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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。2 w8 t7 d; n" \
netlogo自带的social science--traffic grid这一例子当中,
. H% N" ~$ z2 k* R* Bglobals) x+ N. E3 u, c+ R6 k
[( r' J# c( g7 `$ h+ G( @
  grid-x-inc               ;; the amount of patches in between two roads in the x direction0 y( A  C8 M0 S  x1 A
  grid-y-inc               ;; the amount of patches in between two roads in the y direction  _! p0 M) y$ Z4 I# u
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if3 A- {6 f0 Z- Z
                           ;; it is to accelerate or decelerate1 \8 b! ]$ M3 Y7 V! a) N: \
  phase                    ;; keeps track of the phase4 s, X4 P5 A/ B6 ~5 w( ^; P
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
) V' x8 _. E1 u% s+ X  current-light            ;; the currently selected light% {* K( V1 K+ Y4 f# j

0 [- F( f2 v# J. E: U; r0 J1 {. j  ;; patch agentsets. Q7 X) y% @9 x$ ~. F' Z% W  m# L
  intersections ;; agentset containing the patches that are intersections' c9 ]8 _* G3 ?& a# a
  roads         ;; agentset containing the patches that are roads2 d- o+ r. F8 r: Y4 A7 i) @
]
& _+ q* x( l7 m9 Q7 q3 ]
% S7 W5 \5 J  R2 [* D$ M+ v! U& vturtles-own
+ Y& [) g. O- q; H4 ~[/ A% ~3 J% |, o6 M( k$ o7 r
  speed     ;; the speed of the turtle+ ?7 N$ q6 I8 f
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right* i8 h( i! j$ s
  wait-time ;; the amount of time since the last time a turtle has moved( C! Q/ O1 `- m8 X2 z6 F
]
8 }8 s  N% S2 @3 ^! I! a! T/ m! X& Y4 j) w0 p( M: r
patches-own' d/ O5 p0 k5 @* R2 p1 T( W
[1 K6 q" F& O1 x; P$ X" n6 k4 |
  intersection?   ;; true if the patch is at the intersection of two roads+ d5 ^" s7 e, z$ \: S3 i5 C. B
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 ]* I7 u: L5 \+ j$ Y                  ;; false for a non-intersection patches.$ M7 K2 Y& B) [  Q/ A
  my-row          ;; the row of the intersection counting from the upper left corner of the
# h; b; F" ]2 m' c9 z9 N                  ;; world.  -1 for non-intersection patches.
4 s# p% q2 l, Q, L  h  my-column       ;; the column of the intersection counting from the upper left corner of the- f0 G' R9 T# r5 c
                  ;; world.  -1 for non-intersection patches.
) P$ k, o. g8 |% M# A6 ?  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.' A% q1 x  `+ g% T# C4 p# t9 w
  auto?           ;; whether or not this intersection will switch automatically.
$ {" y/ [: z. P1 `* X4 H2 z( o                  ;; false for non-intersection patches.
* k6 w7 w; O6 j* N/ g]
$ y1 u" a! w4 n# X
( l* p0 c3 N% M0 y! Y
& x: N% c2 L) Y* s) n6 ?;;;;;;;;;;;;;;;;;;;;;;
8 j; P% f0 h; w  f3 w% B" z$ q;; Setup Procedures ;;$ H. b% b& A5 b' j, w6 w* T3 R  o
;;;;;;;;;;;;;;;;;;;;;;
2 B1 @4 H+ V! \# L0 \3 r1 y: B# i* u8 T
;; Initialize the display by giving the global and patch variables initial values.8 p- _4 W- z( d1 F
;; Create num-cars of turtles if there are enough road patches for one turtle to5 A' `/ _6 i# j( _% f
;; be created per road patch. Set up the plots.
  x; O& D, d% J( |$ Oto setup7 p7 Y( B% \2 o7 [  ^4 Q
  ca
: N, ^$ R  D# U6 N" b2 C  setup-globals* e! }' z1 p- E/ O3 N1 x

2 P! b& t* `/ @5 |: _6 w) d  ;; First we ask the patches to draw themselves and set up a few variables
8 r' L/ u3 R( t  setup-patches  a4 l4 w  S+ J, X
  make-current one-of intersections- U. W: T4 U! i3 Q" i; n
  label-current
# y! u; s  ^% t8 Z2 X/ S
  u2 `# I1 i6 C5 J7 V, E1 T  G9 u  set-default-shape turtles "car"5 t" r& `. l, F: f

