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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。: H! A1 w9 Z9 \9 ]. H
netlogo自带的social science--traffic grid这一例子当中,$ g! Y- F& @: @1 {
globals" N1 S; A' q+ u: t; S
[
5 U9 V! b" p, ?/ w' K  grid-x-inc               ;; the amount of patches in between two roads in the x direction
7 f& F' d; U" t/ O  grid-y-inc               ;; the amount of patches in between two roads in the y direction
/ M, C( o2 U9 p& T  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
* ?2 s& z1 q, [                           ;; it is to accelerate or decelerate
' T# \- y9 C7 b. u' f. Q  phase                    ;; keeps track of the phase, H9 G: d0 U8 u5 R; k) B0 Q
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" |% R9 v0 I& G4 W% @
  current-light            ;; the currently selected light# ~# x2 V/ U+ C* b/ K. T8 @# q
+ k" Z6 n% z, Z2 T/ S
  ;; patch agentsets
5 K- c9 W  W' F' s  intersections ;; agentset containing the patches that are intersections  ^) M2 ?5 p- H+ T
  roads         ;; agentset containing the patches that are roads  W7 z# q( E4 A$ r! ^
]
# c6 N3 P# d: {
/ V# u' A! S3 Mturtles-own# k' h; a/ _: C5 q; p+ F
[9 P+ F. _) R4 M3 \! k* |" ^
  speed     ;; the speed of the turtle; R. O6 u& i5 I% K
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right  R3 T  J* X# W% d) |
  wait-time ;; the amount of time since the last time a turtle has moved. ?6 G+ s5 }9 B: H1 c! L6 K
]3 v+ E# |0 L5 k* _& g$ A
5 ]5 Z: H* i  @- @/ J. i$ ^, F# b
patches-own
) V' I3 g/ L7 E! N/ _[
$ I; n$ X. p) A' ]7 {  intersection?   ;; true if the patch is at the intersection of two roads
. w4 b5 Q. n& d+ B  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
0 V: e$ X7 k# [! \% o% z                  ;; false for a non-intersection patches.9 b; P) ]: D- L+ j$ b7 h- g5 o
  my-row          ;; the row of the intersection counting from the upper left corner of the
, s: K" o6 A$ E- L                  ;; world.  -1 for non-intersection patches.0 q) I4 _! s9 t5 m$ h9 L9 _" z6 ~
  my-column       ;; the column of the intersection counting from the upper left corner of the
9 ]6 @, M4 M3 B+ Q) @+ F7 P                  ;; world.  -1 for non-intersection patches.6 U3 k/ O* ^# k0 B
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.; l, c. y) w$ b
  auto?           ;; whether or not this intersection will switch automatically.$ H4 h3 M/ U5 x& B7 @5 d; I$ E
                  ;; false for non-intersection patches.! F/ I' K2 |: Q: a
]( n- S- n' ]- R" o  i7 E
( s, B# V+ N: X& |' Z9 N, G8 c
4 |  @% b0 S  k# b" _
;;;;;;;;;;;;;;;;;;;;;;8 C" _' e' ^! f3 F$ S: W' m! }
;; Setup Procedures ;;
& i+ t+ \( G$ m, \! e;;;;;;;;;;;;;;;;;;;;;;
3 K7 y0 j) s1 T1 C% F: C' Y% y" j) m1 S
;; Initialize the display by giving the global and patch variables initial values.
" Q& A: `3 b7 u: b7 V& [% K;; Create num-cars of turtles if there are enough road patches for one turtle to
$ b$ U  R; r- G7 ^9 };; be created per road patch. Set up the plots.
