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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。
5 y4 ~. H4 X* E4 X1 b6 Z1 R  Wnetlogo自带的social science--traffic grid这一例子当中,& c5 L( i, |, R3 k1 x6 l
globals% z8 w8 j- _' f5 @
[; w# m* _6 ~9 k+ O0 Q! o
  grid-x-inc               ;; the amount of patches in between two roads in the x direction9 b/ j0 I' v0 I9 [  a( q) }5 h
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
1 V: o2 V: U0 c9 K8 |  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
3 @5 K" Q0 s( y$ X  A8 O                           ;; it is to accelerate or decelerate# v& M, @% `, b9 S. T4 t
  phase                    ;; keeps track of the phase) f" Z, ?# h* ]( [0 e
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
. a$ H# F; e6 {3 t$ ?9 \: m  current-light            ;; the currently selected light
+ P! ?9 p& g+ f  `* l$ C
2 A2 i" E# P0 i3 u  ;; patch agentsets$ e0 W+ _# C4 i# N2 z% n
  intersections ;; agentset containing the patches that are intersections
5 M: f0 V6 |8 E$ o/ k% y  roads         ;; agentset containing the patches that are roads
8 Q4 ?& a0 ]" k- U* T0 G% a]6 u6 z- ^: z" C, o& Y. h
4 s2 Z/ [$ `+ ]8 }
turtles-own
2 i8 v8 b8 ?: s# T3 D; L/ v( I2 Y[+ Z- l1 n- x9 Z' d2 N6 h2 K5 q
  speed     ;; the speed of the turtle
  w) M  ^* L( @# T7 E, H% ?  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, Q& H' e/ y" p* H; f+ t1 K% l
  wait-time ;; the amount of time since the last time a turtle has moved
' f1 x1 o- j3 y]
4 {( z: F) m0 J5 g0 E0 s7 q" f. P9 H. f; _7 |7 U+ j
patches-own' B) g3 |9 A6 e: D9 b
[' y/ t% J; \6 S8 p! w' U
  intersection?   ;; true if the patch is at the intersection of two roads
! A/ T/ `" w0 ]  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
. ^/ J- u. q4 `8 U" k( S                  ;; false for a non-intersection patches.
1 G! B+ y$ x7 a3 z! h0 T5 V. d! }  my-row          ;; the row of the intersection counting from the upper left corner of the
& z( \& b  P: E8 T, ^                  ;; world.  -1 for non-intersection patches.+ j2 b# P2 ~1 u% P+ v5 Y. U
  my-column       ;; the column of the intersection counting from the upper left corner of the
6 U( m% K9 b' G/ v% ?9 ]                  ;; world.  -1 for non-intersection patches.8 h' d) F+ m9 H$ t/ ]% t
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
- W$ r& S) I5 n6 O, C$ M  auto?           ;; whether or not this intersection will switch automatically.6 l, B* h5 z& |3 ]: X! n1 w
                  ;; false for non-intersection patches.8 N  z2 S7 @3 U/ d+ ~  b: m6 b! ]( I
]
! u# K) h9 z6 c% x, E/ F
- z. x4 N, F  x; i$ [% S- l/ i- W: _& T5 m* [7 s9 u2 F
;;;;;;;;;;;;;;;;;;;;;;$ _% ^' m7 O% v; W
;; Setup Procedures ;;; y: b# ]& A; i% g! s/ e
;;;;;;;;;;;;;;;;;;;;;;
& m7 H' ]% _, U  a( \$ L' [& V: n9 N& y* w1 b
;; Initialize the display by giving the global and patch variables initial values.
' b$ E) O* O* W;; Create num-cars of turtles if there are enough road patches for one turtle to
) D1 E1 H0 g$ C+ N0 Z;; be created per road patch. Set up the plots.
* L. ?- \6 h! S; @, ^to setup, j! J* @' b. N! D' ^% g  q  h. f
  ca
$ G0 \/ M% }2 f  setup-globals3 \7 [4 o/ F! G7 X

7 z5 G6 _% T% U* u# A4 O; c  ;; First we ask the patches to draw themselves and set up a few variables
6 m- M- q# x2 Q+ y9 B5 M4 ]  setup-patches( `+ k6 G$ @( I6 Z1 {' I. \) r: Z) ?
  make-current one-of intersections; u% Y' y& w, Y8 w3 |- O6 \  K
  label-current
, j, ?4 \) i/ y" B% m/ m3 F1 Y  Y+ K
  set-default-shape turtles "car") N% V; f, [; g

