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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。
; A: E% l$ U# s' C) F+ Knetlogo自带的social science--traffic grid这一例子当中,; ^* ?. p, @9 y  y* e' X! s
globals+ N3 e7 m) f( g  D
[$ j0 |) {! j% Y4 ]5 f& u+ ^) y
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
0 B9 e5 s; ^! a8 Y7 ~  @0 O  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, W0 t0 z% N5 d8 N! u  acceleration             ;; the constant that controls how much a car speeds up or slows down by if4 J% A( f! o2 V( z
                           ;; it is to accelerate or decelerate
! m9 M6 p* y( B: M  phase                    ;; keeps track of the phase4 K( @+ w: Q2 a& i7 |+ n1 f8 G
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
  _/ I% ?0 a- E3 c5 l, ?  current-light            ;; the currently selected light5 G8 s1 F$ U8 i  }. R
) K; ~' D8 a! ?, m* P4 M
  ;; patch agentsets2 n" I  n; j: G: n. [: ~+ K8 G
  intersections ;; agentset containing the patches that are intersections! c/ _9 L9 z8 `
  roads         ;; agentset containing the patches that are roads+ J) d, Y  Y1 h2 i
]8 p+ Z2 d" d! ^+ L2 W* g1 `' Q

& E' N+ n: \& u8 [/ Z, k1 @turtles-own
; l+ W/ c$ L. R6 ~[1 C$ `  }# q5 s! K5 p! a: ], A
  speed     ;; the speed of the turtle
7 ?, q( O7 q! E, k3 m1 d  up-car?   ;; true if the turtle moves downwards and false if it moves to the right' T' Q, j/ @, r+ j! V
  wait-time ;; the amount of time since the last time a turtle has moved, }/ o5 q( @& r: M% M* k; N& p2 g
]; G& o( Q' m% H6 `, }: t

" J! r! [. k, t5 h0 H& epatches-own
7 `. i& j7 |' f2 X- }9 A[
5 f8 C9 L% A5 N# b1 `' s  intersection?   ;; true if the patch is at the intersection of two roads
4 e$ v9 n" }$ }# g  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
& ^5 x* y: |7 Q7 G# p3 S+ r                  ;; false for a non-intersection patches.6 m6 f( f0 {; t  }: }* a# M( ]$ |
  my-row          ;; the row of the intersection counting from the upper left corner of the
4 Q* M  R- j1 b# t0 Y* W( l0 H                  ;; world.  -1 for non-intersection patches.
  N( Q4 F: t/ M- ?  my-column       ;; the column of the intersection counting from the upper left corner of the4 _0 E- o+ k$ n* u4 B
                  ;; world.  -1 for non-intersection patches.
+ i: {7 w+ O* i" F) ~5 f  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
7 b) ^$ s% o+ n5 U+ T  auto?           ;; whether or not this intersection will switch automatically.
& ?6 {! |& `2 f3 |                  ;; false for non-intersection patches.& ~1 h* t9 z  l. d5 {
]% }% m6 C! {! t9 g6 f4 ^
* h( |2 t+ t% L
& H+ w# R3 o- h3 G8 o- Y
;;;;;;;;;;;;;;;;;;;;;;
) {8 M. E6 R$ _7 r) Y+ g8 y* G;; Setup Procedures ;;
9 h4 n4 D# ^! d3 e$ Q0 Q$ V, v;;;;;;;;;;;;;;;;;;;;;;( W4 j/ [* N/ H7 o/ s
  d6 M8 D) ]- w# O2 `
;; Initialize the display by giving the global and patch variables initial values.
' P  J6 ?6 J) w) N;; Create num-cars of turtles if there are enough road patches for one turtle to9 R$ R: F7 C) J/ L( ?7 q
;; be created per road patch. Set up the plots.7 z( M  D# R. g2 a# s* _
to setup
( ~! l8 i8 x7 f2 F  ca
" v( W) V3 a  p! H; p1 h& `  setup-globals
; Q+ q" v  x$ b  e4 {9 Q: z- Y' d* G, v9 ?+ m* h- s% u
  ;; First we ask the patches to draw themselves and set up a few variables
4 ^! o( L) N7 v9 r2 K  g( I* C  setup-patches
8 E/ \" A( m! l" w& x0 m' R7 f0 m, L  make-current one-of intersections
. S7 l8 b- q+ H$ p" z9 M/ Y  label-current# [& I' u9 M! T6 D2 N
8 N$ h! t5 D1 e) i
  set-default-shape turtles "car"
- u  K# i1 K0 F% a+ N! [1 }- w' h. U
  if (num-cars > count roads)0 K: T, u) g* X2 v6 N
  [# u9 }5 G) d2 Z2 ^
    user-message (word "There are too many cars for the amount of "
9 W3 A1 m: }/ |$ l9 D                       "road.  Either increase the amount of roads "% b9 J2 A! U2 F* q  u9 Y; L( J
                       "by increasing the GRID-SIZE-X or ": c: i/ N  r" Q
                       "GRID-SIZE-Y sliders, or decrease the "
& a6 N  m; ~6 A0 K0 f% k                       "number of cars by lowering the NUMBER slider.\n"
0 T3 `- k& c6 q) G* @9 n# T                       "The setup has stopped.")
( \5 j" I$ n0 o% m- S4 L    stop8 l$ ^- f5 W  A. L; v5 k
  ]
9 a3 B! p' ~- u  s# i. ]
* V6 o* L5 I8 G. Y( t  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' z/ h7 ^2 j0 D, v2 O" M6 k6 o  crt num-cars
( X9 C: r0 ^' d' C8 I0 m, C" n) |% x  [7 |$ e/ }: W& I" W# l+ J' A
    setup-cars
- @& a  J8 m& }5 C8 C6 I! j    set-car-color. l& z+ U. ?+ C. W
    record-data
/ _* R3 x& w- `+ C' F$ }1 v. Q. [7 S1 B  ]- c4 Y0 e$ J2 y3 n# l/ R2 S! u
& `: h2 ?+ j$ P6 f
  ;; give the turtles an initial speed  l+ Q! |6 }8 O( F
  ask turtles [ set-car-speed ]
8 [5 B: g9 f2 `4 N/ e' [$ ]( s: q; O
, Q5 Q( K( }/ H. W  reset-ticks5 Y  [# A0 y- y' E' u
end0 a( O* T' n2 e$ }& q( H

