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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。
4 n" m: N7 G" U/ anetlogo自带的social science--traffic grid这一例子当中,
4 J2 T2 i8 l+ W6 F7 [: M% o$ fglobals
8 K% @# m8 L% k2 S- y, E( S# \' h[2 a/ O  k# H8 q& |
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
1 s' H# f: ]# Q+ p. m  grid-y-inc               ;; the amount of patches in between two roads in the y direction1 [9 b7 J! f3 P+ b" X
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
4 r+ I, U/ V5 W7 e8 O$ O                           ;; it is to accelerate or decelerate* M' M& P1 _3 b: |4 ~
  phase                    ;; keeps track of the phase
' f$ n1 t, Y$ Q( i  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
# U0 }; p6 u/ ^  current-light            ;; the currently selected light0 Q2 a: Y( j" r* j% E+ C. z
- I1 m. B/ |1 J
  ;; patch agentsets( N$ x9 F# U% K# o
  intersections ;; agentset containing the patches that are intersections0 m# K: `7 c2 E0 {0 i8 J
  roads         ;; agentset containing the patches that are roads
, H, u$ h( o) r! t" t8 E, ~  @1 x% F]/ v& t: m0 J! F1 f( ?/ J! _2 o
7 |* X7 u) L' B! k0 R/ h
turtles-own+ ~, s$ {+ U2 {9 q9 u3 {5 X
[
) i2 C: I  ?% w- R; N  speed     ;; the speed of the turtle
0 Z: n! @2 P- k' t  up-car?   ;; true if the turtle moves downwards and false if it moves to the right! R3 N  i+ Q) U* _
  wait-time ;; the amount of time since the last time a turtle has moved9 j' y! E& b0 l: s: A
]$ h; v$ T$ s* l9 K. p

# M3 e+ y1 w# s9 c' v' I* Jpatches-own8 p4 o/ u; q; C9 x
[
& q; A1 L0 {% i* W0 g  intersection?   ;; true if the patch is at the intersection of two roads
: l9 w5 M- ?5 V% \# ]$ O! J' i  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.1 Z8 r& R( q7 e' o# F; ?
                  ;; false for a non-intersection patches.0 u3 x  u4 m  s1 v6 S
  my-row          ;; the row of the intersection counting from the upper left corner of the
! b+ \7 c: t, ~& D. r& a( L. t$ m. H                  ;; world.  -1 for non-intersection patches.& E) F- R! E: R# v2 d
  my-column       ;; the column of the intersection counting from the upper left corner of the
; }! m+ ?1 A! U9 |                  ;; world.  -1 for non-intersection patches.$ }8 r5 R0 D/ A% m1 z/ e3 `
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
8 N5 C) J; S. v5 ?/ U9 o  auto?           ;; whether or not this intersection will switch automatically.
9 ~9 d. z( ~4 I$ Q) {, o; i                  ;; false for non-intersection patches.4 A0 F' w8 [$ [9 v
]" u. r0 z+ Z- m! u! `3 f, e

, ?9 r2 |* O1 C; W
( a: b5 ^3 n3 n# l, C" U;;;;;;;;;;;;;;;;;;;;;;: r+ K* n# A6 t
;; Setup Procedures ;;
! R# V+ C1 c9 o4 \, h, Z; P2 ?;;;;;;;;;;;;;;;;;;;;;;. m8 J7 \  K% O( E4 ]

