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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。
! Q. B" c8 Q; Z) F1 ?3 R4 R( Dnetlogo自带的social science--traffic grid这一例子当中,) k- f/ u8 x4 t' H" Z  A1 N
globals. X" h' J. `, X
[
( K0 c- s' ~* V* z( B  grid-x-inc               ;; the amount of patches in between two roads in the x direction
0 H5 p. M$ f4 B" ]4 ]  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ Y- G: h4 F5 d& N5 X' n1 D
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
! s1 \" ~, a: j  h1 D" ]; ~+ k( D* u7 v                           ;; it is to accelerate or decelerate
2 u) @1 B# p1 `& O  s0 a! n  phase                    ;; keeps track of the phase: e) j4 K7 n: w0 O% C4 b5 G# U
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure5 @6 d0 ?/ d( v4 f
  current-light            ;; the currently selected light& c; X# B8 f! n7 u, @: x" ~2 ]1 w. A) U

$ B0 [, R" M& f: _3 k; Q) H" N  ;; patch agentsets. A( h+ V! l, w7 l+ D. E& T
  intersections ;; agentset containing the patches that are intersections" f: Z6 X6 \3 o' W8 I
  roads         ;; agentset containing the patches that are roads
! e& S2 x3 W) l]
( k# e) J- e& X
! X0 r  `7 W* X9 J3 z7 n4 j7 y, Nturtles-own
2 e! M9 y9 @& ^- Q5 x& ^2 A[
2 a+ A7 _0 @8 y2 H' v  speed     ;; the speed of the turtle
# L. c' j' [9 a9 g" T  up-car?   ;; true if the turtle moves downwards and false if it moves to the right! a( _, w- g* `8 A# Z! {+ S
  wait-time ;; the amount of time since the last time a turtle has moved( [; Z7 `: ^$ Y1 O& A" Q& s3 [% [
]( a0 y3 @" l% f# d! x5 Z3 k
6 e: F* c2 @$ j2 N2 y1 V4 D% e( q. s7 z' u
patches-own
6 h# g( @- D1 y' n( l4 ~5 z# g[
1 g0 m3 d! U# k! T. D& n0 w  intersection?   ;; true if the patch is at the intersection of two roads
  o7 V& D! z- K) t/ e. E. H* G  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
, s* g5 ]/ E4 L1 l/ B                  ;; false for a non-intersection patches.
) d* t0 u8 ]5 O" v; U. y  my-row          ;; the row of the intersection counting from the upper left corner of the
! R8 y+ H1 @, A& p- ^                  ;; world.  -1 for non-intersection patches.
7 i6 e: J- R, d% {" u0 y% `9 `  my-column       ;; the column of the intersection counting from the upper left corner of the7 h$ k$ \. p3 \: v  F6 e! h
                  ;; world.  -1 for non-intersection patches.
0 @! D' b- l7 m2 f  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
3 ]& d/ M- r- j  auto?           ;; whether or not this intersection will switch automatically.& D: a+ c% v* A. X9 }# `2 g
                  ;; false for non-intersection patches.
- f' i. k; l6 t5 v: M; F9 D0 b$ K]
; M5 ^; _* T6 r7 Q' k+ x: t6 [$ Y0 B. h$ y
+ X; t5 G- j4 x, P# ^+ c& Y8 @
;;;;;;;;;;;;;;;;;;;;;;
3 i: W  t; K: _" c;; Setup Procedures ;;! g2 q# N( a3 x9 W
;;;;;;;;;;;;;;;;;;;;;;/ i* O+ e& d: H' W3 L+ _

5 [0 j2 N+ Z+ f4 d, }1 @;; Initialize the display by giving the global and patch variables initial values., `# h: t( c4 z$ S1 t, {  j
;; Create num-cars of turtles if there are enough road patches for one turtle to
! D: a# }7 \( t$ e3 }' _" C;; be created per road patch. Set up the plots.
3 y4 B% O& g) P3 e2 {$ G# @3 vto setup# H2 ^; i* |/ N( s
  ca" T2 M8 q1 |2 R& n; n% x
  setup-globals( o1 y3 f1 c2 c. v6 H+ k2 m
' w& l- _1 |: V2 [4 `$ u
  ;; First we ask the patches to draw themselves and set up a few variables9 j3 {+ Q0 q* o; N! a1 d: P" n' \+ }# W
  setup-patches/ u' a; n7 l) s
  make-current one-of intersections
* }% Z2 R6 v5 i, ^, r' S" C  label-current; h1 O* v1 B( M$ q& `- E

