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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。
# z3 x. ?' T8 G: Anetlogo自带的social science--traffic grid这一例子当中,
* ~$ Y/ r0 _, M( rglobals: \: |9 f( N" ^! G# Y4 z, ]
[; X! B% e& r4 K- k5 K
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, F0 V# K8 K' f  grid-y-inc               ;; the amount of patches in between two roads in the y direction
( g3 Y  r. }  J. v) t! {8 O  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
4 g! U( I$ e9 B& c0 K( H/ q6 M: ?                           ;; it is to accelerate or decelerate
7 q+ w4 {- _/ f  phase                    ;; keeps track of the phase# [# @" r1 P" R, A! {6 q  g9 p
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# r/ h+ F# E" e3 N- S; @9 w- ]
  current-light            ;; the currently selected light
# ?8 p" T8 w  T. N/ A, ^' [( [+ U/ k% p+ a" `0 t# M* ^0 D+ _
  ;; patch agentsets
; f. m5 W+ A; M6 p1 D: v# s  intersections ;; agentset containing the patches that are intersections' |* W! @: Q' f3 \8 r+ i7 y; L( p
  roads         ;; agentset containing the patches that are roads" A6 B0 k" P' h" L: E- m0 r' J% u  u
]
! z% G+ O) T1 G) t9 T) b+ J& s- w- d, _1 p( ~# k' \, i
turtles-own* H* l4 s5 g7 e
[
4 ]0 P2 L. l% g4 Y  }) D  speed     ;; the speed of the turtle
) o5 i; [  y( x4 i+ l7 S, \  up-car?   ;; true if the turtle moves downwards and false if it moves to the right# H; o  v  q: \
  wait-time ;; the amount of time since the last time a turtle has moved3 T( f! I4 F$ p# M- A4 l' u
], d9 N9 R2 _4 A, A  F
# I0 `- H5 ?; ^7 k
patches-own
" c' n4 T6 u+ `) P[; a# Y* h3 s) t& ~. g
  intersection?   ;; true if the patch is at the intersection of two roads% l( \1 q9 Y3 {7 b: ^
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.4 ^" U! s; T( j+ l" o+ ^7 e$ B
                  ;; false for a non-intersection patches.  [. L/ O/ M; i' h& x
  my-row          ;; the row of the intersection counting from the upper left corner of the
- S; L! G6 P( b' O                  ;; world.  -1 for non-intersection patches.
' W  S, o* [. e' `4 _  my-column       ;; the column of the intersection counting from the upper left corner of the" O; G* o% G8 C8 y
                  ;; world.  -1 for non-intersection patches.% b  |1 G/ Y: C+ y# X
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
6 X3 J1 a# s0 v. \7 C  auto?           ;; whether or not this intersection will switch automatically.
) D# ?+ u( N1 i& Q, g: t& W                  ;; false for non-intersection patches.& i8 R( F5 l. o' I: T0 v
]/ u$ f2 {% ~. n0 F; a( o1 a
; s6 g2 Z+ C6 D( _6 A$ m. @
8 u% q+ K# o& x  K0 _% g, p- ?
;;;;;;;;;;;;;;;;;;;;;;  K; r- y! n3 Q% `( I' E: Z9 R$ U
;; Setup Procedures ;;
7 H! P, ]5 N/ z1 D  O5 E6 v0 ^9 d;;;;;;;;;;;;;;;;;;;;;;
* y& r; b. `; I1 i  l& M. w: X9 I+ l9 N" }4 |7 J
;; Initialize the display by giving the global and patch variables initial values.; W  `) C3 N: b: n% W4 s& d4 z1 U. N
;; Create num-cars of turtles if there are enough road patches for one turtle to
5 j+ ~+ N( q1 Q: W;; be created per road patch. Set up the plots.; s  {3 Z- L  l4 t' [
to setup. ~! x" N' ]8 X4 F
  ca
4 h6 b# Z, m6 R  setup-globals
+ l& ?; O  Y* n/ B: @. R% V! F% B. C" A
  ;; First we ask the patches to draw themselves and set up a few variables# b5 V$ V9 X& N
  setup-patches* G6 f1 M. `6 i
  make-current one-of intersections
. K2 g& G0 V" v7 S( q  label-current
2 w" {) @5 M1 e$ r1 w7 N9 ~
; o3 G* B0 G- F& V  set-default-shape turtles "car"
2 P8 q2 o+ x3 Z2 Z5 F+ {
9 j/ t' D3 b% I7 @( ]  if (num-cars > count roads)
" u$ l' b" C( |  [5 p$ q4 q6 x& ?  ?2 C$ T( t+ v" K
    user-message (word "There are too many cars for the amount of "
. q0 V% ~/ H# ^" W7 H6 W5 Q                       "road.  Either increase the amount of roads "
- Z3 b: Y6 L0 Q                       "by increasing the GRID-SIZE-X or ". ~, m  @8 n0 s
                       "GRID-SIZE-Y sliders, or decrease the "
: _- \: U+ |5 U/ i                       "number of cars by lowering the NUMBER slider.\n"
% U3 j7 W, ]0 N, k; \9 c9 o                       "The setup has stopped.")9 d0 _- N! ~6 C# o, ?
    stop; x+ d/ d& s, _2 p
  ]
; ?; B" U3 g) {% h% }3 y/ K! D0 m' b
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color1 d9 [) \6 h1 K2 x* v0 q1 }
  crt num-cars' }8 U+ _: C' m4 v: S% j8 P
  [- h0 n1 ^- `: y1 x& T
    setup-cars
8 D. S' r; \, j    set-car-color
/ S0 s) k* R' g# m$ A- W2 Z    record-data
! J- H% r* E# h; N" _$ ?  ]2 Z* \7 s) H) G; B' X- n
: N0 d& Y0 g" H7 c* {
  ;; give the turtles an initial speed
, {/ l9 M& n/ Z+ W8 a+ Y+ V  ask turtles [ set-car-speed ]
8 K- E3 i  B, |" S3 F7 R% W  [# X+ t' M" Z* D# I; w
  reset-ticks* `' j& L, I5 V4 \. ^1 Q7 I: T: G
end. W9 `/ M$ z2 D8 C% `5 `' H
# u( r. m& N2 N3 H7 W2 b8 }
;; Initialize the global variables to appropriate values3 U5 G+ W6 r5 e4 w
to setup-globals/ l1 K. Q* O+ L! L
  set current-light nobody ;; just for now, since there are no lights yet0 M$ f0 s3 x5 ^' @7 s
  set phase 0" K2 S7 G2 _) U5 u% o- |! W' Z  b
  set num-cars-stopped 0; j2 @" A$ T. p
  set grid-x-inc world-width / grid-size-x
/ l3 z% y6 P  d! U5 f$ J+ l  set grid-y-inc world-height / grid-size-y+ v' k4 w7 y0 p/ n  H4 O! U* t

