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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。
3 R  N& A6 N3 C/ h! hnetlogo自带的social science--traffic grid这一例子当中,
8 T+ R% S7 m$ n) _. c8 X" x$ F8 K9 Kglobals6 H0 F% c, q' r( _2 X1 e$ H) g
[" Y8 h6 ?0 b. \5 b
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
4 p& ]" e/ @( C4 x" c  grid-y-inc               ;; the amount of patches in between two roads in the y direction- F& u: r& _, `
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* r* U3 b. b$ [- Q
                           ;; it is to accelerate or decelerate
6 E  M' F0 b1 J: i  phase                    ;; keeps track of the phase0 X8 r! y& V  ^. L* \
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ n2 b! I' G- a3 ]  current-light            ;; the currently selected light
: u0 I0 W+ Y4 g  \2 r0 E% z- r
2 O  k( P* K8 E  ;; patch agentsets
! x' [( n2 V$ D. x9 ]" ?  intersections ;; agentset containing the patches that are intersections- w3 D4 [% Z) m5 e3 @8 L& H# I
  roads         ;; agentset containing the patches that are roads5 ^" S) D- E) A# S
]
3 d9 f& d% b! ^2 c: a
; ?  K- R" t. b5 }$ D+ u/ q8 v# yturtles-own. |: Y0 Z! a  j% q: }3 b
[
; Z# e' K" \' j2 g+ \  speed     ;; the speed of the turtle
( W" j& h! g. v8 N$ v& s  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
/ z  f4 E* `; }" _( C" C4 ?2 w( ~  wait-time ;; the amount of time since the last time a turtle has moved
$ k1 ]) B/ X# O8 m4 R6 u9 Y& ~]) l! V; P# i# k! }2 T  |