- K) x! o! s  c% i2 V, `  if (num-cars > count roads)/ e0 f9 X* a( w
  [+ r0 O: T+ d1 ^" V
    user-message (word "There are too many cars for the amount of "" _3 C1 b( b- M7 o, {2 T
                       "road.  Either increase the amount of roads "
. u" u& q! }0 U3 f! E. |6 {                       "by increasing the GRID-SIZE-X or "4 ?0 V  R8 B0 d  f7 Q
                       "GRID-SIZE-Y sliders, or decrease the "7 u" c! Z1 m3 l3 E$ }! Q- t; y
                       "number of cars by lowering the NUMBER slider.\n". t) s; P1 I  L' ^+ v6 R* v% N9 {# B0 a
                       "The setup has stopped.")+ z9 Y7 N2 E, j4 Q
    stop' {3 M% P% T. i1 ~0 n
  ]
: v* }& s9 a) e% H1 g5 B' n$ h8 S/ _& f6 h; S# R
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% p$ F. |% Q& B
  crt num-cars
- k; J9 N5 J3 l: g! J  [, P. Y2 t7 O" ^& Z6 s+ W
    setup-cars
* F' D6 T7 |0 E. n8 Z: a* [    set-car-color
' E% u0 q& o4 n4 I; \! j* G    record-data
1 q, A/ ~. L# L9 e- Q8 z1 O  ]  {( W& e# q$ ^; z. U

  Y1 l, P: p7 R* g! m4 S7 g2 q  ;; give the turtles an initial speed) `- J& ]( f1 Y" y6 N2 b# \
  ask turtles [ set-car-speed ]
5 e" j8 T" p2 C" _; S1 f, t5 f5 N- Z( ]4 X5 X9 k
  reset-ticks
# ~  o# Y4 q" m5 |0 f* pend
4 E+ `1 r2 u  V3 v4 `# O3 K4 o! _# u6 O4 A  a( \2 @
;; Initialize the global variables to appropriate values
- j" _) r8 p& V% H. p, _" b3 {to setup-globals  ]5 h! N0 p: i+ m
  set current-light nobody ;; just for now, since there are no lights yet
3 Y$ X. L" c, h! Z! |5 W' e& b  C  set phase 0* ]" r/ R8 x( O
  set num-cars-stopped 0
  x6 v, N6 G% q/ ~) V; D  set grid-x-inc world-width / grid-size-x
4 ~6 X4 u+ h9 `6 z' v  set grid-y-inc world-height / grid-size-y
; u! e8 F6 p. U4 p" k  Y, Z# d2 R- V  k8 r) D! Z6 c
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 b3 U$ |1 V! y- y9 a  set acceleration 0.099/ f4 v4 L5 @* ^2 }/ [% Q
end' n) @* i3 `% C) N

$ h/ [$ `+ P3 x' E8 J# p;; Make the patches have appropriate colors, set up the roads and intersections agentsets,- B2 \9 }# `' _
;; and initialize the traffic lights to one setting
/ x" Z! t# O9 Q# a4 [( h, Ato setup-patches! h/ V# F, D; W8 y. R
  ;; initialize the patch-owned variables and color the patches to a base-color2 I: E8 k' ^! @) n4 T3 Y
  ask patches2 y7 K: u( U3 Y3 Q* X
  [
+ [; \6 P! t0 j6 Y    set intersection? false
" @* v$ e4 k, F( ^" l% x  Q    set auto? false/ I. ?8 O" M" |' ^
    set green-light-up? true6 J, `  S1 y. W/ X! p
    set my-row -18 m3 M% T: Q9 [* O: Z! u# y
    set my-column -19 w0 v6 \* x: h  ]* l
    set my-phase -12 u: @7 N$ ?& ^9 U5 ?
    set pcolor brown + 3
* M: o3 K* X! k7 O! M  ]
- n* \3 z7 F! T5 X
: V/ @1 [" T- \. ]# K- F  ;; initialize the global variables that hold patch agentsets: Y' ]& i3 D: Z
  set roads patches with
. l8 U0 y! g# D& z+ }  U" e0 v/ T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  F" I6 o6 x8 W% X( j$ s5 k. f% _. A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' g6 ]& n: e6 K* ~
  set intersections roads with
/ X) N6 X8 ~5 A/ N, b5 p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
9 R9 N' A* F0 u; g) i* A! a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  L( A5 I% e! _) k7 l( P: ]
4 f8 M% F. A; h* _+ t
  ask roads [ set pcolor white ]. k8 V3 T& u$ ~" B5 C! Z, j0 Y
    setup-intersections( n5 E8 `  L) o8 q
end5 C8 q6 {# @- a* C
其中定义道路的句子,如下所示,是什么意思啊?
( \/ g3 z3 _" ~! M0 Q3 P; C* z8 }9 H set roads patches with& ~' U7 w+ w/ |6 b4 d' C. I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& E5 r8 g$ h% |, M. t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 V) l9 `% U& a6 `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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