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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。
7 B$ w8 Z' @" J' G- gnetlogo自带的social science--traffic grid这一例子当中,
! b9 g7 w/ d& Vglobals/ O3 j# g  I8 G/ r' O0 ]
[9 G2 n( |1 {7 h. I/ |
  grid-x-inc               ;; the amount of patches in between two roads in the x direction+ T5 G6 B2 h2 B  j9 j
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 U8 \0 [# r1 D& L! E9 r% C  R- y1 P  acceleration             ;; the constant that controls how much a car speeds up or slows down by if9 N/ Q, G1 s% ^) C- R. J; K
                           ;; it is to accelerate or decelerate
) b5 W9 B# W/ G. c  phase                    ;; keeps track of the phase, h+ e9 a0 m! x# O7 X  J& W
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; h1 q/ m  `1 h& L  current-light            ;; the currently selected light* H  F$ c6 ^4 _) c( A0 u

; m, N! g* A& P, S& C0 C  ;; patch agentsets
* h5 g# B' l1 C; a& s  intersections ;; agentset containing the patches that are intersections) A/ M% L. s: B1 c
  roads         ;; agentset containing the patches that are roads, h* |- K/ m3 Z, J0 |
]# b6 R& H# i$ B0 e8 K1 p& Z$ `
: l  m) F5 W" b1 [
turtles-own  Z2 \( {6 ]0 I: o: ^2 i8 K
[
4 l: `% a* y% w' Q, i  speed     ;; the speed of the turtle
0 [2 a* U2 S7 z+ E; p% _  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
- P5 ~3 O- G# }% z  wait-time ;; the amount of time since the last time a turtle has moved
9 G- ~7 F& A# Z3 B8 X- B9 _]
5 Q" N* m" E, F  j* M1 Z4 |' [- L  \- h
patches-own6 a$ x4 @5 ]6 E3 M0 |/ i
[1 X1 g4 Z* ^5 Y: C$ o
  intersection?   ;; true if the patch is at the intersection of two roads
8 W" _, z* r0 G8 N) b! x' `8 U  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
; U$ x/ r. I* c! W                  ;; false for a non-intersection patches.
: ^8 X- g, \5 R6 o  my-row          ;; the row of the intersection counting from the upper left corner of the& V6 h2 C( @: ~) k
                  ;; world.  -1 for non-intersection patches.
$ Q% Z- o. R: {% }7 e  my-column       ;; the column of the intersection counting from the upper left corner of the# j0 c* O# W; m8 I
                  ;; world.  -1 for non-intersection patches.
( W; x, p% a& }6 ?  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.2 z8 V. e+ p1 D8 K/ O/ O2 o% z
  auto?           ;; whether or not this intersection will switch automatically.: ~" X+ W+ O1 D0 y2 D7 z
                  ;; false for non-intersection patches.
1 l( E* [& h$ M6 n]
: Q  v, T" c- {, h' b4 w( A! C2 d4 h7 U- }3 {2 a  u
2 d  K* r2 w2 s) F( b
;;;;;;;;;;;;;;;;;;;;;;
' n9 h" n& |& X; L6 i;; Setup Procedures ;;) [! K0 J" Q) Q4 A# X4 g
;;;;;;;;;;;;;;;;;;;;;;
& V% [- `; u+ I; s/ F; c! c# g5 \) I( p5 J
;; Initialize the display by giving the global and patch variables initial values.
: w! Q# B$ T( u+ B/ T* {;; Create num-cars of turtles if there are enough road patches for one turtle to
2 u- Q, g. d+ u, Z4 S;; be created per road patch. Set up the plots.: i$ x% r+ e; K: l* F4 \
to setup
5 U$ R0 o) g+ {* H  n6 B9 l. U: M  ca
/ z- J: |2 l6 R% q  setup-globals
! u7 T& ~- A  p$ L! _6 F1 k- n, \5 o& q/ B
5 Q. P0 e* f: r" `: P  ;; First we ask the patches to draw themselves and set up a few variables+ E5 w9 n+ n1 M1 V  t- I
  setup-patches: W9 }+ X" V7 c! o: r. x
  make-current one-of intersections, B: W: j5 Z/ j
  label-current
3 |+ ^+ K# S7 j( t/ P$ a- ^- ]# b' w5 K2 H9 r
  set-default-shape turtles "car"0 C5 v- E% O. F* X6 m8 U+ |
! f. T0 `& m$ }- P& R; E
  if (num-cars > count roads)
" B! S/ B* a6 V; s! N. S  [: B9 w2 \, l$ t) c& F9 ^4 Z% d1 s0 c# ^
    user-message (word "There are too many cars for the amount of "
$ }4 Q, d' G9 Z0 \. r/ I                       "road.  Either increase the amount of roads "& G/ M6 l0 l) k2 z& B, E! O1 k/ y
                       "by increasing the GRID-SIZE-X or "
5 l) l1 f1 a! c" h: t9 p                       "GRID-SIZE-Y sliders, or decrease the "5 d0 f, {- x  V/ ^) n$ o2 F
                       "number of cars by lowering the NUMBER slider.\n"# k0 s3 o) ]5 z; F
                       "The setup has stopped.")
