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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。2 f& M' Y' \  K4 X. _
netlogo自带的social science--traffic grid这一例子当中,
) f1 i3 }/ K9 J7 o% M) ?! X* Tglobals
6 B  X* T! F  I% q8 {[
5 V: D! [. I: u6 T1 `8 a1 W  grid-x-inc               ;; the amount of patches in between two roads in the x direction
: F. [4 O. J: _6 W# h  grid-y-inc               ;; the amount of patches in between two roads in the y direction
% |7 u0 I7 h4 j4 ]  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
% n; k: B0 s( c8 q                           ;; it is to accelerate or decelerate6 x0 d1 F  A  T) a
  phase                    ;; keeps track of the phase
& P) T- C! p4 z  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 A+ t  G) X1 m  ^7 @
  current-light            ;; the currently selected light
3 R2 W$ ^& y5 [4 @$ n+ h6 e8 B) X% v5 B$ C0 X4 R
  ;; patch agentsets
/ G3 A4 E1 p. e  f3 p3 n% P  intersections ;; agentset containing the patches that are intersections
5 ~- X* t4 u- m$ o& o  roads         ;; agentset containing the patches that are roads9 f8 q+ e( W) r, ?5 c8 H
]. K+ G5 a; v& ]4 P$ X

) {) {5 Q& L' e: T) p  T4 Uturtles-own7 j8 R% J3 p4 D2 U0 [" t; O! ]
[& ~/ ]- N, M+ t
  speed     ;; the speed of the turtle; N1 e7 ]- z8 ?+ K, N
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
. x% t. h1 N) i) R+ t: |3 _) Z  wait-time ;; the amount of time since the last time a turtle has moved
; H, v! _& k  _8 x9 k0 B8 L  f]
9 S6 t0 Z3 a/ a" r, T, g, `. s! \+ N( ~+ N) E1 A# f  C
patches-own
8 a% a' ~2 Y0 ~1 n9 k% H+ b, I[
% q  K9 F8 |# ?  intersection?   ;; true if the patch is at the intersection of two roads2 D/ G/ Q" V& a! i" y0 V
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
: G; M6 @/ K. U3 I5 L; b" X                  ;; false for a non-intersection patches.
" `+ s% j# o" X9 D& y/ l  my-row          ;; the row of the intersection counting from the upper left corner of the! Q, j+ J" F* I! ^: R  n
                  ;; world.  -1 for non-intersection patches.
7 C* j$ t+ N" J$ L  my-column       ;; the column of the intersection counting from the upper left corner of the
  w4 O! v! [8 b                  ;; world.  -1 for non-intersection patches.
2 B& k, ]) `+ ?; U  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.: J. Y- u# l; T2 `5 s
  auto?           ;; whether or not this intersection will switch automatically.
8 o+ _9 V2 Q: l( a                  ;; false for non-intersection patches.6 }* X' v: g3 F- C1 }$ I, t+ k3 D" A
]) o& ^! u+ w4 ^# W0 O
, Z0 f2 z6 N: n+ {$ E% e6 g' m
4 u* Q" w/ s& ]8 z2 [0 i+ d
;;;;;;;;;;;;;;;;;;;;;;
5 x% f+ B4 s; _. d: O8 ~+ W2 n;; Setup Procedures ;;% k3 t7 K! ]* t9 K
;;;;;;;;;;;;;;;;;;;;;;8 F. U  d8 L, z2 s, X* |

' Q- }: M3 L0 g/ v! W;; Initialize the display by giving the global and patch variables initial values." ]; _% o& T3 S5 \2 {
;; Create num-cars of turtles if there are enough road patches for one turtle to' u, ?9 A) F7 ]2 B0 [
;; be created per road patch. Set up the plots.
4 h& p: e% B6 z8 S6 v" Zto setup+ \5 Z/ `3 u) B$ N
  ca
& o# Y8 C2 n, @3 f2 k  G  setup-globals4 ^$ o$ r; K" @7 x8 Q/ i; F* U

6 @, X& h0 m; Z! N) t  ;; First we ask the patches to draw themselves and set up a few variables
+ H1 Z1 t; M! `( |7 k  setup-patches" U; H3 s) _  Z* x. f% d
  make-current one-of intersections% M5 k! g  C9 J  c
  label-current4 F% _7 M- d3 N0 P5 J. G1 u" x3 u

