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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。& g8 T+ B6 W0 A7 A/ B% C
netlogo自带的social science--traffic grid这一例子当中,
. i7 m# h9 w$ [8 w. }& z% pglobals$ }7 x6 r9 h$ n4 b' {- u$ Z; F
[/ _! i  b  W& ?3 ]0 f: j* s7 o
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
/ W* e* |& S# x% Q" H- I  grid-y-inc               ;; the amount of patches in between two roads in the y direction5 I/ r/ Z5 \' s& y4 p5 L6 I
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
7 t0 z7 g$ `: W' S0 _                           ;; it is to accelerate or decelerate5 V3 k# L  S* J7 M5 @1 Q& l
  phase                    ;; keeps track of the phase6 @7 v, b+ A- x: }
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
& @* f4 g5 `- |+ A6 ~  current-light            ;; the currently selected light
4 Q4 |) K% C$ h7 J# O/ e, ?# J6 e' f% F# R0 w; Y) B# [% V6 F
  ;; patch agentsets" f/ ]% z- ?- C0 \, s6 d
  intersections ;; agentset containing the patches that are intersections/ Z1 E4 j5 y) D8 x5 J7 l% x0 Y. ^
  roads         ;; agentset containing the patches that are roads  S0 {" M+ \) _- O1 F. y& r
]
- t- [$ {1 `1 z$ S* @" O
5 I# `: o* z* Qturtles-own
& ^" @1 O5 q/ ^& E7 K8 @[& P  l  ?: v$ ?2 A4 M. `! \9 O
  speed     ;; the speed of the turtle' d, e0 T9 V+ c$ N* j: j; G) u6 g
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right4 y  H5 e2 {- \3 ?5 o+ \- `: ^
  wait-time ;; the amount of time since the last time a turtle has moved
1 q" R- {4 m' G+ l: b3 T], v1 h& W! Z* h! R, k$ ?! V# m" N

" U& {3 `% S) Rpatches-own4 z# q7 V5 _/ w. D
[* X: k$ U) ^# K: M# }$ Y
  intersection?   ;; true if the patch is at the intersection of two roads
6 w. U) r! r; T  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
2 R7 S9 Q# }, N+ k5 ]6 Q                  ;; false for a non-intersection patches.6 v' H9 {& l& C1 |# M2 P
  my-row          ;; the row of the intersection counting from the upper left corner of the$ x8 U8 T  G4 S" D% g0 b
                  ;; world.  -1 for non-intersection patches.
* x0 j* j( \' h( i, F  my-column       ;; the column of the intersection counting from the upper left corner of the
, G+ k3 E- G+ r! y' q3 g) j% @3 W                  ;; world.  -1 for non-intersection patches.
2 J! X& ~; V( t" W  }  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
7 _, R( C3 ?; v# Z# g/ a& f/ V  auto?           ;; whether or not this intersection will switch automatically.
3 t; a+ L7 n5 V. F/ a/ N: I                  ;; false for non-intersection patches.
" q$ N) k& I( _0 W]
$ e+ \9 z/ m% X0 y  m1 b( s# b4 `
8 P+ V9 _; n4 Y9 i/ ~0 |9 ~: e, f# _$ v8 K0 M  [0 N5 E
;;;;;;;;;;;;;;;;;;;;;;
, H( b% p/ P. V$ U6 k/ ^;; Setup Procedures ;;
' x5 i$ i7 \5 |; a* R5 w7 f;;;;;;;;;;;;;;;;;;;;;;3 U% H" Y8 }' u" j1 b

$ n0 V- J7 c1 x3 e" U;; Initialize the display by giving the global and patch variables initial values.
! E3 G$ f, a4 T, X5 C) p7 A/ H;; Create num-cars of turtles if there are enough road patches for one turtle to
% e. n9 G1 O4 D1 z! m1 [9 u. J3 w+ J;; be created per road patch. Set up the plots.& g# v+ G' g% ^/ ^7 z' N/ u2 g
to setup) |/ s0 H9 I/ W# o2 g
  ca
4 G- W0 j$ @+ s0 B/ ^& d; d  setup-globals. h, u2 F3 ?0 ]" J' |
2 v- l1 d& _3 [! w. l
  ;; First we ask the patches to draw themselves and set up a few variables* a' a) q7 j4 j+ O8 j& V, y
  setup-patches
2 H. v' w8 h1 j2 ^9 A  make-current one-of intersections
! \+ }3 ?8 z0 r/ ~$ C  label-current( ?' m  c3 ]$ j2 W6 c

