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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。
" J- \2 Q% l# z' e7 Nnetlogo自带的social science--traffic grid这一例子当中,  d1 P  q5 ^* k$ b9 F
globals
/ q& O5 L0 T# G8 N! h[2 Z, i8 c( U! O
  grid-x-inc               ;; the amount of patches in between two roads in the x direction% a7 \7 E! u: O( X
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 x. {. I) |  x, J) I$ F# t. Y  acceleration             ;; the constant that controls how much a car speeds up or slows down by if& D' V- F3 T. w$ W$ y# C
                           ;; it is to accelerate or decelerate- E* g1 }' J' z( ?( h6 x
  phase                    ;; keeps track of the phase+ G0 h2 Z( G$ s6 K" G! x4 `, f
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
' f$ U! y, J) j# j) o% E) f# a  current-light            ;; the currently selected light' S6 a$ _% T! i& B5 v, F
' c! ~; n! r. j4 k
  ;; patch agentsets
: r. R6 x3 `) Y: J7 S+ m- W( {  intersections ;; agentset containing the patches that are intersections
" c' r. u. _  r: A  roads         ;; agentset containing the patches that are roads
: t) X% `6 E8 P% z% l  v5 T. Y; }2 `9 {]
  j' g* ?% y1 h0 q2 |8 V' z3 O$ n; `0 z7 w+ f
turtles-own; \0 K9 c: K/ i; `3 J' `7 s& L( T
[' i% {9 O7 P: g$ h
  speed     ;; the speed of the turtle. N8 @  S0 X$ M! D- v3 b6 ]$ S! G
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right+ ~. C' p, f  y) q% @- ?
  wait-time ;; the amount of time since the last time a turtle has moved5 Z4 x- R" p) ?! ~8 I- o
]& q9 z! D4 X2 u# a3 C6 b

; ^+ k5 P  p- E6 u: h6 O; |0 Tpatches-own
7 _6 u1 P0 `! i) ?3 V) h[- K6 V  Q4 R$ u/ C3 Z! b9 ?
  intersection?   ;; true if the patch is at the intersection of two roads) Z# X( z. B! u$ s8 \- O6 E
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 |7 C; x6 }# f/ k* z2 w8 O, u                  ;; false for a non-intersection patches.
: |( u7 a  W# r0 n& O# M5 r5 y" Z  my-row          ;; the row of the intersection counting from the upper left corner of the
) e5 a! o# _3 A" L                  ;; world.  -1 for non-intersection patches.; i' `5 t( b9 L
  my-column       ;; the column of the intersection counting from the upper left corner of the
* S( [( @! T  b( N/ T                  ;; world.  -1 for non-intersection patches.
- u$ B4 {" ~# I1 X5 V8 d. T8 m! ?  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.% J* f- H4 l- M4 Z, J, K
  auto?           ;; whether or not this intersection will switch automatically.2 }5 A7 W7 w/ b
                  ;; false for non-intersection patches.$ r9 S/ g& J# @1 d0 }
]: X3 g) m$ y( }
# T9 J6 D7 E+ [7 ~5 W. U

; n8 ^" Q+ w) D( ?2 ?8 J;;;;;;;;;;;;;;;;;;;;;;
, Z0 R2 p+ O% g;; Setup Procedures ;;
) c3 [( D3 O' N; e+ v;;;;;;;;;;;;;;;;;;;;;;
. R( A4 D! ^# t( V  Z1 M4 C) y- r+ _! I( |/ h
;; Initialize the display by giving the global and patch variables initial values.
: N( U) W" k$ U1 n# ]2 v;; Create num-cars of turtles if there are enough road patches for one turtle to& ^* [: I  ^8 a  W
;; be created per road patch. Set up the plots.
3 x! A2 ?4 e5 pto setup- Y- r- S! o, h- p2 U" b
  ca
$ Z/ }* b" h& M) p3 x& q# F9 B7 [  setup-globals9 q: W+ n$ p& ]& m" N

