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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。
. T) g0 E: F5 H8 t. Xnetlogo自带的social science--traffic grid这一例子当中,
% _1 D4 w' {# L. b* v& Mglobals
& N5 H6 }) x5 l! [[& D- R; ^+ k4 r2 ?1 m' j$ O
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
2 d$ A2 n! z* e: x, J% z) E  grid-y-inc               ;; the amount of patches in between two roads in the y direction
8 }$ Y9 V9 }2 f! x- G8 q9 H3 d  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
1 D3 q  J" M/ A) n" m, j  Y                           ;; it is to accelerate or decelerate  T4 N$ [0 D* Z) w6 g7 P
  phase                    ;; keeps track of the phase
  Z, ~* W- B7 v( L  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; D) s2 J0 e4 e( r: Z( j+ O  current-light            ;; the currently selected light
4 O4 V7 ^3 V$ ?, Q3 X& T+ M1 q8 X8 }; Z* @+ ~. y0 @5 B# B
  ;; patch agentsets; ^4 @  w$ ~9 ~2 A! \% w" `
  intersections ;; agentset containing the patches that are intersections
$ R) x8 h$ M1 r4 @  x  roads         ;; agentset containing the patches that are roads3 R, n9 C; j, b7 H- l1 b/ O
]
) H3 t+ O1 Z+ G2 A/ A) a/ b* n' M: Y" x& L: e( q
turtles-own
  d: a7 v6 [- ^' R0 q) P[
& D: d  ~; {% |4 s: E  speed     ;; the speed of the turtle9 h( ?' `. |, E. \' A2 F
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, a; [8 E' P: U2 V0 W  O* g1 S
  wait-time ;; the amount of time since the last time a turtle has moved
5 }  W% S) I& p5 m]5 i6 x; @# R6 u5 [8 {, Q5 t. Y
5 Q  j  R% i, X( x
patches-own& N# T7 g2 g! [& J/ l6 _. l9 S
[: X- |5 }9 e( I3 m' a: y& W' I
  intersection?   ;; true if the patch is at the intersection of two roads
; `  e3 M8 f. N" `  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- r! m# h7 T3 K. n: [
                  ;; false for a non-intersection patches.8 T0 T2 @+ E( L* G
  my-row          ;; the row of the intersection counting from the upper left corner of the' b/ b) R  C! K; q# I5 ]: z! @5 v
                  ;; world.  -1 for non-intersection patches.! P  D- u+ `# P- f
  my-column       ;; the column of the intersection counting from the upper left corner of the$ h) M( t( T0 z- i9 o6 V( \
                  ;; world.  -1 for non-intersection patches.
$ D! B9 K3 |7 a& [# M9 {7 u; N  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( z' X! V, x0 V1 t& o) |. R  auto?           ;; whether or not this intersection will switch automatically.
( s; ~$ T" ?( M7 |& ]7 i& O                  ;; false for non-intersection patches.5 [2 N3 s1 {& S" Y* j# @& v- l
]; g3 }: c% S0 j! C

0 M, s/ j1 V! \/ l
- D* v4 W7 N2 o' D;;;;;;;;;;;;;;;;;;;;;;
: l$ l2 j3 L8 L' H1 O;; Setup Procedures ;;% T! v* F% X8 Z# K1 j
;;;;;;;;;;;;;;;;;;;;;;& e5 I5 X8 g( ?

' |% Y6 I+ o; |6 w% h8 U;; Initialize the display by giving the global and patch variables initial values., s+ M9 r0 e- x$ U0 D0 e2 v
;; Create num-cars of turtles if there are enough road patches for one turtle to
2 T$ `7 M  m* Q- L7 {! s- W. X;; be created per road patch. Set up the plots./ w3 ~- J- i) o# }6 B/ d
to setup! ~& w' Y0 u$ v, u# P$ P
  ca8 P0 B- _0 b. @7 T) I# K4 e: S
  setup-globals. x! _9 A2 C/ I, Z
/ @& T" a1 R, y. P
  ;; First we ask the patches to draw themselves and set up a few variables
% D, X( H- ?( H7 A0 }' E3 q  setup-patches* k+ C+ e9 i1 O& p8 |
  make-current one-of intersections
7 x. M+ J6 C7 m+ X& a$ p) \5 r  label-current
6 o  u5 Q8 u2 t8 S" }! G, ]4 O" A2 y: N+ P: g$ L. m# k
  set-default-shape turtles "car"1 E5 P& g8 h1 |/ k0 f

