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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。" `' N- K+ }* ~, [
netlogo自带的social science--traffic grid这一例子当中,
2 D: S$ |5 `2 i# |3 uglobals" R3 b. f: L* t5 Y
[
( V' d, k+ @( b5 _$ W1 r! g  grid-x-inc               ;; the amount of patches in between two roads in the x direction
! v( B4 J; O- e  j5 M2 j  grid-y-inc               ;; the amount of patches in between two roads in the y direction4 V' a5 q- ]$ G. X* ?% s7 ?6 z/ x! U
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
. }  M3 M' b7 L9 D8 \4 B9 w                           ;; it is to accelerate or decelerate
! i4 S" C. U2 p* S  phase                    ;; keeps track of the phase8 e$ U3 ~. T1 }4 U
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
5 T1 P6 p. v# D# j  current-light            ;; the currently selected light* Z2 K. g9 ~: }9 ^2 r+ ^% `0 p' s9 Q
4 M. e6 r# _0 [- l
  ;; patch agentsets
9 A: o6 A* E, d5 X& x; o, x  intersections ;; agentset containing the patches that are intersections3 Y, L3 z5 \; g
  roads         ;; agentset containing the patches that are roads  c0 U  P" e: T: N4 ?" _5 J% I
]
, |4 F2 g# o2 Z# x: C' x- |( q5 [4 ~6 Z5 P' }
turtles-own# h( l& h" a& Z& B
[
- h( O  ?9 b3 d  speed     ;; the speed of the turtle) K* {- k6 M9 _/ f" c
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
6 c6 _/ x2 X! e5 C. @9 W) e5 w  wait-time ;; the amount of time since the last time a turtle has moved  J! h6 x4 f% r; _3 ?0 e) ^0 F
]
1 j# Z- @' ~& H0 h, n9 O) O
  v+ d7 R$ Q& L& Y5 wpatches-own: [5 }" X$ B8 N
[
7 v: }, x$ w/ e5 B1 J# n  intersection?   ;; true if the patch is at the intersection of two roads
) g% i3 W1 r9 M7 `: P. G2 k# d2 s6 @  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
6 ^% n3 W- E# t7 t0 @0 k& u0 E" l                  ;; false for a non-intersection patches.
/ P! p* x) R3 U& L9 y% X  my-row          ;; the row of the intersection counting from the upper left corner of the
1 t% B# n" L, i- d8 d; y5 V                  ;; world.  -1 for non-intersection patches.
: d! T2 q" k2 ^' ~+ `  my-column       ;; the column of the intersection counting from the upper left corner of the, C4 J' I% [% t! S( {
                  ;; world.  -1 for non-intersection patches.! C4 o4 w2 r& K1 i5 i8 F' B
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.( X1 v/ g1 N5 m  \! h0 X
  auto?           ;; whether or not this intersection will switch automatically.0 p2 ^8 j, O3 w1 l
                  ;; false for non-intersection patches.
! G8 M* B2 C" ]; S4 X]
, r. I2 D7 b( V  z# O  i' }8 l1 A4 P4 R8 b6 R

3 W1 ^* C+ B0 v8 b;;;;;;;;;;;;;;;;;;;;;;
/ J( t# r' b9 Y4 l;; Setup Procedures ;;! R% S0 ^. _/ D# F
;;;;;;;;;;;;;;;;;;;;;;! i5 {, ^# V4 T$ {% Z5 P& K6 K

1 T  P6 e2 [  C4 L+ g* v7 |;; Initialize the display by giving the global and patch variables initial values.
! O' X+ U; J% _. ^& @;; Create num-cars of turtles if there are enough road patches for one turtle to
  @7 r7 V- a  F. f;; be created per road patch. Set up the plots.
, p/ |* i  v! Nto setup
, S1 w# \1 u- ~) E# A3 L  ca
3 ]; t' X' R) [  setup-globals
2 Y- N1 a1 |% @! v
7 E7 u% _& j. ]! R& @$ X4 q  ;; First we ask the patches to draw themselves and set up a few variables
: z* v7 p8 R' F% f* L, m# G  setup-patches2 P) X2 {  y+ x
  make-current one-of intersections: D8 M' b7 O8 _4 I0 Y6 M. E$ s/ ?
  label-current
4 ~( z. j4 [& P7 Z3 G+ p& ~; m! f& d3 ?1 s; t
  set-default-shape turtles "car"6 [' b/ v0 U; I1 V

