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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。
: e  q! z& u, D: [2 O2 C% P: ]netlogo自带的social science--traffic grid这一例子当中,- q$ w4 ?+ O. o) S, s2 s
globals
) D+ |4 Y7 S; _: u  Z[  u% V! A& h- M. G( G* q2 W
  grid-x-inc               ;; the amount of patches in between two roads in the x direction+ a9 B2 D" t' \
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
7 o6 c, ]; E0 E) k, x  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 P5 S# e* {1 m6 a! D- l                           ;; it is to accelerate or decelerate' i' a, V# V( y* o
  phase                    ;; keeps track of the phase
, n; f2 q. y7 j9 t" R* _' ~; ~9 L- o  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
% `9 O4 o! Q- U6 v$ B) e5 P/ u  current-light            ;; the currently selected light) i; ^* ^$ Z* r* @4 @7 E

+ N* W/ j- x8 N7 D4 @* i+ X  ;; patch agentsets
" M  M6 K7 P; H/ |* ]0 b7 f) D  q  intersections ;; agentset containing the patches that are intersections
/ P  z( m9 o( X. @  roads         ;; agentset containing the patches that are roads
. ]& K4 G5 i7 R+ k! @6 p2 I]' r+ p3 P3 _, \/ N6 D
3 C' e3 W1 E8 m# r* `) r2 d: C
turtles-own4 J* d# k  H' C9 E6 {
[6 f* H8 H( o- O2 O
  speed     ;; the speed of the turtle" O" [1 D: S7 B- s: d7 Q! M( b- @
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
/ N1 v$ J5 C+ y3 O1 v  wait-time ;; the amount of time since the last time a turtle has moved
2 a& I9 y- }; S& o* ]) j, @]0 ?8 [. H0 B& S1 k* n; \

0 q$ g, l& J( R/ epatches-own
! l( x% P# ?4 i+ V[3 v7 A" z5 p- g; o! [) ]( c2 m
  intersection?   ;; true if the patch is at the intersection of two roads9 [0 Y& f8 M( t- u) J, j( f
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.7 \) \* P, T' d8 E% P" x) V
                  ;; false for a non-intersection patches.
; X1 A( I3 d, ~1 k0 D  my-row          ;; the row of the intersection counting from the upper left corner of the5 ^* h7 _) u6 N
                  ;; world.  -1 for non-intersection patches.
* Z3 W) y1 }, _) |. X/ A  my-column       ;; the column of the intersection counting from the upper left corner of the
$ z; {- _/ R5 F3 c8 T% o                  ;; world.  -1 for non-intersection patches.
1 m1 U% n, R8 x- ]6 u& o2 y  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.- G5 ]  m  Z' m# X1 b
  auto?           ;; whether or not this intersection will switch automatically., c0 g4 I( M5 t+ x$ \7 e  T2 |% C
                  ;; false for non-intersection patches.
! N! }% q9 }3 [/ R8 f], a/ e3 G5 v' S. V" R. ^

# q; r$ i, \" i4 c
% E, q6 K! a3 q- l! g. v;;;;;;;;;;;;;;;;;;;;;;5 v# x5 n2 {- w& s5 f9 o/ L! z
;; Setup Procedures ;;; \" i  q  h2 [# J# ?
;;;;;;;;;;;;;;;;;;;;;;
5 `' }( w% h/ A4 v& J2 b) u' G3 t/ R5 L4 e# n2 q  n, t
;; Initialize the display by giving the global and patch variables initial values.0 c7 [3 D" T! i8 |3 n
;; Create num-cars of turtles if there are enough road patches for one turtle to
' T: P; z3 ]8 Y8 v4 s4 p8 [9 }3 I: ?;; be created per road patch. Set up the plots.; [2 ?. y; a0 M5 O7 V0 h  h
to setup
! d) m3 M( a. Z5 r  ca& w, c) }7 c0 ?1 r: e0 O0 s
  setup-globals
& c8 f9 R0 ^' A8 b
4 E; U( k; b' |( X0 o  ;; First we ask the patches to draw themselves and set up a few variables
- F1 ~  f/ W, q' f( Y% @+ G' F  setup-patches
' W) M1 {8 [$ A$ T  make-current one-of intersections" l- s' E! k: P! C9 W" z5 T
  label-current: }) n6 B2 f. @7 o5 Y2 U

