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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 S; U6 P2 I) B- e# N2 Unetlogo自带的social science--traffic grid这一例子当中,' ?1 z- `% {3 @' X: z7 ]  d( j
globals& V* a& D: ^/ w! e4 C
[! T  R! m# X6 l
  grid-x-inc               ;; the amount of patches in between two roads in the x direction) b6 Y: l9 J0 f/ r
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) S  {, @* |2 r/ p8 \  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* Z% g/ ~7 N% v
                           ;; it is to accelerate or decelerate+ L& I+ K2 M, X0 M, m; |
  phase                    ;; keeps track of the phase9 W/ J# z# V' k+ _0 i
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
5 X8 k. p, M# M/ D& \  current-light            ;; the currently selected light
+ w; P. n, p9 U) o: H& m$ B! m
4 d" r3 D4 v+ _* d' `  ;; patch agentsets3 Q7 C4 S7 l; c+ [
  intersections ;; agentset containing the patches that are intersections
' H) v; [9 \8 D  roads         ;; agentset containing the patches that are roads
* O( `, N. N1 y" l5 Z]
9 Z" Z: Z9 x( i" A# s% o8 {2 u! p! g' o% i: C: j. \" W
turtles-own8 \0 u- s& G; y1 i& U. J4 ?
[
6 z5 H! r# I4 ~  x1 G  speed     ;; the speed of the turtle
1 {. {) W5 B; c; y0 z) X$ |, ]  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
( K! r. ]# l0 F% ~' s  wait-time ;; the amount of time since the last time a turtle has moved) `+ |( S1 t2 m, o
]% ~' A& d& O8 Y' ?6 L% D

  A9 ^1 J6 L* j9 Epatches-own
/ F# a7 Z* w9 Q! \8 L: H4 \[- v2 M# j; |9 ?- q3 E
  intersection?   ;; true if the patch is at the intersection of two roads
0 o8 ^% A$ A8 @& |$ s& t; p  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% n. l# X% F% @) I$ \7 I" B                  ;; false for a non-intersection patches.
# e/ Z4 c! T4 ~. V! x+ @2 m% H  my-row          ;; the row of the intersection counting from the upper left corner of the5 k5 T0 c. O" a; S# ^% Z
                  ;; world.  -1 for non-intersection patches.
" B, G) Q+ x& X3 Y& {& ~  [  my-column       ;; the column of the intersection counting from the upper left corner of the4 O: a. H- u1 ~1 `5 G2 _
                  ;; world.  -1 for non-intersection patches.- _; F$ ^% N! n
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
8 Y' G6 g, F) o) T0 i  auto?           ;; whether or not this intersection will switch automatically., ~( u# }- v6 x9 V
                  ;; false for non-intersection patches.# x# F) w. }7 z" P1 e1 }
]: U: k# O: S; Z. G
( u( {, R# d: O! s
1 B# R4 t1 k7 h) n, o
;;;;;;;;;;;;;;;;;;;;;;
* u/ T4 ^" I- c6 y% w; `0 Q" k;; Setup Procedures ;;
# y7 b) z( E$ }2 Y' r% i;;;;;;;;;;;;;;;;;;;;;;
7 P/ t( s9 J2 ^9 a4 I8 X' h3 _3 h( `( T! q$ `8 N4 _* v0 z8 I
;; Initialize the display by giving the global and patch variables initial values.) Q; N" u. M# I* d/ Z! f
;; Create num-cars of turtles if there are enough road patches for one turtle to
1 n0 y& a) L1 Y) C3 N5 |;; be created per road patch. Set up the plots.: P& N0 f2 X- t
to setup! ^; u& l8 ]* w6 U9 _1 i
  ca
7 @  b( P+ H3 U# o1 D  setup-globals0 @. t$ z) q: t

+ a$ f3 G8 L/ g8 W' f8 A1 {1 G/ ?  ;; First we ask the patches to draw themselves and set up a few variables
, _1 G+ I% I& x  setup-patches
# B  ]& y# a  p% [. k9 Y  make-current one-of intersections
4 o' E, R# u4 U/ o3 t' x- g& z  label-current! N% j/ R% p3 P5 T5 t0 b& e& ^
# f; u+ q( q" B- F! j7 [, n
  set-default-shape turtles "car"
7 P7 v& L+ S$ n1 |. U) Y' z
& G4 D& |# I9 R$ c  if (num-cars > count roads)! y+ ~4 c+ f7 @+ v. J' ]* G1 `
  [- X' e+ [7 P# }8 u) |0 S
    user-message (word "There are too many cars for the amount of "
& I$ w9 R8 o( z                       "road.  Either increase the amount of roads "
$ {" M: K* o* {/ g9 k                       "by increasing the GRID-SIZE-X or "
) u0 B4 v$ F7 ?: X& P                       "GRID-SIZE-Y sliders, or decrease the "$ u/ U/ ?# [& s8 A, ^
                       "number of cars by lowering the NUMBER slider.\n"& C/ F, b, _3 j  X. _
                       "The setup has stopped.")
