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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。0 E5 L" m/ l! O& M+ `
netlogo自带的social science--traffic grid这一例子当中,* S, n: S4 A# Z
globals
6 I8 `# N4 I/ A$ v6 e1 C" p[
$ S0 k9 y& M( K& t5 p9 G2 K  grid-x-inc               ;; the amount of patches in between two roads in the x direction
7 n. k6 ~, I" ^& |3 m8 _8 o7 T  grid-y-inc               ;; the amount of patches in between two roads in the y direction3 S7 i- V) w$ k! J- h
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
5 f$ k8 P) b) S3 Y3 K. z                           ;; it is to accelerate or decelerate
% Y1 z* _1 q% D# ^# q( ~* D" r6 Y  phase                    ;; keeps track of the phase# z! T9 I( ^, I! p; ~6 `$ @
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
( Y* N3 \+ }, ?6 k  current-light            ;; the currently selected light7 d. b! B. }) t4 x; a! f3 N- s( a
2 \" |2 q1 a) r6 x" l
  ;; patch agentsets& ?- e! Y) S! M# _
  intersections ;; agentset containing the patches that are intersections
  C0 r9 g( M$ X7 C4 @" q5 a1 {. r' T6 y  roads         ;; agentset containing the patches that are roads
6 b6 w" [* c6 B# y. U3 C]* K4 r% r8 C- T! m2 Q5 Q) D
5 F& z" W5 u6 {+ G- N
turtles-own6 H, E: C2 K9 |" @0 k
[7 I* D+ U0 X( c$ I4 S  x" L7 w
  speed     ;; the speed of the turtle( V7 n( S) I5 k0 u9 W, r/ X& r
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right) ~& |8 R% Z0 x: D, j0 R3 M
  wait-time ;; the amount of time since the last time a turtle has moved
2 U7 o! V$ j4 f3 D1 m' z0 q]  @# P) B$ `- L: H" K1 G
. x% e% Z; Z' j5 t9 e
patches-own
6 l5 T! ~; }! w% V/ f1 G( e. y[2 P7 w+ J$ `; k' f$ V* ?
  intersection?   ;; true if the patch is at the intersection of two roads3 d" T; w, d- s9 O; `6 R
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
: {& O  i: E6 b# k6 R: g                  ;; false for a non-intersection patches.) e; }5 [3 C7 R2 x
  my-row          ;; the row of the intersection counting from the upper left corner of the' g- T, Y& h4 n& l$ F8 \0 P$ z
                  ;; world.  -1 for non-intersection patches.
# _3 a  L+ e" c0 Z  my-column       ;; the column of the intersection counting from the upper left corner of the8 {+ _) C1 a4 s& _
                  ;; world.  -1 for non-intersection patches.7 ]5 B+ Y" O( F. l. {. N
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  {) u0 t6 z3 H$ ]- X# W) o' f  auto?           ;; whether or not this intersection will switch automatically.
  `# I  _! U( m  i                  ;; false for non-intersection patches.2 Z' R+ J' M6 s: k
]
: {8 F; A3 T: a! Q2 M! A6 q( D9 `
) X# t  K1 P6 ?8 L# {+ K- e& ^$ f+ M* \4 Z+ F6 T
;;;;;;;;;;;;;;;;;;;;;;
2 }3 D. z4 |. o6 z3 }$ H;; Setup Procedures ;;- `5 {' o5 E, C$ e
;;;;;;;;;;;;;;;;;;;;;;* d  b- M- I8 C& W

5 @; D# h/ z) r* A5 S# O# H! S" C;; Initialize the display by giving the global and patch variables initial values.
" k4 x3 z( ~4 d$ g& Y& E;; Create num-cars of turtles if there are enough road patches for one turtle to
! x! m0 ~% G+ _' ]# j( j+ c;; be created per road patch. Set up the plots.
, G' X5 u' ]9 `% N# S+ Mto setup
% d. c: F; C- I, `  ca9 R$ Y& {% _1 E1 d, C7 U+ y
  setup-globals
2 ?; [" j+ ^2 X( W: L/ E7 x6 [* F6 \% U' G! \0 `+ \) ?
