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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。- |+ k- N' e( L+ r3 i% w
netlogo自带的social science--traffic grid这一例子当中,
/ c8 ^+ G. H7 H  X& \globals
! j: T$ n  I1 b; a3 T[
; e% Z6 n  Z. u, P. b  grid-x-inc               ;; the amount of patches in between two roads in the x direction* u7 l# Q8 c4 t1 d
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 b- _$ W( j# J! I- I  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
* e+ w7 P( C1 ^                           ;; it is to accelerate or decelerate/ Z) }' i4 j3 A0 ^
  phase                    ;; keeps track of the phase
) a$ G/ C' c, Z8 `) E- A/ o  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
* z; u9 f  z* ?( V  current-light            ;; the currently selected light
% c3 E$ ^4 p- P: r' F1 z- S- R
  ^/ ?, D$ j! X- Q  A- }  ;; patch agentsets
* L# Q& F. @  Y% p  intersections ;; agentset containing the patches that are intersections3 V. }& C- z; {
  roads         ;; agentset containing the patches that are roads3 S' c* T# f5 X9 ~( y
]1 K% @4 |+ N9 D2 ^7 |. v% |

& P0 R) \) l9 m. v: }( _turtles-own5 O8 O! N8 Q0 J. t
[
5 B7 L& A5 a7 T) a4 n  speed     ;; the speed of the turtle
  w( H& H, T4 T  up-car?   ;; true if the turtle moves downwards and false if it moves to the right1 r, l/ X' k% O0 Z* R- E
  wait-time ;; the amount of time since the last time a turtle has moved
% b& b9 n, S1 y. G) c# P' k4 V; o5 V]$ i. q7 {& j$ e! L, Z
% T2 \6 t5 M! J* v' X% O
patches-own
7 _2 e- C9 Z3 G, l8 S[5 g8 Q# k3 r; f% q2 G' q% E* Z
  intersection?   ;; true if the patch is at the intersection of two roads
) D* V1 l! R, o# X$ K  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
: v( X% _# t. c- w, D4 E: x- B                  ;; false for a non-intersection patches.
. ^# g. @2 C8 j/ d/ X+ Z, A6 m% F! B  my-row          ;; the row of the intersection counting from the upper left corner of the4 _+ D- _/ u4 I4 g) W2 \) I
                  ;; world.  -1 for non-intersection patches.
9 N7 p( m& n. ~1 C- B2 u7 [  my-column       ;; the column of the intersection counting from the upper left corner of the
3 [" I1 N7 ?9 V: k                  ;; world.  -1 for non-intersection patches.5 J" [/ ?; \$ Y- d7 o8 Y
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; h: P1 {9 e% }' e" L, t0 ~2 x  auto?           ;; whether or not this intersection will switch automatically.9 _8 ^7 m4 ^: l( h
                  ;; false for non-intersection patches.
" J7 J  O6 V% v- B]5 @! a* @+ H' O. j. G+ |( c
; y( }. W0 _# e8 u$ k2 D6 j# l
7 F3 P9 J: x; w; v
;;;;;;;;;;;;;;;;;;;;;;. ]9 g' @0 K3 ~+ |% e
;; Setup Procedures ;;" D) Q- ]+ p9 u5 H
;;;;;;;;;;;;;;;;;;;;;;
! l: ^, V( r3 K7 f* r' Q, ~/ V5 q  D) a4 w8 O3 z- J1 {6 a2 Y
;; Initialize the display by giving the global and patch variables initial values.
/ Q' n- ^  y3 t* g0 x1 ~; }* f;; Create num-cars of turtles if there are enough road patches for one turtle to
0 `: z. k% `. S2 q7 w;; be created per road patch. Set up the plots.
; T% G4 `; ^  V  b; A9 Wto setup7 G2 n% j2 Z# ]5 \
  ca0 E) h, v' ?1 G$ B: s* W$ F
  setup-globals
. q# q& }" n, b9 D& |1 f9 \% [4 z0 A7 h0 b4 U+ ~# ?9 z
  ;; First we ask the patches to draw themselves and set up a few variables
( \* i2 K5 T0 w/ {  setup-patches5 K  I& u$ z8 Y5 A( h" Q) F
  make-current one-of intersections
( N, B! z; z6 Q& y  label-current- b' }7 q: d1 ]% e% s, Q% l4 P, I" W