$ b. d0 |5 E9 z7 `# R    stop
- C5 W  l0 ]; h! ]  ]
: p# o7 T8 k; G7 g7 i
0 q! M& V; |4 ]  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' A: ~5 t: R- d, [  crt num-cars# U7 Q+ p& V# }% p$ O) t  C
  [
& T1 b8 U* O$ V- i4 Q    setup-cars" [8 P, w  f1 {9 S* j8 Q
    set-car-color
* a" Z. L; {; _' f/ ~    record-data
+ U9 A' M3 q5 {* b  ]
) v) n6 A. ~4 P/ ?* k3 k
; S, U1 u, @( l! |  ;; give the turtles an initial speed
$ t+ D: B2 w" j& _9 e, _  ask turtles [ set-car-speed ]
, N. c- x& Q7 u. ?% P1 p3 v5 L5 C# L$ U- ^$ R3 p4 }
  reset-ticks
0 y* u0 I1 ^; xend) N' e& U- j9 t: A# p7 i% `
5 K! p3 l& @9 X4 V( r
;; Initialize the global variables to appropriate values: h6 l# D/ @/ N) r% `3 y
to setup-globals
# [/ t2 Q. @$ b: A  set current-light nobody ;; just for now, since there are no lights yet2 K7 z2 _6 b9 Y6 |# @7 V# _) f
  set phase 0  M1 R6 H* j9 m0 \% ~" a- G( m: b7 \
  set num-cars-stopped 0" o7 Q, T% I5 Z$ @9 {$ ?, }4 U
  set grid-x-inc world-width / grid-size-x8 |9 `( P8 k+ n' |
  set grid-y-inc world-height / grid-size-y, X  H) p/ D1 {/ W% R+ q
: A- s9 u1 C1 b
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary7 ]1 P% U& g7 e& u
  set acceleration 0.099
; p& V& _# F' G: b' Yend6 C. a# X7 w' T( R  w4 n% w
* u* f, B- E9 k/ x1 l& S- N; V& Q% n
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,; j) S- ~/ k. y6 l( [' I
;; and initialize the traffic lights to one setting" k) S& H- F: [
to setup-patches* T+ l8 V9 |" p/ e
  ;; initialize the patch-owned variables and color the patches to a base-color& [# }- S- M0 |& u+ m
  ask patches
! ]  ]9 [; f7 A) n: P  [. C9 p' o0 M# M9 j" v$ }. h6 j" `
    set intersection? false( d" }5 g& d- t4 o+ S7 L( g' _
    set auto? false' R0 t3 X$ g8 s
    set green-light-up? true
) H9 v6 `$ D2 x7 [- d8 r' _    set my-row -1  }! d0 _6 }9 `' Y# {6 ^, T
    set my-column -1) c) `/ C. X) a( W6 |
    set my-phase -1
$ y7 e& p2 h8 S( y; x: h    set pcolor brown + 3
, |% V( \6 K9 j6 s6 |: L$ C  ]
1 e! A0 ?4 h# ?. `2 E
; M% O1 S8 q/ A5 Y9 A# R2 ~: c  ;; initialize the global variables that hold patch agentsets
9 r+ T" H! M- ^* d+ G" g  set roads patches with# x/ z& i1 [& `: O2 y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! ?8 Y/ J1 w( x% V7 {    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ p+ {9 Q* a% c( y  set intersections roads with5 a5 P- U1 g9 r4 w7 @: j+ k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and! R( A  [* ]8 j7 _9 v- l8 L  c; E8 s
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( m, l1 k: s1 _" k- V6 ^8 q& U9 o5 m0 ~# p% x' z
  ask roads [ set pcolor white ]
* H  R, s( y& r' T5 o5 j    setup-intersections
' ?" M3 `' i1 K% [+ Wend2 B9 ~3 T4 D+ w+ u
其中定义道路的句子,如下所示,是什么意思啊?
& H: w/ U- A6 C! r set roads patches with
" k+ B& X5 I, g0 j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 j' I- d% g. b9 j2 A' B& U/ @2 L
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ `4 \0 g. x+ T; G. k" W" J& F2 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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