0 ]6 p& K* I" v# q! Rto setup
1 M. y& q! v  x& H  ca
3 a5 X" ^7 C4 ^5 q% }' I  setup-globals; z0 p4 x/ c4 P  O' u% \. Q, L

& v; q# ]- x6 `& u& w) [  ;; First we ask the patches to draw themselves and set up a few variables
% N* W9 q7 Z4 m; i- N, ^( {  setup-patches& ]0 s' V$ ~% ]3 ~/ q$ P
  make-current one-of intersections
9 [$ I0 e: Z1 U; N  label-current& k$ r1 p/ d1 F( A3 c
8 k; k2 s1 m1 G$ b' k/ C1 c3 ~
  set-default-shape turtles "car"+ J$ z' p1 ]0 ]# ?  y; W8 l, d2 E2 x1 U
% i# Q, S! s; \
  if (num-cars > count roads); F$ Q- h  A/ ~
  [* y  m3 @7 i2 X
    user-message (word "There are too many cars for the amount of "
6 ~- j0 @# h! g8 }( Y" s                       "road.  Either increase the amount of roads "
  _( l' x, k% i5 H3 i' i4 ^                       "by increasing the GRID-SIZE-X or "* a; y. T# D( Z! n. l/ k2 I3 L7 D
                       "GRID-SIZE-Y sliders, or decrease the "
  h! e( c# j+ A: G) `, ^                       "number of cars by lowering the NUMBER slider.\n"/ n' K! r. x& @2 r( \2 J$ L% @
                       "The setup has stopped.")' B7 R: w5 w7 ]5 s* T7 R1 d2 I
    stop
( c" H; c: e8 w( j5 q  ]2 N' O+ S" Y) m8 _6 X; Z8 H8 |7 `

7 @7 @! j7 n0 W4 R$ p8 H  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color& P9 V0 A2 R' ~$ ]( K, ^
  crt num-cars
3 H9 }. {) D3 T5 Q  [$ l: m! `+ g1 z3 W0 z
    setup-cars. ~% W# m# Z! W- U- M
    set-car-color
  c9 U; e: ~( r' Q4 g$ d. `8 a    record-data" u2 C  P. B7 d/ e3 U
  ]
9 s# f& C1 @4 a8 Y+ B' F
$ S3 Y& R$ N1 T) D5 t# a4 z  ;; give the turtles an initial speed  {" _; i) n* H( L* `& m* D! k
  ask turtles [ set-car-speed ]
: X$ H( t5 D5 j9 G# ?8 O/ q1 y; T( K
  reset-ticks
2 X! x# ~) i5 r% L! ^end: w, w% o8 @+ L6 ], U* i+ c
  F; Q- k7 n$ p0 i" q
;; Initialize the global variables to appropriate values
$ j( \7 P" s6 C7 Q3 S3 @1 |to setup-globals: h: _6 D7 u" t3 [2 C
  set current-light nobody ;; just for now, since there are no lights yet" X; H0 N# v8 S. W4 `7 k1 J
  set phase 0
4 v1 k6 w! }* u3 m# R  set num-cars-stopped 02 ]) j$ s; W0 K) p" J1 g
  set grid-x-inc world-width / grid-size-x
  G) I3 \( B3 K& U4 l7 ^" O( `  set grid-y-inc world-height / grid-size-y
- z* s( u* G( n! N6 f
2 m$ t3 ^# _) [. P- j  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary! s; E$ x9 j6 D, I. h' s
  set acceleration 0.099
( a3 r3 ?3 t6 N; ]) @2 W6 jend/ e/ U4 V! t6 {7 I: w/ M8 f
7 L" h: D0 |+ V( W( I! ?" X) B
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,( Q5 G1 f, J4 Y8 ?
;; and initialize the traffic lights to one setting# _, E# K1 ^& j0 a
to setup-patches
! `3 e( g( |! ]8 }  ;; initialize the patch-owned variables and color the patches to a base-color
. m; C8 o. Z4 F  ask patches* U' @- O0 l- [0 Y/ Y. E+ @, ~. Z
  [
' {- R9 E3 ~: C5 b    set intersection? false$ ~4 }$ c# a8 v+ L7 k; d0 k6 T
    set auto? false9 J4 y% u! v2 m, L6 {& p3 n
    set green-light-up? true
+ R. Q# j% H; f7 L( I    set my-row -17 T( m8 U) l+ J6 o4 E7 g% N0 ]
    set my-column -14 ]& H# M5 T, h3 H$ w
    set my-phase -1& O& l) N7 t3 Q1 p. p2 U
    set pcolor brown + 3
. m- b. ]4 c, H- @) c2 x0 [  ]2 r# K: _- S, m, @( R
! E- l' P9 t% v; |! C: v: ?8 F
  ;; initialize the global variables that hold patch agentsets
& k% ?; Y$ }0 Q8 }8 Z- d  set roads patches with
1 C# ^& }# C6 e/ p; ?* K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 v+ ?& Z; |' `
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ b3 d  G* @; V0 _% c% F( c# S  set intersections roads with
) \# j/ I% H7 e/ S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
1 e( T2 i0 o/ L9 r+ H. j8 X3 g; \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 Q! {3 o" ^! A6 U
. D- }1 B$ ?4 b/ D
  ask roads [ set pcolor white ]$ x+ L" t+ L* ^6 @
    setup-intersections- P/ P- b" h+ I) f. Y9 x& n8 `+ f" ~
end7 ^2 o- S- |0 X8 q- y( H1 A
其中定义道路的句子,如下所示,是什么意思啊?7 A9 u9 b6 G" r/ p. P; x( o
set roads patches with
$ W+ K  Z# r; W  I, G( }    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 i& ~8 w5 z1 p' k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ }/ U) i, `: S9 f8 i0 W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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