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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。+ e" ~# }0 E7 F: r8 H
netlogo自带的social science--traffic grid这一例子当中,% p1 m: t9 b/ y0 a$ m7 b; ~, r
globals' q  L  M- t7 v* S, J  u
[
" N+ j4 g1 L2 Z, c* g0 f4 G" a  grid-x-inc               ;; the amount of patches in between two roads in the x direction
6 Q% ]8 k0 B& S: _/ J5 f: o  grid-y-inc               ;; the amount of patches in between two roads in the y direction( M- n6 s' F2 [- c$ b2 E5 f
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if9 _* K  }& S1 R9 Q% }! G
                           ;; it is to accelerate or decelerate3 w; i; N4 k+ ~9 r- J
  phase                    ;; keeps track of the phase
  m8 A9 x9 d: G. ~0 b  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure  U2 o; f4 m4 P6 B4 F( ^9 r( X
  current-light            ;; the currently selected light
2 G3 y* N% z& ]) U3 Q
7 V+ Q; P4 h5 X, h* f  w' p  ;; patch agentsets
+ s5 t  t8 w+ q& c* E8 S) T  intersections ;; agentset containing the patches that are intersections, G! s& a9 Z% x# I7 Z  Y$ F+ n( q
  roads         ;; agentset containing the patches that are roads# `% M! K# v4 Q! O2 `7 h
]
: y* H, `6 j5 u* W5 t2 }+ x0 H" Z
/ o; W! d6 O/ c* _1 _9 ^turtles-own* D6 Z( F1 _' ?, x$ `& t2 I
[
2 J+ D( E! C% C7 [- {  speed     ;; the speed of the turtle$ F, \+ l. V; t3 X4 g
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right' Z# a: d$ T3 s& s+ M
  wait-time ;; the amount of time since the last time a turtle has moved# [, N3 ^. Q) P/ T% n1 R2 t- O
]) R) _6 Z5 ^( t1 F! Z

$ Q8 v$ p( F/ O7 e+ X8 Ypatches-own4 P$ V) A+ _) c* }7 y
[7 u6 A0 H" @5 `5 F) ~( B; K  b
  intersection?   ;; true if the patch is at the intersection of two roads
2 |1 e8 y7 x7 q. ?& l& y/ O- h  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.+ b6 F3 Z$ |. V) j0 i# b
                  ;; false for a non-intersection patches.1 ~8 w& X( K) m+ n7 h
  my-row          ;; the row of the intersection counting from the upper left corner of the7 n" y- ]; C. D
                  ;; world.  -1 for non-intersection patches.
4 b: K; K. S) ~6 p) X4 E  my-column       ;; the column of the intersection counting from the upper left corner of the
4 [: X" ?% I' c& p                  ;; world.  -1 for non-intersection patches.
; Z% b2 ]3 h/ e: U  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( u& a" a8 X* O- n$ h  G4 r  auto?           ;; whether or not this intersection will switch automatically.1 c; L" }% n2 Z5 ^
                  ;; false for non-intersection patches.2 j6 p# u- k5 Z) s
]+ N+ l. f# s* @& E% G! T& a# `# m* m
6 j4 \9 y! U7 C* d' U" T

" g: z2 ^- a( Z;;;;;;;;;;;;;;;;;;;;;;+ M9 O2 J# _1 ~
;; Setup Procedures ;;) u; K0 y& Q3 p5 I: n9 Z
;;;;;;;;;;;;;;;;;;;;;;- O8 n+ C. Q, T+ U8 m# ?- C

9 i* }0 s& q! S- `;; Initialize the display by giving the global and patch variables initial values.
2 z5 i$ W3 d$ d! v( k+ R6 v;; Create num-cars of turtles if there are enough road patches for one turtle to
" t3 }$ a, B2 m1 u; k;; be created per road patch. Set up the plots.2 G* @+ ~) I' s; r+ L6 X
to setup
& E/ H! C6 x, h+ s& e  ca
( I2 R, T. g1 J  setup-globals3 z0 d- u# U( @" B& o+ H. P

; l. ]# L7 C4 ]* W/ {5 U, }) |  ;; First we ask the patches to draw themselves and set up a few variables
! h2 R/ X3 [6 [# a  setup-patches
. P, i& @& U& J" e" h/ w  make-current one-of intersections! r* l. t5 d: ]1 w
  label-current5 T8 |" B- q: O

