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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。/ o/ y% P; i3 t, \/ s: D
netlogo自带的social science--traffic grid这一例子当中,
* J1 _& l+ g4 y" p* H% rglobals% T0 b" {' \) Y, y2 }" o. b
[) {+ M& p0 e! b1 M; h2 _
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
/ Y7 ], P4 h' S$ P: L  grid-y-inc               ;; the amount of patches in between two roads in the y direction2 d5 e( G- A3 Z& R  A
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if1 B* n6 q4 y* t" H2 L" r2 Y
                           ;; it is to accelerate or decelerate
4 d& @+ B/ m* X% ^% d% H3 F  phase                    ;; keeps track of the phase
5 p: S6 |6 r4 G% X  R" ]9 m8 G5 x; D! O  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
  a" n# h6 ]* E% J  current-light            ;; the currently selected light) Z$ u/ v1 J. d* w0 q) a- }# j( v

9 b5 z$ H! \+ O1 o! M) l  ;; patch agentsets/ ~' f+ V1 [* V  [  X
  intersections ;; agentset containing the patches that are intersections
1 S& U: x1 M- O( a' X  roads         ;; agentset containing the patches that are roads3 k; G6 h' y* h% d4 N
]2 N, J5 {# A; L  A7 h7 M' o
1 U; B8 ?! n7 f% L& |& I; U4 U
turtles-own  z$ S' K. P& ], K
[/ C. a2 C9 U3 B! N  S
  speed     ;; the speed of the turtle
5 V6 ~" I0 v: x. B/ N4 N  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
/ b4 X5 N& e) K; o( j5 ?  wait-time ;; the amount of time since the last time a turtle has moved
# r) b' J+ f  u& [6 h$ |1 z- @7 e' ~]2 ]9 O! e  `. p

2 ^2 ]$ [# X5 L/ _8 y+ c/ fpatches-own
2 @) P9 F/ i6 K  g8 h3 F: E[/ j  w8 V2 O1 W! \( ]
  intersection?   ;; true if the patch is at the intersection of two roads
* x- H  z' |5 M' Y; ]  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.2 M: N% H: D, Y, ^3 F) l1 s: ~
                  ;; false for a non-intersection patches.7 O: f8 L4 i! E) ], S
  my-row          ;; the row of the intersection counting from the upper left corner of the4 {) f- b5 x; [( n2 k( g
                  ;; world.  -1 for non-intersection patches.
- @# `( p5 H' J0 `: J  my-column       ;; the column of the intersection counting from the upper left corner of the$ y6 }# l6 @$ g- y( {& `. O
                  ;; world.  -1 for non-intersection patches.4 r( s. c# ^* e0 N+ B- \% J
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
4 {. u5 C; U, C. ?# W, Q  auto?           ;; whether or not this intersection will switch automatically.
" R6 }3 e% Q! A+ q4 b6 v                  ;; false for non-intersection patches.9 M- g  P$ o5 K& `% j. d& O8 o
]
$ o1 @' w3 e5 w7 g' h$ h$ L1 q0 N/ L) `0 [; U7 W' M
: m: C! H+ E) o+ @( \/ L
;;;;;;;;;;;;;;;;;;;;;;/ `9 o! x6 s& o
;; Setup Procedures ;;4 D- ^% L2 c4 C& b0 }* H
;;;;;;;;;;;;;;;;;;;;;;- d8 \6 v& r5 C) r+ ^6 ]' a
$ q$ L$ l3 h# j# S( i
;; Initialize the display by giving the global and patch variables initial values.) B/ K6 \) ]: F
;; Create num-cars of turtles if there are enough road patches for one turtle to8 ~( {' W! |) E9 ~! ]! a
;; be created per road patch. Set up the plots.6 I1 L& }* {! r: W
to setup
; @% s3 I) l8 w7 [7 Z  ca
0 l* I' c1 z3 }4 a0 y" h( w  setup-globals
$ Y$ R! {# O' ~4 N) B1 O0 X$ @( V: l/ O( F6 S) R
  ;; First we ask the patches to draw themselves and set up a few variables
, D3 l; w% k5 L9 B2 h* b* C+ Y# V  setup-patches
9 l+ L- h4 b" H, T  make-current one-of intersections
1 x& z. j9 w$ N5 L  label-current
$ S6 e+ n4 K1 ?+ M7 r$ @
* H, h  c0 u0 w  Y* U  set-default-shape turtles "car"
) k; c4 l. o% k; s; U6 |
; @4 n. I; `' @* ?, x  if (num-cars > count roads)% h* k7 M; {: X. F4 k
  [. P; l. h: E! e* f8 U: T
    user-message (word "There are too many cars for the amount of "( w7 Y6 N5 b! ~
                       "road.  Either increase the amount of roads "! |1 u* f0 r, {6 K2 b* V# \
                       "by increasing the GRID-SIZE-X or "
) P4 I8 h1 F& a  ^2 G0 x' U, U# T                       "GRID-SIZE-Y sliders, or decrease the "; i$ ~& G  T  F* n9 a" R9 ~6 i
                       "number of cars by lowering the NUMBER slider.\n". J# a" O. W) E; r* L; ^  _# J
                       "The setup has stopped.")