4 ^+ |- W2 Z5 A/ Q& [) S' e, c  if (num-cars > count roads)) P7 Y1 I; ]( |) P' M6 g
  [5 N6 e5 q$ d+ |6 d! G5 I6 O' k) q/ h* W  p
    user-message (word "There are too many cars for the amount of ": K! o: }+ W$ p( V# S; @  E& S
                       "road.  Either increase the amount of roads "; \; L* U0 _3 F* e8 D
                       "by increasing the GRID-SIZE-X or "' u0 T8 `1 `8 B2 n4 Q4 n1 L
                       "GRID-SIZE-Y sliders, or decrease the "# [; {! O9 B9 a% |- m
                       "number of cars by lowering the NUMBER slider.\n"
) D+ U7 x, I9 ]. d# b: {$ W/ K2 b                       "The setup has stopped.")
# A3 J: k# D/ L$ l5 P! S    stop
- r# R2 l3 K0 y& Z. {' ^6 a, \  ]3 T& B. g1 u, c8 _: ^/ T( h5 T, f

4 A; A/ P7 S: X/ b. K. h) Z  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color' o" P& |- b6 J1 ~/ w/ l/ I
  crt num-cars  N: @* q+ e" u: H6 o2 W8 i0 s! L
  [7 g0 v& y' b' [( x: A
    setup-cars2 m: D. d" M( t1 c5 K
    set-car-color
8 N4 O( [. |% t; d    record-data
  a/ [; V! Y$ c+ ?/ D0 b2 K/ B  ]
* P. o" f5 L  \7 c& U: q. l5 ?2 T# c  F
  ;; give the turtles an initial speed
9 k& G9 z- r* ]1 K$ o* d  ask turtles [ set-car-speed ]: Y( |0 S* i4 O  n. v
- E3 R% m4 F7 a+ y( c
  reset-ticks
) o' b' i0 w' D. n3 D% Y% d5 `8 qend
2 W- q& E! Q, j$ t/ D
+ x( Y0 s, y# x;; Initialize the global variables to appropriate values
- U' `/ [7 n6 uto setup-globals
) p) N$ C7 w( T* d8 t/ D2 p( H4 A5 Y  set current-light nobody ;; just for now, since there are no lights yet
. e/ G. h% _. h( c7 d* L8 G) g  set phase 0
" [% d) f! M! V" g0 q  S  set num-cars-stopped 0
9 F) \$ n7 K2 _; H( F9 {  set grid-x-inc world-width / grid-size-x& d; O* Z( `! J4 M
  set grid-y-inc world-height / grid-size-y
( ^# f: R# N. Z6 ]- x7 @8 w' A/ z* ^2 B2 h; N# U5 m
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary( b' N1 B: }- y
  set acceleration 0.099
9 B7 X2 a8 O! o& V. L. ~$ Aend
* r, w% n& f' [: H, j6 I* v8 S9 ?1 K
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
, q2 G  Y' b- L1 w  o- V;; and initialize the traffic lights to one setting
0 K; j* G0 U! u; O1 Rto setup-patches
- w: T0 l+ j: T  ;; initialize the patch-owned variables and color the patches to a base-color+ ?6 i4 s4 y2 W2 K+ u
  ask patches
* I* n  W: `* I* b  [, Y$ g! b- t' e  T
    set intersection? false% }1 s) P/ n7 H& L# B
    set auto? false5 Q" ?& @- o4 E$ U* s: |6 x4 j2 ?
    set green-light-up? true1 g1 _. E$ g: ?
    set my-row -1
( \- L" Z3 `/ W  |% a# V    set my-column -1& l) @3 x: D( d: u: }( ?
    set my-phase -1
! O# P' `/ F  r0 ~8 i    set pcolor brown + 3
& }$ x: c0 |4 @0 F1 h1 T  m: b  ], F% |/ X2 D$ h$ C. U

( w4 Z. @6 V& `# k, }; O: K  ;; initialize the global variables that hold patch agentsets
0 p: B1 l2 w) L# i' v  set roads patches with
+ D1 r7 R" B) V4 |0 Q) X+ o; b. d# T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# t. N. E6 z+ A5 g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ z! d9 {+ }2 q6 Q5 e# W  set intersections roads with
7 h! X6 y. s) N. E" L& }    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and5 K6 H9 B. I5 K' }
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& m3 s  W7 q5 J4 R9 t) Q/ y$ _% X! f' D
0 i# Q. g: n, `% P. Q" ~  ask roads [ set pcolor white ]
  P8 U$ H9 F3 c- |+ s2 ^    setup-intersections
. Z6 d# x+ C# J2 o9 C, Iend% D8 G  I, c8 {. O
其中定义道路的句子,如下所示,是什么意思啊?6 p4 c) h1 @) R) z+ B, ]) Y
set roads patches with
) r! S/ e0 G6 v# I: @5 F: C    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, v$ c# U2 B, Y$ E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 O- W3 J& ^* N3 Z3 U; G" A4 C! ?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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