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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( w# U: c5 H% {netlogo自带的social science--traffic grid这一例子当中,9 s) A, C3 s. O, i  J+ |1 ?6 C8 v
globals) r$ l" p$ o: y, r/ Y
[
. q5 N) ]' u: h  u; Z  grid-x-inc               ;; the amount of patches in between two roads in the x direction( w' u0 o# t  [, m/ M
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 C4 q- g2 O) d7 ]6 Z  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, m7 z6 s% |4 z+ e$ O                           ;; it is to accelerate or decelerate
! ^3 O- W5 Y2 P' m  phase                    ;; keeps track of the phase6 a$ u4 f& f1 z/ M. K9 s; V" I  _1 ~
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
- d: M5 U2 C1 I1 V3 f) l  current-light            ;; the currently selected light
# F2 m( |; p' x
- b) V( ^. K; K; T  ;; patch agentsets
' R7 F( L$ w  }+ Q# P  intersections ;; agentset containing the patches that are intersections* G! V8 y' L4 G6 Z  `9 H; x
  roads         ;; agentset containing the patches that are roads- C( }. ^) h/ p% i2 a$ m
]$ D7 `* `5 c/ @+ o6 T
; u+ j2 V+ ]/ m: }$ R
turtles-own3 e$ O# @( y7 V9 A3 V0 _
[4 y: G8 g! x! p' i
  speed     ;; the speed of the turtle
) z% h; W3 k) S( `5 ~# b3 \& p* b( S  up-car?   ;; true if the turtle moves downwards and false if it moves to the right4 r1 O, y* l% o0 i8 ]) N& Y
  wait-time ;; the amount of time since the last time a turtle has moved
! ^% z& ?1 P8 \: w3 H9 ~* U]8 _  Z! X( ~, z  o
/ N$ V8 I3 ~- i& c0 P
patches-own
$ c3 z  c3 V4 y5 W# n+ n[
1 P7 x, _7 Y( n. m0 T  intersection?   ;; true if the patch is at the intersection of two roads1 v1 ]$ G0 w% G. t* b
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.  p1 T% V0 }! Z$ Q) A6 I2 Y1 ?
                  ;; false for a non-intersection patches.0 C* S! _( i* `# p
  my-row          ;; the row of the intersection counting from the upper left corner of the
7 G9 F6 C/ w. E% i( @                  ;; world.  -1 for non-intersection patches.
/ o# y# c; T( W. m. J- t# Q  my-column       ;; the column of the intersection counting from the upper left corner of the
1 u- ?" v. u5 ~) Q                  ;; world.  -1 for non-intersection patches.
& v2 n8 E% Z4 l! {% X8 T$ v  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
: x9 p  Y7 ~0 ~4 l  auto?           ;; whether or not this intersection will switch automatically.& c; g8 m  B' a& W' ^" ^1 \
                  ;; false for non-intersection patches.( Q/ f" C! w  V
]# h  |. M7 p- o. @4 N
. w4 {: ?# O+ z- a6 _! D7 j
+ B8 u6 A; d& I
;;;;;;;;;;;;;;;;;;;;;;
: p: S2 p+ ~* s3 G. o* x;; Setup Procedures ;;
. C2 d& i3 Z- r! _' z;;;;;;;;;;;;;;;;;;;;;;' k3 T0 i0 K; |6 L) G8 V8 B; T
. r# g: I  ]7 _- c1 j2 w/ z% g
;; Initialize the display by giving the global and patch variables initial values.# L3 T4 {* V4 n: _5 ]
;; Create num-cars of turtles if there are enough road patches for one turtle to
; u) O; l& x0 f+ `' J3 k9 |/ V;; be created per road patch. Set up the plots.
' n1 a0 v. f# w: b( R) J8 C- \/ `to setup
: U0 A5 g9 B, D/ B# S! E5 z  ca
( x( Z* R6 X/ F  s% @4 P  setup-globals
6 W0 m' \' ~6 u3 v5 z# x0 l* @6 w9 B' B& J' T& h, h
  ;; First we ask the patches to draw themselves and set up a few variables
6 V% w, w. w. ~; ?: H  setup-patches- C  ?: i; o+ E+ f
  make-current one-of intersections8 [/ c* _  m+ O
  label-current7 Q0 Q+ Z7 e) O7 f& D
. m1 R! X/ N6 b# {8 G9 n0 ^
  set-default-shape turtles "car"/ I- D+ {! ]3 r* F) F4 K9 ^: H8 {