9 n3 ]1 h* C" _" p- h  set-default-shape turtles "car"$ a  h! c' C. ]- |* \9 w$ i: n3 K/ S) P
% l0 [+ e  }3 e8 U( q3 q1 f
  if (num-cars > count roads)6 J; ?: j9 ]. O& A" ?( m, V8 L
  [& |, a1 [2 O. S3 w
    user-message (word "There are too many cars for the amount of "& r- f4 @+ ]0 ?$ h" G
                       "road.  Either increase the amount of roads "$ s0 o. r5 X( W6 u
                       "by increasing the GRID-SIZE-X or "
1 t. u0 Q  ~2 V& A; N- w# L                       "GRID-SIZE-Y sliders, or decrease the "0 s+ v  C" D, z! a; @# I
                       "number of cars by lowering the NUMBER slider.\n"% p3 M2 {$ f- q+ t$ r" j
                       "The setup has stopped.")1 }) d0 H4 D) Q+ U
    stop5 U& \4 c% n) p6 D% O
  ]
" Q/ S8 M' i: d% F( O0 m
$ d0 a( Z0 g$ y/ c4 M; t  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color+ t" h) K: R$ u6 O5 y. h! ]
  crt num-cars
- j6 l/ d7 X  @  \" b! y4 I2 T  [# U' S- v' D/ w7 N" A" v
    setup-cars
% I4 H+ o; E- X, b) E    set-car-color) z9 l' N7 m9 h0 ?+ k
    record-data. m6 q* z. V" S  A5 r8 `
  ]! h1 B' N7 M1 ~+ I
6 v. ~" w# b/ h% P# H
  ;; give the turtles an initial speed
; A- r+ x  Q! p2 y  A  ask turtles [ set-car-speed ]
) T8 h4 |2 A0 E. y9 _& ?! w2 f1 o0 c2 U8 n$ _  h
  reset-ticks
  D6 \; e2 e9 ?5 T2 ]1 P4 ~end
# g2 [" W: ^% C: S# O
# I; H3 N! F6 E( q# |;; Initialize the global variables to appropriate values
( ^  n* e) }3 i& d$ ~0 V$ ?, S0 nto setup-globals
) G  S: {6 C9 q: |( ^+ b  set current-light nobody ;; just for now, since there are no lights yet
$ g  m9 |+ b5 e2 ?  set phase 0
: j2 r0 j) }7 f; D5 D1 \5 r  set num-cars-stopped 06 Y% a# ]3 Y* H- P7 y, f$ o! U1 E
  set grid-x-inc world-width / grid-size-x
( K5 W2 |& A4 v- g* E  set grid-y-inc world-height / grid-size-y
9 X( b5 k+ s& f( R
. ?  c" `2 n$ t. q9 A3 E  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary* r, S7 R1 K4 t! F; E8 C7 Z
  set acceleration 0.099
5 _# u& C; O1 ^! j9 D9 i$ n0 ^& dend+ q+ F) s" Q1 I4 [8 h
" I! Y2 }* y9 _, @: N- H$ @* i
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,8 P0 S+ [! Z! V1 C
;; and initialize the traffic lights to one setting% i/ s( \, y! c: n, Y5 b) ?
to setup-patches
% g$ g4 }1 X9 ^1 g. Q- A  ;; initialize the patch-owned variables and color the patches to a base-color2 D% C. y; c1 F8 Z
  ask patches5 ^- q5 S( o2 ]
  [
- d( K7 J: X7 g  @9 {" f& I    set intersection? false7 x% q$ Z3 `  @. d# i
    set auto? false' O  |, X5 S2 p" ^
    set green-light-up? true
! I; O/ R) r( j# w4 i$ I3 R9 K8 k    set my-row -1$ j& i4 H3 ~2 h& d7 f
    set my-column -1+ Z6 V; M  H* e! v
    set my-phase -1
) _- D* L- c. E    set pcolor brown + 3
) |5 T8 z, u6 X+ h- D; \  ]0 H7 R6 L! M+ N9 v! t
9 b! N( s+ N. P5 c( v9 n
  ;; initialize the global variables that hold patch agentsets
5 e) m0 q, A  d9 y* o- i  set roads patches with
, h% x  |; O* Y' n% J) b- m5 q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 y; e# q* W& G$ n3 u1 q; \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. n5 V# v! t  n6 E! I% f  set intersections roads with: |9 d- [3 \) b. e
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and: P( ?5 g/ R5 K) ]% c( |& f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ E( o* O, l0 k* g8 I9 I1 ]/ b3 v% a! t8 `& Q$ v
  ask roads [ set pcolor white ]/ @5 K4 L; g3 j% M& h; h
    setup-intersections- T% e' l7 `$ z6 T" f" t9 a
end
. o. Z9 w8 E" k, w: y* F其中定义道路的句子,如下所示,是什么意思啊?
- z$ ~+ I1 x6 i# M. n set roads patches with& Y$ F' d: p% L, Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 b" b# q& u- w# ~! `" K  R
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ u/ c$ |5 v( b6 W% Q. B- F
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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