( O% X* J" |+ d/ C& [9 {! G4 J) g;; Initialize the display by giving the global and patch variables initial values.8 ]/ o& p" K. H- E: ^" q' I: |$ B
;; Create num-cars of turtles if there are enough road patches for one turtle to  b& g  M- m. N+ X& P% W
;; be created per road patch. Set up the plots.4 Q8 W& z  ?3 j. q9 A) L! o; k
to setup
  j. |* {" g- R0 ^  ca* R8 U: p0 S2 _' Q! d( }
  setup-globals
# O7 J! S; E. a+ R* q1 J& ?7 X9 o+ h; q1 Z: \0 X8 D4 }  H
  ;; First we ask the patches to draw themselves and set up a few variables
7 V& F' S7 D% y& R2 O2 [) r, s& S  setup-patches" C( u6 T7 }, K2 r
  make-current one-of intersections5 X, s+ u& r* g) s: u( C
  label-current7 S: R/ M# k  p
& t8 R5 [. j; J* X/ o+ X; l( ^% U
  set-default-shape turtles "car"
$ E3 s$ Q' p- f7 [% v2 u& ?0 `) O- S# K! Z, ^
  if (num-cars > count roads)
6 t( ^, f0 q9 c  [
" w, @8 P( u6 l: I  ~8 r. [4 I    user-message (word "There are too many cars for the amount of "
. R# X  o7 b/ c: r5 A# \7 y3 h  i5 X) v                       "road.  Either increase the amount of roads "
/ H' N3 T' T# v) {* i                       "by increasing the GRID-SIZE-X or "5 i( A. `* B$ x# q6 E/ u7 m5 X5 O
                       "GRID-SIZE-Y sliders, or decrease the "
% q* R# J4 j9 z2 X+ M                       "number of cars by lowering the NUMBER slider.\n"! {6 r! ^$ }0 s, V% ~! y8 ^
                       "The setup has stopped.")
6 ~1 q4 o) A7 a6 i- G' C5 E) M    stop* |  f$ r8 W4 J/ B7 K
  ]/ D0 a; o+ s$ V% t% P
6 ?% z$ C' X2 a+ n; M  r' s
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
% w) Y! }3 p) Q5 E: O" F! G  crt num-cars6 @0 A3 O9 H1 y3 U" j5 a
  [% f. Z+ }1 _; T; {! t' t$ j' P
    setup-cars
8 i4 m) P6 ^9 P7 v( x1 C7 U    set-car-color
7 j" W2 m1 b! G: a7 L: V    record-data
  }' R! e& _" X7 D  ]
4 @+ g: S' Z/ ]
$ M: T) |# c  [0 n" P% @+ w  ;; give the turtles an initial speed
) ~* P7 {8 p  N8 }) N& q# c8 ~  ask turtles [ set-car-speed ]
1 d0 `! x6 X3 a& _
4 ?0 O  Z7 b4 N5 E5 F8 q$ ?( B! ?  x  reset-ticks
. h( n4 Y$ z9 {9 B. mend
# z+ }! ?7 v! x+ S- Z" b' ]" _( e! d
;; Initialize the global variables to appropriate values4 w9 x' g( L+ E- K. T! m, l
to setup-globals
: L( r9 s  P6 V9 s) V) J( P" ]' A  set current-light nobody ;; just for now, since there are no lights yet2 L+ e9 D. x" w) C( ^; x
  set phase 0
0 `/ Q& j& |3 _  set num-cars-stopped 0+ m& q7 p% T/ K1 s
  set grid-x-inc world-width / grid-size-x$ P/ Z9 K  ?6 ^
  set grid-y-inc world-height / grid-size-y
3 M: H8 d0 t( w
; }" y/ Y" }$ U* s  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
9 g$ K- f2 p+ V# o/ k, {. V  set acceleration 0.0999 l. A% ^) E% v. w" |1 s% K1 K1 L
end6 l- h3 \' G+ c% `1 X! I

2 W2 N! N5 s. ];; Make the patches have appropriate colors, set up the roads and intersections agentsets,
7 x3 k. ?% d9 M0 v;; and initialize the traffic lights to one setting" h* z- o+ ^: v' F& d2 U
to setup-patches
; w1 I" a, p1 {  ;; initialize the patch-owned variables and color the patches to a base-color
6 y9 b. n9 X; b7 \/ j$ K  ask patches
; i/ j1 F, ?4 A2 s  [
* ?5 o: z! x" \5 P+ H7 k    set intersection? false4 {% U3 o" X; ]
    set auto? false
: C2 Q9 l5 v7 z! h; |  d    set green-light-up? true9 q+ j9 x5 Z" H9 ]  |/ v
    set my-row -1. n. c/ L' ]. p% n" t
    set my-column -1
; C- m5 p- j* O4 F: c$ q: Z    set my-phase -14 l4 N6 {  r5 u# q9 Y. T
    set pcolor brown + 3- K! m* j9 t! S1 ?: x
  ]" G: [% d! T; R- }& s* u+ x
0 G4 _8 {8 Y& y" b7 f
  ;; initialize the global variables that hold patch agentsets( r/ R, {* a; S! ~+ W; t) u
  set roads patches with0 o/ |( n. R& G4 N3 q: O
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 O8 `3 X2 z& f) R- z7 p4 X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& O/ b" I+ {# F  set intersections roads with
0 c" @9 p1 o) @4 t) {6 x( a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" K% U9 D; K8 y3 V    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( E4 T8 _- O& X8 G, G
6 h( Q# }2 W! d) q" l  ask roads [ set pcolor white ]3 Q8 Q# y& i: P( V0 o, e
    setup-intersections
. h$ G& E, g8 T! j) \+ o4 a, }- a2 [) fend! K' z1 i* ~  _  w# T
其中定义道路的句子,如下所示,是什么意思啊?+ Y, h$ ~; n, S" J
set roads patches with+ F# v0 ]& ^+ N- ~( R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 v! E* O; k* o, D' i, D
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 C( o- M) m- }$ u' V
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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