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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。
; _$ d& q* j- P, U7 K9 pnetlogo自带的social science--traffic grid这一例子当中," c3 j0 j9 `1 h8 s: Z( X& k4 i
globals2 F  @4 a& Q, ~# H" D, K
[
$ A4 y7 v. H! Y+ T3 Z5 T; \  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 y, ~$ m- W! [
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 F7 K* x; t6 ]  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, H/ s; l' i; z8 W                           ;; it is to accelerate or decelerate
7 R. r0 r3 R0 Z1 M6 t  phase                    ;; keeps track of the phase
6 W& T( a, g4 `6 x  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 q* p& g" \! G" }( v" O% O
  current-light            ;; the currently selected light8 H4 T" @2 S5 z
- j6 X0 ^! o1 D
  ;; patch agentsets' l7 T7 J3 r! J; L
  intersections ;; agentset containing the patches that are intersections# D6 x7 x* J/ Q7 [$ l, P$ o* F
  roads         ;; agentset containing the patches that are roads5 E8 g: \/ v* P8 ]$ \, l" a
]
% T7 P0 z) Q) H1 }) S. Q3 f+ \  h
turtles-own
! x; P3 l% h2 }0 E/ ~9 V! c( F[, }* g* O9 r9 o8 u) q4 [
  speed     ;; the speed of the turtle0 Z$ o/ h4 s5 G2 V- E% o
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
( ~& M! ]$ m6 w2 N  wait-time ;; the amount of time since the last time a turtle has moved
. V$ M3 \- N3 G! P2 l2 E5 n3 ~]
: X- ^7 i% ^# A4 i8 N8 w! G
9 p9 j; j& a0 _( Q9 Npatches-own
* b) t) a7 }' L[% h5 b' }1 ]% ^1 H8 E
  intersection?   ;; true if the patch is at the intersection of two roads0 g1 c2 M1 N' p
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.( G1 z$ J1 u+ l' M
                  ;; false for a non-intersection patches.
, Q4 B* m- L/ N  my-row          ;; the row of the intersection counting from the upper left corner of the
$ q3 x2 U. Y. F5 H( p9 n- u                  ;; world.  -1 for non-intersection patches.2 a( |# y" d' t. U
  my-column       ;; the column of the intersection counting from the upper left corner of the$ Y. r, M! n# V8 S
                  ;; world.  -1 for non-intersection patches., a- k/ G. |( J. I: ^
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.7 M; H. q" s( M& \9 x
  auto?           ;; whether or not this intersection will switch automatically./ m/ l1 ^8 ?$ B0 d4 Q* Z1 J
                  ;; false for non-intersection patches.4 r1 R- B7 y. U9 u
]* I* h8 d% d( t0 c- `+ v/ C

; M+ A: W* b" b4 E0 Z
0 n( A$ C8 U2 U" A6 f# E- C2 };;;;;;;;;;;;;;;;;;;;;;
! z: P" c! |3 O% @4 i;; Setup Procedures ;;
: D* d& C1 O  u' [& m4 k;;;;;;;;;;;;;;;;;;;;;;$ s& d1 T  _* J& g' g  Y
* \8 s. e/ Z+ E( k5 Z- F
;; Initialize the display by giving the global and patch variables initial values.: a1 f) `: ]1 s* ~7 `; H% j- ~
;; Create num-cars of turtles if there are enough road patches for one turtle to
9 G/ p# }' w; ^* ]. J) `;; be created per road patch. Set up the plots.
2 x1 n1 _6 s. f: V( Oto setup
% C4 C2 ^% w/ e/ O/ B+ Y0 ?: _  ca
7 l! i! R& ]4 W( m7 I' o  setup-globals
2 w% E* Z; r% c  |- K8 V5 q; i% \% q7 t9 z9 Q
  ;; First we ask the patches to draw themselves and set up a few variables  u1 E! [% G! b; u$ K
  setup-patches" {! f7 y0 k, H  o! V$ W; o
  make-current one-of intersections
' f  d, p4 [4 o, P4 J3 r' d  label-current- G3 L% \9 `! s  W: W6 T' K
3 B# R7 O5 d% V
  set-default-shape turtles "car"
5 l7 Y9 G4 t( ^) n
8 }: y9 \* t/ p- ^+ ^) T- j, W  if (num-cars > count roads)
3 n; N# a+ m' E2 G8 V4 \  [
  j8 z8 E* b0 N+ P    user-message (word "There are too many cars for the amount of "
" e& q' K) `' y+ h* v# a                       "road.  Either increase the amount of roads "
2 m. ]$ b. \) O  e2 h                       "by increasing the GRID-SIZE-X or "5 N6 B/ _% l3 U% ~% m8 u5 I
                       "GRID-SIZE-Y sliders, or decrease the "2 y' t6 Z4 y. x* Y# V
                       "number of cars by lowering the NUMBER slider.\n"
7 s; D& ?; U9 z2 H                       "The setup has stopped.")