1 d. E, Y# Z: O1 i+ d  set-default-shape turtles "car"* o: R& k5 \7 g8 A$ S" m

4 x' j! x9 P, p% P% n  if (num-cars > count roads)
) y, T' U  C4 e: ~' v9 L. ]  [+ M2 J7 k6 F. F; ]- i  f# K- `( c
    user-message (word "There are too many cars for the amount of "" }4 k( z; U/ \; Y% j
                       "road.  Either increase the amount of roads "
' ~( p. C8 @1 v( o; C                       "by increasing the GRID-SIZE-X or "
. w; R$ K' Y& T' a: s                       "GRID-SIZE-Y sliders, or decrease the "  Y0 w' E) Y. T+ [7 o
                       "number of cars by lowering the NUMBER slider.\n". \6 l4 P! a3 }- x% a! P. ~/ J
                       "The setup has stopped.")) {! s. `/ G- s1 G. [2 A
    stop
$ C: S! @( f/ Q' z0 B5 p/ c  ]2 L; I% O: O. O7 ^& G- \
" r7 N" G  Q+ p
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
( j/ A8 [/ q, j5 c' C  crt num-cars' S: R% t. b6 D; i  I  {' d
  [
. e" U0 K# o& F. c( |3 P    setup-cars& U8 R( h( M$ D8 R
    set-car-color7 g7 M! ~' @# ?
    record-data* [9 R0 e: [" r& k7 S0 j* m1 ?
  ]8 e4 h0 o6 D8 P$ j" U7 t
; e6 `! m$ K  r* S! ^: }  n
  ;; give the turtles an initial speed
# K8 W8 T' S2 p  ask turtles [ set-car-speed ]
; ~; Q% Y% l# ^: g
7 y' J5 x# f# [% o9 g  reset-ticks
2 \" j5 e9 i7 O3 dend$ O  Z) K) k& I, z7 k4 S# H+ f
+ `) O( d, C4 m- H1 i1 l
;; Initialize the global variables to appropriate values( e' F3 Q3 H9 o+ _  D) W/ s! f
to setup-globals9 p+ a2 M: N. L. v
  set current-light nobody ;; just for now, since there are no lights yet
8 h$ j* C) [9 R: X# M" M  v  set phase 0; P/ s' x5 P+ H/ Y+ E: U
  set num-cars-stopped 04 \' H9 u0 C; O( m! }8 A$ J0 Q3 ^( Z" v
  set grid-x-inc world-width / grid-size-x) {; c" n, v. A1 h
  set grid-y-inc world-height / grid-size-y/ B" m' A) @4 k0 M  U0 w

5 X5 v& d$ R6 K6 O- O  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
/ O% E9 O$ Q( x' p" H0 ^  set acceleration 0.099; D8 E& }* I( W3 E9 J9 `+ L
end. W4 Y* x# y" V/ X3 }

# C# D% W/ ]2 p) I1 I+ W5 T, N;; Make the patches have appropriate colors, set up the roads and intersections agentsets,# u; [% U% Y: [9 ?
;; and initialize the traffic lights to one setting
# f8 m6 ]6 v, @9 q" n* Y+ R5 Jto setup-patches
# g" m+ i( t& e7 X  ;; initialize the patch-owned variables and color the patches to a base-color# A# b3 S1 w' p* M% w: U0 `
  ask patches
' s0 }% @7 Z! h# C  [
! `" r5 L8 y& m) M* {    set intersection? false
. Z1 ]4 u- \/ {$ t    set auto? false9 t; e' H3 v, c9 w+ i  K
    set green-light-up? true
; L' W! W, d. T/ l    set my-row -1
5 ]: y5 A3 r$ I0 o4 \5 y# s    set my-column -1- o* d  @; e& F2 r
    set my-phase -1
6 j& k& h- {  Q9 `    set pcolor brown + 3
7 @, V' ]. W1 H2 C( B8 |5 g  ]
$ }4 z. T; [) I4 ]
$ M2 I# T" m# R: ]' F5 S" _  ;; initialize the global variables that hold patch agentsets
9 o- I% r5 }8 y, h1 a+ v  set roads patches with
' ^: ~  K; ?- X0 C! l; A& K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! s1 }: p: q) D- K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ u" r" Y+ o$ H, O4 n  _8 Q! ~5 f
  set intersections roads with1 U- }6 `8 [* d* i, T5 ~2 ~- o  L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
4 J& H" o+ ]+ S! B/ Y3 o4 w2 w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( A. c' c  M7 b" s0 [" P& j4 u* l* M$ {
  ask roads [ set pcolor white ]6 l2 f8 H  m: v# W' C/ P
    setup-intersections
, m- l* a# `# G3 gend
! O' {+ g; p0 L2 F  p* G其中定义道路的句子,如下所示,是什么意思啊?; X) U: }) L& ^! L# i- B2 |+ u
set roads patches with. M# z+ t( L2 Y% W. p: k# j
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# z5 J+ h. \4 u. s. H+ h1 H' u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 k! Z! R# F" M
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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