0 w  g+ z/ I1 ]! o    stop5 [* Q( u$ U& |+ P/ A$ I
  ]. V9 f( V/ [3 b: v8 P* L
7 e. ~, A+ N0 q7 g
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color; x# Z& U( s; S. B* j4 \1 S( p
  crt num-cars: {* c8 G- H6 R; r
  [
9 t: P7 _. J5 j    setup-cars
9 A. H  l0 J/ s7 w    set-car-color
6 C  a$ a- p/ z; g0 e    record-data! q, a3 @4 c$ b% v% ^/ O9 u5 t
  ]
5 I* [, m, m' Z0 v7 M4 a8 t
8 @$ W* v3 D( F. p  ;; give the turtles an initial speed
$ }) x/ t8 S6 a0 i  ask turtles [ set-car-speed ]
5 \7 O5 U3 u" b; C  y9 @5 D* C4 j! q7 y% |  C3 B5 a8 i
  reset-ticks
1 [4 R& o5 ?3 o2 W3 E8 o# gend
/ ]" S; X2 o3 u  ?4 t5 r+ f$ t, u- K! x2 X# D( V
;; Initialize the global variables to appropriate values
, L8 R' V( M: Rto setup-globals
( @( M8 @) e9 n; Y$ `3 F3 _  set current-light nobody ;; just for now, since there are no lights yet% u6 \3 y! a& G  [
  set phase 0, i6 |1 V+ N% R6 }
  set num-cars-stopped 0' t$ ^% Q2 Y. B$ [9 h% ^2 i
  set grid-x-inc world-width / grid-size-x) H: D( [& L- o" I
  set grid-y-inc world-height / grid-size-y
- u( w9 H- [# e, Q+ M1 ?7 J8 _- _8 a
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary% T1 q' }1 [% p) y3 J- i6 H# H
  set acceleration 0.099& t% x. k0 L/ F8 _' }5 T5 t
end
) j7 L* g- Z6 ^, C" l$ J0 K/ ^; G
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
2 g) U) X, l+ ^4 S! [6 b;; and initialize the traffic lights to one setting
: I. F& n2 Z; |3 B7 o6 ?to setup-patches% |& L) y" P& v6 D4 N
  ;; initialize the patch-owned variables and color the patches to a base-color
6 m: [* A, C& L/ W; J5 ?$ H+ W  ask patches
3 Q: H' @4 c1 {. ?- j, `+ B% h  [. v5 g6 J% W6 {$ |7 z# P
    set intersection? false
6 F( U! Y- U9 `; L    set auto? false
: e& [- E; L# t- k9 [8 J& g    set green-light-up? true* J. _/ G* k+ g
    set my-row -1: }5 t& l+ s2 h& f4 Q* x# k  f
    set my-column -1& i' y# ^2 i: H
    set my-phase -1
5 k6 a  V6 m) {0 Z" c' H    set pcolor brown + 3
) L" E2 u7 l; r1 t  ]
" I; Q& ^/ l) U! s% K( U2 o3 G) m8 O! s
  ;; initialize the global variables that hold patch agentsets* o( o4 \+ b+ l# U) F$ V& G
  set roads patches with
# O+ Q; m  K  o. U  u7 W! s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& i5 U5 F' {0 j$ ]9 I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 B6 K- z) `3 l; I% _, [" W, g) B  set intersections roads with
0 g  S  c( V& j) z( `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and! s5 \! Y* S2 s& V% i8 t
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 H# p2 x: L  n4 ^3 U- m: W& {4 W7 s9 U# l& v2 H# h
  ask roads [ set pcolor white ]: T; L5 r) G' |) O. Q
    setup-intersections2 O% X& ~$ D$ K: t% q: p
end
6 v% L4 Z; ]0 r4 L9 O; u其中定义道路的句子,如下所示,是什么意思啊?
& k* @1 O: C! f/ m9 g* ^ set roads patches with  p5 ]4 V- p5 A" H- H) _( T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 S2 `" R4 p2 w- V4 X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& }+ e4 r+ B% \8 v
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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