2 H. {. ]) O1 |! {  if (num-cars > count roads)+ D* K  ~+ p, y( Z  Y! n3 D
  [! M' d% D# `( d, M- @
    user-message (word "There are too many cars for the amount of "
: d$ F& q- `% I& Q$ B                       "road.  Either increase the amount of roads "
+ o# T# H+ u/ {7 @. D/ G                       "by increasing the GRID-SIZE-X or "1 U; m) m( G4 j8 a. t; o, G
                       "GRID-SIZE-Y sliders, or decrease the "
7 w" s8 c4 R1 K% H                       "number of cars by lowering the NUMBER slider.\n"
2 R# L' ?! ]. V4 F% [0 e                       "The setup has stopped.")
" O* u, Q% E* v0 n    stop
8 J+ V1 S9 O/ H& [  ]
" M0 x1 Y: K! y
8 r' C, o8 |7 [  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color. x, m& d* K/ r  \% W& M3 x" v* Y
  crt num-cars
3 y$ e- n- d; m' D  I  [7 ?3 d, p0 r$ @1 P
    setup-cars
. z0 `* Q1 c5 s  J    set-car-color/ V7 w( e, X7 i5 a3 b# o
    record-data
) z6 X" C) q4 T1 @8 X8 B+ S+ a  ]- W0 D- I5 h. {5 V( w  n- G
0 _1 e: f8 W, y2 g5 Q! h
  ;; give the turtles an initial speed
  _2 K8 b) q$ q( ]  ask turtles [ set-car-speed ], N% a: @! l, c7 `5 g

7 D5 u/ D. P% A% F  _/ x7 y  a2 f  reset-ticks
8 t$ u, [, q- l5 w8 d: ]; iend; U. V: I$ x2 T1 t+ v

% \3 o* T5 R8 Z* O5 \7 s- Y;; Initialize the global variables to appropriate values7 ~  K/ i+ u+ V6 f
to setup-globals
5 `1 w1 ^, O; L0 b) K7 h4 [9 I  set current-light nobody ;; just for now, since there are no lights yet
/ H$ m, p8 Z1 A3 ?+ K  set phase 08 n; w1 z" i1 c3 Z& V/ Y+ `
  set num-cars-stopped 0. b) ~, i: w% o3 D
  set grid-x-inc world-width / grid-size-x
6 I3 l( z& b' t6 ]. e& N! I  v9 j  set grid-y-inc world-height / grid-size-y- M9 D5 v( `  A. z  p- K6 p

2 J0 O4 e% Z8 j( ~! H" R  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary; A2 ^% U) F, v: I
  set acceleration 0.099
+ B" R- M6 B+ fend
9 K2 O0 t2 E! A$ f5 T! J- c( g* ^4 l% [" f5 t7 o1 G3 K5 V( r
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,* I6 v) O' h) N* Y; u, Y
;; and initialize the traffic lights to one setting
2 y' o2 U' a5 E/ a( R; @to setup-patches
! A" N: R; ?, g( D  ;; initialize the patch-owned variables and color the patches to a base-color5 M. e. T, m, f5 ]7 V
  ask patches
# U) i1 M$ y# I$ q' \- Z  [: i* u8 v& o  j) ]: u9 I% O
    set intersection? false6 h9 I+ s# a( B- z) K3 e
    set auto? false$ J6 h. m! y: n$ o- R# Y
    set green-light-up? true
; R9 S% _* F) e9 O" O( l% q% b    set my-row -1, s  [5 F/ ]5 ]2 h( d( \( u1 O) O
    set my-column -1
! C2 N9 `2 E. t$ t- W! W    set my-phase -1
& _! K; }' H1 ?' }2 V) u% |    set pcolor brown + 38 U8 @! a6 e$ G
  ]. _2 m( ]8 `% l6 _% W! o5 x

0 i, x6 e) K1 C$ u' T. x  ;; initialize the global variables that hold patch agentsets
) c8 u6 \# w8 X3 c, g( {- r  set roads patches with
5 V: n8 b0 I5 @8 H$ W* j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ L2 a2 d1 w- y; P" ]; f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 C- m% w+ f' O1 ^" r1 P& @  D
  set intersections roads with
: h  c: @& R" o, N' X1 \/ X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" D% M' ^' K7 l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. X1 F- g/ E3 c& |$ u- j
0 M) i3 e0 t9 D- t* W
  ask roads [ set pcolor white ]/ u# O, C, o$ I. i
    setup-intersections! C$ g; J- ~+ o# Q% n/ H
end9 g! F0 G' z2 i: z8 o. w7 {: H
其中定义道路的句子,如下所示,是什么意思啊?
6 t9 i- k) I$ E# `: ?4 ]4 ] set roads patches with
* x/ R" X9 e* e6 f9 E& v( M; Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& r# M- e' a8 f+ J
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( B5 Q+ F8 q2 y% d3 D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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