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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。( C" M9 u! E0 J( r. k
netlogo自带的social science--traffic grid这一例子当中,
6 s8 O4 x1 {3 c1 A& I8 t) L' ~globals
( ^# g# q- Y3 r) u2 f$ ], v/ M* j[
' x4 c3 f; d" W2 t2 c$ c) t  grid-x-inc               ;; the amount of patches in between two roads in the x direction) f) h+ X0 Q! y
  grid-y-inc               ;; the amount of patches in between two roads in the y direction4 @/ m7 _9 y& ]4 @( m) |
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
& q% m2 r/ h6 h4 \) `5 `1 y+ W1 c                           ;; it is to accelerate or decelerate$ h! D* g1 g7 L0 ]4 j3 v
  phase                    ;; keeps track of the phase& S; V( M% E5 p/ z; |  {
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
9 c% s  e% @+ d9 b. q  current-light            ;; the currently selected light
6 T# a* ~) v3 V& V# h, e+ j: J
8 _2 F9 \* J8 ?8 L( c$ p" c( [  ;; patch agentsets3 e/ g3 Z0 z, f' }4 d
  intersections ;; agentset containing the patches that are intersections- u4 w9 |2 e$ X; l+ _( I( T) U
  roads         ;; agentset containing the patches that are roads1 A: r/ T$ m5 U
]
. U  ?& B% L8 ^+ F/ X' Z- x' M! i: ^- u
turtles-own6 ^3 u" ~4 ]# Z3 T' r- y' F1 n1 W
[+ m. g- P0 k+ S/ r& E
  speed     ;; the speed of the turtle: E* K8 t; ?9 a5 \
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
+ d: W- e4 W; g; m$ m* M  wait-time ;; the amount of time since the last time a turtle has moved5 n. s8 g8 q5 n/ A6 r3 q" j' N
]
$ t2 C% f  U1 u+ \5 E2 Z* X& J2 ~
. s0 c* ^- e' [  `: Z* G3 n0 \4 k& spatches-own
0 x% U" |) M. L$ l! V7 Q[. s. ]2 B2 s1 a& [8 f
  intersection?   ;; true if the patch is at the intersection of two roads
( q4 ^8 C+ `8 p+ A. c; z  [  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- ]1 y: T* V: B1 k
                  ;; false for a non-intersection patches.% u# @) X' J8 C! l& v0 ~1 V! p. A
  my-row          ;; the row of the intersection counting from the upper left corner of the
( d! e' P4 {0 B" k" E9 k& C* w                  ;; world.  -1 for non-intersection patches.
" H  g# n- [& l4 ~! ~& {8 D  my-column       ;; the column of the intersection counting from the upper left corner of the6 Q) j: i  k2 F) l
                  ;; world.  -1 for non-intersection patches.
! e9 X8 `# }: a( U- F( }3 ~) A  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.! J7 X/ z. k1 w% U0 E$ t" h. T
  auto?           ;; whether or not this intersection will switch automatically.
3 y/ _4 I8 ^7 K  \% N& d( ?8 z                  ;; false for non-intersection patches.
/ ^, v/ u* ^7 X' l1 ~7 L]! N) Z( \; K7 X/ u: [  g2 |

  ?% u9 j7 I$ z/ [* U' W: X$ S, l! K2 ^; o% ~# b$ F) o3 w
;;;;;;;;;;;;;;;;;;;;;;
4 x+ Y6 E* D4 u2 V;; Setup Procedures ;;8 r; s2 I5 @1 V* K  Q% t8 U
;;;;;;;;;;;;;;;;;;;;;;. {2 R8 D- W+ P! E9 b/ d
9 ?( j5 D  \7 c' R. y/ a9 o& h
;; Initialize the display by giving the global and patch variables initial values.7 H8 r1 `) g" s
;; Create num-cars of turtles if there are enough road patches for one turtle to
, N: W7 `" Y( }$ k" Y3 A;; be created per road patch. Set up the plots.+ {1 W0 s! t: V' J
to setup" M5 Y! x4 @% ~$ v
  ca
0 `* J" U/ X; K/ W  setup-globals
( o  Q: j1 z8 P* Q& ^) Q
# c& i+ t6 O  D9 P* E5 M  ;; First we ask the patches to draw themselves and set up a few variables
( k% q0 C0 w7 l4 J& K+ m  setup-patches1 w$ y$ n6 p/ m  v! Z
  make-current one-of intersections
! u6 P; K# v0 n8 z  label-current! u# k( Q, w( B5 V' ?

