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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 G1 |8 e7 @8 P( I# Nnetlogo自带的social science--traffic grid这一例子当中,# S3 [  G  E! b, U" s5 F' n  p5 Z
globals# \5 g! F& D# V/ S/ D& A2 J8 D
[
) J. i3 D6 U' [1 d# i) Y1 k% s  grid-x-inc               ;; the amount of patches in between two roads in the x direction4 {8 n  q# A) `$ Z' c
  grid-y-inc               ;; the amount of patches in between two roads in the y direction" y; E6 c7 y- n0 ^  H
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
: x# Z. K  z5 V' r$ R  `$ X                           ;; it is to accelerate or decelerate" V" l2 M! y% X9 ?3 Z. [
  phase                    ;; keeps track of the phase
" I9 l0 p7 |6 P( `  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure4 ?" H, w) a* O- L& z, t
  current-light            ;; the currently selected light5 y5 J! @9 }+ a( O: i
# Y8 ?) x. l  J, Q+ C
  ;; patch agentsets
4 @. T9 A, B) S4 }" @9 `  intersections ;; agentset containing the patches that are intersections& T* R+ X7 N+ t( ]$ U
  roads         ;; agentset containing the patches that are roads/ U7 O1 w& T% r: A
]
% p% q' c0 A) I* {! j! s& C+ S8 U- Y- W* h  d; Q
turtles-own! T7 G3 c! N3 L
[( U* H0 ^; M+ @4 J. U- J8 D* K6 W
  speed     ;; the speed of the turtle2 ^5 Z7 M! \- _- k$ O% [
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, C. }# a: R% R  F: R/ a8 J$ [, w
  wait-time ;; the amount of time since the last time a turtle has moved
/ Z7 w- O8 U8 z]
7 z' y! M. ]% J; V: k' O5 q) P+ ~9 s, v
patches-own
& w# `, p  d5 i* i[3 L, H% t  @. i/ D
  intersection?   ;; true if the patch is at the intersection of two roads  o9 e( D& \' i& L  u' T2 T( X8 T& p
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.& E5 L5 E3 B% \1 K* `
                  ;; false for a non-intersection patches.. u. j- b# _& x% r4 q: E; U5 S/ G
  my-row          ;; the row of the intersection counting from the upper left corner of the
. u% W+ U& c8 ]- L  v/ O! J$ \0 R                  ;; world.  -1 for non-intersection patches.  w3 t- R& n( x  j! A
  my-column       ;; the column of the intersection counting from the upper left corner of the
1 {5 d. Y5 r1 c+ W                  ;; world.  -1 for non-intersection patches.$ _. K# M7 }; _% L* R
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  l: \% U6 l% i- w) i  auto?           ;; whether or not this intersection will switch automatically.& \* i( W  a1 d4 J. {! i3 R
                  ;; false for non-intersection patches.
; Q# U& j2 M* m$ Z$ J# Z' n7 j]# A) s, S- |: i7 O2 Z& J$ Y
1 {' u; d: [9 s! T1 j1 I; V

8 s  s$ M. Y4 N  K; z;;;;;;;;;;;;;;;;;;;;;;( C. d2 Z% L3 u  R8 Y2 V; Z
;; Setup Procedures ;;% b. ^2 u5 ?: e4 a( h7 d( |# F
;;;;;;;;;;;;;;;;;;;;;;
' [: M2 j/ T8 r6 Q" v
* N% B; z, }+ u0 c;; Initialize the display by giving the global and patch variables initial values.$ F3 h* c1 J' B+ W/ `& Q
;; Create num-cars of turtles if there are enough road patches for one turtle to
* Q4 P8 v; R& J1 @# ]2 a;; be created per road patch. Set up the plots.
" t/ j" z/ _3 K6 `& k% Pto setup5 i' g. I1 N- \4 q
  ca: V2 i5 S" k  l  ?2 [4 s1 I+ s- A
  setup-globals
4 B9 o  Z; O* y/ X% C3 b) Z5 b) d& h3 i" y7 r. [( r( M; m
  ;; First we ask the patches to draw themselves and set up a few variables
6 ^) B; F7 @' `8 Q$ q" F* ]$ q  setup-patches# ^& L, N, J- c2 ]3 f/ c/ Q; M
  make-current one-of intersections  _7 z' S8 p5 u- z% z- I' f
  label-current. S, H! C2 U& m4 k
7 s* m8 \0 ^3 E7 _5 D& z
  set-default-shape turtles "car") J8 `! v. M& I, `- x5 K8 a% B& U1 {

