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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。$ g1 i& O6 P6 v  |2 H& _
netlogo自带的social science--traffic grid这一例子当中,
" K  R0 ^) o6 p5 `6 Wglobals
$ q' w/ M# C, F1 H+ `; q5 s, e" O[
* M2 j' S; {+ q6 r  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, G, g. V4 m4 Y1 T! Q3 Q  grid-y-inc               ;; the amount of patches in between two roads in the y direction5 }! c/ \& @: n3 A
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if; }( r; ?0 k: K+ v- B6 w
                           ;; it is to accelerate or decelerate
! i& w, ?) D0 i- j1 W( [  phase                    ;; keeps track of the phase
& U) E3 e7 V- s/ \! n! b  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ P3 l! M- Z' [; C. Y  current-light            ;; the currently selected light
3 J8 I5 u& n3 E! a
; W% k4 i- h* e" b6 o4 k  ;; patch agentsets7 f- _+ k5 ^* j. c5 [) R
  intersections ;; agentset containing the patches that are intersections% ^& f- o+ C3 c" }9 z/ s/ {
  roads         ;; agentset containing the patches that are roads+ @7 Q' Q) J( H/ ]
]/ @- E. S$ B7 t5 c1 b2 l: z

5 w9 ]1 @& A+ ?) yturtles-own
& `- B. k. L% @3 ?. R9 {$ G[& M& x$ r' G' G3 v8 z' E% S
  speed     ;; the speed of the turtle% t/ _) M9 ^0 A$ b% }) z
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
6 M$ d9 e; Q! G0 l  wait-time ;; the amount of time since the last time a turtle has moved
$ V! E3 p" t4 K3 }+ a]3 v/ J) \; g+ R- O

. i6 ^( O5 [# O: @patches-own3 d1 d6 R9 {) E) j; p+ _
[( e( i7 m" e1 i; a+ ^) o: ^- M
  intersection?   ;; true if the patch is at the intersection of two roads# M/ \! F0 n6 }/ X* V
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( O$ W- f1 b6 a4 D; x                  ;; false for a non-intersection patches.
( A% G) i* D; q, L0 e+ t* t  my-row          ;; the row of the intersection counting from the upper left corner of the, s$ j0 p' G1 Q" O0 M. s! j  g
                  ;; world.  -1 for non-intersection patches.
: W) |2 j' Q* X5 J5 C& l  my-column       ;; the column of the intersection counting from the upper left corner of the0 m. ?- o9 P$ x- c7 t
                  ;; world.  -1 for non-intersection patches.0 R  m) `# N% A$ Y/ s
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.6 E9 b; ^: k( s/ z* W* p
  auto?           ;; whether or not this intersection will switch automatically.# C- U( _5 a. O) k# [
                  ;; false for non-intersection patches.' O( h, G1 d/ h1 s
]7 q2 _( c0 ?# X6 \
/ ^" T( A6 i, g; w" F! E1 X3 I" [
+ a9 S: B: y7 d% _8 U3 u
;;;;;;;;;;;;;;;;;;;;;;: t  V+ H+ b  d3 d) ^4 M$ x
;; Setup Procedures ;;
" c1 b- x. E+ \4 n: b;;;;;;;;;;;;;;;;;;;;;;& Z5 p3 f" s) W3 U5 [4 b% s- p1 n
/ y0 m2 x/ p0 e* J" e( A) |
;; Initialize the display by giving the global and patch variables initial values." q, W4 ^& [* I/ ]" x9 k; G9 M
;; Create num-cars of turtles if there are enough road patches for one turtle to  O! T# Y  u9 S) N" v* z4 z
;; be created per road patch. Set up the plots.
, `6 ]  f" O/ h; J/ h2 ]/ Hto setup( {# F3 T2 [# ~4 [$ S) K
  ca: b, h4 t9 }4 g, z  m( N
  setup-globals
7 @" W: D# p2 t
/ p3 R7 ^8 }3 E. P' _% I$ o  ;; First we ask the patches to draw themselves and set up a few variables
0 S2 M$ [' @( R& Y$ k3 _) u( \  setup-patches
4 x: Q0 d% }1 ]5 |2 G9 W9 d7 l7 p6 A  make-current one-of intersections
6 c. t3 x* Z6 T. E8 c$ O) @  label-current
8 q6 Y7 }# z/ S- M8 h  f9 R! [6 Z$ @8 `# {' P: [
  set-default-shape turtles "car"
: N" ~6 Y# _8 c  N4 t+ ^- \; t4 v+ b0 \# Q5 [2 \
  if (num-cars > count roads)4 `' u: u7 T% W$ R9 r, @) W! J
  [
. {2 z, o9 ]) @! K    user-message (word "There are too many cars for the amount of "' P1 M4 H* b  g' e  @0 S
                       "road.  Either increase the amount of roads "
2 ]+ S' h" C- J& t+ T- u5 N                       "by increasing the GRID-SIZE-X or ": y8 C3 X- b, Y8 w! u! e& q. \' t
                       "GRID-SIZE-Y sliders, or decrease the ", o6 s0 |1 ~: X* B
                       "number of cars by lowering the NUMBER slider.\n"& ?3 D$ u1 ]6 H  V! K, `2 b( ~8 e: K
                       "The setup has stopped.")
3 A' u( K" B8 R- g7 i    stop
9 ]# ^+ R0 I$ x3 Z6 C  ]
0 J, @: ]/ a3 y; J( S
8 Y3 i$ p1 I3 l  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color, w  U2 s" i/ w5 s6 G8 V
  crt num-cars
" V) S3 d" L3 u3 M+ z. P  [0 N% X9 t4 e6 f. F  C
    setup-cars
, T' V. a+ ]- M  i2 [2 N    set-car-color
" V3 W# q, n& Y- O    record-data
  F6 A/ y) V( ]" t4 ~  ]& P- M. f3 Y# o8 Q) K+ v4 n, B2 a) [

