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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。
2 H, |% g; Y3 s. h) P8 v. Lnetlogo自带的social science--traffic grid这一例子当中,
) n6 R& s/ S# ~: v5 u; N* sglobals- }, m9 t" Q. k' t/ h6 L
[1 n: T* ]/ L3 h! }1 a- U
  grid-x-inc               ;; the amount of patches in between two roads in the x direction* M6 I5 r& x( ?* w8 j
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
# U. D! u3 [% y1 E1 N% S  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 U& O2 R( w  ]2 l( t                           ;; it is to accelerate or decelerate
  _) P; W5 f+ a+ n5 M6 ^: h/ J  phase                    ;; keeps track of the phase
0 S, n! J& f/ i( L% n  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure! R  O6 x8 m( K& Y" [
  current-light            ;; the currently selected light
/ p. e* l! V* O5 w" v5 E8 f5 d' N
6 S5 w7 f% w- P" U8 s) N7 D  q  ;; patch agentsets; A9 P, t. Q! \! S2 ~/ w' M
  intersections ;; agentset containing the patches that are intersections$ S( u5 a: y0 x: E1 X( l3 w9 p7 \
  roads         ;; agentset containing the patches that are roads
( R( w! u( u8 a6 _4 |' d]. ~  A9 k8 x* M
) J" x3 z. _3 o4 W8 X' R4 ]: P
turtles-own
3 z* k6 U' T* w! f: d  G) V* C[
4 K) \  M3 O2 ?; {  speed     ;; the speed of the turtle* \6 U  J* B  T- e4 k9 D) H
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
* E: Y. u, t' q9 N- Q! b  wait-time ;; the amount of time since the last time a turtle has moved
: V4 ^9 ^6 f7 V0 ?]
1 T1 e* [; h4 v# {" A$ V8 k$ f5 V- L* O: {1 G
patches-own
" }% h. ^* }4 e: {: z( E[8 g% N' z! l& a$ i% @+ C3 s
  intersection?   ;; true if the patch is at the intersection of two roads
! G" V7 U: F- R. m) `/ k  X4 j6 t  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
$ K1 G& y& b" ?2 E% m, R; }- t                  ;; false for a non-intersection patches.
  |; `3 _9 s- g8 d  my-row          ;; the row of the intersection counting from the upper left corner of the
5 c7 c: y% s7 {% H. s. P1 I9 H9 Q0 Q9 x; C                  ;; world.  -1 for non-intersection patches.
: o6 ~% ^& d% L8 H$ R, e; L  my-column       ;; the column of the intersection counting from the upper left corner of the. y5 T6 t; A' k% e$ P
                  ;; world.  -1 for non-intersection patches./ B0 s/ o/ z" N  o# [# s9 R) k) k
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
& i1 a/ Q8 W& M% }$ U9 R( c  auto?           ;; whether or not this intersection will switch automatically.
, u# S! R  L6 P: N1 b  n                  ;; false for non-intersection patches.& v- ~/ Q# Q) |4 J8 M3 D
]& {7 O, m2 Z! T: i4 a  J$ }0 f

1 a! ]- y' @2 Y. A5 q. p7 @$ x9 v! d* C1 ?
;;;;;;;;;;;;;;;;;;;;;;4 z, N* G, @/ A  A$ s! r
;; Setup Procedures ;;+ y9 b8 k! J: Q4 i
;;;;;;;;;;;;;;;;;;;;;;
, T6 [( J# T5 }. q. {  j3 B( y
;; Initialize the display by giving the global and patch variables initial values.
- l8 y- J$ a6 {1 o& i2 l;; Create num-cars of turtles if there are enough road patches for one turtle to
  X, T4 D- @0 J  R2 u$ q;; be created per road patch. Set up the plots.
  d9 ?. `/ g6 v+ R4 C) a- hto setup$ r7 |! g  h% n4 C$ R- v8 S6 J
  ca. K6 c) g' C- _0 s8 _
  setup-globals" M/ ^& u; H9 p  H3 e$ I* L
' l/ P9 S% J6 b
  ;; First we ask the patches to draw themselves and set up a few variables
. H3 Y9 O! g' W5 U0 O* o5 p  setup-patches
* w, y1 F1 X2 n$ U  make-current one-of intersections
5 ?2 ~; v/ C) }) W. u: c9 N$ c  label-current# j% ~5 [2 F# O) s

