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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。1 a4 v, s0 _2 z3 x! Z; K5 i
netlogo自带的social science--traffic grid这一例子当中,
' G7 ]/ A% l- _3 A: B) ^globals' f! ]9 H, o- D9 a, i2 J7 x
[$ {" _" [0 e7 T
  grid-x-inc               ;; the amount of patches in between two roads in the x direction" J7 G5 w5 o) y! W! ~3 _5 @
  grid-y-inc               ;; the amount of patches in between two roads in the y direction8 r' e* f) `; R. O
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if. L6 L' ~7 ?& p5 h1 o9 T8 ?
                           ;; it is to accelerate or decelerate
5 |% G. ]% ^0 u2 v/ [" d  phase                    ;; keeps track of the phase
& l& z) L: J9 F, q1 p. W  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; N2 I8 e$ @' S' X  z, a4 a  current-light            ;; the currently selected light- w* W3 ~0 ~' l& n) @
/ G4 _# K* ^2 r- E( z% }  P" _
  ;; patch agentsets
7 w0 c" F4 |4 ^- ~* y9 c; B( K& ^7 L  intersections ;; agentset containing the patches that are intersections( Q# m4 E2 e2 m/ }
  roads         ;; agentset containing the patches that are roads& w9 E2 y9 Q' ?
]
; Z. v6 z* S$ b4 I; @. u/ M6 X) o% Q* K
turtles-own' a- i  ~. i. d
[& O: l9 |" j2 D: L
  speed     ;; the speed of the turtle: i7 H1 M! n" ~; V; D, M7 V
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& v+ ~# C! j! Q/ P3 k  f
  wait-time ;; the amount of time since the last time a turtle has moved# h4 A( M3 y. g" V: c/ F
]
4 G8 O2 @! z: q& W& |# i& k4 v3 ]' C" J8 U' {
patches-own6 x1 ?0 H* l# ~& M( x4 J2 r7 l4 d
[
* O" }8 v8 S) x: B+ c$ y# _" \  \  intersection?   ;; true if the patch is at the intersection of two roads9 q) \& v, d" q2 F& f
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.# k3 U' _& `( t+ ~& s2 J. c
                  ;; false for a non-intersection patches.
$ i1 u2 w  c+ U$ q6 w) y  my-row          ;; the row of the intersection counting from the upper left corner of the
0 G) c8 Z! d# A                  ;; world.  -1 for non-intersection patches.
/ \' k2 I) P- D' p: m0 g4 H  my-column       ;; the column of the intersection counting from the upper left corner of the
$ r( @4 r7 b. `1 m3 `                  ;; world.  -1 for non-intersection patches.
  P0 m1 @! Z7 a' O2 M  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( S9 J! C. X7 _/ X  m  auto?           ;; whether or not this intersection will switch automatically.: w+ G# ?( v2 t9 @
                  ;; false for non-intersection patches.
, H' W  N! }6 J8 z]
4 I* Q( ?. e; E5 L* F6 s
/ t0 H& R( q0 J! C2 W" o; N4 e- Q/ L! K! n! x% [2 U2 D
;;;;;;;;;;;;;;;;;;;;;;/ E7 a6 V! P3 ~" r1 T' J/ d
;; Setup Procedures ;;
& X7 q7 `( y4 C0 B8 c- W9 J;;;;;;;;;;;;;;;;;;;;;;
3 w, Q5 V- k8 x- l
$ [4 m# g5 |+ u) \/ V6 ];; Initialize the display by giving the global and patch variables initial values.; C8 e  K8 \9 a" ]8 c, s* n
;; Create num-cars of turtles if there are enough road patches for one turtle to
! S% h  N5 P5 f0 R;; be created per road patch. Set up the plots.& E6 T' Q! a+ F5 N" r9 D
to setup% K: u' K  N: j; o  M% D4 ?) Y
  ca
& w, s! Q# d! y1 a8 o8 B  setup-globals
' N2 M3 o: B! P. b8 a% f
; ]8 ], [+ b) m( G3 p  ;; First we ask the patches to draw themselves and set up a few variables7 Z1 k% ?6 `2 J8 g- K. h) _
  setup-patches8 p  ^9 ~  G1 z7 Q2 l3 B  Q7 c
  make-current one-of intersections
2 T* W3 z% ]. F, p- M. s7 e/ ]4 G  label-current7 L2 ^9 j! @7 D
; e$ F6 R% Y6 d" b- B' _
  set-default-shape turtles "car"$ e$ G5 I5 j$ W' u! F3 Q2 X+ [
1 [* b- A' _1 o. ~3 {
  if (num-cars > count roads)0 t% `. b* X1 y+ @