! k/ V( h/ p- f- H3 q# A1 @, m    stop
$ \, P9 w8 Y' A  ]# f3 N6 {. ~) |" m" n* ?
8 A1 Q/ e  X( Q+ L, C
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
1 k9 i' o6 H7 N( V$ a/ g5 b  crt num-cars
0 u, A1 Y: ]9 ^5 M  [
* G  m9 T; g4 @0 X" x/ u" K    setup-cars
# }, p  A$ |  x. x  [; R    set-car-color
6 n$ L* H% o# y. f+ W    record-data& X, \8 W" r5 i; R! _' I) n
  ]: E, ?# N1 e) c# }2 u# I
& \6 h7 l4 G3 w& J& k; L
  ;; give the turtles an initial speed9 P' i+ {# R, w/ g( z" M9 A) F
  ask turtles [ set-car-speed ]1 m; y5 v5 W9 |% ~
# d' W/ F% U0 H0 H$ R
  reset-ticks
5 j2 }; K2 H5 J; B; w% x% i0 B5 s2 Hend
) x8 d- }! D% [" O  h, D4 E) B9 Z/ I# }. a
;; Initialize the global variables to appropriate values" M3 t; f- k( F. t3 |; J9 v
to setup-globals. F$ }& ^, m7 ^1 W$ |8 }
  set current-light nobody ;; just for now, since there are no lights yet
/ F2 s; `. V0 q6 ]9 I  {  set phase 0: w6 l# ~0 e; u* }
  set num-cars-stopped 0
7 m$ g) F1 ~# l# i$ g  set grid-x-inc world-width / grid-size-x
: k0 c; [) d! r& N' J; u  set grid-y-inc world-height / grid-size-y
# q! g# B$ T6 s* S& o' }+ P) F( S/ N! k2 t4 n' Y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary8 S) R8 k+ R5 T- `' e1 Q7 W$ q
  set acceleration 0.099; W% [6 V+ ?$ L7 ]# P8 n
end* g( X5 E# C0 D# |
9 S" B9 F8 ?6 v" ^
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
- p, w: ?6 P5 N8 {;; and initialize the traffic lights to one setting
4 g+ W' s0 W& e% U  u. k( eto setup-patches
% N6 v$ `) q+ h4 l  ;; initialize the patch-owned variables and color the patches to a base-color2 F: `0 O6 O  M+ B
  ask patches2 r& [% _3 J; d2 ~
  [) @* _" B- ~( l; F5 W0 @+ T. x
    set intersection? false3 V8 l1 l# n6 s" m9 L1 n" ]& V
    set auto? false
/ ^) T4 v5 Z+ T9 h$ I4 v    set green-light-up? true
! C/ b/ u: N2 C' a3 o9 [    set my-row -1$ [, O" L) Y9 p3 z( z: H, e! I; v
    set my-column -1/ Z: I& M- ]# A4 D) d3 Q# }/ B$ F
    set my-phase -1- c! D" n' h5 F- ^  s
    set pcolor brown + 3# v3 |* @2 }- |1 Z( Y/ e; ^
  ]$ n$ f8 F$ q: D4 ?

" e9 T5 l! [5 ^$ g- Q: S  ;; initialize the global variables that hold patch agentsets! A6 B% G/ I9 H: E
  set roads patches with7 x, D/ t" m& U4 K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ O2 ?( p* w0 f$ v; r4 [- B0 r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( O2 P- H, o, R5 q# @  set intersections roads with
( Y5 r0 d' r$ n* g# P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
0 ^1 c9 ~7 W/ J& C6 V    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( e7 L9 V$ _/ Z8 j% q* _0 k
; J# Y  [) y) h% j. B1 x8 ?  ask roads [ set pcolor white ]( Y+ K3 R0 m8 z) l; X
    setup-intersections
% h: f7 B: k0 g$ |end
+ o) a" `# Q3 `/ V! M. |4 e  B; R2 c其中定义道路的句子,如下所示,是什么意思啊?
- ~! ?% A2 W# H/ O set roads patches with
2 X4 n! J0 Y2 ]2 G; V5 X" v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 S8 U6 a3 Z) ?  U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# Z( K8 G/ S1 b' H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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