# {( h: ]. l. E- w* Mpatches-own  {* `' ~. q. V% |% B9 ^# c8 @
[
  g6 o  \* c# u2 N  intersection?   ;; true if the patch is at the intersection of two roads) H1 P1 r9 t, \, M$ C3 c
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% D+ h: n# m& d$ p. q                  ;; false for a non-intersection patches.
( N6 d+ o' @- O) |  p/ G  my-row          ;; the row of the intersection counting from the upper left corner of the6 l/ D) W- u  g3 d, |2 m
                  ;; world.  -1 for non-intersection patches.
. J. l+ ?  s/ m$ a6 N  my-column       ;; the column of the intersection counting from the upper left corner of the; v; n2 H# |( Z4 l6 @( D
                  ;; world.  -1 for non-intersection patches.$ a4 A' L4 w. G* h! l- C% p
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
5 L$ O$ h- _: w% M  auto?           ;; whether or not this intersection will switch automatically.
  E0 {0 g; e+ C5 p% o1 e6 C                  ;; false for non-intersection patches.* T7 g( C+ O9 b1 w2 T
]
- A4 g& s; m' R6 {. F& A5 ]. V! f
" I1 }: T0 n5 w
% V; k; U6 V/ N/ N2 o;;;;;;;;;;;;;;;;;;;;;;: V+ `7 }' K" [' f4 Q( [  a
;; Setup Procedures ;;+ b+ ^4 u3 O- W5 g
;;;;;;;;;;;;;;;;;;;;;;
3 ]# _/ E, O, D1 @! d  f) P/ B* [8 V) k- m3 y0 @. H
;; Initialize the display by giving the global and patch variables initial values.: r9 D2 p+ d" l& y* T# [/ Q7 ?9 D& K
;; Create num-cars of turtles if there are enough road patches for one turtle to
- r# t% M. O+ L;; be created per road patch. Set up the plots.
. C  k" J1 P' s  \4 U3 Qto setup
- P. x% W. e4 }+ x  ca  ^: ?: p& J4 n5 g5 ^2 J
  setup-globals; y4 |! O: e" E' y7 U
$ ?& \! N- j& i% L! z
  ;; First we ask the patches to draw themselves and set up a few variables* G. W; G% f( T5 d/ T
  setup-patches
3 m& m2 g' d- u4 J2 V+ d  make-current one-of intersections1 k8 L$ I( C5 Q& n0 Q! h; {2 E
  label-current4 ^$ {/ L4 s0 F3 d+ o) ~
& g% {; u2 |& z3 x
  set-default-shape turtles "car"
, t# M" k) Z2 W5 L; \  ^  A3 i  e5 ^) J7 h) ]' ^% D8 x- j
  if (num-cars > count roads)
$ p& {. ~# I0 Q! c4 ?1 D$ U0 k  [: Q: ]5 w% t5 R* D) O3 F( \' n, A
    user-message (word "There are too many cars for the amount of "
( @1 b9 N: M2 M, k                       "road.  Either increase the amount of roads "4 I7 _8 b; z: `
                       "by increasing the GRID-SIZE-X or "/ d) l- [8 ?* C, n7 ~
                       "GRID-SIZE-Y sliders, or decrease the "5 Q* M" @6 O2 D: w* a9 J* T3 U2 {
                       "number of cars by lowering the NUMBER slider.\n"/ V! `7 l' y5 u, O3 E# N
                       "The setup has stopped.")
0 M4 ?4 w. D& t( k- d" d" d    stop, }; W8 o4 `/ @4 F4 w1 q! R+ Y
  ]
- z  k% q6 R( w1 D, O- K; C) W9 D% f6 c4 A+ T
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color1 |$ p! z7 U4 G
  crt num-cars
. ~7 @! K, E& q  [* l* V: V5 \+ T% S3 z, y, i7 r- ^
    setup-cars% v; g" `$ F3 ?$ @- |
    set-car-color
  R3 i7 J! y3 i; ]) m    record-data
' V  l) q4 v4 D: L- p9 m3 {3 \+ g  ]
9 W  m4 \% B/ Y7 m2 m- E5 j! s' A$ |# i
  ;; give the turtles an initial speed; @- p) n  Z$ j, {3 O
  ask turtles [ set-car-speed ]
) B9 r: W9 v8 r8 R7 r  z! Q7 v: S* _" z0 X0 c* `2 o
  reset-ticks
7 x0 v% A# Y6 T: G7 O4 r4 wend. _$ R& G6 K) m
2 z) e+ z  B5 ^3 B. Y
;; Initialize the global variables to appropriate values% ~# J& E9 x9 N3 Y7 t% r; L5 r1 r* X
to setup-globals
  k; O1 R6 C0 H& s. P  set current-light nobody ;; just for now, since there are no lights yet
$ F( L) W! h! R" q" ~$ L9 d  set phase 0+ z! U2 B/ M3 ?% }0 _& ?$ }# z+ }8 s
  set num-cars-stopped 0
$ X; M* ~! m9 J6 `: m% u  set grid-x-inc world-width / grid-size-x# c. t: o# n8 @9 T
  set grid-y-inc world-height / grid-size-y
+ ]8 c) c/ g5 h2 P$ C3 n- P$ @
2 C' O7 I! i0 z* c" E* z+ p/ P  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary1 k9 t0 K  J$ w4 I1 z6 B
  set acceleration 0.099/ M# S1 W" W) g- k; }* F' x- i- k
end
, e4 S1 }; ^' M, S7 \: S5 a8 r! T
4 d: m$ i$ G+ S7 @/ ]5 c;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 f3 d& M2 k5 y& N2 f8 L. f;; and initialize the traffic lights to one setting) X4 |; R9 L0 }6 N9 X( @5 F
to setup-patches% j& I( f& q/ E/ ?2 H, [( l" F5 g, C
  ;; initialize the patch-owned variables and color the patches to a base-color
8 P/ J1 S1 f! T' D+ F  ask patches( ]- f, x: ^* k3 r- z) p! d+ Q
  [& \3 |7 X# l( Q# }$ @& V5 O' q
    set intersection? false
+ Q8 |& t$ O: E/ c& l    set auto? false
" S, Q; ]1 l" J* T0 k$ z& W8 r    set green-light-up? true: ~" h9 |4 s$ y. |. n, i  V
    set my-row -1; E- i- W8 ~0 ]# H0 }# p
    set my-column -1
1 C. [, y! ?8 y& z( W    set my-phase -10 S6 U! x2 b& m7 J( ^: d9 m# F
    set pcolor brown + 3
7 Y2 b+ Q% Y. F9 o8 y  ]5 f, w( n* g6 Z* C7 `/ F

' ?& R, Y* ^; ~0 r8 ~( ~  ;; initialize the global variables that hold patch agentsets6 M; S5 [. P8 w$ T0 C" M
  set roads patches with
+ ~' t* X4 v+ F3 W, ?7 ?    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; S) I7 ^9 ?* |/ F- L6 S  v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 j7 c! g8 p9 |3 p: n; `$ r- M  set intersections roads with$ V8 @8 I6 ~. s" D, z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and* v- ]" r2 `- S( A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* g/ f& C/ s/ J0 o. ~/ h

# _( Q; V# G2 I% b& h5 Y  ask roads [ set pcolor white ]
2 ]" w, a+ b* T; [% V- i, U    setup-intersections. b" m" G; d. C: t; m
end& B7 N- q0 w" q( `. u2 h
其中定义道路的句子,如下所示,是什么意思啊?
  f% p( C1 ?2 r4 K set roads patches with
+ n0 ?- Q) Y+ V9 z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 Z6 E- v8 U' }4 U; \' u9 k    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) J) h; q8 i# c3 a2 x+ k# L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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