$ M0 w* @2 V" E: ~  @9 y' |  set-default-shape turtles "car"
) ?0 @3 n9 v0 }& V$ V- ~" c; D4 x8 x. t2 w# I: B1 F) R
  if (num-cars > count roads)! u" W& R; V, `' q6 ~( I
  [
! h  H5 K$ p/ N    user-message (word "There are too many cars for the amount of "
+ I  C. K* w5 J                       "road.  Either increase the amount of roads ", O- m. W" J) ?# y- N% R. p8 R
                       "by increasing the GRID-SIZE-X or "( m4 E+ Z5 X  u
                       "GRID-SIZE-Y sliders, or decrease the "
9 t1 X, W: H# ?; }( m' g  Y                       "number of cars by lowering the NUMBER slider.\n", A8 X% ?9 x7 I
                       "The setup has stopped.")
5 c% \$ A1 Q8 M  t+ k/ p" W+ b$ d    stop0 E, \1 O& q: `/ Q5 I: I
  ]
- N4 a( f3 T: r& P% M& y' ^: \+ @  G6 S6 @5 K
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color0 J  y% H) y8 s9 y. `+ A
  crt num-cars
; }$ j9 h2 ~5 _7 z  }' q9 z  [$ |8 H5 x& z" C3 u
    setup-cars
$ _0 P% r6 h. r# i" C2 }    set-car-color
3 W+ F) W4 g4 D! s+ i7 S+ K    record-data$ y: m5 r( p, B2 {) ^4 ^* ^
  ]
1 X: J7 y7 U) i) I6 o' N9 K+ ~4 [' ?& O; F1 x2 Y
  ;; give the turtles an initial speed
5 A$ ?: L5 W* T4 C# A  ask turtles [ set-car-speed ]# S. u. n( S5 l7 D

) w( c* Q9 ]& l' L$ M) ~  }# s  reset-ticks
' @1 ?& P, ~( X1 T! V: {end! u, j% d7 A6 C- L& o
0 f9 e- E; r- r7 l0 ~5 U( _& I0 C
;; Initialize the global variables to appropriate values' J1 _- m( v% V( K
to setup-globals/ z% h2 n$ c# [- \1 F/ ~
  set current-light nobody ;; just for now, since there are no lights yet/ s% u2 F/ |7 ^/ I, a1 e, q( C* M
  set phase 0  X, s$ G6 M5 V2 B' Y% B8 p+ l
  set num-cars-stopped 0/ J$ K  W2 ^, [  O7 B
  set grid-x-inc world-width / grid-size-x
: V! O8 w0 ]/ h6 @$ g  set grid-y-inc world-height / grid-size-y8 c$ d9 G& f8 x% w& Z* [

% n2 l1 W0 e! q  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
) L1 d! d, j- N1 W5 v  set acceleration 0.099
1 I! J- S4 y3 \end- E. C! x1 p' c+ ~+ q6 O) l6 R
1 Z' |* i6 n; k& |5 w4 F
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
* `+ ~- u" A1 S# y; Q" _# U;; and initialize the traffic lights to one setting
- _/ d. G; j3 ], |3 ~  C0 d* e. sto setup-patches+ Y8 \2 s5 h) G" `* [% \
  ;; initialize the patch-owned variables and color the patches to a base-color( t: E! K* E9 |+ t. k
  ask patches, P# ]% ]' C9 b( D' X1 D
  [
$ J# [" B, Y0 a: R1 r6 l$ R3 Z; ]    set intersection? false
0 g6 {+ U8 j9 j' `    set auto? false
3 @, I. ?" z7 y2 x) z  l. ?    set green-light-up? true
, }' G9 [4 C' s. V! T, Z) U    set my-row -1
6 v% R' o" U  M+ j; q; O    set my-column -1
' C5 b4 o. U1 U% v+ P/ S    set my-phase -1
; h+ F3 r. f, x/ [( a, U    set pcolor brown + 3& n0 a7 m* }0 }/ s- L
  ]
( v* L) i% e& H" m1 H8 ]6 k: ~& B
6 j' U, P7 R( ~4 T  a" g- V  ;; initialize the global variables that hold patch agentsets' Q' `( F4 h2 h1 c. x6 q+ R
  set roads patches with
: ^( E& J  ?: ], u! I1 A    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, I/ Q, F1 F: {2 \' H! O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 Q: _. M9 S5 _! g) v) Q  set intersections roads with
  d9 \9 L2 X( d2 ^( w8 `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 t+ o( m0 z+ [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* ]5 Q0 S  G: c% p/ d$ o
3 d1 g8 `$ x. N* Z$ C+ v  ask roads [ set pcolor white ]  Q5 l1 _0 y- _1 `
    setup-intersections
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其中定义道路的句子,如下所示,是什么意思啊?
7 u+ {# C+ c2 K, A set roads patches with
; {3 N5 \) k& A( g8 Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 G& C1 n# u8 u
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. Q# K4 k& V) R" D8 |7 M
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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