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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。
% e2 K' C/ _& xnetlogo自带的social science--traffic grid这一例子当中,- p7 ]- W: b$ Y% y
globals
" y* r( c3 q7 J6 m+ V# C- b: B[& G" }* w0 S5 e, A, T3 [6 |
  grid-x-inc               ;; the amount of patches in between two roads in the x direction* G1 i. I8 r, t4 O$ q
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
7 c2 U$ A/ t# I4 D  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
" M$ G+ N9 H, X0 D* ]% \! b$ K                           ;; it is to accelerate or decelerate& R( \" J5 c; \8 O
  phase                    ;; keeps track of the phase
  e- A4 ^+ M. r  z! h; c1 w& `  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure: ]. l( |' m9 i8 Q& |% O$ D2 \
  current-light            ;; the currently selected light( _# i2 ?3 r& P. F7 h* @) L! ^
% f: p% y* @% b. l
  ;; patch agentsets( \" J  i. k9 F" v
  intersections ;; agentset containing the patches that are intersections/ z. {# y1 s6 a
  roads         ;; agentset containing the patches that are roads8 _9 S( F2 U0 |" G& m
]
+ s- ~: B# J9 x* e' R' @9 i$ U6 R- ]* s
turtles-own
( r+ W- Q0 r% m  R8 `4 c8 Q[
9 c/ Q6 \5 M9 J# K7 g. }6 X  speed     ;; the speed of the turtle
  ?$ t: S: ]; A& D6 F  up-car?   ;; true if the turtle moves downwards and false if it moves to the right% C' r9 ~9 g  K7 t1 B9 X
  wait-time ;; the amount of time since the last time a turtle has moved
1 D" D/ E$ J( _]
  |' ^$ J* G3 _, P* @
  G( H* ]+ w% Bpatches-own/ C1 N( t* v# n/ W3 T
[; L7 t& C, c2 w" H  A9 E
  intersection?   ;; true if the patch is at the intersection of two roads% `9 u2 g3 O/ ?
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.' K: x6 u/ M: f& _5 n9 P
                  ;; false for a non-intersection patches.
- |: M7 A0 [8 q5 s$ F' J( r  my-row          ;; the row of the intersection counting from the upper left corner of the
6 t( h9 h3 H* z5 N2 u( Q/ B                  ;; world.  -1 for non-intersection patches.4 G/ _. w. ^% C0 e4 r) A
  my-column       ;; the column of the intersection counting from the upper left corner of the- `7 G$ u, U: {! I3 M
                  ;; world.  -1 for non-intersection patches./ p. X. e) B) z& p& C$ u/ S
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.+ ]4 K5 d( \# L& ^9 ]; J
  auto?           ;; whether or not this intersection will switch automatically.
. M( m) a+ e  o+ W) J0 ^                  ;; false for non-intersection patches.& i) B* {* x' B) R1 y0 o- Q# w
]0 k! D# |+ [2 N

% @1 C, \$ Q  ]; X+ J- Z) p# B' w) t3 l) s/ z
;;;;;;;;;;;;;;;;;;;;;;
# z! t- s5 K  D3 B;; Setup Procedures ;;
: n' x- n% z, ^7 H% J* h;;;;;;;;;;;;;;;;;;;;;;  L/ z" W# q, U! G
+ J  ?# Y$ w6 a
;; Initialize the display by giving the global and patch variables initial values.
