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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。
: |5 J3 ]6 l+ \; Tnetlogo自带的social science--traffic grid这一例子当中,* [0 i- y: f5 y* H% |
globals4 M$ |4 i7 s* B% d/ H: |0 g3 z
[1 Z3 S* y7 D' V3 J" L8 L" S4 {* ?
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. |0 [. w" t6 f: I: m2 S  grid-y-inc               ;; the amount of patches in between two roads in the y direction
' s/ T1 m9 r, \, X  acceleration             ;; the constant that controls how much a car speeds up or slows down by if' [' f2 C3 ]! N8 z9 O  \1 L
                           ;; it is to accelerate or decelerate
; R  n; o% l1 X2 Q$ g+ n  i  phase                    ;; keeps track of the phase
/ a  r" B/ E1 o* _+ M) c* Z  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure2 u& y& N$ ?8 Y, L  T$ c
  current-light            ;; the currently selected light
8 Q# V: f6 X$ a$ m: N1 m
$ ]$ z8 B9 U) H! H- r8 @5 y8 h4 U  ;; patch agentsets  l# G: @& g' K0 k) A
  intersections ;; agentset containing the patches that are intersections3 y+ i2 n/ T' N3 N$ E% ^% h
  roads         ;; agentset containing the patches that are roads8 `. {5 y! Z9 C# ^) e
]9 b5 V5 O! J. Y8 L4 |8 _2 F
* F+ h4 Z& L8 Z
turtles-own; i8 [3 Z3 z7 M# V
[
/ z8 _. E8 P8 B  speed     ;; the speed of the turtle
2 [9 i( F' m4 e& M8 w  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& A' S5 B) J0 X6 P1 S
  wait-time ;; the amount of time since the last time a turtle has moved
4 s. f! z' N/ G* H; T8 t6 ]]
3 N! ~5 f: I( B& l2 r, a7 {' l4 [  P$ D8 T0 U+ x8 @0 H! a
patches-own
/ s" l2 }' ~" E* ?6 D9 ^( }[" Z7 M) e! E  l& f* x0 F  p
  intersection?   ;; true if the patch is at the intersection of two roads) e# ~; I- M8 M/ l* Z  ~
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
6 w% j6 T/ P" i                  ;; false for a non-intersection patches.1 [. R* K0 z% b7 \
  my-row          ;; the row of the intersection counting from the upper left corner of the! \& Z( L* |5 b
                  ;; world.  -1 for non-intersection patches.
0 k1 i& p* _0 a  B9 f  my-column       ;; the column of the intersection counting from the upper left corner of the# D( H" e* M" G* F
                  ;; world.  -1 for non-intersection patches.
) w; t( f1 c5 b6 E; q  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.9 z6 o! ^2 B% D4 E/ X* x
  auto?           ;; whether or not this intersection will switch automatically.$ }$ G* O2 b2 Z/ p2 S$ }9 T* ~
                  ;; false for non-intersection patches.
6 b. G) ?; Z: w( e& v]
* i+ z6 W+ J& f, q+ \$ S
% M# s  T4 r& J" D' h  R: r& ], P
;;;;;;;;;;;;;;;;;;;;;;  Y, B1 e! V& k  p5 Y/ v6 [# @4 O
;; Setup Procedures ;;; Q! X& R! y0 J7 x5 Z" x( X+ L
;;;;;;;;;;;;;;;;;;;;;;/ A9 N9 Z7 h# e, X

* i/ |8 j, y8 m* Y+ J% h1 |;; Initialize the display by giving the global and patch variables initial values.
& D3 h2 `2 m& c, `;; Create num-cars of turtles if there are enough road patches for one turtle to
8 j  t3 l  @, I( y;; be created per road patch. Set up the plots.) h: l6 i& u/ o& k0 i
to setup/ }3 s, j0 h3 R8 v" f6 N) A
  ca
* s5 D+ p7 R; s) d  setup-globals
) ?3 w3 q* }/ J4 a+ u8 R2 g6 ~7 r/ e- P' L9 U" R# P
  ;; First we ask the patches to draw themselves and set up a few variables" M- ~7 v7 b& O' F' y
  setup-patches6 z8 C' p# |$ v
  make-current one-of intersections& v8 i$ k0 T7 l3 w& K7 H# Q( M
  label-current+ D9 o  R# a# f+ c0 \

( |/ j! `9 v3 ~( _  set-default-shape turtles "car"- \8 `4 B8 \9 m8 T9 e+ g4 t! Q5 u9 y