" L' h% z( `5 p9 k  }  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary- O, w. C1 h6 ^; [
  set acceleration 0.0994 T/ z+ ~/ T4 @2 f. X+ t& o
end3 B% V+ u5 |( B0 ?& I; x; V
8 v2 `" c4 T; j
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,8 S) i! B0 T( D' K# m; L
;; and initialize the traffic lights to one setting$ J1 Y/ D. Q( d( ^
to setup-patches
5 c0 q7 b- ]9 r) n& J4 c) Y  ;; initialize the patch-owned variables and color the patches to a base-color+ I% `+ ^5 |5 b+ a: A. G4 Q
  ask patches4 `# |5 L& C0 [: r' H' V
  [
* ?" p, o6 I$ E5 s( n    set intersection? false
0 e* Q; S* z6 u  t6 K% j: S3 ?  P    set auto? false
! F% c' b" N, R4 L' ~7 [    set green-light-up? true
  ^+ X" q( l0 X5 A; F8 W6 n    set my-row -1% c& c7 b  u) Q' @$ L
    set my-column -1& ~+ x  J! A1 `$ X) w* I7 z
    set my-phase -1
, I& c1 }% [% l8 Z8 K" T2 Q. y1 o    set pcolor brown + 3/ ~* r! A% s  {( t
  ]2 Q( ~+ q& ~' E

5 v7 D, S8 v8 S8 \; x  ;; initialize the global variables that hold patch agentsets
; [/ D0 u/ |, S8 x. q4 C: E* g  set roads patches with  C+ e+ c6 t/ [6 y; g6 N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 N3 @; {- k6 N& {! \- C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' a; p4 _, |; N6 T5 d; ^1 X  set intersections roads with/ m- }4 N! g5 Q" ^0 W. j
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. j; q4 ?! ?7 |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( [. j8 G* i4 o9 I5 M0 h) K$ {

/ K/ s2 M# u( `' Y: l) `' s  ask roads [ set pcolor white ]5 X0 Q4 i5 ?! ?! L
    setup-intersections+ Q$ B( I  N: {8 G4 K! H; z8 ~
end
; K( J: n! O7 F' n8 J% s. h1 n! V其中定义道路的句子,如下所示,是什么意思啊?* s$ T1 f6 R# U8 F& b, M- X( s
set roads patches with/ I( \9 w" o" {$ p* ^) ?
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" x! t8 l5 `3 A; x
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 [  H1 F; x3 R
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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