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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。8 Y; |2 j( y0 A7 F# ^- n' j
netlogo自带的social science--traffic grid这一例子当中,
8 b; N8 p: m4 e. I3 n5 Z; ]" Qglobals- H+ L" u3 p1 s  j
[
6 ]& j/ C8 q3 P5 \4 R! \  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. S+ D8 T% `5 Z! H3 A, N0 ~, u  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) \- |7 O" ^: ?6 n  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 g7 p% s* g9 o+ Z- o                           ;; it is to accelerate or decelerate
/ t/ M. T) O6 q7 [5 A0 y# C3 j  phase                    ;; keeps track of the phase+ G; x/ @" J  ?
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure9 t2 {0 L, E. w+ }- t
  current-light            ;; the currently selected light
; X- W$ R) E; x6 k0 n' Q7 L
% }! e: \" A, A6 t  ;; patch agentsets% T$ c$ C8 E" g  b2 O8 D/ T, w6 Q
  intersections ;; agentset containing the patches that are intersections
5 D, c; s, E7 ]5 P  roads         ;; agentset containing the patches that are roads
4 _% u: T' j5 |3 x: C]
# `( ~* {# l# `' f
4 I0 e2 c9 Z% s9 u. ^, ?) dturtles-own
/ q" M/ d3 O) {  Q[
5 Q* [5 {' u6 p1 w) Y8 C  speed     ;; the speed of the turtle
1 b, Y/ h" ]8 m3 p# o  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
4 O% N( l& z, F4 {# _  wait-time ;; the amount of time since the last time a turtle has moved! u- ~! V: \2 e$ Y' U
]
+ w- ]  ^+ k5 q+ [0 q; J) R1 Z; e* c' Q5 l5 y- a# f
patches-own5 Y( X* n0 ?3 q6 s- M
[
, L. b3 ?% {7 T( Y3 D( \1 J  intersection?   ;; true if the patch is at the intersection of two roads2 S: m, B* u+ L5 p
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
5 ^$ Y2 W3 H1 a/ S, m  x6 I                  ;; false for a non-intersection patches.
# t* \, p2 h& b6 Z! r' E# Y  my-row          ;; the row of the intersection counting from the upper left corner of the
7 J( z8 m6 M0 ?& S7 n' n                  ;; world.  -1 for non-intersection patches.% w# k; z$ {; t% q, L  a
  my-column       ;; the column of the intersection counting from the upper left corner of the1 R5 O( [$ [6 r0 z3 C) d4 A3 Y
                  ;; world.  -1 for non-intersection patches.
- @. G& S  T1 u8 o. r+ E/ `  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.2 N+ g# }; @3 a4 U# j2 R
  auto?           ;; whether or not this intersection will switch automatically.
& x0 O- B3 J, S' O- r  {) K4 I                  ;; false for non-intersection patches./ x2 `) s5 V, o- X9 i- I( `  L% N- M
]
+ s8 y: [7 T7 M5 Z0 x* _5 u/ d- `# R  R$ Z9 P+ `$ ?+ x1 \

4 x/ I! F$ S: i/ w# D- a;;;;;;;;;;;;;;;;;;;;;;
! S* ?- P% c, c8 t% d( y  C;; Setup Procedures ;;  `$ |1 G3 n2 |
;;;;;;;;;;;;;;;;;;;;;;6 _$ E& h! R& E# Q' G& g) g; Z& F- D% ]

