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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。9 T( w& ^  z( g0 I5 M
netlogo自带的social science--traffic grid这一例子当中,
. v6 i$ R8 h* ^" u  n/ R0 J( Mglobals8 c4 Q9 e+ z! ~4 e2 y8 W
[
; Y( {4 Y/ C0 p3 H  grid-x-inc               ;; the amount of patches in between two roads in the x direction
9 Q7 d" J) w* `, j/ r6 v  grid-y-inc               ;; the amount of patches in between two roads in the y direction
$ P0 e/ G1 D: k) k& f( @2 B  acceleration             ;; the constant that controls how much a car speeds up or slows down by if- [. H; J: g) b4 y! R$ L8 n9 r
                           ;; it is to accelerate or decelerate
7 `, @" N( I( U$ R; E4 _, s) ]  phase                    ;; keeps track of the phase
% A5 u! e0 T0 w, p& Z7 T  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure0 B0 k, \; F; Y  E
  current-light            ;; the currently selected light7 A3 p! C1 ]0 A  B- L$ w

* y% F1 ^5 k: p  U& F5 J& v0 B  ;; patch agentsets: [. v) N' O4 c1 w
  intersections ;; agentset containing the patches that are intersections
6 Q  I1 `5 X  q- K  roads         ;; agentset containing the patches that are roads; Q2 f& j- M8 }4 o/ G+ [" S. Q
]
3 j$ |3 e0 L# j, V: B. l! ?8 D1 {$ O: @6 V  e+ J
turtles-own& `5 b# [- ]7 h# y8 M
[# J  y" F- D' @0 z" N% C
  speed     ;; the speed of the turtle. t9 U3 [+ Y2 n6 X% s' V; B  r6 Z( N
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
; w* s! D9 Q0 N/ u6 d7 a# e  wait-time ;; the amount of time since the last time a turtle has moved
6 K% K! Q6 ?+ h$ L1 W- k]
8 W; z  u1 h5 p1 ~+ B$ E/ F: j$ o7 ]9 `" b% x: @
patches-own
/ X' x! f9 [4 Y& s- H( Q[6 ^) b% \# }2 N4 V
  intersection?   ;; true if the patch is at the intersection of two roads" g6 Q- J9 k" A$ f
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
# M+ L5 \8 Z2 D6 E0 `                  ;; false for a non-intersection patches." f8 T7 c- T. L/ H7 E) e+ G
  my-row          ;; the row of the intersection counting from the upper left corner of the
6 V. d# i, ]7 t& F& W6 I                  ;; world.  -1 for non-intersection patches.1 k7 s+ H$ h' k
  my-column       ;; the column of the intersection counting from the upper left corner of the
2 T( F' q- d# Q( s                  ;; world.  -1 for non-intersection patches.
" A0 t+ Y: Z/ r7 Y  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.3 r# j* c5 f' f. a' ?% t* q) D6 B# p
  auto?           ;; whether or not this intersection will switch automatically.8 V' d3 P& k4 i! e9 o! w$ K  p
                  ;; false for non-intersection patches.
8 v9 V1 I3 t1 s; j+ Y/ u2 G+ A0 ^]! Y. ~# ]" G/ [; z4 @7 I
0 ~& N$ w& H- S6 Q9 B/ U  ^1 @6 I
: f; T( B' G1 s9 s) ?+ d
;;;;;;;;;;;;;;;;;;;;;;7 X- S( i2 r' d' V( B( T& X! w
;; Setup Procedures ;;
- o) R) q% l1 F3 B, |2 r1 H# e;;;;;;;;;;;;;;;;;;;;;;4 |! e8 ]) B& J
; s4 ]9 e( M. j; F; H
;; Initialize the display by giving the global and patch variables initial values.2 F# O5 m9 b/ }5 m% k2 b
;; Create num-cars of turtles if there are enough road patches for one turtle to
7 F5 A1 d5 ~+ q1 ]  M;; be created per road patch. Set up the plots.  j$ |% }- ~+ P8 p1 l
to setup
/ v( S. u, {* T- E* V" Y  ca( S* O% O0 r8 K6 I: K
  setup-globals6 h+ e! j1 p* p% a7 ]
: H" z# H$ X7 O* k/ f' p
  ;; First we ask the patches to draw themselves and set up a few variables
+ F! P- p+ D$ c6 Z: x1 Z' o1 u  setup-patches
! M1 l# @9 r$ A  @$ ^. B2 h* u' l  make-current one-of intersections4 }, q, ^# A3 Q' g
  label-current
9 d& ?5 d+ T7 z3 `1 _8 B; I0 T, R# d5 a( H/ C7 H4 a& ?0 B
  set-default-shape turtles "car"' i. _6 Y4 l8 O% F! b