  [
. K9 I& K. c2 D9 R7 [* @    user-message (word "There are too many cars for the amount of "6 V- _* c1 g- B
                       "road.  Either increase the amount of roads "* g3 S: G2 z6 _) \, U2 f
                       "by increasing the GRID-SIZE-X or "
% v* l* K% A, E7 h& [0 I- V                       "GRID-SIZE-Y sliders, or decrease the ". N8 _( p. t9 C" I2 ~
                       "number of cars by lowering the NUMBER slider.\n"
" @& p+ r5 B2 E5 T1 W                       "The setup has stopped.")( y  |. i$ b7 f
    stop
6 ~  d, i& f, C6 J0 H  ]4 D$ l0 I) j3 ?* W/ R# L$ ^
* R+ ?: \8 E; |3 D" G) x) D2 f8 V/ n+ g
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
4 m$ Z: d/ @' g" ?7 h8 B4 M  crt num-cars
# M0 ~; P( ?7 ~. ]3 q5 E: H  [. @4 e) s: V# z/ |+ g0 y; _' D
    setup-cars- Z/ Y. _2 S. {, X, O$ I0 [
    set-car-color
3 j2 B( }0 x! Z; v    record-data& A& ?: S, z  X
  ]# r3 K  Q' f2 O9 _. M
" _; i# C1 {# Z) Q' p) u
  ;; give the turtles an initial speed
) z: R* T" W* C6 S! T  ask turtles [ set-car-speed ]
+ m. M; k0 y  k: r5 @! J
0 w* @1 b) d3 R% p3 N. B  reset-ticks
# D. f: v3 J" h4 ?0 fend0 O) I& G5 H' P: f  Z3 j+ f' U9 x
& D7 }3 x* n( x0 f+ L( e2 j
;; Initialize the global variables to appropriate values9 }' \6 D2 g* t# a: m
to setup-globals
5 }3 d# t. [  ?3 J# r  set current-light nobody ;; just for now, since there are no lights yet" u. B: _# V  z! ~7 L! z
  set phase 0; c) I+ [  m5 d, a$ V
  set num-cars-stopped 02 k7 y& P* K; @) D
  set grid-x-inc world-width / grid-size-x* S; S! r- h8 G1 M% ~% z8 T; b
  set grid-y-inc world-height / grid-size-y, [- s$ ~3 z' C$ p; S) c/ u

: z8 I$ D- Z: x1 s, t% M  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary5 c* s) D% E0 R0 @1 U, i& U2 e3 M& {
  set acceleration 0.099
6 i+ ]1 @) d# tend4 n7 l5 d4 f/ T0 y* F& v* n3 U5 d
7 G2 J, \; y4 w" x$ I" D! M
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
- G  F' c& Q3 W9 Q$ \;; and initialize the traffic lights to one setting
# {1 D3 c/ R7 [' H3 e. z/ x3 kto setup-patches
/ p1 K; F, S  g+ \  ;; initialize the patch-owned variables and color the patches to a base-color
9 n) W' d) w. y) L0 j  ask patches
! P6 c& X2 D2 q7 S  [8 R. |" p" ^( }
    set intersection? false" i3 ]/ T2 q8 I4 c0 G- y# \) e
    set auto? false
% o2 c( m, R: W; A; S. i; v  T    set green-light-up? true5 b, M. y8 ~! h! M
    set my-row -1
0 H. \0 ]% z- ~7 U( y0 ~; F    set my-column -1
: f5 P# b8 i( N# P+ h9 N    set my-phase -1
; i6 _6 y0 F  t    set pcolor brown + 3
/ z- n- \5 s$ f) p" y  ]
$ W6 S3 ^* N8 y6 j0 [& w+ r2 d7 z" `
  ;; initialize the global variables that hold patch agentsets
4 [9 n9 F9 V# q" B3 @- |  set roads patches with
+ t& A5 O* p8 Z. a- ^9 B    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 `6 k% P0 l) s' S3 z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. t- B0 C; r; ?+ j3 ]% N  set intersections roads with: _6 f( v" L# x8 `: }4 A
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ {, c/ L2 K/ k4 i$ Z9 c
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ T( ?8 D1 ?1 }, s- T& h
+ C& C  \" ]8 l" {8 \  _
  ask roads [ set pcolor white ]
0 n9 A5 O, e: x/ ^7 C    setup-intersections" j6 |9 t% _$ u  r* x
end
& _( m' }! D7 T! [4 ~! L+ q其中定义道路的句子,如下所示,是什么意思啊?
9 E' l  `$ z3 k( R5 j6 a/ Q/ Z set roads patches with1 A" Q3 g: R( p5 w% u  f' |7 v4 L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) y& E. f& u5 l0 T- x* t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( E+ i7 G: Z, ~2 q& j* z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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