# q+ q5 n) K# i5 `  if (num-cars > count roads)7 V  Q3 O, g5 V2 O! C
  [  }8 J/ m; \+ x/ a. M7 s& L" z
    user-message (word "There are too many cars for the amount of "- v/ X6 U! V! |" e
                       "road.  Either increase the amount of roads "( B6 p7 v( r$ b2 _4 |6 r: I4 B  l
                       "by increasing the GRID-SIZE-X or "1 ]. X/ h: C" P1 J
                       "GRID-SIZE-Y sliders, or decrease the "* M  m. i- Q( D. F4 Y( e, T. P
                       "number of cars by lowering the NUMBER slider.\n"
0 p1 T: g5 z; K2 c                       "The setup has stopped.")+ _1 T* L- K1 T; `. w8 |
    stop
- y; ^+ P7 ~1 V6 d  ]! }# a. _/ M2 \& v) `! L

( C/ B2 V5 B& g$ N; n  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color8 h, ?5 m; L$ Q! g% N- Q# X) ?
  crt num-cars
9 m' Q% H; C3 S+ t- o% O9 S  [/ I) X$ c, Y) r9 t$ U0 w9 ?4 C
    setup-cars* ]2 j$ I, z8 v: Q
    set-car-color$ \4 E" {7 V" ~  `  Y' {
    record-data
! u! `0 ^: o$ X8 R9 Z5 p2 M+ ]  ]
5 E, Q# I! x9 w0 T  s: J: Y
/ H, ?# o  x# F( v* ]' w  ;; give the turtles an initial speed
" W3 ^" A& ?8 d0 W: p7 ]5 {  t  ask turtles [ set-car-speed ]. o9 Q7 {, S9 L5 p
' P! M: w, e# O- d+ f) ?( }
  reset-ticks& y7 h' I1 s. i+ u7 ~
end
; }9 O+ f6 l2 F+ z( k% [; P" B3 U+ ^: T
;; Initialize the global variables to appropriate values
# _; X) v1 `- eto setup-globals5 p, _& d* F6 g2 t9 i
  set current-light nobody ;; just for now, since there are no lights yet
, X6 P) a4 ]/ {; U. `+ v  set phase 0
4 ^+ H4 }& f/ @. q5 k  set num-cars-stopped 0
& R+ J# K' t, B1 D! R  set grid-x-inc world-width / grid-size-x. n, v5 o/ o2 `9 _: D$ h9 P
  set grid-y-inc world-height / grid-size-y7 k% H, G& M$ U+ V, o6 r! L9 n

: J# m- k& I; t/ b4 P! A2 _+ u# @  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary8 n( }) {1 }+ |4 T& ?
  set acceleration 0.099& F3 M( I; Q: x) _  V- \
end) S* c# I+ U, k5 t6 J5 ]7 v# z/ o3 [- ~
. o- t" E5 J: h9 s: C
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
1 Q; _* _% y: j;; and initialize the traffic lights to one setting4 a$ @1 S1 z' M
to setup-patches8 f0 _$ U# x* Q) z+ \" g, U' V
  ;; initialize the patch-owned variables and color the patches to a base-color- C9 ~1 }& \- R/ r
  ask patches
  f! @6 e+ b9 M! x5 \1 I& I  [2 Z. @0 T0 I, ~" F5 y: x
    set intersection? false3 V# t+ x# b$ S
    set auto? false# ~; Z) w5 o; G7 P7 n) o1 N% s
    set green-light-up? true3 _1 F" P  s* Z* d
    set my-row -1
# h3 @( h3 R2 C' p& {: H, S2 P6 L    set my-column -1  X! q4 N/ I  A, y0 z6 t7 T1 s; E7 {
    set my-phase -1
/ \& H" [5 {+ A' a" b* K7 F    set pcolor brown + 3
* m1 p( a8 f4 s, b- Q  ]( \/ R& h6 ~% \8 r
* M! A( R. D3 n: T
  ;; initialize the global variables that hold patch agentsets5 z* u$ e" j8 M0 E6 b
  set roads patches with
" N8 k1 O& B1 \$ B$ ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) K: _6 \5 h  N' ?1 m
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" M% b* C9 O' I6 ~0 Q  set intersections roads with
  f7 f. Q3 l4 x% e: F" I    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
  @( n. _+ d0 C4 N+ @& ]0 K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 _/ q) u& R8 p& A& q/ x
/ `5 x2 l* O" o% B
  ask roads [ set pcolor white ]$ w" _+ K' p: w6 S9 y$ l
    setup-intersections- o, a6 k; N! L) b* O/ D, r$ J; z
end
" K; G0 c, \! S3 O% i/ E: R其中定义道路的句子,如下所示,是什么意思啊?
! j7 Z/ o( I2 d+ b set roads patches with* o2 `' Q5 W. A. J" `7 d3 d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 W) _3 d; I& U6 @* Z. X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], A9 b/ S  a% v, i$ V
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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