* S. ]9 c: p1 F. x" w* H  if (num-cars > count roads)  S0 e: e: p3 t( U/ O* F2 a
  [+ p- \' w' @" I* u( d
    user-message (word "There are too many cars for the amount of "
6 \9 n5 ~* U8 w                       "road.  Either increase the amount of roads "3 @' k1 |9 P. c
                       "by increasing the GRID-SIZE-X or "
" S- w. c, F  D0 [. m                       "GRID-SIZE-Y sliders, or decrease the "
8 m7 B7 d: i  y$ T7 V                       "number of cars by lowering the NUMBER slider.\n"
, Z, B' K% x$ G6 U                       "The setup has stopped.")# W7 L, @8 I, d, s  M  f3 Z% g
    stop
6 h6 k) t6 G2 l: P1 |9 A, P  ]5 B& ]" T& N& w5 U) O% ^
! @# x1 s- M! W1 ~4 }; E
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
1 K7 D( M- @$ [  j5 }  crt num-cars
) f# e+ r! |& W7 T  [
1 w  ^7 C: ^( n  X4 l    setup-cars
1 j2 n9 ?$ A+ b" r: B    set-car-color* o0 n: |9 q7 K
    record-data" c4 o7 K# J% }- _8 q9 q
  ]
2 B6 o' \6 O1 b
/ Y; t* B4 m, S& K9 G7 F  ;; give the turtles an initial speed
: _* [3 y+ _9 @# {. a& t& l5 b* n  ask turtles [ set-car-speed ]- @& j; u, u% x& w  N
' V1 R1 T! v0 X% `8 V1 @
  reset-ticks8 g9 f, B. {0 I
end2 E; z8 k1 }+ @  i2 K, C

/ O& }' X5 I# j/ u  M;; Initialize the global variables to appropriate values! q6 d5 _8 J& B0 S
to setup-globals! k3 n2 f$ ^- i: `/ _: V
  set current-light nobody ;; just for now, since there are no lights yet
# o3 F7 t* C. L; o, [/ E" M  set phase 0
( U" V- X; H0 R2 \/ d+ B+ ?8 _  set num-cars-stopped 0. x9 I* w. A& F  z
  set grid-x-inc world-width / grid-size-x  y2 e; O  V1 M; M- X$ C
  set grid-y-inc world-height / grid-size-y
* M* G6 f0 @2 o$ p1 L5 d  D  B
: e3 p5 }7 l& l1 J8 s; S  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary7 `. t& \% s0 ]) H
  set acceleration 0.0993 J1 E& R4 E; j( D7 [3 y
end+ j; B5 [1 Y; X

$ c% m, j" h$ n: \% p3 F;; Make the patches have appropriate colors, set up the roads and intersections agentsets,1 m" C& d$ f  g4 U9 k
;; and initialize the traffic lights to one setting( l# e% @+ Y# @( U, k: C
to setup-patches% O6 N1 d! g6 X; f
  ;; initialize the patch-owned variables and color the patches to a base-color' n& i- g- r3 d
  ask patches4 R0 h: @6 c: J8 S2 S, s, E
  [5 y* u5 T7 v- \8 T* O
    set intersection? false" ^4 A" ]. f6 z  S- y' r8 u) b
    set auto? false% A) W+ R2 T9 Y1 q4 b. m
    set green-light-up? true3 E, i; Y, e6 ^2 c/ f
    set my-row -1$ E7 h& |9 O* P# z
    set my-column -1
# o  t( _# x$ m- r, r7 [1 ~; h% F+ Y    set my-phase -15 |. b( W  m' w8 f( L8 b
    set pcolor brown + 3) |9 N+ p6 f7 \0 o, D7 o; G
  ]
' e" ~1 q" @5 h6 @: r  U+ G% `& q  G
  ;; initialize the global variables that hold patch agentsets' e, d4 B6 n4 [* L7 s+ a& n# D% K- h' G
  set roads patches with! ~7 Y2 X/ r; [; P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 N4 A* E, L1 x6 I+ @( W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- W. O' ~  @; [$ s% u0 `  set intersections roads with% K! W& M9 C; ^0 o8 m& l
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and& h0 s: N  y1 J
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 g% T6 t  |  A) H6 I
9 ?( b( ~* p, N1 e/ k4 F9 P
  ask roads [ set pcolor white ]
0 r' p  @8 B# w( p$ n$ Z7 Q( I! `    setup-intersections
  n" _" f- b6 K' z" [2 F3 }% Iend
! ]2 g2 d& a! s! {0 {其中定义道路的句子,如下所示,是什么意思啊?9 W. K$ ]2 u# K9 B9 W
set roads patches with: i, _0 Y/ r3 S3 ^! I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; h6 w# D/ j, W7 ]: H& [% S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 E, f' T1 A0 j, I5 H
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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