! H" E: w3 t& b5 ^) f  ;; give the turtles an initial speed6 t0 `6 Y6 s$ [' c, @- g
  ask turtles [ set-car-speed ]. @7 k2 e( t5 z0 a- d4 @

- ^6 K# ?9 h4 S2 X3 s1 G1 B  reset-ticks6 N' j( L. ^9 ]* k
end/ v5 E7 R9 R7 f3 u% E* }& {2 q
- }4 w, S, X7 I( Y# T
;; Initialize the global variables to appropriate values
' y- G- N2 F0 {* D3 _( W/ z4 Ito setup-globals
) B; J! q: Q5 t2 o  set current-light nobody ;; just for now, since there are no lights yet
" d7 V0 e- o) X  set phase 0# Y: s: E3 r1 y0 d& @
  set num-cars-stopped 0( a1 g0 H' Y& W" Y
  set grid-x-inc world-width / grid-size-x
$ p. \4 O7 k  x7 d8 K  set grid-y-inc world-height / grid-size-y) M! s) ^2 p- W- j1 K' _  \
4 \8 T* A7 ^1 K& n. [* m7 C
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) v$ O$ J7 C( O& d/ W3 |
  set acceleration 0.099
# O7 j& G# Y/ |" I* M( r7 ~1 \end
* t4 y( x& U- o0 w" m9 ?7 C( G5 E4 B9 s
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
) r! r- `+ z3 H( x;; and initialize the traffic lights to one setting
' v% u( M5 I! ~4 Fto setup-patches& Q6 U. |+ }  l; C# Q" k
  ;; initialize the patch-owned variables and color the patches to a base-color& e! m$ |: g0 F' R  `% n8 b
  ask patches2 [9 D0 X* W8 H7 Z5 @) b3 h1 Y! A
  [
, `' B1 F$ v- g    set intersection? false' f& y0 O6 T, O7 G
    set auto? false; l$ _( ]( c  P; S
    set green-light-up? true# x! Q, j% O7 C* P+ Y9 E
    set my-row -1
4 Q2 p! n1 |8 D- o0 D8 |4 M    set my-column -1% e2 c$ G( }7 b- w. }
    set my-phase -1
8 P/ b# K  ~) R: A    set pcolor brown + 31 R6 u% U3 h' k: T$ O
  ]
4 R' u6 W) X# F5 ~
5 U# t, j; Y* D/ |  ;; initialize the global variables that hold patch agentsets' a: ]3 B$ f2 x
  set roads patches with4 E7 ?& Z  g2 W# |% a7 N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 l! F- W5 c1 ]( Z! p0 k    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. G) L6 J6 v9 Y/ D$ V
  set intersections roads with
" x4 F) q* w+ F  A    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 g; W5 u  R! |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! G5 |. B4 p. {- b1 Z0 V
: X5 {# o6 E% b: ^( f5 \
  ask roads [ set pcolor white ]
) }# t. A% h5 s& B4 |' r  q    setup-intersections6 i) Q8 ~. s7 X- p! s! q9 x$ z6 j
end
6 O2 V9 l9 [! y5 @, e其中定义道路的句子,如下所示,是什么意思啊?& ^6 d/ [9 t) a6 \
set roads patches with1 ^  u+ H1 R, |/ r
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" t7 M# @2 M& n2 j1 a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 ?( ]. H- ~, 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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