 j* p+ E% J
                       "by increasing the GRID-SIZE-X or "
, g, b6 J- Y- z( N                       "GRID-SIZE-Y sliders, or decrease the "0 u# k8 ~; ~( z4 U
                       "number of cars by lowering the NUMBER slider.\n"+ ?3 ], ?: e: \
                       "The setup has stopped.")2 U1 B$ H1 @7 _
    stop+ M3 L" N; ?0 i- A& H6 M
  ]
5 n7 h" F2 y( R$ m5 L7 C+ `; }8 X6 G5 }4 B1 h! n0 G
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color3 p" N# x; v' F0 g+ ?. ^- J4 ~
  crt num-cars
7 b0 |  x6 Y* }* |2 b, s6 ?# {  [
8 G) x5 S8 g" P' U( R    setup-cars, ?7 N, F( h* z9 d& V
    set-car-color
! S. A* E( b* `+ [+ Z; i3 p" g  J    record-data
9 ?9 M4 r: t5 e, W5 A0 j2 F  ]
+ B. X( R) p7 v# w' E5 g$ B3 b
1 |0 H0 N& Y/ w; i  ;; give the turtles an initial speed
  H: r5 v4 I, `* f  ask turtles [ set-car-speed ]
$ V- Q8 C0 _* [* F2 G1 j; u* _/ A' ^" }+ @0 G- j( a2 ]
  reset-ticks& c2 C6 B( T( v0 W$ l" I7 G
end
6 H: G5 W1 O8 `
' V6 M& ~8 q( p6 R;; Initialize the global variables to appropriate values7 t7 j% K" S# p( c3 y
to setup-globals
. Z+ y6 i; [) B1 V  set current-light nobody ;; just for now, since there are no lights yet! V' D" {- A9 O& G+ w) x" d% N
  set phase 0- i, T  Y4 a& {: ?, v; Y- b
  set num-cars-stopped 0" y7 {5 ^' n+ [) V5 q. @. L
  set grid-x-inc world-width / grid-size-x
0 j0 c+ K: z5 E" _6 e& Y  set grid-y-inc world-height / grid-size-y  j2 O/ ?( c0 p% _
' |7 ^4 T  j% \
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary6 g1 f* Q, d8 {7 r" `3 h# C2 R
  set acceleration 0.099( P, E" O3 {4 j4 p5 q  F
end( B9 ]( }. r0 T1 A

* e2 N- `: N  F, Z$ m" }2 [;; Make the patches have appropriate colors, set up the roads and intersections agentsets,0 L) w: i* N2 J) ?- ~
;; and initialize the traffic lights to one setting
8 ^  S4 G& U7 Uto setup-patches* s# U3 @! ]3 C. ?; W: j& }
  ;; initialize the patch-owned variables and color the patches to a base-color/ k4 U$ k$ c* |' L5 B5 q4 W
  ask patches
: B, V7 n. h/ p7 ]- F' B+ Z  [
* W" q1 B2 s0 A8 P$ p    set intersection? false
, D) }$ P  j* Y8 I: y, r3 N    set auto? false
2 U* l" o3 _) h+ `6 O* Y+ ?3 @  g    set green-light-up? true
  r/ d4 P+ T2 l; w! b    set my-row -1
: a2 B% V8 _9 x2 G, t! L    set my-column -1- D5 W6 x$ Q* l  `* r5 o) }
    set my-phase -11 g) w! k) S$ O# L  r7 p- G  A, S
    set pcolor brown + 3
6 v' \7 |' X4 |( }8 D  ]
1 X0 E3 K8 \2 T; S4 g
# T' l6 U2 G; G1 G( V4 E  ;; initialize the global variables that hold patch agentsets+ w* U' v/ m1 V: c9 }& f
  set roads patches with- t; W- f: s% Y( K. S  l& R8 e( S
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' t5 `  L8 N" ~& N+ X5 c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( X6 x) J( b- W! o- K1 M
  set intersections roads with
- ?/ D  W8 S. m    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
3 n, \0 h3 P+ _4 X( O4 j2 f7 P    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% a/ Y4 R5 Q8 @0 P' Z
! D. L" T, m5 p- L1 p$ b+ l- Z
  ask roads [ set pcolor white ]
3 W  o1 \+ J% ^2 L" |5 x    setup-intersections
9 S4 K' L8 y6 }' Y. nend
/ w  G; K6 f3 W# [其中定义道路的句子,如下所示,是什么意思啊?% j/ |3 f& x! N3 w
set roads patches with
) g7 K7 C8 Q* y+ z6 N    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& O3 e2 C  x) Q' [6 ~3 m; o- h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! e) F& S+ k- F2 D& n2 A8 ~" o
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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