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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。
4 [! J4 t1 C% }" ]8 i3 Dnetlogo自带的social science--traffic grid这一例子当中,
+ M# h, X$ h) ^, U) _- Y' P5 U4 Kglobals4 W0 k/ \. Z& i6 \, Z9 z8 n
[
4 ]. G! Y. p' V" n. J8 I  grid-x-inc               ;; the amount of patches in between two roads in the x direction
* k7 @" S/ p! V0 _9 d  grid-y-inc               ;; the amount of patches in between two roads in the y direction5 z" I: z) D0 |2 l. N
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if: V% i" M0 P; d8 w4 z, F
                           ;; it is to accelerate or decelerate: ]" b8 ^' H' z, J" x  a* N6 L+ h
  phase                    ;; keeps track of the phase
5 N* \. M% S$ F1 c0 u5 h8 n  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure& Q" A; T- K9 k" d  h: f
  current-light            ;; the currently selected light
# H- f* y8 g: }0 Z: U6 x; i  B$ Z% w/ ]& Y" D( `7 R
  ;; patch agentsets
" J' i2 Z5 Z' A) _/ Y  intersections ;; agentset containing the patches that are intersections
- o: c+ b1 w6 N- K" r& O8 w: w  roads         ;; agentset containing the patches that are roads+ ?& ~" S, i( e1 M5 H# J: T
]7 B0 x4 X% @( V) L  `- g5 t
+ l% a3 {& Q$ u7 N6 I
turtles-own
9 d; J1 \, r! s/ ][
4 x) k1 P, u, p) V2 w4 E" w  speed     ;; the speed of the turtle
3 a% B3 E3 j" _7 n, B  up-car?   ;; true if the turtle moves downwards and false if it moves to the right+ {+ P. P! u9 _. n
  wait-time ;; the amount of time since the last time a turtle has moved
# o* T% q$ M  V! g; o' K]
7 }' W$ q" Q. D# }6 Q' O+ S, n; h$ l
patches-own
$ [, K2 u; |! K[( i" l. }: K: W- _
  intersection?   ;; true if the patch is at the intersection of two roads3 J& L2 ~3 i: _9 `& Z- [' [3 C( ]
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
) E/ \. c% @5 P9 W' v2 Y                  ;; false for a non-intersection patches.% |' ~$ n1 t- P, U7 p; W! |# x" _5 a
  my-row          ;; the row of the intersection counting from the upper left corner of the
3 g+ T9 j$ j5 K! i0 O6 r2 v                  ;; world.  -1 for non-intersection patches.% [; p: C- Z$ t0 O
  my-column       ;; the column of the intersection counting from the upper left corner of the
% T% ]- m# m( ?( d; K/ m                  ;; world.  -1 for non-intersection patches.
3 C( m, |* O0 @" J/ v: g  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# D0 j3 @; Y- N8 r4 _- T% U
  auto?           ;; whether or not this intersection will switch automatically.
+ N1 u. b4 @/ l' E- \' H  D                  ;; false for non-intersection patches.
; _1 F, w7 {6 Z  g; S]
9 x7 R1 V! y6 h* @. ?" L: V
6 z5 F$ W: O0 X4 l
1 C& k1 Y) B8 F;;;;;;;;;;;;;;;;;;;;;;& U3 M& L! G; Z. a4 S* D) r
;; Setup Procedures ;;
% H' p* g+ O  n* S( Q9 F6 p;;;;;;;;;;;;;;;;;;;;;;
) l  {1 J4 P( L/ q1 k
6 b& x- I* l: e. d( `;; Initialize the display by giving the global and patch variables initial values.
$ C& L+ H5 B& t% ^;; Create num-cars of turtles if there are enough road patches for one turtle to  B* ^  ?+ t8 A) c, G
;; be created per road patch. Set up the plots.
9 v1 K7 `, d5 ]to setup
* @+ @: y- D$ Z$ E  ca
/ L/ }$ \: _1 k) J0 `  setup-globals
/ Q1 \7 Y% d+ T8 q( Q2 N; w  L( _
  ;; First we ask the patches to draw themselves and set up a few variables
2 _3 d$ f. m+ n+ q/ n4 r  setup-patches2 u1 T" n* J, l9 Y$ m8 ]; n8 q
  make-current one-of intersections8 P" p: O$ B& e+ n( t, K
  label-current) J: y; w+ b1 I) X6 `( O; n

5 g# b% s: Z5 d( w0 U' x  set-default-shape turtles "car"* z8 w7 g& d6 Y: U

5 p, D/ p, P) @3 D" n  if (num-cars > count roads)
& ]  N% }+ z- G+ g$ G6 V  [' Z+ s: j) ~  s8 J+ v  u1 l
    user-message (word "There are too many cars for the amount of "
4 T; A. P; v6 l" _" F  L: J                       "road.  Either increase the amount of roads "
; ]/ z7 n# ~* U8 y. P                       "by increasing the GRID-SIZE-X or "7 S/ W, i& Y; Y% j5 |6 A
                       "GRID-SIZE-Y sliders, or decrease the "
4 @. y1 ?. M- l                       "number of cars by lowering the NUMBER slider.\n"
& H1 G, g  p! ^: i" [! J! }                       "The setup has stopped.")
