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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。% x& t) c9 t/ t' X8 r. K
netlogo自带的social science--traffic grid这一例子当中,8 L5 ~  g. {# O5 W  |
globals; Z: N: D! r3 ~& [( N* |& D
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  grid-x-inc               ;; the amount of patches in between two roads in the x direction
& \# l& _* y! P1 F8 V+ K  grid-y-inc               ;; the amount of patches in between two roads in the y direction
% f# z" Z8 ^1 r9 T* d  acceleration             ;; the constant that controls how much a car speeds up or slows down by if9 e9 g) `6 [! i' H
                           ;; it is to accelerate or decelerate
# Q3 F3 v8 b) _3 S/ B  phase                    ;; keeps track of the phase8 y/ `5 Y' h; F" D4 H
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 k8 K1 A% y5 x- x* T
  current-light            ;; the currently selected light
, A. o  [# d; D1 n$ G( ~* [; {7 L# Y3 X% |
  ;; patch agentsets
. u1 _6 y* e* E  intersections ;; agentset containing the patches that are intersections: O9 X1 K* {/ N; `+ |& H! \
  roads         ;; agentset containing the patches that are roads
4 L+ M# X- Y6 S  `- V0 T3 W]9 ?9 x1 v$ @/ \, g/ h$ l

9 p3 B, P* q2 i- O" L  j; bturtles-own
( c; D- w7 ?; [/ C[9 ~% l! u% I7 V% h; |7 n
  speed     ;; the speed of the turtle' D4 m+ F* E3 @, I9 O; {7 I. l2 |
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
9 g1 t& ^5 N, B  q+ F) |- V6 V  wait-time ;; the amount of time since the last time a turtle has moved
2 ~) G, \4 |' N) A& n1 u]+ ]4 h7 ^% W6 b7 o2 w
" r2 v3 P5 v* Y2 S
patches-own
) W: x/ W  f( [7 A[7 b5 R# ?2 k- D" f
  intersection?   ;; true if the patch is at the intersection of two roads% h& q5 I% ?5 J) t. ]4 u: i
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
' i+ Z. I5 F% t) k                  ;; false for a non-intersection patches.( g7 I9 l9 o( f! H! A$ r
  my-row          ;; the row of the intersection counting from the upper left corner of the3 T9 E* F' k: d3 C8 K
                  ;; world.  -1 for non-intersection patches.
3 `1 x3 q! p- I9 V% f, }% [  my-column       ;; the column of the intersection counting from the upper left corner of the8 h. f, P" I0 ~& R
                  ;; world.  -1 for non-intersection patches.
& ]8 H/ t" |8 _! h6 E  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.( B3 j: c: K  O! A
  auto?           ;; whether or not this intersection will switch automatically.9 U2 o+ P; i/ r2 e
                  ;; false for non-intersection patches.
! h) D1 R0 d  z# e, H2 B]
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0 u. Y& [( t" g0 a
  Z% D0 I1 i) q;;;;;;;;;;;;;;;;;;;;;;
0 U8 O# E/ E2 s6 d' H! L2 ]! n& |6 a" z;; Setup Procedures ;;  H/ ]& k/ R6 s$ e9 C* n0 \& }
;;;;;;;;;;;;;;;;;;;;;;. Y$ Y  t! p1 _- l! g
# {* q$ D6 t: f) P$ A1 @
;; Initialize the display by giving the global and patch variables initial values.
5 E& @# w, U: A/ I3 a& N9 y1 _;; Create num-cars of turtles if there are enough road patches for one turtle to9 h8 L# w: I+ t6 {
;; be created per road patch. Set up the plots.* U, T7 Q' a- @$ k/ s9 P- w
to setup
! j4 K" d" J1 D6 y% V" }  ca9 ~3 P0 Y2 S  k- ]2 s, s, X
  setup-globals
  r  }* P+ b7 q8 v
; N/ v& [, {* H+ X' m6 _& \  ;; First we ask the patches to draw themselves and set up a few variables6 n5 V* R" {& ]6 \* X  q3 M, M1 \
  setup-patches
' B  {' p3 f- n2 |/ F! A' @# d  make-current one-of intersections1 Y& T! r, r2 z* x' V, @
  label-current
9 p# ]2 x/ P" a/ v8 F0 e
" Q8 R" u$ q: l( _3 }) v7 j) ?  set-default-shape turtles "car"& Z6 o# C' u- j8 \+ Y: n( F) F% O
) E$ q. i8 A: j8 {+ s7 X) D
  if (num-cars > count roads)
3 ~  v! D, n9 E& x2 @1 s; c  [+ n+ Q4 d6 t% d$ ^* X
    user-message (word "There are too many cars for the amount of "* s7 D$ [+ Q' i5 I
                       "road.  Either increase the amount of roads "  l% I5 E, }' `; c% \. ]
                       "by increasing the GRID-SIZE-X or "& f% r1 S! d  v, x) K* l* ?4 n( c
                       "GRID-SIZE-Y sliders, or decrease the "
# q  T% t" w! {. n* x                       "number of cars by lowering the NUMBER slider.\n"" M$ f0 J1 v: M: \0 Z! N4 m& P: j4 `
                       "The setup has stopped.")
