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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 R7 _1 D/ A2 ?
netlogo自带的social science--traffic grid这一例子当中,$ V' o! @) k' G; Z% N. b
globals+ ^/ I! M* i% l4 F3 }; P% I
[
# g9 S* X3 y+ n$ [* m0 w  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 m4 X" `& u- Y* L
  grid-y-inc               ;; the amount of patches in between two roads in the y direction9 a# u1 C9 A) `6 d( P5 T& n$ ?
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if; v( Y( P$ G6 M
                           ;; it is to accelerate or decelerate$ `0 `6 Q, m: P3 U0 I$ K
  phase                    ;; keeps track of the phase
: x2 L4 x5 y( X3 ]( X  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
4 Q- X. Q/ ~3 \  ?  current-light            ;; the currently selected light& c+ Y" M6 J- J) r3 n& r
) `1 z0 }* e5 N' e" d
  ;; patch agentsets
( y" \: o% k7 R1 R$ i  intersections ;; agentset containing the patches that are intersections
  Z5 B  b! W* X  roads         ;; agentset containing the patches that are roads# f! ?0 M8 `9 U, V( }* d: S
]( L4 Z# p. j5 F1 Q/ N. s! d9 a

9 P; I; K. E8 L- }  d& Y. jturtles-own: e2 ], a# E- ^+ K. L" ?& A5 ?
[  |5 Y0 ]9 o8 |
  speed     ;; the speed of the turtle
% v+ ?( v( A  u6 R  n, l: {  up-car?   ;; true if the turtle moves downwards and false if it moves to the right  b4 l5 }2 a' P$ ^- F/ w$ I
  wait-time ;; the amount of time since the last time a turtle has moved- C2 ?( r$ T3 c# d
]3 m7 ]3 w0 N% O9 a6 M

