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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。+ M2 A+ ?/ m8 P: w/ H
netlogo自带的social science--traffic grid这一例子当中,6 h0 b4 u- V- R$ X0 y" E& C* |4 ]
globals8 _0 m  C' P/ S4 H1 z
[
/ \& j- m( l3 }  _7 Q* ^  grid-x-inc               ;; the amount of patches in between two roads in the x direction
* f' W7 i/ O5 j3 K) k  grid-y-inc               ;; the amount of patches in between two roads in the y direction
" n8 C1 E0 @# a' \& d  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 T8 g) u8 {7 s
                           ;; it is to accelerate or decelerate+ |. }! |6 y, G8 l8 `. B, y1 J5 i
  phase                    ;; keeps track of the phase' y4 i3 A1 ^9 }
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
- j; V# {, Y' P4 B- q2 t( w  current-light            ;; the currently selected light! E" e1 l0 x5 l- f7 S, Z

3 O" m8 H! j/ Q# J! `" m  m" E& Z  ;; patch agentsets* x& T! c3 p7 W0 z6 d9 L$ y! J3 b5 B
  intersections ;; agentset containing the patches that are intersections/ C& b: S. j, p* e$ c- B
  roads         ;; agentset containing the patches that are roads8 k$ x( K* f4 l4 E
]- q7 n, ^8 [: g+ ^6 Z

$ H3 {. f* V) }0 j# Cturtles-own
  U3 v% y$ f+ m9 k7 b1 L# T[
9 W& F' Q/ |" t2 h  speed     ;; the speed of the turtle. r# h+ L' Z8 {
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right6 X3 U, F; |- J) m% S
  wait-time ;; the amount of time since the last time a turtle has moved
. K" |& b2 a/ K+ I1 Y]& K* u( x  L5 f4 Z

, ?; C+ I; l+ T! S; n* ?patches-own
' ?: j" z+ E! S4 e[
; [1 u* P* _# f. F7 b2 s* G  intersection?   ;; true if the patch is at the intersection of two roads- O5 C5 B) i# C0 ~1 Z! ?
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
; b3 F+ c9 L1 T, [                  ;; false for a non-intersection patches.% [- ?9 t) ^- S6 d! @8 C
  my-row          ;; the row of the intersection counting from the upper left corner of the
7 I# k& h7 e+ |0 E( @$ h, i                  ;; world.  -1 for non-intersection patches.- l1 R" W! Q( r
  my-column       ;; the column of the intersection counting from the upper left corner of the
5 Q6 M+ ~+ c" X  b$ v4 ?                  ;; world.  -1 for non-intersection patches.
5 |- J; i- m, ^) l! ~8 q. O  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  I' i; P( {, y% j5 a* F
  auto?           ;; whether or not this intersection will switch automatically.. E6 i" G% U2 ], q, ~. I
                  ;; false for non-intersection patches.3 I+ d' u) h) \. L
]
4 I) p; Q3 l' }9 V( J6 J, M3 u8 R
6 A, U0 E" f0 ~) L
: x3 i* C9 J3 i: H;;;;;;;;;;;;;;;;;;;;;;+ D( |- w& J7 ~$ |
;; Setup Procedures ;;
  D5 H4 c" q& h* m8 V# v;;;;;;;;;;;;;;;;;;;;;;
4 o/ s' S- x3 I& D
2 f. ^, ~3 ~: f) V/ P;; Initialize the display by giving the global and patch variables initial values.
2 h3 B9 P- A% k$ T/ O* E9 N$ z& X;; Create num-cars of turtles if there are enough road patches for one turtle to
( t) Z7 c% l  G* w;; be created per road patch. Set up the plots.
7 @) e( V; I1 H  _8 Bto setup
9 [& n; @7 a1 a7 ~! M1 [  ca! K: s  E8 s8 Q8 e2 n' ^& c& y* b  y* @
  setup-globals
) t% b2 A: Q% t3 C
7 s# r% `) I# i8 q  ;; First we ask the patches to draw themselves and set up a few variables
" d- ?+ |" q2 `6 ?6 Z. H  setup-patches
( a$ ~5 O! N* Z- K  make-current one-of intersections' i9 c" r! p; G( s
  label-current
% P$ j& H2 k3 a6 y; h2 {5 h5 r) J" p- n  I  o2 O
  set-default-shape turtles "car"( B+ ?+ b2 `0 _
; x) ~  [$ F& a& A8 n  E/ H
  if (num-cars > count roads)
3 k( b# k* U. q" T" P3 }& @# j, W& W  [
5 T5 T1 k2 T, ~3 i. g    user-message (word "There are too many cars for the amount of "5 _" j. A3 W; |8 M
                       "road.  Either increase the amount of roads "
: ?. H  w) \! @$ C                       "by increasing the GRID-SIZE-X or "# y3 T0 _8 ^, R
                       "GRID-SIZE-Y sliders, or decrease the "
; N0 m) W5 j) X, r' k. d3 E                       "number of cars by lowering the NUMBER slider.\n"
' F! b, ~, [! F5 f* p                       "The setup has stopped.")
- ^; y" m/ L2 m3 G3 t    stop: f, z: Q+ n+ D. `5 S0 E4 a
  ]
2 |+ y! }$ I6 O- p) ]3 D6 K) x; M, r
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color$ b; m; p* W: e, c
  crt num-cars" J" \/ O8 g: G* S$ x
  [5 @  F, l  l3 c9 Q3 H$ I+ h; c9 r6 N  Q/ Q
    setup-cars7 t# B/ i9 S0 c* F1 l/ X+ g. i# I
    set-car-color# O6 x1 @4 E- u
    record-data- N% F: ^/ H( o0 I9 x1 y  d; i4 F
  ]* M+ D! Q) F4 l8 K; W9 l