, M! Q9 Z& a4 p6 D  ;; First we ask the patches to draw themselves and set up a few variables
, Y* _- V- t, C4 Q  setup-patches, P0 O2 i& w/ z- n; V
  make-current one-of intersections
* a9 t1 f3 p) d" y) _  label-current% Q6 ^" Y8 n1 |9 ]* f' [
  m6 u& |: }$ ~1 J! c5 T6 z5 t
  set-default-shape turtles "car"
  i9 T" h! S) @. \' T9 N+ h6 f# y2 f* ?1 B
  if (num-cars > count roads)1 O+ {2 ]8 F, W( s8 o! g$ s
  [& E, B8 o) n! [
    user-message (word "There are too many cars for the amount of "0 s/ t( W0 u% {- M# I
                       "road.  Either increase the amount of roads "5 Q" y5 Y; ~5 l8 x( j& k
                       "by increasing the GRID-SIZE-X or "
, p8 f4 a8 T' l8 ?# [' K                       "GRID-SIZE-Y sliders, or decrease the "( X8 ~$ N" |) T/ E( k
                       "number of cars by lowering the NUMBER slider.\n"$ ?( b6 ~% Y/ Y% O
                       "The setup has stopped.")$ Y6 D+ |& O/ z, h+ m; Z
    stop
8 V' Q  G8 w% L* A! ^( [* Y! |# P3 _  ]
8 k7 O2 d6 ]6 s, |# W0 C! I  h
1 [$ |& r$ K9 E, ?3 k5 C  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
& m+ p% t+ Y: |( Z4 e+ T  crt num-cars  n5 Z2 t; @& p2 P0 A$ N- ?
  [
+ k; o! g3 l8 M3 p    setup-cars
1 m2 S: ^) c9 `( F; p    set-car-color
, F+ p" V- z0 N    record-data- K) p* i! F0 c1 z9 P& c
  ]
! J/ N% V9 k1 a! R, ], N) ^
9 o; d# I  \  t  h  P7 @* L/ z  ;; give the turtles an initial speed
3 H1 R* I& \1 y* N5 T  ask turtles [ set-car-speed ]5 l. {6 ]3 i2 P5 N) J% O. R

( b' ~! J' L& R% F7 e  reset-ticks* a  `1 A, `! x% B0 ^" `3 U& i. D/ _9 _
end
7 A: z1 R( k1 ~6 S: C; k$ w+ F* Y. D0 U0 w4 }! \. t+ T
;; Initialize the global variables to appropriate values7 p) T7 Z0 @6 v9 m9 o" b6 \
to setup-globals
# Y& ^2 }! L- j  set current-light nobody ;; just for now, since there are no lights yet
+ F9 C' @5 D) }. Q! t0 @+ _& [  set phase 0
- j$ W  n" m( ]+ J; b! S" u  set num-cars-stopped 0
* P7 {$ @. H9 P8 e5 f  set grid-x-inc world-width / grid-size-x2 z9 H0 }  \: S1 @6 ?/ K
  set grid-y-inc world-height / grid-size-y$ a; w9 r3 g/ I1 I
3 Z$ h2 a+ L6 B8 M) {/ l
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
3 ^+ k( S; P" \1 n9 _  K( c  set acceleration 0.0999 w- A# a( W7 D) }# ~- \
end
$ N% k4 g6 N4 M2 y1 D* ~' H- J0 f% K- h1 D% e- s
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,' }# R* c" M3 u- r1 N
;; and initialize the traffic lights to one setting
$ C; o. J4 h( o6 q& g% C! \to setup-patches
% E6 ?( U1 M1 S" t  ;; initialize the patch-owned variables and color the patches to a base-color" G; M% E4 i* }8 }' X
  ask patches/ z5 t# o6 d8 W8 H& ^
  [4 A% M( Y" K+ x! s
    set intersection? false
3 ]' Z* G9 V# F2 v4 V* n    set auto? false) [/ Z) u6 z' c* k8 d/ Q
    set green-light-up? true3 D" i% }7 L4 _9 W: l$ f, ]! A6 E9 z
    set my-row -1
* J8 r( L8 f+ K8 v( ^; `    set my-column -12 J) W+ I( P6 K2 Q) c% h* O2 K
    set my-phase -18 D  @+ J% l* z6 p
    set pcolor brown + 3
$ R! q! u: e" E% G) \. W. Z& N  ]
7 C) p' A1 ]# y, G9 B9 x. W0 [$ q7 m9 E0 Q
  ;; initialize the global variables that hold patch agentsets
+ [! P6 c6 R" N' a) [  set roads patches with
- S: L  f" V* s2 h( S3 f( s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* K1 W  P9 d! `( C! L& w
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* h* ]6 s/ @1 F" y% p& O
  set intersections roads with
% u, r/ K" b9 W8 y% c! i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and1 n0 n5 |' a) ~( T% ^* @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  t: f, v0 w8 V; d% f

$ S  Y, U; Z5 K' O: M' H! y' V  ask roads [ set pcolor white ]
; q9 ?' J% M" d9 j, I* W    setup-intersections# ^5 Y% B9 L* g8 Z' V
end/ t) o2 f; m" g% R4 N
其中定义道路的句子,如下所示,是什么意思啊?3 E& f- m: O4 L# |6 e
set roads patches with. D0 w: c( n6 w( @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 w. P6 Y2 L7 J$ t5 }
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ e  f8 ]9 S! r' F1 M1 q$ m' A
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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