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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 p1 U' ^) p' H/ P$ p8 i, \8 Anetlogo自带的social science--traffic grid这一例子当中,* u& D8 g7 Y" S3 G2 l* _
globals; G% Y; e$ J: N1 w8 ^; {
[
& j- s6 \6 n9 l0 b, ?  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 J' F0 F; O; t/ w9 I" [6 q
  grid-y-inc               ;; the amount of patches in between two roads in the y direction: W  |$ Y; A0 `! T" j6 l( Q
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if! }% a3 B. u. K$ ^; P) a: Q
                           ;; it is to accelerate or decelerate  M0 I  i" R6 p$ }& E. c, n
  phase                    ;; keeps track of the phase
3 h2 t" z4 d" f  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
6 e$ ^& c' T' B! [  current-light            ;; the currently selected light
: N9 i$ e4 j4 J+ W; Y: I' g3 X$ }. \6 H
  ;; patch agentsets
% X9 i. j, d! B1 `5 w5 _% w  intersections ;; agentset containing the patches that are intersections
# l9 l2 o9 v5 B8 Q4 N: ^  roads         ;; agentset containing the patches that are roads
1 C+ i% k- H; M! q9 h]7 g9 o1 v7 d% [8 ^! ^
3 \! S' r1 V2 i) z1 H& P
turtles-own
* y$ n: H) L- Q3 ?[
4 q; O' \4 d/ n* e5 c0 T1 [3 U  speed     ;; the speed of the turtle
0 A. v& d# m3 k' r' u  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
8 `5 o$ F: b9 j- @% m+ l  wait-time ;; the amount of time since the last time a turtle has moved# _* G  X3 H% j, ^1 h
]& u" J# Y1 R4 g4 t% K0 Q* |+ x
: v% O' _7 X! Z6 s2 i- Z
patches-own
4 x0 f; l( }7 F3 B' w8 ][% V# ]: n, W. i1 L+ Q
  intersection?   ;; true if the patch is at the intersection of two roads3 |4 o6 g+ l( W( r- u% {$ M
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.2 W6 {  ?- f' [
                  ;; false for a non-intersection patches.
0 A" I; P6 F: T  |4 K3 s. i' ]5 E  my-row          ;; the row of the intersection counting from the upper left corner of the
+ b/ g" w5 |' [! X) M                  ;; world.  -1 for non-intersection patches.
0 h+ F2 s6 o* s  my-column       ;; the column of the intersection counting from the upper left corner of the
6 e$ P# ~0 U# v$ [! G; s                  ;; world.  -1 for non-intersection patches.! q; N& B( }2 y% U% }
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
- }! ~% o& R2 l8 A$ a  auto?           ;; whether or not this intersection will switch automatically.' Q& O) F# j6 i) u
                  ;; false for non-intersection patches.  w4 \! R4 |5 Y8 E
]( D+ G2 U+ h, U3 e) d# }) X. \
, s3 d  g. O* q$ j& P& w
6 M: U0 m" \$ F$ o9 U& F+ P* }
;;;;;;;;;;;;;;;;;;;;;;4 w8 X) l; L! `& F/ L" M
;; Setup Procedures ;;
' }* }: v0 Q9 f( P3 H0 g;;;;;;;;;;;;;;;;;;;;;;
; p3 ?. v7 `! E- J0 K& S0 }( \
( n0 B- I! f7 u: u, @# C;; Initialize the display by giving the global and patch variables initial values.
2 q& Z( m6 a! }" N: s) \9 t;; Create num-cars of turtles if there are enough road patches for one turtle to7 N* q, \2 t+ C
;; be created per road patch. Set up the plots.
3 @( O% S3 w7 B+ p/ X& C; Ito setup
; F4 B/ {) h5 w, W9 R  ca
# L- a- ~# G& O1 l/ a2 n  setup-globals' k  S9 N- d  W+ \
4 L- C6 {7 a1 O4 `; D  n
  ;; First we ask the patches to draw themselves and set up a few variables3 V0 v9 A2 R2 l2 b5 I! r9 g
  setup-patches3 {+ S; i) Z7 y! X. i; C
  make-current one-of intersections% [9 C9 C5 h+ ~) J( H. I5 |7 }
  label-current
9 u2 X) `) v; w
# T. V4 y' @( G6 m! V5 O  set-default-shape turtles "car"
- `4 E: G) }% e
' o# U3 K& K3 w  if (num-cars > count roads)' `3 h- U7 T: h5 r
  [1 l& r5 d7 Y, f$ S6 ?: c
    user-message (word "There are too many cars for the amount of "* W: L( v( R/ F8 M! p' X& M" {
                       "road.  Either increase the amount of roads "
; n) v7 U* Z5 b/ U9 F7 r                       "by increasing the GRID-SIZE-X or "
( J0 c, b9 r) }                       "GRID-SIZE-Y sliders, or decrease the "5 Q  j6 k$ ~# d$ z, G, ~
                       "number of cars by lowering the NUMBER slider.\n"
& N& J% v/ k4 b* `2 {" X, s3 `                       "The setup has stopped.")
