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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。
& r6 C3 _4 K  }0 ~4 ?  nnetlogo自带的social science--traffic grid这一例子当中,& x4 f+ ?! j9 ~8 z
globals
0 }) i; M$ _" e, K% r[
$ H7 J0 s" [; \- j/ d) n: q( l  S  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 }  T  p- s' _0 E! v- f
  grid-y-inc               ;; the amount of patches in between two roads in the y direction; R3 Z) @0 M1 m/ h' i
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
: v- G; t% g. Y# _) u                           ;; it is to accelerate or decelerate
) Y; v1 [; }, i6 _! a6 n  m4 N  phase                    ;; keeps track of the phase) n/ |. j. A, C' Y  M
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
, _* R' m9 K  o& j0 G+ Y1 R  current-light            ;; the currently selected light$ c6 z( U6 p0 W9 T, E! P8 D
8 o5 Q0 H6 X6 |1 U* {& I; M% m/ p5 q
  ;; patch agentsets
/ O  u8 X( Z: j1 E* }+ K  intersections ;; agentset containing the patches that are intersections2 a1 O! d0 Y* n$ `
  roads         ;; agentset containing the patches that are roads; A9 r& ^, r& A
]
* l; M4 [" F$ ~% v% @/ z  T2 U; m9 Q
turtles-own
  \# Q: |% N" R" N# F. V[
5 k- w* q7 U9 o; K: ^# }9 H  speed     ;; the speed of the turtle; H/ R2 a% Q3 N+ |; p; }3 B+ _$ p9 o. e% I
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
* @6 B/ @! U6 ]' p  b0 y( G4 M4 x  wait-time ;; the amount of time since the last time a turtle has moved* g  D$ b0 U' u! u
]' v# ?7 [0 [; d2 E0 D
) s9 A, w9 @; e5 D+ R0 d+ b
patches-own
7 A' p3 b  W+ |- h1 L8 g8 w) _[
- Y1 V- v4 A; F& J  intersection?   ;; true if the patch is at the intersection of two roads+ X/ M. o# }8 f; W9 n0 n1 J3 {
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.4 a4 l( r" ?7 ~5 r. ?
                  ;; false for a non-intersection patches.
' v2 R: `1 N( R/ Q& \  my-row          ;; the row of the intersection counting from the upper left corner of the
/ Y. C+ k1 p0 R! ^. s                  ;; world.  -1 for non-intersection patches.
; Y2 S4 K8 Z' A+ [( J5 a. Y7 q! u  my-column       ;; the column of the intersection counting from the upper left corner of the& n7 g5 q/ i# j! g5 ~1 y
                  ;; world.  -1 for non-intersection patches.
+ q3 s3 t+ z7 ]/ p5 w& U0 }1 N  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.2 l# `4 i* d1 a) O6 b8 \4 G' f& Z
  auto?           ;; whether or not this intersection will switch automatically.
  [2 v5 @$ K/ T! k; ?! w: Y                  ;; false for non-intersection patches.
& h& B8 A; ^4 [# a; A9 f# Y0 f5 v: ]]
# p3 A9 M, T" e# G" I' n- H0 l
. \+ P# L- y9 M. D& a2 s9 f
8 f/ y3 F# N! f. d;;;;;;;;;;;;;;;;;;;;;;% k# e' D" D! e, x- B4 p' L3 j
;; Setup Procedures ;;8 s0 R( P+ V1 m0 M- Q- B
;;;;;;;;;;;;;;;;;;;;;;
& p; Y0 `9 W8 `+ e) }( u5 P, ^
* n) {, [+ a$ w% p) `6 {) S;; Initialize the display by giving the global and patch variables initial values.2 o0 X! P+ f9 Q$ u  o) V' s; x5 _, w
;; Create num-cars of turtles if there are enough road patches for one turtle to
3 [" b8 |9 o# j# z/ q$ c3 z2 }  p1 x;; be created per road patch. Set up the plots.
: Z# n* O1 e9 P2 uto setup
; h* `# x) b, e) g. L  ca
# m+ L% T  U4 v% I% ~% u# v; Z  setup-globals2 y  {: t0 h! r7 q  [