" f/ M) E/ u) u- f1 o: j;; Initialize the display by giving the global and patch variables initial values.. ?8 i: t3 I+ e/ p* _: d
;; Create num-cars of turtles if there are enough road patches for one turtle to# j8 w9 L8 J5 A5 L" {5 b- P( g
;; be created per road patch. Set up the plots.
( A6 o5 ~* @; b# {. zto setup+ U/ j  q  B+ c! _' d$ n8 f
  ca) Q0 F. ?% ~5 y/ j: o7 T
  setup-globals4 [! R4 Q, f- |" m4 T: N2 ?
% w. u# \2 z) S  |% S3 J$ u
  ;; First we ask the patches to draw themselves and set up a few variables
5 ]( b5 t1 v- {7 [- z- ]$ J  setup-patches
  k5 Q+ K; L: t( r4 |2 A1 S  make-current one-of intersections3 q; D% `! }6 D. z
  label-current$ [7 w! t  j, ?% F* Z
$ x: ]) E9 T1 [$ m& S, S
  set-default-shape turtles "car"
9 B5 k2 w  g8 A" g7 c4 R7 ~0 U- X0 Q8 h5 Q
  if (num-cars > count roads)
3 v  A7 O) u% h9 |* K  [* O' l( ]; ]9 A% E! t
    user-message (word "There are too many cars for the amount of "" Y. I% N( F4 P6 Y1 o+ |
                       "road.  Either increase the amount of roads "
7 B# t- e' f. D$ H( Y                       "by increasing the GRID-SIZE-X or "5 _. @! ?/ c. N  N1 P
                       "GRID-SIZE-Y sliders, or decrease the "
) C8 K4 k; j, j8 C* U! ?# D! R                       "number of cars by lowering the NUMBER slider.\n": J6 m9 b5 S" }( T
                       "The setup has stopped.")
% `) Y9 |) F5 d0 z1 S0 F0 W5 X    stop0 f& E* a; D. b) A, Z7 T
  ]
) R9 i' f" [9 t
4 p! {% Z7 _, W  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color# a) j. S/ J; w: F; G5 w
  crt num-cars" q9 M  K2 I# `& t( k
  [' G3 {2 x. N+ B  _9 e. r
    setup-cars
* s' d; Q+ |) x2 A: o0 C    set-car-color' Y4 w9 `) O! r; `% D& x0 G- k
    record-data
) `' j0 K# }, I& s% v  ]- A- ~# _# b! R( O- V
7 N2 U0 P. @: I- g* a
  ;; give the turtles an initial speed' Y8 E* {9 v2 I' m
  ask turtles [ set-car-speed ]
, Q% l* H  p4 m3 ?- ?: B
2 y( @  J+ \) F. W/ n) n  reset-ticks$ x6 h$ y! L; g! Y
end8 Q- d! O' M3 R$ o* a

9 F; x+ ?4 o* E; J4 t;; Initialize the global variables to appropriate values
$ l- P$ U7 W: C1 f$ z( C1 [to setup-globals
. A' p" x1 K* D; T. b" w( U1 W  set current-light nobody ;; just for now, since there are no lights yet9 c( a: x/ q4 T
  set phase 09 \% @! @9 ?: s: U4 i& V
  set num-cars-stopped 0
" `- M4 M& F" Z/ J  Z  set grid-x-inc world-width / grid-size-x
1 |" p/ I7 c  B5 n6 f5 I  set grid-y-inc world-height / grid-size-y+ Q' C7 m$ E5 |9 Y
2 r5 h7 N0 Y6 [! W5 `5 ~
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary6 d, a0 I3 Q/ a+ c- @) {
  set acceleration 0.0994 R4 n+ f  i6 b2 x! v/ b
end
6 S# [. P1 g5 N& L3 C- m( r) r  w0 E, ?( J: s$ v$ l& S2 @
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 P6 y0 M7 q# A$ v. O;; and initialize the traffic lights to one setting
$ q# X% q3 P2 \+ zto setup-patches- X9 y) w5 _9 R1 ?3 Q2 Q
  ;; initialize the patch-owned variables and color the patches to a base-color" ^2 {/ J6 R  Z# D
  ask patches
7 r5 n8 d  O; |8 Z6 f3 a: m  [+ h( p4 j" Q7 z- _4 v# T
    set intersection? false" M. x: G, M& D( X% p; X
    set auto? false9 k/ P: g7 v) F  H" F2 H0 _
    set green-light-up? true5 J$ p6 L% B! u, e3 s# K
    set my-row -1
. }+ n5 b/ w7 Y5 |9 u2 n    set my-column -1
6 |$ G4 c" e0 i    set my-phase -1" @( {9 T4 W) N& r; a  j
    set pcolor brown + 3% \) ?8 Y( r* [) v
  ]
6 H, |! l" y" T, N# U0 e' i) T, q, a6 Z; g0 C
  ;; initialize the global variables that hold patch agentsets& H, F3 t. G% p7 V: i3 t3 W
  set roads patches with6 D! J6 e* M/ _% t0 V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' D# [3 i7 h0 B9 G( b  f( P    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 K- F. b- j7 d7 h8 F# D# j3 c
  set intersections roads with
9 h3 l" O& c' ~$ g2 O    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 L+ ~- M9 K8 }# l* D" h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 X' e2 H( {" `" k3 t
+ F" U0 F! k* i/ }% J  ask roads [ set pcolor white ]
' w8 U# Y/ t+ [% y8 c    setup-intersections
' [. c& A1 p9 e. D9 W/ J. |- pend% G$ X* t# J6 I" |* L, X' L) n$ a9 g
其中定义道路的句子,如下所示,是什么意思啊?# K/ Y* y$ v$ x& `+ J- R7 `  G- m0 t
set roads patches with1 D& }% u+ c8 D
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; N7 j% s4 U% x. f6 }! O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 o* X$ n& A" z' _, K/ ]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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