  ;; First we ask the patches to draw themselves and set up a few variables% Z5 D' E; X: |6 |( r5 F; g6 f6 |( H
  setup-patches) n" Z( L4 \* r% E
  make-current one-of intersections9 j7 t9 n* B0 s1 p: f
  label-current
. {- f1 l; V. s4 ]3 W) ]7 F; k* J; E* m1 |
  set-default-shape turtles "car"7 c* o5 s6 {6 I
) P4 m+ N) X# ~+ E3 h+ f
  if (num-cars > count roads)
' G! W9 q, i" c( j0 y, G  [+ U, w; I2 q- n. q# M2 ~& Y; z0 i
    user-message (word "There are too many cars for the amount of "* Z1 r) Z( [# M& N  i& P7 N7 l4 B
                       "road.  Either increase the amount of roads "
1 m* k) U$ Z, M! Y                       "by increasing the GRID-SIZE-X or "7 x3 h7 s5 Q, I1 x" M
                       "GRID-SIZE-Y sliders, or decrease the "& G8 D$ H! ~* _6 ~, K
                       "number of cars by lowering the NUMBER slider.\n"
9 E' J. ?# |- a                       "The setup has stopped.")
6 c3 i' P7 b* S7 X" ~6 o( o    stop
" W, z3 Z5 q0 Q. U: }  ]
0 ^4 Q7 r7 w. {( s( b4 H8 [
: k" c$ m7 I$ L/ v" _4 h: J* ~  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color" D+ M- k% d- @( W
  crt num-cars3 w  @4 r2 K- d5 B/ H$ ?% R3 H
  [
! X2 O( z3 e% h    setup-cars
8 A( t5 g& `, F( `, `9 J    set-car-color# L  P+ k& E& I
    record-data6 ~5 P3 _) s2 U9 m4 B* x3 x( T
  ]- S) y' z" G7 h9 X2 c3 N
, y" r6 Y3 d1 }' k( e8 A  u" k
  ;; give the turtles an initial speed6 G; S5 E  c$ ^! S6 ]$ f2 A/ h
  ask turtles [ set-car-speed ]
% q) A8 l/ [; [  X, J+ D2 {8 k% f0 @9 y9 ^" `
  reset-ticks
! B8 C. N! @" K7 Y4 q$ nend& B  Q& k  u$ l/ w4 S& e' [
# A# b8 J3 \4 A% g
;; Initialize the global variables to appropriate values
7 q, c' M3 q8 V% B6 ~1 v# Sto setup-globals
) _% Z  N0 A2 M) I( ?) M4 C$ H/ z  set current-light nobody ;; just for now, since there are no lights yet, K2 T" l6 [6 [* \% M1 Z  t
  set phase 0
* w/ w0 y$ g8 v" \; X  E6 O: {  set num-cars-stopped 0
; A% @, j0 n" M# N4 C  set grid-x-inc world-width / grid-size-x! H2 g5 P6 Q  g5 W2 j! F' A/ m8 N
  set grid-y-inc world-height / grid-size-y  f( T( g- U( e2 b/ S: z* x

/ {) V) }7 V' F$ s) K" z  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary  ]- z5 K/ \, E
  set acceleration 0.099
4 K: E' f2 {1 `# q6 mend
8 |& U6 |2 n8 G5 s
2 z8 s" k8 H' S- w/ }5 v, T. C;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
. I% @1 h4 K' Y+ ^;; and initialize the traffic lights to one setting
3 R. ?; N" {- G9 q/ hto setup-patches; B( e& W0 T. N1 c+ R4 ^
  ;; initialize the patch-owned variables and color the patches to a base-color
& P3 d% q. k6 g5 V: O8 l  ask patches* K' I& a- D/ A9 J+ Q; ^
  [
% e9 S1 \: \6 T# Q$ M    set intersection? false
4 M, G6 t  c% k, @3 |    set auto? false
* Q4 _, _8 j* P  r    set green-light-up? true
3 o% q: i1 c2 x2 c4 {6 @7 j    set my-row -1' Q+ M( y* @8 i0 B
    set my-column -1# m+ P/ o6 m: H7 {! h
    set my-phase -1
* c: O( N8 m& d. o    set pcolor brown + 3/ j: w( ~% A! r* z0 q
  ]  v6 G, N" d$ r( ~
* G' D4 i9 [% O% p# E, w
  ;; initialize the global variables that hold patch agentsets% O; t) Y- V- p+ `% z, g
  set roads patches with0 W* v% K! z1 z2 F: j! B! w% S4 h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) `+ o3 H# @: U9 J. r
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 v. m1 y6 U; \; d( u8 Q  X6 Q8 R
  set intersections roads with
# o8 L7 V& j* c& f0 }" j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and$ P9 G# Z) Y, U9 j  `
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ M4 s0 m7 |6 r5 `% R/ W9 x6 t" e+ U; G1 A$ |6 W; U
  ask roads [ set pcolor white ]: K$ ^& q# w( I0 t* I0 x5 g+ F' ~# P
    setup-intersections. Z/ W. Y* O5 y- g
end8 J1 q8 P* b, V+ \
其中定义道路的句子,如下所示,是什么意思啊?& I, F/ j( X' p2 b4 C+ b/ h! H
set roads patches with
/ R7 D) D' {5 s# C    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ q' v8 S( j8 B" l1 i
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 w3 [( R2 e" Y7 i
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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