$ x& P$ ?( o% \& ~  Q. u  if (num-cars > count roads)
- B1 u0 b) N' W8 R  [. L5 G: N& c$ T# C  _! \
    user-message (word "There are too many cars for the amount of "5 ]% U5 f7 k' j1 z7 d1 M& u( W/ x, u
                       "road.  Either increase the amount of roads "
+ h1 |/ a& k* n7 ^  g                       "by increasing the GRID-SIZE-X or "
% _# Q+ W! ?( L. k# ^- \                       "GRID-SIZE-Y sliders, or decrease the "+ c9 d/ G2 t% ?" F9 \
                       "number of cars by lowering the NUMBER slider.\n"
' p! m/ a4 m8 P" s# k4 l4 a# y                       "The setup has stopped.")
- n' U3 u/ k! Z; J9 y    stop0 }5 z0 g0 ^" X3 p( b& H
  ]
: c4 }  I  f# p) D, j0 }# b* C) y) t, t- X! l2 {: \3 b
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
, @( _7 G" a" p: l; M6 j  crt num-cars
0 ^' p& ^, G. i4 i  K  [
+ o- m% h: G# u; h) l( a! Q    setup-cars; m! ~' \& }5 T% B: g& m
    set-car-color( p. {$ M+ \4 W# m7 e
    record-data1 x8 ^- M4 T" s% q
  ]
' r* B% I( Q+ R" c' H6 U9 `% k+ G6 N8 y% k
  ;; give the turtles an initial speed
8 L9 o0 H; r0 y! _5 c3 g9 u  ask turtles [ set-car-speed ]  v- T: x+ D' U1 \3 [

' K( M% }" |) V  reset-ticks5 f4 I8 S6 c" o" Z
end
) s6 s4 p* I2 W( m* s- z9 H$ b3 E6 ^7 V( c8 k$ J
;; Initialize the global variables to appropriate values2 c4 m# c8 J# F
to setup-globals
4 L+ a2 E- Q. q# D, I  set current-light nobody ;; just for now, since there are no lights yet
, i- K0 K7 j; u& b3 H; Y6 R) j  set phase 0# w1 T" L, m  {* {, Y
  set num-cars-stopped 0
9 Z3 }* I8 q- y0 w+ o- H  set grid-x-inc world-width / grid-size-x# ]% h3 R/ G; D+ a+ w5 o5 s8 x
  set grid-y-inc world-height / grid-size-y8 f# A3 X. J9 w# K% m5 s
+ {# j( E* Z8 ]
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary+ C! H( s2 g6 K$ i! U, K" N
  set acceleration 0.099/ A- S. m% e8 B2 B, Y
end
- K' f3 D0 G9 A- K
9 f2 R7 \. R) J/ D: {3 B; T;; Make the patches have appropriate colors, set up the roads and intersections agentsets,  s' a- n, B0 q% k+ M& J
;; and initialize the traffic lights to one setting
5 \, ?# s6 C4 {# U- y  ^2 I, _to setup-patches
" V- P8 Q* S9 w9 B: N  ;; initialize the patch-owned variables and color the patches to a base-color8 L' f  r9 ?' z, k4 o
  ask patches# C. K& K. S2 a/ r5 P7 N6 k5 X
  [
7 ~3 I. R: C! s5 D; y    set intersection? false  y9 A7 _% s* a: O; e/ _+ k
    set auto? false
& E2 n3 `7 s% P3 o4 J- B$ B! h8 [    set green-light-up? true( }: |# `. I( Y
    set my-row -1
' J% V3 w/ Z5 E( e    set my-column -1/ G4 @# b' i$ `4 P& |# b
    set my-phase -1
# e# h; ^8 W* N    set pcolor brown + 30 c7 r' ^9 [" k: e3 s+ R0 }
  ]
) P' w4 x( Z8 @7 j9 h& @7 o- P1 |( a$ f3 p1 ?$ _  ^6 B
  ;; initialize the global variables that hold patch agentsets
& C% b& j' o  o4 T6 u: U  set roads patches with: L( r! \; `- S+ T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& z; f: g% S4 U+ \! z, G* h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& @9 l4 U9 H1 B2 Y7 e% J  Z
  set intersections roads with
+ f2 r0 M& Z# L) s2 u% f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and. h5 H+ s4 @$ F/ S# F9 L: p, [
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 M( t" a0 z" Z5 m
9 u+ B4 y# c( G
  ask roads [ set pcolor white ]
0 }/ J' V4 B" z0 |% M    setup-intersections6 g* [. A, W% ]0 |: T, h& X% k% E
end: P4 x# E3 U- }; C6 {8 J$ E/ ~% m
其中定义道路的句子,如下所示,是什么意思啊?
& E8 q0 _. A2 W9 [2 r set roads patches with+ [0 d( ~$ h+ ]) B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! R9 m- [$ {: }& W  M9 \2 N
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& a* i# B3 p: r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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