0 e+ O  g  c' P$ e  set-default-shape turtles "car"
* W1 @) C  w1 e) H9 U: X
3 G. f6 `9 e3 o" `  if (num-cars > count roads)
0 f0 d: @1 K, O2 s5 L4 [  [0 p' ^0 ]) ~3 Q0 I1 i7 i
    user-message (word "There are too many cars for the amount of "
3 r% P: s: ^0 H! _3 u# l* ~                       "road.  Either increase the amount of roads ": U8 V5 z, Z; @, M, B
                       "by increasing the GRID-SIZE-X or "
! m. F# R) c, G& N5 U, l                       "GRID-SIZE-Y sliders, or decrease the "
. a6 n( `+ O& ]4 {, N0 J' @                       "number of cars by lowering the NUMBER slider.\n"0 o% E6 |$ a& U: g
                       "The setup has stopped.")% I; W7 }. Y: M! J! e) _: w4 s
    stop) s: d+ B: N5 F: O6 |$ Z2 \7 t( L
  ]
: l6 A/ ^7 ?! o3 ~6 V- [9 n& @$ Y; N  z3 T; d% F
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color5 v& D2 Z3 P7 X' I/ s$ C2 _. x
  crt num-cars
) w8 \+ J- e  q. C1 ?2 L  [* [  Q! {; ?  f8 q
    setup-cars
! ^* _4 A/ A1 \( h- U    set-car-color9 `  _5 h% O: `# U2 V8 I
    record-data
9 V9 t# S' t0 e. e+ y  ]
4 d* l. A) A/ l$ W4 L
1 |' f- L' e# ^  ;; give the turtles an initial speed
/ x# O0 Z, l/ q2 ^- E' `  ask turtles [ set-car-speed ]+ L4 Q. e$ r3 P1 J$ g: O; N

7 C3 w' f7 k+ ~0 L2 Q) i/ E  reset-ticks4 u$ M0 a1 @% K2 x6 s
end
5 F7 V# Z2 Z4 O: U! {1 w$ ~9 V' G* \" g/ ^& m
;; Initialize the global variables to appropriate values
( ]2 ^2 _4 C, H; S: vto setup-globals; W8 R  K8 ~4 _/ _6 b% P" _
  set current-light nobody ;; just for now, since there are no lights yet) M( N2 W( c4 V" ^. U
  set phase 0
+ Q/ Y+ G9 C1 ^0 e4 i$ @  set num-cars-stopped 0
4 p. j( `- `3 O; q  set grid-x-inc world-width / grid-size-x
! t! p7 G+ _) m- k  set grid-y-inc world-height / grid-size-y0 ^! Z) t- \# b
9 l$ Z, |7 D# ]; w
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
6 |3 H" s8 s0 y4 G, _  set acceleration 0.099% U1 M# D- M1 j9 l2 _
end
$ x' x  {! L) ^- R( o0 w  P6 z/ U* ?! {  v9 _
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 O* k" G1 N) X" n* a
;; and initialize the traffic lights to one setting
9 ^, l+ y4 l' `( Eto setup-patches+ Z9 g( e0 G" h5 ~0 J$ _8 U
  ;; initialize the patch-owned variables and color the patches to a base-color
# B2 o& o. w. a4 {" x  ask patches  U- j  g: n) M; }% Q
  [
8 y8 d/ ^% C3 E9 s    set intersection? false
" U2 d* N4 l* ~  w    set auto? false3 b8 z) s  }& \4 Y
    set green-light-up? true
4 f: r4 _8 E, n    set my-row -1: w2 m+ t1 C+ q/ R3 f/ M; O  \& K
    set my-column -1
" \5 G# V2 `" p" Q: [    set my-phase -1, x. e# g6 e  }* c+ _" E
    set pcolor brown + 30 Q% g( W# K$ P9 y: t) ?( p: Y
  ]" O/ g9 c9 g9 v4 J
7 L" _) e) A2 P# I9 b
  ;; initialize the global variables that hold patch agentsets0 i( f4 F3 C; @6 Q7 u, A
  set roads patches with
* d. G. K, m/ N2 w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 K) \3 s* b* x  }9 Y6 T. S3 d    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) C2 c9 e; @1 q$ `* {
  set intersections roads with
; ?0 R$ X' ]: v+ H    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and. `" ?) r' W. d' b7 T+ B0 t
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ C2 M5 r% F: ]' T! s1 q" S, _' U9 x  ?8 T4 c
  ask roads [ set pcolor white ]! Z3 \/ Y$ k1 n& U/ n
    setup-intersections
. e" @2 g3 R+ j7 X- V  ~end
! o: C% z9 ~+ l6 P) n' l其中定义道路的句子,如下所示,是什么意思啊?! p, k. G* a9 F
set roads patches with0 B" ]$ U5 S  x  s9 r7 R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- \1 ]" O) X! s4 F+ W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 ]& s/ C; P6 Z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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