2 r2 X) E1 b$ T4 h" |9 K8 m    stop' E6 h6 P: S1 X' [4 H' ?( j
  ]
$ B3 Q+ D. o+ i1 d1 W  ~+ [! }. l9 V) }7 R: y$ q0 D2 Y
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color& v6 F3 e. u$ T2 g- u3 ?0 Y! j
  crt num-cars
3 i8 Q) p, Y& P. I  [
. J( ^5 @3 J/ ?. \' r  w    setup-cars
. T& n9 T1 D, l    set-car-color# |, h. S! y3 d+ C2 j+ n9 P
    record-data
+ M: H: e: d$ {2 {  ]
1 b7 H, `; j) V1 c
( r1 a/ A9 H! z/ v  ;; give the turtles an initial speed
2 r* U4 y2 E' V  ask turtles [ set-car-speed ]
/ j4 J% @; n- {5 V' b( v7 k
. Y# p; H+ O' c& i$ w+ e4 z- a  reset-ticks
$ a8 j( I0 x0 O! l8 nend) J. A& C  c" e( q6 [
3 j. K1 \7 k! J+ d
;; Initialize the global variables to appropriate values  z5 e/ S& l/ [/ V5 b# m4 H# v
to setup-globals* ~; O$ F! T* R' H# |& x/ ~, k
  set current-light nobody ;; just for now, since there are no lights yet/ D( A2 H1 B. t  w
  set phase 04 J. m& n) O2 I  ?; Y
  set num-cars-stopped 0
1 U# h, c- F! ^* E% U& ~2 T  set grid-x-inc world-width / grid-size-x
! C% Q; U" q) l4 J$ T  set grid-y-inc world-height / grid-size-y
0 s" v7 c( M6 P" S0 J
2 f# r+ V- r+ q6 e+ L0 r  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
* ?) @. C7 F: H8 X  set acceleration 0.099
4 A2 s+ ~% w2 D  tend
: n9 S" E6 ]8 x3 {- G4 D& R) O8 B4 x8 x" ?% T' \8 c
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,% z: B' c6 K) \' b6 n
;; and initialize the traffic lights to one setting
2 E9 @0 M0 h! x5 g" pto setup-patches
' m% X; v* r& r  ;; initialize the patch-owned variables and color the patches to a base-color
' M! J! F0 O/ `  ask patches8 d; m1 R+ f  ]
  [
$ Y& o0 e: l+ Z0 y    set intersection? false* X0 n* ~$ S' y1 B
    set auto? false
; l/ H2 O) _% B+ m( j    set green-light-up? true
/ T, J1 x. u& g6 g9 _( L    set my-row -1! V4 _) f5 ]4 P  h
    set my-column -1% Y; e$ w+ E$ a+ Q, _7 ]' [7 v# X
    set my-phase -1
; N3 U9 D. q1 ?* z. P/ ?    set pcolor brown + 3- X: q: Q  S* _6 O4 T
  ]
4 I4 b2 F* B! ~8 s
4 i8 a8 q" i9 t& I; W( D' I" e( o# E  ;; initialize the global variables that hold patch agentsets
5 q  F" g: s8 Q2 g4 X1 ]& p( N  set roads patches with
+ B6 |' v% F& U# X% D$ x1 s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( Y/ y* Y' L) K1 s0 |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 b$ ?2 o* ^3 f; I3 P
  set intersections roads with$ q0 X4 O! [. t! W/ ?
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and5 u, y* A) k+ S
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' I) e9 H1 p+ O9 e- ~  m& R) W! E
  ask roads [ set pcolor white ]( e) W& F% o( x& `! N; M* i
    setup-intersections
. S5 ^$ K7 Y/ a4 }" H8 I1 d, Bend
* S& C4 E5 d# G; v' z其中定义道路的句子,如下所示,是什么意思啊?- d& d6 G. k* Z( J* ~- U
set roads patches with2 z  V" [1 o. d: c+ _8 ~
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* [# j4 w- x) D3 i" K, x    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, o+ S8 B! t2 P7 {, @- ?( m; h5 }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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