: V; b7 c6 Z- i. q2 D  set-default-shape turtles "car"- O! S* U5 B( o2 b

4 V6 J+ Z% [+ k0 v3 Q& O  if (num-cars > count roads)! [1 F. d* Q  d' N7 x. ]
  [
4 B$ ^- \6 c8 }# l3 P    user-message (word "There are too many cars for the amount of "
5 j" b  u! F. Y                       "road.  Either increase the amount of roads "
5 l% q) F+ D2 \) L                       "by increasing the GRID-SIZE-X or "
( V' v! i. h5 V+ C                       "GRID-SIZE-Y sliders, or decrease the "# i! O4 ]" o- Q  U! |
                       "number of cars by lowering the NUMBER slider.\n"
3 I6 b& [* D  k* |+ f# ~0 O/ u                       "The setup has stopped.")
1 f( x6 D# g( m; O' I  J0 v    stop
! z( ^$ L/ T+ q+ U: @4 `) n  ]
; r! O/ T4 Y4 ~9 X" \; \' ~
& Y2 B( D+ s0 p. T$ p6 c$ z8 N, R  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: @9 ?+ t3 E( Z8 U' n( {
  crt num-cars
! A/ J# ?! G; Y; J) \  T  [
6 e! K" m" X) V( Z. P3 ]    setup-cars2 t6 Y$ O+ }" u/ Y- G' W8 `
    set-car-color
! [2 l; |1 \5 [    record-data* |3 y% P$ i8 [1 m; G9 {$ `
  ]
" V  x( R  U8 c% @/ c& R" Y
4 z! X( U; j2 z% o2 Q4 g0 d  ;; give the turtles an initial speed
; g  n0 k; M' o5 j  ask turtles [ set-car-speed ]
: v) c4 e& i9 s5 q, B' {5 t' |9 }0 A& Q% ]9 I6 I/ Z
  reset-ticks! W% M7 d. q( h" X. e: _
end
& l/ R& E( R6 _: c* R+ k3 H- U% E6 \! m' m% P1 y5 Y/ Z
;; Initialize the global variables to appropriate values
$ ?$ _4 f* m' |: S" O9 w% lto setup-globals
+ e+ |' ]+ x& T. D% P" ~  set current-light nobody ;; just for now, since there are no lights yet
1 `3 l. F! p' f, U8 H9 I  set phase 0  E- ^* ]% P7 q% q( b+ |& w. U
  set num-cars-stopped 06 H/ E$ N3 G/ f7 q
  set grid-x-inc world-width / grid-size-x
, o9 ~% g% O) i: }  set grid-y-inc world-height / grid-size-y
$ Q% f3 }) u' r# o! m3 N8 m
7 H( H& R( n, q# A  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary5 i' m4 n# @' e; k1 U
  set acceleration 0.099& E+ N! m, k) `) r+ u8 t
end
" U5 z7 ^0 T( x) w1 O8 K3 [6 e5 t/ w# O* o% O1 c
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
+ P% {& v1 ~, K( ];; and initialize the traffic lights to one setting
' ?- q- |. o$ \8 H" \8 z+ ?to setup-patches
4 ~" I' R- [2 [0 ]! O  ;; initialize the patch-owned variables and color the patches to a base-color$ P, |' R0 n! S; ]
  ask patches
& E7 [- \2 j- O( V  [  p5 f2 `0 S2 ?) S0 v
    set intersection? false% b7 i( C+ c9 l3 x/ l' Z6 ~  u
    set auto? false
/ Z& h  ^2 v. }  G3 Y    set green-light-up? true  a( [) |+ w% F( S. o1 V. ?
    set my-row -1
) w3 d) C2 M# P    set my-column -1" N7 @6 k2 F) h" {! K
    set my-phase -10 E0 h/ V8 g; A6 @0 y
    set pcolor brown + 31 V' V8 {/ ~# N8 h0 C4 ^
  ]1 E4 ?4 G8 o  Z; i

' I# X! L& h) n0 v; W. X  ;; initialize the global variables that hold patch agentsets
4 m' i6 U% @  \, X8 R' I  y  set roads patches with
- O# b' W! n0 \* o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# p( Y" r! G/ a0 S
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, p2 p& {* v4 u' p& j  set intersections roads with
. Z% M! e1 G. k. O/ G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and9 ]" C# }4 s5 i! a7 e5 T4 B. Q; U, R
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- b, T$ K: B1 X
( F0 k2 x1 v( U8 y1 p6 z$ }  n
  ask roads [ set pcolor white ]" ~/ ~! o# R5 ?/ I4 O' A9 T3 Q- v
    setup-intersections2 ~! n7 `: g# i+ z
end. b1 B6 f& A; k
其中定义道路的句子,如下所示,是什么意思啊?0 m+ H; x1 A% f0 `/ j2 s# B6 l- n
set roads patches with
# |; X7 R& {) e8 F* ]/ C- v5 W8 s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! G- f5 ?) Y! \( X& D1 y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) y$ o: B1 _0 A  c) K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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