- ^1 Z: y( V% ?& I9 j  set-default-shape turtles "car"
9 I" A" ^9 o% _9 H% |! u( h
2 d: o6 y, s/ l4 w2 U  if (num-cars > count roads)
: s  U7 y# ?+ |3 c( Z" m! l' D# Z" B  [
; }& R) Y  @( u' A    user-message (word "There are too many cars for the amount of "
+ o: l9 D7 _/ [! v' n                       "road.  Either increase the amount of roads "
5 h4 ?2 v' d- @0 n; Q6 e6 T% b                       "by increasing the GRID-SIZE-X or "
" Z. k5 W( ?# F. Q- Q8 F# w4 y# O                       "GRID-SIZE-Y sliders, or decrease the "% M# p$ _4 N) a% i# R
                       "number of cars by lowering the NUMBER slider.\n"
7 u9 D8 M" G$ i8 l                       "The setup has stopped.")
; G8 ~9 M9 m- e& v9 u6 M- ~+ R    stop
+ Y$ M. b6 |( c' N1 \# {/ o; q  r8 ^8 g  ]- C. c3 ]) O! d1 j# `& D1 C  O

2 I# R+ k6 f( H  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color# ~- ~4 \  Y8 R5 P# a
  crt num-cars
& ?' R# x( o  C: h" f; A  [2 L3 f* @) }( A& B* d; b7 O
    setup-cars% e/ F. M0 V3 X
    set-car-color- x$ Q4 B8 N! t9 _) y* a! ]
    record-data2 q4 K5 n" r' d9 S3 k
  ]3 {1 n: Z8 z1 ?! j5 ?3 W

6 x7 S0 I% N) Z/ F  ;; give the turtles an initial speed$ p' F9 i/ G, ?  ]2 t
  ask turtles [ set-car-speed ]# \" G. R0 [, ~8 E) f

- M- D. H7 i4 H9 W0 v2 T& t  reset-ticks
% N; ?4 O6 S" O2 Tend
8 q8 _4 C; s  q4 Y5 Z' o; h/ n/ J8 D" `
;; Initialize the global variables to appropriate values1 K( S% ]( i" x* M, ]$ t7 ~2 i4 T
to setup-globals/ S/ c8 Q" i/ q
  set current-light nobody ;; just for now, since there are no lights yet) K' K1 z) Z9 o) w$ Z! l0 F  j
  set phase 00 w2 L) z9 }5 C0 ]
  set num-cars-stopped 0
/ A5 A, |5 }" x9 a& V$ H, k  set grid-x-inc world-width / grid-size-x
, E2 p1 ~) M% n# t. q) \  set grid-y-inc world-height / grid-size-y6 \; E* H! O9 @( i# v  ]

7 i/ ]9 I* `7 `- a2 W' [+ P. o( C  a  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary+ q$ i# h% q: c# F& k5 ?  x& k
  set acceleration 0.099+ ^2 ?7 t; J; U9 g/ C: C
end; K$ R* P  Q$ \3 G  Z) U
4 q, Y8 n; }& U+ T
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
+ j' {7 F' v/ K8 D  R. Z  \0 Y;; and initialize the traffic lights to one setting; a9 s, A2 n# {6 m, C
to setup-patches, r" p' Z) @2 p. I0 ?& O: ?+ g
  ;; initialize the patch-owned variables and color the patches to a base-color  H* N* S6 x; ^) M# t7 H4 v
  ask patches+ M) C1 A% w: [9 v0 O9 Q
  [: e9 E1 B, F% ^: K1 O  y" e
    set intersection? false) Y2 d+ X& }: k8 x
    set auto? false
0 I! Y, m  A8 c5 U0 D7 x* x, w    set green-light-up? true6 s& J; ^* r0 P1 P  I
    set my-row -1
$ W! u* d/ c: p$ g    set my-column -14 A' X0 K8 y" _1 Z2 v. ^9 o( e
    set my-phase -1
3 J9 P  d: n3 U: y- j8 H0 U    set pcolor brown + 3; C- g0 V7 Q; B$ \6 C+ k
  ]
! M9 k+ F/ i: x6 C, m, m0 Z- ?/ f! U9 M. q, F  D
  ;; initialize the global variables that hold patch agentsets
) _0 v1 l( ]" r& ^* f5 A  set roads patches with4 c# A# B! A5 Y, R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( \/ d, O7 u. M) @9 L    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" ]. a5 n$ m+ G; t; O5 y  set intersections roads with
$ C. f/ G7 Z3 v# X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and* Y8 X! H/ B9 E* v+ v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( Q( i! i2 m9 K. b  z' {

% V+ U2 E+ x. z8 h7 G, W/ J2 H9 H# ~  ask roads [ set pcolor white ]6 r# ^2 v. c5 y- g7 ]
    setup-intersections
4 b4 d+ w! f, R. j( Rend9 i/ O) P" u( ]
其中定义道路的句子,如下所示,是什么意思啊?
6 G1 H5 _+ y/ O& S6 C set roads patches with' K# w  O4 z) n; l3 D& k& q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 y' f5 Z: g$ C2 G, a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: v$ W. x& [, X! _& i
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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