; J0 W: a0 L9 p' ~) v6 n7 X5 R" B  if (num-cars > count roads)
0 x9 J. W6 u- D; }$ g+ A  [7 G* D  e8 F. Z3 ~' u
    user-message (word "There are too many cars for the amount of "
- ^5 |4 w4 x: M/ Z  N                       "road.  Either increase the amount of roads "
/ C5 b' F  }- E                       "by increasing the GRID-SIZE-X or "
  b" N0 m" K" c% B                       "GRID-SIZE-Y sliders, or decrease the "
1 u" g1 U& S9 i1 O                       "number of cars by lowering the NUMBER slider.\n"9 j7 T9 p& v7 n
                       "The setup has stopped."). O2 F, }, D; r& _7 Z& d) z
    stop4 t) X: X1 l5 v# m& i2 L
  ]
4 w1 [- z2 T* r- }6 ?# S3 j
, Y/ K+ H. K0 u+ s% @8 y0 i  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
: B# B. E! C" h. a! |  crt num-cars
, T% C' A" w; y0 z' M% R  z  [
3 J* D: U* U& R0 M; u    setup-cars( u5 G4 Z' U, f' L/ I+ g* K: Y
    set-car-color4 S- @3 d: B; F3 Z
    record-data
- h* V; T1 }: \7 ^  ]8 g. E& _7 {2 C0 K3 J1 [! `
% K, K4 X( l; g% g$ C+ [$ N# Z
  ;; give the turtles an initial speed5 j+ L, }8 l: D$ c5 x, ]: V
  ask turtles [ set-car-speed ]
, @3 g5 K! v$ K! M: F5 g4 d1 J
. B2 ]1 H6 x" y, H' n: C9 _& n* ?  reset-ticks8 y$ ?( E7 ~9 ~, f* {
end
& V' ^& G1 g/ d1 T( v  P& P- W& Y  |
;; Initialize the global variables to appropriate values
" |# _# m6 r: K* F9 \; b8 X% Tto setup-globals
% A/ H) k" i4 B5 \' D  set current-light nobody ;; just for now, since there are no lights yet
! @9 [( X& t0 a  set phase 0$ T! C$ p7 t* ^4 ~9 G9 |
  set num-cars-stopped 0# E1 d7 B$ a$ u3 k, P
  set grid-x-inc world-width / grid-size-x
6 [  m& l5 ]6 I, V! @  set grid-y-inc world-height / grid-size-y( _1 ]5 p( r) o, ^1 M+ z

( `; z' @- M. g+ z  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
- p2 Z5 \6 ~! g6 M$ A: P5 A1 n6 W  set acceleration 0.099
* q- u' V! G( i( pend6 {* _% q6 I/ y/ M' m/ ?8 E0 d

( \6 o4 A, \' N& ~! D;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  N4 X0 t! ]1 r;; and initialize the traffic lights to one setting
/ I1 M( e5 c# T' uto setup-patches
/ n4 ^# P" M, j+ k, x! T! m  ;; initialize the patch-owned variables and color the patches to a base-color& e0 a. ?4 p* L7 q
  ask patches
# K6 V7 T& o3 }  [7 z* Z2 S. D. a
    set intersection? false2 e8 I3 H! i: s0 Q
    set auto? false
# _1 H  {- J& y1 M$ Z$ r  {7 X    set green-light-up? true$ ^9 B( j! {- B" d( m
    set my-row -13 h/ F; z. h8 k+ M7 a1 A
    set my-column -1
; T7 u. t1 O6 C6 D- V/ f    set my-phase -1
" D% q. V3 |4 t. v0 C3 q5 [: X    set pcolor brown + 3
- V, u, Q: m& B) d  ]
4 W1 K' D9 E. [& T" k* ]
+ F& E( A; V3 c3 F  K" J  ;; initialize the global variables that hold patch agentsets
* I5 Q" e8 [5 m  A/ J0 M. a7 R* Q  set roads patches with. O; p( @8 q6 f% D# F+ c/ x3 |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& g, B% s7 [9 }# b& R) {    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ Z: W0 I$ O2 m, m# d% k; \  set intersections roads with
% X% t* S  s/ @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and" a: E- M* _5 J" Y2 h3 Z+ o( X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 J* P2 j6 B; k1 i- g) D0 E: U" k0 Q, o* ~! o4 ^# _
  ask roads [ set pcolor white ]
# g& l6 ^- f$ k9 q+ M2 E) u; `    setup-intersections$ y, x5 W/ W7 Z& g0 k/ x9 Y9 t
end
5 ~! _) M8 J/ l+ a1 s( h其中定义道路的句子,如下所示,是什么意思啊?/ k; c. d# U: a
set roads patches with  t. f+ a5 C9 d) U4 v0 B- d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 w1 [/ @; ~/ Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ n0 e" B7 V/ n) D8 A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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