. t6 L1 Q9 d2 z" I. g" Q    stop
+ z; m9 {+ a& [5 t  ]2 v* i. B: H: L5 A5 r/ e5 N& Q
7 |2 c6 M7 x; a- ~; ^; m
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color# K" e  ]9 ^9 ?! i, D! j
  crt num-cars# F( u4 p! j3 |7 M$ Y0 L# g  P
  [/ J: p5 H" L! y  r8 ~' B
    setup-cars( L* `  ^( ?! Z
    set-car-color
$ I9 M" m9 q$ }+ ~* {: c    record-data2 ]3 E2 n* F- t9 b$ V
  ]
9 z9 P6 O8 [' L5 v
/ P3 E% }2 \; x# u! d  ;; give the turtles an initial speed+ H$ p5 b2 W# h9 Q/ P
  ask turtles [ set-car-speed ]4 `0 u) p! b5 I0 C  I( l
/ |; v" a8 g) w! J1 q- j* T
  reset-ticks
; R4 q" [9 m. v6 eend( p1 j) K( l5 [6 e* j2 U

: R- e  E' ~8 I;; Initialize the global variables to appropriate values
/ B& ]4 W, L( \0 p* s  n$ f' N7 _to setup-globals
6 u2 e" r; ^6 B! k3 ~( ~4 V& X  Q3 _  set current-light nobody ;; just for now, since there are no lights yet% i! e+ d# w- S5 o( P
  set phase 0* J3 O$ g6 z: x! `
  set num-cars-stopped 0
- o4 t& V& V4 b, Q" k  set grid-x-inc world-width / grid-size-x0 ]+ p& m5 F% H  Y. n. u0 ^
  set grid-y-inc world-height / grid-size-y7 S; y5 N6 n6 z% D9 }& X
# j$ m( t9 ]0 T8 K* f
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
( ^. R$ z6 y2 ~/ a! Y2 z  set acceleration 0.099
3 O0 K% q% L$ t* Tend/ d" U' y% K  k# x7 ^( `( G
0 z$ v8 q  u7 y) P/ C  R- e
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
3 \4 y3 F# x; E;; and initialize the traffic lights to one setting
7 g8 x. ^9 \5 `5 @% Vto setup-patches* ~/ q6 O& N6 \
  ;; initialize the patch-owned variables and color the patches to a base-color
8 p' W/ p- @- F# ^" o" {  ask patches9 d' {. C- U) a, z9 @- U$ R
  [
) T' u8 `5 F1 i: K) _    set intersection? false
) @! M' R# f; c( h# _% k3 f    set auto? false
* }4 y9 M( S( O# Z9 b) y    set green-light-up? true
4 H& x, p- f+ A: K! }7 K8 ~    set my-row -1. o* }" P0 {% Z( h% G/ P
    set my-column -18 v' J4 ]! a0 i) B6 p& v
    set my-phase -1* K" o- j2 C5 W$ i. W, `9 q
    set pcolor brown + 3
9 U8 q" k/ M) O+ J! p- l5 ^  ]
- @/ V$ f( @8 D0 q" B
6 F% M4 a: l; N: B4 E! j( Q/ K6 a  ;; initialize the global variables that hold patch agentsets: h0 o" _1 K9 i% b5 K
  set roads patches with
* `  }1 N- L- [; r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 a0 w" A* |3 O' D/ Y$ E) [! U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 U. D5 N: b' a! k/ R& \  set intersections roads with
1 }, ^" c0 \/ P6 [    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ _8 ?* ]% o+ r3 L6 c. i; L
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 r/ d, y1 @& w+ W( q& L( l& w3 V8 ?8 c4 T% L
  ask roads [ set pcolor white ]3 n3 K+ n+ z7 O
    setup-intersections
% P3 n$ z# \9 `! Q0 bend
4 m5 m- Q0 W) k; Y0 F4 g( x其中定义道路的句子,如下所示,是什么意思啊?
0 A- j8 ]% s" h( M set roads patches with
% O$ {9 |* L- x; `( G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% t. f1 Z+ x+ X" Q! s% u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 U! ?1 }* `5 }6 b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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