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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。
+ b. Y. R4 u8 z1 Q, H9 X5 U3 Qnetlogo自带的social science--traffic grid这一例子当中,
  n* d# n3 \2 |: P8 D& p9 N: L. tglobals
9 {! n9 s/ W, Z/ Y' @: i& s[
' S$ ~9 r+ F; `2 j, T# j. k& `  grid-x-inc               ;; the amount of patches in between two roads in the x direction
1 a7 f7 |2 {) k$ O' v  grid-y-inc               ;; the amount of patches in between two roads in the y direction; d4 r9 l, b- `
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
/ C# q/ o, D; E3 P9 y                           ;; it is to accelerate or decelerate
& d7 S4 F7 w1 z  p7 Y* H: E  phase                    ;; keeps track of the phase% j9 i0 P" E7 Z# ~2 S, l9 i+ p1 M+ N
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
& H( W5 G& Y* _4 \" t  current-light            ;; the currently selected light
6 v! E" J" r" e; M- v4 O: N/ l6 D! r( K% t9 ^& G9 Q" q
  ;; patch agentsets
: ^; x. {* J. q8 n' p# P  M: p  n  intersections ;; agentset containing the patches that are intersections
6 z4 X6 T/ I" S, e  roads         ;; agentset containing the patches that are roads
2 Y4 Q  K+ @/ B0 L9 j]1 O  J. S2 ?% \1 M  n
5 _6 T) z) e* K& L: t, ]$ \
turtles-own8 M4 G( \1 x9 h7 N/ m7 e; i
[) |& A/ t) y4 x2 p; _
  speed     ;; the speed of the turtle: g) p% Z2 Y6 ]3 ~
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
) C+ v( Z$ n3 a) X6 i) ?5 _: ^  wait-time ;; the amount of time since the last time a turtle has moved- ]' X6 T6 s' C% m# @0 t) u% G$ m
]
1 @3 W, E5 _, z% f# b% `8 `3 N3 ]+ h9 r& o9 H, p
patches-own5 ]4 [# u4 u0 ~3 E' e! L: q' y! i
[8 W4 u; \9 S/ A( r2 t$ {
  intersection?   ;; true if the patch is at the intersection of two roads
6 `( V1 Q8 U2 Y7 c  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
7 h; G3 n' K2 g  ^% v                  ;; false for a non-intersection patches.
5 K+ ^# H  K' D- D* U0 P  my-row          ;; the row of the intersection counting from the upper left corner of the
, Q4 |6 X8 ]! d( j8 Q                  ;; world.  -1 for non-intersection patches.
8 p) W5 i- ?5 z' y5 I9 H  my-column       ;; the column of the intersection counting from the upper left corner of the
' x' h$ V% ~& {" T1 k( N                  ;; world.  -1 for non-intersection patches.
% x# ]- Z1 l' P5 q6 |2 t+ i8 Q# Y9 v  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% D) M  k* N9 u" L6 X8 j( |) f  auto?           ;; whether or not this intersection will switch automatically.. X6 u& @2 J! `
                  ;; false for non-intersection patches.
4 @0 w+ Z6 O5 M* F' {9 |- T]
1 g8 \0 N7 L3 Y# M2 f# R, h& X5 e! m3 S: d, @3 r

) X# ?: l! k7 ], d" g; h' q& ?;;;;;;;;;;;;;;;;;;;;;;% J/ J- T' b1 h& [
;; Setup Procedures ;;
3 S6 _0 H( r- Q3 G9 K: F;;;;;;;;;;;;;;;;;;;;;;
& [8 w( K5 U# ^& G: ?" j
! p: B8 x) b4 E% Q" \5 M;; Initialize the display by giving the global and patch variables initial values.
) s" [  y* C1 S) Z;; Create num-cars of turtles if there are enough road patches for one turtle to/ g" u2 @1 F' j" v
;; be created per road patch. Set up the plots.
. g; M& x7 g+ c' p& x2 rto setup1 |2 X# m7 u' C
  ca5 P8 u9 l9 {. `* }
  setup-globals
8 M" e3 @* F' W1 W: I1 v
6 ?2 |1 l4 ]& h  ;; First we ask the patches to draw themselves and set up a few variables$ ]4 Q$ N8 S8 u6 @6 w
  setup-patches
3 s, e( O/ R% k! E' [1 [% l7 F  make-current one-of intersections. ~# h9 w! G7 |9 c$ B" M
  label-current) h3 r9 O# M1 t
! r" M; B8 j: b
  set-default-shape turtles "car": c5 X- z" O& r9 g3 H$ b% K
8 }% w( @* Z$ T% |
  if (num-cars > count roads)
3 m2 J' Z2 ?3 O, y, d2 F  q8 ?  [
5 |. b4 L/ M5 C    user-message (word "There are too many cars for the amount of "" j& ]4 ?9 j8 W) _
                       "road.  Either increase the amount of roads "2 b( {" o  f3 b" e" |* H
                       "by increasing the GRID-SIZE-X or "  e2 k* [' J3 U4 c! K" F
                       "GRID-SIZE-Y sliders, or decrease the "4 G" M( R1 |5 |: }: `. @9 g
                       "number of cars by lowering the NUMBER slider.\n"+ V5 }! e" E0 a/ d1 u, o
                       "The setup has stopped.")
8 @+ _2 I9 N; f    stop
! j" [" W7 `9 N+ ^4 x- R  ]3 ]) e5 J/ I6 c  }2 Q* O