; m% H* c) D# X3 mpatches-own. x$ j1 R( W" |$ j
[. I6 D( U+ l; z' G
  intersection?   ;; true if the patch is at the intersection of two roads
6 M0 T; d# n; v) u& O$ I2 D  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
" k$ k9 ^) @" \. T. n" _                  ;; false for a non-intersection patches.
4 U/ ^: h$ e$ ]2 H! G" _' I% l  my-row          ;; the row of the intersection counting from the upper left corner of the. D8 B2 b* G9 ]* O6 ]
                  ;; world.  -1 for non-intersection patches.$ S6 `. S% @1 q0 n7 S$ n: y" C
  my-column       ;; the column of the intersection counting from the upper left corner of the! ]% F, P1 ^2 Y" y: W: S7 Y2 u" X
                  ;; world.  -1 for non-intersection patches.
% ~- b3 b# l: b3 l  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.6 S; ~. l5 j2 ~( G
  auto?           ;; whether or not this intersection will switch automatically.
; F+ |5 q+ j8 @% V- Y                  ;; false for non-intersection patches.
/ ]  j. J% v" J) Q$ ]6 z9 U6 }4 F% V]
% U% b) d( M; R
, S7 m$ ~( V8 I; W
% e* i% x5 r* u8 |0 l# P& A;;;;;;;;;;;;;;;;;;;;;;% ]9 g7 c  e$ N# R+ B
;; Setup Procedures ;;  ]0 B- B, ^/ A; p7 h
;;;;;;;;;;;;;;;;;;;;;;
" Y& K8 ~- ]+ {, f: ~
2 A# M9 ^2 S# l! c5 m;; Initialize the display by giving the global and patch variables initial values.
1 b% z: M4 j( {, U/ E;; Create num-cars of turtles if there are enough road patches for one turtle to
' h0 j( K/ L' [. e6 |( ];; be created per road patch. Set up the plots., a2 d) V& x* e+ }- n& T: l* }$ N
to setup; j$ z/ A0 F$ v! A
  ca
# d% o, F3 C/ k  setup-globals2 h$ _" ^" |7 L% n) o% h1 F
' E% {+ j2 v4 s: l$ Y
  ;; First we ask the patches to draw themselves and set up a few variables. q1 ?$ U. g4 @5 E: g* D; Z8 B/ m
  setup-patches9 Z0 v( i. ?0 o. y9 Q2 Y' a% W
  make-current one-of intersections
  z$ X, J" _9 j( W  label-current
8 c  h# M5 @' x; p$ z% ], P( \* Y7 }
  set-default-shape turtles "car"
0 }% ^8 W' i5 I. E5 j
! l4 T8 j; m7 m9 c9 t9 F0 O( p, y) c  if (num-cars > count roads)2 c3 [5 i8 b& P# M) X* e; [
  [! }" N7 b1 u8 L6 |& Q, i' v
    user-message (word "There are too many cars for the amount of ". K2 s. s& L+ }: o0 A+ x2 A6 D; v
                       "road.  Either increase the amount of roads "6 j0 h0 D! p1 O4 d
                       "by increasing the GRID-SIZE-X or "
3 k; e" P. o9 [$ E, i: c# n0 D$ H                       "GRID-SIZE-Y sliders, or decrease the "
( X" F1 a0 u% H6 @0 j: z                       "number of cars by lowering the NUMBER slider.\n"
  l) q$ C$ o. y( E) A' @                       "The setup has stopped.")! R+ f" \- d7 L0 i7 w4 x
    stop1 B* }) Q4 A7 Z9 d7 R
  ]
( N/ q" t" o2 G- q3 V- K) G5 z# T3 }& Y8 S
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color8 M/ b' `5 l" `: n! T) f
  crt num-cars5 b& h) W1 E$ S
  [% A% a+ K4 M; d1 @
    setup-cars
" Z1 e8 N4 X. ?1 w* _/ w; C3 Q    set-car-color7 T# R1 z7 F' A$ w
    record-data
/ R$ w8 ^( D8 {0 R, S  ]; }( g# D# n+ H6 c3 `* {. n
+ ~; i1 O: i! u# x6 e5 A
  ;; give the turtles an initial speed
3 {% A0 v4 X( d, h9 U; w0 l$ I  ask turtles [ set-car-speed ]( {( C2 W* Y8 O) r, i6 L  `
# V4 n, {: _% |+ t; l
  reset-ticks; Y4 {$ j5 D: _" S. Y2 t1 c* E: S
end
; H" x/ \3 C6 ]* a0 w3 D5 }$ i" b' o  F9 m4 J1 b! w. O. ~
;; Initialize the global variables to appropriate values% B1 V+ ~- t! j& Q5 [0 R3 J# V4 G
to setup-globals
  K" K9 @- ~6 E0 k  set current-light nobody ;; just for now, since there are no lights yet, V1 k: W' Q- b
  set phase 05 a7 _, G! e; K' `
  set num-cars-stopped 0
: ?3 k' c4 Z9 _; z) U6 f& H  set grid-x-inc world-width / grid-size-x
: S, |6 Q" ?! ^: k9 w3 F# \  set grid-y-inc world-height / grid-size-y6 w- P5 H; k8 R8 R8 y" S$ v4 \
: n. ?# \4 W6 N" R& Q
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary4 ^8 j% ~: r8 j8 y# J4 G+ t" n4 E
  set acceleration 0.099. }  C- @; q; Y, c1 p
end
8 H* H. {$ s+ v) M1 L" t
8 ?5 ~* Y! {( n- ]" f: r2 v;; Make the patches have appropriate colors, set up the roads and intersections agentsets,3 b0 j6 ]; I8 A$ w' e* v8 m5 Q( F
;; and initialize the traffic lights to one setting' R9 b/ O+ X2 I( U$ Q; u. T4 i" m! J
to setup-patches( K" z! ?3 r$ D& @- h, B8 a
  ;; initialize the patch-owned variables and color the patches to a base-color
) ~3 Y5 F3 y5 ^9 \" O) R( |  ask patches& d7 h/ I: B' e8 I
  [
# `9 }9 h: X! \' Q" S4 F    set intersection? false8 C6 k) y( ~4 u0 V6 d  O1 {
    set auto? false/ t' E$ D8 j2 `  a3 D
    set green-light-up? true" H' j5 C4 u* y- G3 F1 S
    set my-row -19 U5 S. ^/ N# i( B
    set my-column -1
" X7 R& O) V/ n& M! Y    set my-phase -13 S. |  [& L# Y# Y7 l- h5 P: v/ u, z
    set pcolor brown + 3
8 O1 Y/ t* T) n# p& g) }  ]4 `5 H7 B) {8 c/ V) |

" `  K; P/ X2 v" f& ~  A! O  ;; initialize the global variables that hold patch agentsets2 U0 j1 l) ]% i% \9 @/ J- t% K( Z
  set roads patches with: ]: i# I! M- x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* E( g8 K' p2 v- U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 _! T1 E: I; y7 D  `% e1 J$ x  set intersections roads with( v7 Z: v- T6 f: ]- w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and* s* o) f( j: L) o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ T( D6 _( A! B. f5 W
9 S+ m2 q( w/ d8 {! v
  ask roads [ set pcolor white ]
% _' u8 H* x, t9 y# ]) ?! Y    setup-intersections7 F4 ^9 Z% j* B4 L* ]5 f
end" V; q! p+ A; |* L
其中定义道路的句子,如下所示,是什么意思啊?% c  S' ^4 }# }& @$ L
set roads patches with' W5 j- k# |* _) K* x" k2 c
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" ]5 E6 \5 T! s" Q% H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ U5 y: y$ c+ Y  U
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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