; w" i% W- q6 e4 c+ `  set-default-shape turtles "car"
; l, X& q* l. @8 ^* w- M
; r& S  R$ M" X9 I5 G( h  if (num-cars > count roads). s+ L5 ]5 B! s1 ^' I/ G
  [) x% \6 W! ?2 o! j* V8 L
    user-message (word "There are too many cars for the amount of "
, f3 Z: J$ [  f8 o" k) o6 Y                       "road.  Either increase the amount of roads "7 C9 z' s" U+ p' y0 d$ h" y; ]
                       "by increasing the GRID-SIZE-X or "
" F9 D5 q. K0 @  R' c4 _& p                       "GRID-SIZE-Y sliders, or decrease the "- j% O% f6 B/ y1 E: U( i# o/ J4 Z& r& l
                       "number of cars by lowering the NUMBER slider.\n"' d- B8 \& j9 S  p4 @3 H3 p# a
                       "The setup has stopped.")+ J( L9 O+ g! V# h+ u3 f
    stop5 L: Z0 s, a, C* S
  ]. n: F0 L5 w. D* F5 m# r
) g$ {' K3 b- m6 |
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
9 K0 K9 t6 Y8 v  a+ A5 @  crt num-cars
2 R0 ^0 b7 G9 M. H8 o" f4 [  [! L5 Q% t* W7 R9 _0 A" `, C
    setup-cars% f# n1 p& Z$ g& u+ n$ E) r3 d. I% q  n
    set-car-color" _4 I1 k6 V2 Z, u( o' U4 G
    record-data  R; m: x3 w4 j
  ]
0 d; I9 l! S) o* U# N+ S& d0 M* ?' H0 U& I
  ;; give the turtles an initial speed  J( E0 U  T5 U9 u
  ask turtles [ set-car-speed ]
) b, a8 _8 d* |/ S. b
7 S; S9 ~6 s8 G: R- p  reset-ticks! t) c; ~/ H0 h' d; o0 C" l7 S- u
end
5 S" d4 e& ]5 d( x+ d& K9 n. k9 _$ P- B" i( Y
;; Initialize the global variables to appropriate values
* M* @- h, [2 F# d0 S8 ?to setup-globals5 ], B! e% ?" r- T. Z+ G5 a5 N' G! j3 s
  set current-light nobody ;; just for now, since there are no lights yet
: i, X8 P) a8 B/ \! m6 R  set phase 03 e( A: @8 \* z. g/ v. _+ p
  set num-cars-stopped 09 M; s- u: u3 D) V
  set grid-x-inc world-width / grid-size-x
: A, j1 B% }  T3 X: q5 o  set grid-y-inc world-height / grid-size-y
1 ~8 j; i# G3 V' `6 M7 z+ j3 W' t
% d: C% k" W- d$ ?  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
3 W: `1 m4 n0 z1 B9 o! T7 M. j  set acceleration 0.099
3 A& K+ s, i/ p7 Iend
- V. r% L* y, ]6 u% O1 O! [" s
  v! R5 @7 P0 x. u4 G% e2 S# t;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
4 f4 t/ h" D0 e, e6 H& b3 N: x;; and initialize the traffic lights to one setting4 a3 h& P+ d: T- U7 \+ ~0 x
to setup-patches
) t* Z; `+ j0 ]3 K, D, n# c# `  ;; initialize the patch-owned variables and color the patches to a base-color8 Q* C' P- v7 d% s8 ~
  ask patches1 T( I5 n( e  ]3 f& J9 m% y
  [, Z$ o# I7 j& N0 C
    set intersection? false
+ K* ~. l$ b' `; Y- E    set auto? false
8 k9 K. P3 k8 u7 D- o    set green-light-up? true
1 [# b# y* T' ^    set my-row -15 Z: B8 ?/ v7 b% l' f/ P5 ?
    set my-column -1, L. @1 B! I+ {) a/ q. Q4 e& L
    set my-phase -1
, o/ S  L# H- O2 B* }+ l! G    set pcolor brown + 39 ~7 a# }3 B/ C1 s9 F
  ]0 a9 w* r+ j( T+ P$ H/ ^; _/ \

$ q" W+ P# d4 S  ;; initialize the global variables that hold patch agentsets% G; g3 l3 }' ~
  set roads patches with
+ a+ B0 Q( D5 \9 h8 h: v- @, \    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 T) J7 X7 E4 |/ ]0 q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( m; [% q- f) Z
  set intersections roads with' U8 z) x4 w4 N3 _4 D
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and, J" Q4 R' t/ h" s$ `5 |7 N9 v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 B1 |$ h# H* G% Q3 O; U4 ^7 {8 W: c1 z
  ask roads [ set pcolor white ]/ c& J" P2 B/ h( g! ^8 k" b& n4 }
    setup-intersections
1 K6 x4 T7 j) l7 i- x3 w  lend
0 O3 f( _. q. k: S7 ]其中定义道路的句子,如下所示,是什么意思啊?/ h2 {7 L) @* @  Q- O) e+ w
set roads patches with3 {- `! Y) [5 d" J) ?% n9 K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! ^6 {/ y- h! X( ^- V; ]9 J
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) ~9 C! t  y* C+ p! O6 j& P
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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