" T, Z0 a, l2 e  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color. ^2 b4 {5 a+ D! X
  crt num-cars% S% M" G) a( B& J1 [
  [
6 V! z( V& C5 f' l! F    setup-cars
- T' F+ W, X! @5 U    set-car-color! x2 X3 E, s7 X5 i7 g0 U
    record-data& I! b; k0 R! ?1 P+ W# F
  ]
1 C6 q5 o) u: Z: c/ k: I
$ M5 W" ?0 F$ b& l* y! _* l  ;; give the turtles an initial speed5 b, b  a1 N2 p. a  M
  ask turtles [ set-car-speed ]
5 S$ K5 F0 A5 y1 ]( t( g; x: h, v  H* r4 n1 v, s
  reset-ticks$ e$ a3 S! j, V, v! }1 G* [
end
( |5 P9 r3 I! Y# b5 ]: R; y  _
5 C. r6 }( Y: G% Q4 I;; Initialize the global variables to appropriate values1 t8 u! q, I+ g$ n* C
to setup-globals3 H; Z4 `8 K* Z
  set current-light nobody ;; just for now, since there are no lights yet
* Q* g1 t6 Q/ p  set phase 0
5 Y; g4 ~+ ~4 d' B3 @# j  R; p  set num-cars-stopped 0' X: z' @9 W2 I. ~7 P" O
  set grid-x-inc world-width / grid-size-x
* G& \% [1 D( N/ D' \* [  set grid-y-inc world-height / grid-size-y
7 K) |; m4 f) p: [
) X" }) B! x& k, C- _" [8 Y  L# V  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
- D7 A5 f+ W( I1 `1 I7 [7 ^  set acceleration 0.099  ?5 K" y( ]  k- j/ H% O7 O
end+ ?* X& W* x: a! m7 @9 K% b
# e8 _8 P6 W& Z* {4 Z1 P1 |
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
! \+ x# t6 x9 o& {5 G) C$ K+ @;; and initialize the traffic lights to one setting
- z% [# y0 f7 {8 ]4 Zto setup-patches6 @/ u( N- l% b) ~+ ?2 I
  ;; initialize the patch-owned variables and color the patches to a base-color+ K1 a2 K- |& b4 g, ~+ U- y
  ask patches
/ O3 z2 s0 l# F* L  [. f- D0 L$ @2 a
    set intersection? false9 s% m/ S+ L" g# c  c
    set auto? false
# z( V4 E7 b/ @    set green-light-up? true
! M2 Y, R: a( h% D7 H: o$ P$ M% Q7 m9 e    set my-row -1( H& m1 }* o) K& b" W2 J- T$ r- H
    set my-column -1) R+ N) X, G. F2 Z! W" I
    set my-phase -1
3 o3 @. I, u& P" x* b* K    set pcolor brown + 38 Z; J9 H9 b+ r! d
  ]  F; p! y+ S' @8 _/ ~: r

1 R7 o; t7 d1 N( c' _( _) s7 S  ;; initialize the global variables that hold patch agentsets
1 \5 T; z, _: l9 G  O# |: x+ F  set roads patches with; I& w7 q5 W+ W9 y6 d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" k( P* q7 w6 p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% i, o3 t5 ~0 Y* C  set intersections roads with% m8 J, s9 Z) w0 l0 @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
1 j2 G: Y& d* {- ^, F( |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" X" ]* r* Q( k) y# {7 u0 W, ^, w
8 }( Y) B7 Q9 E+ w
  ask roads [ set pcolor white ]2 D" I6 r" S( o0 ~
    setup-intersections
2 @. }( R9 }7 |. @/ k' e) Yend. Y! b1 J, O5 M
其中定义道路的句子,如下所示,是什么意思啊?
! v" A. w" {  U& C" E5 V9 W set roads patches with: S! a, J7 Q& ]5 w' w# H2 k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 ]' W! |+ P3 w3 i8 |# H  g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 S. s4 @+ S0 S8 U8 X+ I) [5 y( q
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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