2 Y8 D% R+ Q4 d    stop7 v- T  y" x8 d  ]+ B7 m: h
  ]% I+ X$ H% F/ w  S3 m% d3 M
$ m, B2 V; |0 W1 C) G* \0 i0 G
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
8 e; U. p7 S8 {  crt num-cars
2 W4 C& v( X1 c0 C1 w( N7 U  [& u% k% e2 _& U6 P7 q! U& e
    setup-cars
: r' D" h5 W0 O) k! ~1 ?; a    set-car-color
% g, D; R+ s$ t    record-data7 ^7 w: d1 n( B) ]+ X+ T" D
  ]1 c( u- G) `8 y# l; ^. X  K
# l+ e' L) F; J* G  R
  ;; give the turtles an initial speed( H( B9 \% a. p* X& q
  ask turtles [ set-car-speed ]
' w! E; P+ d& f9 V0 K- z$ O7 Z1 R6 `- p$ B9 v; `3 Z
  reset-ticks2 Y7 t' A% r' a' D; W. N
end" I8 f( f* w" j! |8 q
- s; p/ K, }5 Y& @: ^* M2 g- u
;; Initialize the global variables to appropriate values% C9 p. d0 `% t  z: D! }
to setup-globals
; x+ X9 X0 ]' F3 d/ x- R2 u4 F  set current-light nobody ;; just for now, since there are no lights yet
' `% @# d8 |6 x8 E" Y  set phase 0
: L6 h% g1 P" s0 S/ \; r  set num-cars-stopped 06 M4 q5 F# z! A" E8 v
  set grid-x-inc world-width / grid-size-x& F7 D6 N. {6 l6 T2 e. h4 @
  set grid-y-inc world-height / grid-size-y0 `( q$ Z" d7 J' E  A: [4 C8 o
- A) J& {' M! P7 }( \/ y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary9 U( ?3 o+ Q# G  _) u, v& Y+ w$ |% C
  set acceleration 0.0997 A" S/ J. v. z& l
end- A. }/ {% E  E& K

( g/ p5 F* a6 o- C;; Make the patches have appropriate colors, set up the roads and intersections agentsets,6 L( z$ H; o: i3 J+ Y( Y
;; and initialize the traffic lights to one setting! M$ M: r- @1 N
to setup-patches- p9 S" u; u- G6 @
  ;; initialize the patch-owned variables and color the patches to a base-color3 N, P9 ]% C% f" S, `# s
  ask patches
5 z/ F. i* f6 z6 l  [* }9 {3 z9 t4 v  H0 @
    set intersection? false
' J+ F4 K5 L+ Q    set auto? false1 ~2 m$ B; k9 B6 e" ?1 w
    set green-light-up? true
% Y. D$ n3 n5 x! L3 x" a% W2 N    set my-row -1
  A1 E! z& {4 W' P$ l2 O1 r4 e    set my-column -1
4 U" g' O8 _4 a- ]! a    set my-phase -1( k& G2 m8 T$ {. X! Q
    set pcolor brown + 3- g0 M) C- i3 ]/ X& g: d! g1 C
  ]
( |) h1 Y0 B) U8 M6 z  x$ }& f: \3 A+ v' T: s; Y' f8 h4 J3 l
  ;; initialize the global variables that hold patch agentsets8 {( J1 e6 F; J! `" F
  set roads patches with
: K) P& C2 z% @' @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- w- |, ]+ P+ t( W1 Z6 H! v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 U. U- @+ W  O) U6 l+ D  set intersections roads with
. ~" k. m7 \  T* R3 @3 `  i7 m    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and: @0 d7 Y. l- A4 e0 _2 ^
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& w) w# `; E9 U. D" W( a. L4 I, f4 L5 q0 T; [; z3 ?
  ask roads [ set pcolor white ]
: }5 d  S7 _1 E: t    setup-intersections4 P* J# ~3 ?. J- ^
end
; h, V) P- H# `. [/ |, g其中定义道路的句子,如下所示,是什么意思啊?
4 \: f; v, }9 t# ]# s set roads patches with
0 f5 X  I- n0 f% X, L# \- f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ {3 H/ @! c% y: O, i5 Y+ `) ]    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 N8 i/ J$ R2 w, j) V" f) J6 Q2 \/ _
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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