( m1 t9 P; k9 ~( {1 I  Y. \2 w" a) ^  set-default-shape turtles "car"
  X# |7 p: t! ?$ E) a, C
7 X/ [" K# J' t9 S7 m% V! }; D  if (num-cars > count roads)
2 a8 w& S. X+ [( t; _' Q" V  ]+ D  [# {0 W% @3 H5 L$ _
    user-message (word "There are too many cars for the amount of "8 E6 b) t4 H1 a& p- }( F- @; N
                       "road.  Either increase the amount of roads "# U6 m/ d5 \4 a/ |# B. \
                       "by increasing the GRID-SIZE-X or ", V* E0 T) [( O
                       "GRID-SIZE-Y sliders, or decrease the "
7 ]* H, c, ~! y9 b- U- o4 z                       "number of cars by lowering the NUMBER slider.\n"
$ T; d5 \( ]1 u: b- Z1 }                       "The setup has stopped.")
9 n; j: l. ?$ U% }6 m! `    stop
- o' }" {- z/ ~( G6 D7 x4 J% P7 b/ Z  ]
/ v  o2 d& H2 G, C8 L
9 g9 x" I, O1 X$ y) M  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color( w7 O! f9 n& M$ H) p% n& Q
  crt num-cars
* T. _& k; A0 N; p0 Y# S# X  [
( a, }) ~. W  e" Y6 C' ?    setup-cars
  e" H; k5 x, L$ B) }( e! @! E- F    set-car-color. Y& V, \; U) p3 u' C0 q; `7 O
    record-data
& u& X: J8 c& G4 P& r8 Q4 n7 r. k% ^  ]  g7 j1 k: |$ m* V( g

. G4 `, V1 r% E  ;; give the turtles an initial speed
% w) `* [) ]" ^/ w# Z" t  ask turtles [ set-car-speed ], Y) q# h0 K- `7 U; `
( E, I" G- f/ A5 E- r
  reset-ticks9 H9 a. e6 C' X
end  A3 K; R: v5 f& x
$ s& l0 @: E9 v" D' G
;; Initialize the global variables to appropriate values
# P( m% i3 Y; y$ b7 ^& S( |to setup-globals. w7 g7 z+ y) @  t( |( L. {
  set current-light nobody ;; just for now, since there are no lights yet7 \3 }# }) ]% T7 @/ p8 r
  set phase 09 G. f" l2 i1 Z8 p; `$ @
  set num-cars-stopped 0) {+ \% S- m1 V9 J8 w
  set grid-x-inc world-width / grid-size-x
. r4 h6 ^! @4 ^2 d7 c  set grid-y-inc world-height / grid-size-y6 f* z- B& m4 f; C: W2 D/ O" B
; p: p% f7 u% `4 S  q" l7 u& p
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary0 N3 F' L' l6 a% A
  set acceleration 0.099
1 u9 m! W0 J  C! Z* rend1 a& P# d  p2 N) L4 [1 z
  q( I! r# r" B: o2 A
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# p" {. h+ E8 Q1 f/ C: J9 v;; and initialize the traffic lights to one setting
& G" A3 H/ {6 ]& ~9 h$ wto setup-patches
: G) |7 R. ^0 p& |* }  ;; initialize the patch-owned variables and color the patches to a base-color
, ?5 H5 V* f* z- F6 C  ask patches  j2 H: d: Z6 D( [
  [: Z' n6 a4 r+ a6 ?2 p( g0 r
    set intersection? false
( |9 ^7 d3 ^6 ?    set auto? false
7 {' d! D: ~; c9 G    set green-light-up? true' ?. g2 e8 `0 C* d7 M8 ~( D
    set my-row -1
+ a8 q! G9 B$ M+ S- v0 G& D# }, [+ Y    set my-column -1
5 d0 ~# C( e2 k2 A+ h' S, R* r    set my-phase -1- t) U0 C8 J) _2 P' W7 I6 j
    set pcolor brown + 31 T# }! W/ a! Q3 t$ H; ^2 e
  ]: T# ?* B8 i/ Q- Z3 |

- C" b& o7 ^1 o' l: O3 ]8 H* B  ;; initialize the global variables that hold patch agentsets- G" t3 j! w5 k* X3 Z- A
  set roads patches with) `& a- L" e7 l0 M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# C6 z  j" F; b4 \/ d2 e) G$ w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! d" o6 q; a& P" ~+ Z1 V, I  set intersections roads with
) _, R% j; x' I, l& e7 _2 s" n; v- W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. r0 S9 E* {. w+ h' m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& y9 i9 s7 e# K0 z0 y) o/ ^" c) x) B2 L) r4 ^& {1 t
  ask roads [ set pcolor white ]& X; q( D3 w2 |9 f4 B
    setup-intersections" J. a, r: S- x: F
end
5 \: B. U5 Q7 B0 J其中定义道路的句子,如下所示,是什么意思啊?
- g3 Z1 c# @! `* O1 `' o9 R set roads patches with
  l) q9 w8 E3 @+ l, W3 E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 Q8 K& ^' f, S" @# x8 M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 R- f  D  T3 `; ~% L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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