( S3 H2 P/ D6 c: b. b4 _  ;; First we ask the patches to draw themselves and set up a few variables
0 a+ x1 g% T! V- U& M0 D  setup-patches
: J% I7 Z- B. O3 u  z  make-current one-of intersections
) v0 J5 H/ u  C' ]  label-current7 Y" i7 N1 Q' Q, P6 A

  h5 ~! R! ~0 D  set-default-shape turtles "car"
1 q1 j1 h: H5 q4 R' @) _" C) t4 s
  if (num-cars > count roads)7 ]" Q, D9 x8 x$ z% V0 z* B
  [: z" ]7 Z- q3 R+ e
    user-message (word "There are too many cars for the amount of "; |; a# U5 [& P% f% C5 F8 l$ i7 Z
                       "road.  Either increase the amount of roads "
! f  h. M: e4 e! W0 R) s                       "by increasing the GRID-SIZE-X or "
& s3 \: ~% f# M' a2 c                       "GRID-SIZE-Y sliders, or decrease the "1 k4 i2 ^  t/ @3 }0 c# P% D
                       "number of cars by lowering the NUMBER slider.\n"
: Q3 ^0 o4 B7 i- u$ t                       "The setup has stopped.")6 L: @* K2 e. P2 S4 }0 V2 m5 \
    stop, m. J( M3 \5 {
  ]
3 M5 x. j! D. P/ W% j9 i! x/ J: h0 @1 f8 k
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
& I" k2 w+ ?  [1 Z3 [8 `  crt num-cars# v8 T3 n: t( ?
  [
! }' g  w6 L7 h    setup-cars
/ r$ d1 A4 i) D; y: x    set-car-color
( ^2 e$ {- M: M; a& _3 `% O) i    record-data
$ H* ^% r" n9 M+ n) Q  r2 r  ]2 y% X4 L; [2 _! A) m, D; a) l1 t/ c
# f/ @" Q& x, x
  ;; give the turtles an initial speed
' L& N: R- u* A  ask turtles [ set-car-speed ]! o  d2 o7 r! z3 Z  t$ V+ ?( ]

4 ~0 h/ w" r0 m  k) e  reset-ticks2 z% s+ P6 I. |+ w( A  d+ j
end; Y; K! F+ O, y5 `0 ~
/ N8 M; T' k2 d; ?3 m
;; Initialize the global variables to appropriate values/ k8 }0 l# l, D" W  ~9 U9 J
to setup-globals
9 h8 j$ S0 p' Z  set current-light nobody ;; just for now, since there are no lights yet. T/ K) `) i7 k0 o! D2 R* {3 M# _
  set phase 0
/ O0 `, d& v# k, ?, d+ d1 |  set num-cars-stopped 0
% N8 i# l# }  |4 ]+ d  set grid-x-inc world-width / grid-size-x/ j: Z1 ~+ |9 `. p
  set grid-y-inc world-height / grid-size-y5 N# T  Z3 c' s9 u
3 g+ |3 v3 p; F% a
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary0 g+ Y9 V' U. S% D- [- R- k
  set acceleration 0.099- O/ x1 T1 w& R8 u. f# _9 S
end- ?  U; E) a3 }) J# F

4 p" l+ B7 w1 n;; Make the patches have appropriate colors, set up the roads and intersections agentsets,! [7 E- [. p9 s" F# S. e' b) P
;; and initialize the traffic lights to one setting
, I: _: }- \& T, Z& w- f0 Lto setup-patches3 ~$ \& F3 K7 \# J; j6 p% v/ B
  ;; initialize the patch-owned variables and color the patches to a base-color' a% d: m: o) V+ f
  ask patches# M8 @! l" D; l7 x4 p- U
  [
- q/ M7 h$ y0 H3 r. e( d    set intersection? false4 m- r- d+ ^, A; }: \
    set auto? false$ O' U% F( q4 [' q2 d/ G3 x
    set green-light-up? true: d7 G+ V( X7 J5 b$ a7 ?
    set my-row -1! p$ ]2 N* \4 G0 [9 o% R
    set my-column -1. m0 |" I2 a: r. y- ]- R; d
    set my-phase -19 a. v! i7 c& Q
    set pcolor brown + 3- U8 C5 A. M9 ^- M& T8 t
  ]
1 d. X$ V, m6 ]. ~1 G+ w; S  H& `/ m' G( b) p9 e8 Y6 [5 M
  ;; initialize the global variables that hold patch agentsets
+ e1 a9 i' a4 S/ u" I  set roads patches with: p( X) \4 u) X( P$ Q- o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- c; @- E7 W1 V; |3 T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% a" U; C. A6 i/ g$ m- v
  set intersections roads with6 _) A) D$ I3 R* Q. t6 y+ J4 K+ h' F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
! U/ F5 r8 ?: O/ U' M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( o/ t9 J( |$ B  @& t  L$ I! H" |9 l- k# V
  ask roads [ set pcolor white ]
- x; Z. {# e. P$ j3 R# k4 `    setup-intersections
0 B( {6 ^+ d. ]( _2 g$ p' l1 Nend7 O4 w* N+ m# I' G* h
其中定义道路的句子,如下所示,是什么意思啊?
1 q& [  \; ?  r* ?3 G set roads patches with/ g8 U) m. B- I; D: e$ {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- E  h" D' ]! [
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 l- j0 I+ J- E9 `) E$ d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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