+ F' A2 Y+ A9 ~- P1 S;; Initialize the global variables to appropriate values3 w1 r- V. i" N' ]
to setup-globals% K/ U# Q7 f# m# s8 K
  set current-light nobody ;; just for now, since there are no lights yet- ^" ?: J+ X0 W
  set phase 0
$ d- I7 l' L+ C; [/ }  set num-cars-stopped 0$ N4 c- Y4 s4 z7 r: m5 {% D
  set grid-x-inc world-width / grid-size-x& l. f/ K3 u* g0 a. [
  set grid-y-inc world-height / grid-size-y
: ?9 f; O  v# [0 ]* r: V! d
7 n2 f) O. |3 a' ?$ I) q6 q5 }6 t  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
  _( ], x  k4 E+ C) o  set acceleration 0.099
$ o) }' H0 V) {/ v! g  ?5 V9 J6 ^end
! @* {. ?* Z" [! `# R3 ^8 l. h, H
( d+ y; K/ o* _8 b3 a  |- c;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
* _  ?0 W- w6 U7 M% N;; and initialize the traffic lights to one setting
7 l4 y/ x) l, ^% Q- R6 Mto setup-patches: T) S, {/ ]# Q; s* i
  ;; initialize the patch-owned variables and color the patches to a base-color/ u% H$ f' O8 p5 l, d" [/ r6 Q7 \. H
  ask patches6 L/ V" W; D- ]# z' P
  [
2 A# r4 L% O. Y; s$ r! L: `3 N    set intersection? false9 }' z2 M3 N+ n; Q7 \' |6 I. m4 [
    set auto? false
* X/ S8 C! o" Y! M8 Q. x    set green-light-up? true0 z# L9 P# D- Y" \2 L( [' m6 n
    set my-row -1( b2 l+ E& w% q7 }. F- J
    set my-column -1
7 t; Q' ?' Y; g8 }% d  Z3 W8 f$ j    set my-phase -1
! u7 t" P) F  A6 _$ m: |    set pcolor brown + 3
! ~$ C) Z$ M! ~4 N6 h  ]& `6 G9 u& C8 y$ C/ V- y, W
! }! I9 d0 I, |4 F  m0 s
  ;; initialize the global variables that hold patch agentsets
' {% B* p% ~. ^& ~1 T  set roads patches with
# X) l! Q9 r% _3 v) ?' P' ?6 X5 Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* _3 G/ e% A% }- J6 s    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  D8 K2 L/ I# n- W/ a4 k  set intersections roads with
+ Z" t( A- f& r$ V0 \+ ^. ^) R0 a5 d$ a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and4 g; d4 `; _4 C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ @6 ^3 _9 k6 w# k# q# c# Q$ I. x( w% s* m8 @7 s2 q# B
  ask roads [ set pcolor white ]3 }3 O- Y8 w2 d
    setup-intersections
; h! H5 ?9 ~/ o/ X9 B8 Xend
1 S7 ~2 y  D6 {; }6 j其中定义道路的句子,如下所示,是什么意思啊?
" t3 a, Y) h8 B7 _; w( W set roads patches with3 ?6 H+ a+ m$ w4 Q% `7 t% q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) n4 h, V2 `* }) x- C7 L    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. |8 S" W' w. Y
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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