* u4 u5 V' V3 Z+ ~( s5 {  ;; give the turtles an initial speed
& R! c0 A* j2 W  ask turtles [ set-car-speed ]& B) D$ G3 r' g" |; o/ j/ h

8 ^9 k! `% U4 P( t  reset-ticks
( @$ _; g( M( @' c1 ^2 N5 f8 `/ W; a8 s. aend
$ C+ a0 W8 D/ \$ l/ W& M, o9 u4 ?6 I3 @; M" ~% x  x1 G
;; Initialize the global variables to appropriate values7 x- a* m$ O7 i' d) O
to setup-globals
" M, V3 X# d5 q0 n& S  set current-light nobody ;; just for now, since there are no lights yet5 U2 ?6 g5 u& [7 V5 g0 ~6 c* c; W
  set phase 0
& {# U0 N5 Z( \  set num-cars-stopped 0
- J$ o1 |# M8 x. d' C9 O" u  set grid-x-inc world-width / grid-size-x1 D8 L/ s, a, d: Y2 k9 D, f
  set grid-y-inc world-height / grid-size-y
7 `9 |; I8 ~8 @; R. J9 Q
/ c9 |9 b1 I1 T. z# k, e$ v! y7 r  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
& f0 L; r+ X9 i7 A- D, d. t  set acceleration 0.099: I& v/ Q* o! X  m
end' P  e* z1 ~+ |% {/ l

) ?) D/ h: C5 p: X5 B;; Make the patches have appropriate colors, set up the roads and intersections agentsets,8 S( {$ J* N1 V; I
;; and initialize the traffic lights to one setting
( c: Z7 ^5 a& w, _to setup-patches
, s/ F5 N9 D+ g: S  ;; initialize the patch-owned variables and color the patches to a base-color- A7 `; L" f9 d3 O$ k; u, w
  ask patches
& h' J# ^$ m& l. L# y5 C  [* \+ s4 e- ?2 y# N# f  L1 V- T
    set intersection? false
1 @7 p; J% J5 l    set auto? false7 d: M; S/ r% {3 k
    set green-light-up? true. j& ^1 O. ]6 c4 n7 |. ?
    set my-row -1$ z8 V" I% S5 z$ s3 Z/ m
    set my-column -1
- x2 U& ?7 O7 Q# w2 m( o    set my-phase -12 K1 L9 Z2 G+ k" s5 u5 f7 |) S' T
    set pcolor brown + 38 U5 F: J- |/ [4 {' c
  ]/ e  `1 \8 q2 {6 I6 k2 Q
# Y4 s/ Y$ s7 G! Y! v( P" J6 w  ]
  ;; initialize the global variables that hold patch agentsets% P) w& C4 O/ w0 k& t
  set roads patches with3 C' Z7 k. C1 @; W) F9 j2 C% e) L  W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( j0 G0 n" D7 T6 s  e$ T
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 n8 G% K6 |: r7 r1 _  set intersections roads with
3 U1 |% i" E2 A) h/ N5 @  ~% y7 J    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
8 r# [6 ~" g5 [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ Z3 ?" F  o6 A* U: t1 j# F% ^  ~( N
$ Q' K' M' D8 V
  ask roads [ set pcolor white ]
( k7 W- |9 R! O' O- J/ o5 @    setup-intersections
( R( V0 w6 C! H2 Nend
& p# t9 L3 p# `) S* [  e- h其中定义道路的句子,如下所示,是什么意思啊?
" t: y6 a6 m4 s2 P set roads patches with# U! m# Y8 W& G0 W" w) \, t! _
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 v. C: Y# g: z8 [+ C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 Q; j& g& {4 G! K, g0 F3 q5 F
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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