9 Z1 e( y2 I. N5 w* {) z& P    stop
8 x8 i+ E5 ]1 _% P7 c9 k1 z  ]
; d( T) g; R5 M( I+ t7 ]' Y  c% i" J) l* f+ X! \" U
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color9 `9 e6 J  c& o4 Q* n
  crt num-cars
3 ~" \; \: D% u7 M& {3 Z. p  [
, m  q2 O# N# s1 r4 z: o! z    setup-cars
1 g/ w8 x; H' d# _8 l% o    set-car-color
2 c6 i+ P! ~+ M, [, t/ U& H; u    record-data
2 b. h+ i8 c" H5 V- }7 ~  ]" `( x- H6 j/ l0 p9 A8 c
; n, W  C8 q1 n8 M
  ;; give the turtles an initial speed
+ X+ u4 _) g2 K! Y) y0 J  ask turtles [ set-car-speed ]
9 c' P7 t4 [, A9 @  c: K( Q% c
7 `% Q* m; k& o6 a" L  reset-ticks% e% O- ]" ~5 a3 `
end
% b- U1 k6 M8 a! p$ J
$ [1 U7 Q, I* a' ~, D5 r0 |8 n;; Initialize the global variables to appropriate values' @; e* o* a/ k
to setup-globals
& T9 R+ E# {% d: ~9 k) C  set current-light nobody ;; just for now, since there are no lights yet& f8 \+ f. k% y5 R+ V+ P/ k* ^
  set phase 02 g1 q! O$ j9 W' l
  set num-cars-stopped 0
7 A9 a( F# E5 i1 v- M2 ^3 o! {  set grid-x-inc world-width / grid-size-x& o8 D$ O3 U& R2 v8 g7 U8 L
  set grid-y-inc world-height / grid-size-y
- n; X9 G1 B8 e, l3 M6 y$ D) O  r% _( T
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary- C2 \* \! N: h" \% u
  set acceleration 0.099) y# M: _( Q$ |( u- S: U' ~- N0 h
end7 t* e6 K1 [+ `7 Z; q5 Z

9 p8 W2 R  u$ L2 p% L# `9 F' |+ g;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 I/ u% g# G* `# C  D0 @. C;; and initialize the traffic lights to one setting9 E4 g, T4 A) P! Y' `% t
to setup-patches+ P/ m( f0 }6 K& ]! Z+ N
  ;; initialize the patch-owned variables and color the patches to a base-color
, F; ~, c# q1 G% i  ask patches% b; |" o" ^4 H& j8 Z6 t
  [
( z% P# B# w: u% Z/ {    set intersection? false/ j7 Q. F3 R9 X; o
    set auto? false
* G. Y8 B- V1 h3 e/ y: r& z    set green-light-up? true3 c3 o! ]) [! F/ o) ]
    set my-row -1
3 i1 L3 p7 I+ _' F' u# O    set my-column -1
) b. p+ T5 x! p2 N% b; d/ o8 [    set my-phase -13 X  N: T. B4 ^+ r, h0 G
    set pcolor brown + 31 r$ c5 s1 P% X4 o
  ]
' R# M! S* V7 Y2 X$ P% x5 T& a$ ?6 B  }, y
  ;; initialize the global variables that hold patch agentsets1 x' \% B* n  v' a9 c
  set roads patches with5 C& \$ r# S( N, J* e+ `' Q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 C' x0 t( d- w2 c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  O: K: ~) L4 v% Q' a. D+ v
  set intersections roads with
3 t: U3 h% ]* M4 G& K# C+ k& {    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
! L; z5 U& o+ ^3 A% A4 S* @5 W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- R6 ~$ C1 m( w+ e! z  ~3 K
0 U; h' X6 O& b
  ask roads [ set pcolor white ]) h1 [& S! n  y4 {! i; d
    setup-intersections
! B5 [' p. ~, W9 O; R% I' kend
, J7 E: o" Q& S. G其中定义道路的句子,如下所示,是什么意思啊?' t4 T; T5 q( v- G9 f' \0 k% [
set roads patches with
# ~. p9 V  o; C    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 M$ t% E6 B3 ^+ D, e/ E! @, \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ C* T" G. s, J4 [! Z! h9 f4 W# @# N
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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