4 L+ i) x, h) f% _9 I;; Create num-cars of turtles if there are enough road patches for one turtle to1 j, U2 ?/ ]0 ?0 _) E; A' \$ d
;; be created per road patch. Set up the plots.( {5 B  `* \2 [. H  M
to setup
5 A" M( ]  K1 a: u  ca. x& P: I: ]1 b, L& @
  setup-globals; X6 l+ f7 w  R: a& T$ M7 d1 o
) f$ W( }) k" m! E3 q4 z
  ;; First we ask the patches to draw themselves and set up a few variables; W9 ~( _0 |% k+ F6 |4 u) P
  setup-patches
  `& X- J$ m0 z( w4 C2 x  make-current one-of intersections
7 o5 X$ @" M' n% U( |0 v- Y  label-current
# }2 J* x5 Q. _3 ]# h( O
9 l5 s  l, [( s& s  set-default-shape turtles "car"
# u* f4 ~2 V* k
# h! F/ e+ H$ n; P% B: J  if (num-cars > count roads), u5 r1 Q9 n1 f2 a
  [
" p7 G9 C+ s2 `6 i, Q% q    user-message (word "There are too many cars for the amount of "# P1 H. m- D+ ?. d
                       "road.  Either increase the amount of roads "
" B7 U5 S5 `9 `4 U! K9 Q) Z                       "by increasing the GRID-SIZE-X or "
$ ~* p8 g2 s9 c: S, h                       "GRID-SIZE-Y sliders, or decrease the "7 r0 t- e. G* {9 K% ^
                       "number of cars by lowering the NUMBER slider.\n"
2 K) k8 i7 `0 S                       "The setup has stopped."), z- ~! P# O3 t3 d8 |  k) s6 Z
    stop- @' i& i( W% Q3 D( A
  ]
! T7 c' i/ x' e4 L8 x+ o8 }; K/ v4 K' M0 D5 P% k
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color, _. G3 z4 A' L# W
  crt num-cars
$ l& i( P' C5 C" N& r% r" m  [
/ B$ J$ K* x9 |0 X& R4 `/ Y    setup-cars
. n, d# f+ h1 b- K' m    set-car-color! G) @8 a  g. L* _& m; i7 q! s( r
    record-data
3 }0 Y" ^, r4 h& V3 e# ]  ]! h  Y# y( \% [# f" s6 M; f1 M
3 `7 @' U, @( L' v2 s5 P
  ;; give the turtles an initial speed
+ m; ?( m1 S. _: R  q3 w7 `  ask turtles [ set-car-speed ]0 Z1 S0 Z9 [% K/ B) z; w

( T7 t8 S3 K# j* Y5 A# U  reset-ticks3 _' N0 W4 K+ U. {% R0 }7 D
end' y8 B% i8 e+ @
) B6 ]3 f$ |  ^* E8 E
;; Initialize the global variables to appropriate values4 y, E" s. Z  J/ X- [$ `6 q! r
to setup-globals
4 b, P: T$ |: ^# Y  set current-light nobody ;; just for now, since there are no lights yet
) N8 |; {2 l. V$ S) ]$ }  set phase 0
/ B* a: N* X5 i% O+ d  set num-cars-stopped 0
8 i: n+ }  q0 \# m  set grid-x-inc world-width / grid-size-x" A( h: x& S# }3 z0 ]2 a8 o
  set grid-y-inc world-height / grid-size-y
; ^0 |+ t4 b7 p
  ]1 Z: M7 F+ i$ ]+ Z& D! n  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary. i5 r3 ~1 @" ]+ H5 p
  set acceleration 0.099
5 r- J& L! f& t. [, w% Bend  l; y# e4 x) c
/ P9 ?& f- P& |. b0 x: l
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,- A0 [) y9 j3 ^/ ?+ s4 ~5 B
;; and initialize the traffic lights to one setting
' Q6 s, {: r- q: xto setup-patches
* g5 N$ d( e7 C4 u* O) a! a2 p& ~& E  ;; initialize the patch-owned variables and color the patches to a base-color( ?+ B# l# _1 s; c) h4 ]
  ask patches
( g% Q8 y3 S( u4 {6 _& Z; K  [
. S, B" i5 Y$ Q9 Q6 O, B! y    set intersection? false1 {) k  Y( s2 |. [* Y5 q
    set auto? false
/ C( [: t3 O8 q5 @6 c/ Y    set green-light-up? true
9 H! }  P' d/ E* J& {+ T    set my-row -1
6 m5 \; M, h: c* p% D    set my-column -1
# ^) _! K  c, {+ |& J9 z7 R    set my-phase -1
7 i- o( t7 _7 |0 W" Y    set pcolor brown + 38 P& t. W9 r! x: {, F7 f
  ]
2 C, f  ]6 X  F, {& L2 |( n3 J$ F" }% M) [7 E  c
  ;; initialize the global variables that hold patch agentsets
; g. d3 Z: Y# f0 l# E  set roads patches with
. k6 _% T! `, t$ D    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 S. ]! h% O7 Z6 q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# X$ y4 c1 N" u+ j6 }  set intersections roads with
4 D( k# j- c% L& e; z& B$ x    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 w' W" }* t* ~! c4 ]3 f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 ]( d2 R- C. Y
, Y% g9 l+ q" Z/ }1 ^) C2 O& y  ask roads [ set pcolor white ]) r' q3 ~7 ]; W( g) s
    setup-intersections! }. j% Q* H+ J# b$ y+ ^4 X- j
end; t9 W' J. ~4 G, A7 z: @3 W
其中定义道路的句子,如下所示,是什么意思啊?/ X7 M  }: M7 N+ g
set roads patches with3 e7 u- l# L$ t4 `: x. |! S
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; b8 t+ G) x2 z* J    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 J% P" d; a0 g+ O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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