9 [% F7 b4 ^  V- e  if (num-cars > count roads)
( W6 D- O" ?% o6 B$ M4 b% T/ j  [* ~% T! |/ G  u2 ?! [4 S& C; _* a# a
    user-message (word "There are too many cars for the amount of "
, L3 U* e# |( x, m8 K; M                       "road.  Either increase the amount of roads "5 D! D; l2 S8 C! D% g: i$ S6 L8 _
                       "by increasing the GRID-SIZE-X or "2 s/ b) Y- A8 @5 L7 Y& ?
                       "GRID-SIZE-Y sliders, or decrease the ". i; ^: g/ X: i- a) t# j) x" _
                       "number of cars by lowering the NUMBER slider.\n"
% I4 a  J9 k/ }* @                       "The setup has stopped.")0 e, I* x$ U, t- }% t4 C
    stop  N- s, N$ s* h' ^) Z" |
  ]' y4 V  |( {! f: v1 c, R( \
* _: x  c' Q3 @' b4 a- C0 L
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color* l; r  x4 P( r9 {+ c- r
  crt num-cars4 ]6 N3 R! }/ c
  [$ ]4 \/ T! K' O& }5 T# M
    setup-cars
' c$ z) I, n  t3 A3 K    set-car-color! r7 o) o* ?$ G* u4 j- B! M; O/ ]/ _
    record-data0 @, O3 Y* O2 ^& I/ R9 A3 `/ g
  ]
) b: T* N- i1 m; O/ o! d# a! g$ j- M( c4 Q6 K& ?
  ;; give the turtles an initial speed7 x( D8 [: t4 B: l) ]) Z  H/ H
  ask turtles [ set-car-speed ]
: ~! c0 K. |% a- h2 f$ _7 n! J6 o
0 |0 [8 ^" f: h0 N  reset-ticks
+ I/ e& \  l3 _8 d5 Nend
) a' K3 O2 s/ ^; o7 H; n
8 j) p. E: K1 [/ `;; Initialize the global variables to appropriate values% Z- K9 j8 t2 O
to setup-globals: G6 q6 I; @4 M! b; h$ ?
  set current-light nobody ;; just for now, since there are no lights yet
. f. x+ l# J! c2 @  Q  set phase 09 g4 Z( F5 Q3 u, }
  set num-cars-stopped 05 \  k# `0 K) E  |5 n8 E$ m
  set grid-x-inc world-width / grid-size-x
6 f) b; O) B/ H6 D( W" V  set grid-y-inc world-height / grid-size-y# G- I1 T" D1 }: Z+ L, N- W
2 z: L7 S! m0 g% I  o. }5 {! `& Z, {8 p
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
) v2 ]# Y! ^* e" N$ }$ A  set acceleration 0.0992 t  c& V( Q7 Z/ _1 _) Q
end
( S) \- `  t6 a/ p8 W# ?( g, i. C7 G5 P( j' T, a
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,+ \  F- K4 x; H
;; and initialize the traffic lights to one setting
# u9 F1 ~* V+ Bto setup-patches# K& F% J% I+ d5 Q  U+ Y
  ;; initialize the patch-owned variables and color the patches to a base-color
' J: v. Y, f8 f8 j7 n  ask patches
9 B7 @  W7 V/ v/ E  [
( D- V! o" ?0 i: H7 d9 M+ R* z4 N    set intersection? false
5 Z# c7 A2 k5 z8 M) u    set auto? false" H# t9 _1 x# v7 f8 x. ^6 O
    set green-light-up? true
3 H/ L  h4 ?$ T5 q- ]! y6 i    set my-row -11 |, x: b) ^0 o+ `6 }4 m( Y- m! X
    set my-column -1
5 z: t; q: K, H6 |- |    set my-phase -1
( X. x! p; T; }; s7 O2 _+ A' I, U    set pcolor brown + 3
/ P- P# L# g1 {( V8 H- J  ]( |. l5 c9 `4 K8 Y
; y' H- g& t$ U+ u6 i
  ;; initialize the global variables that hold patch agentsets
8 V( _' o# S& j0 G* [  set roads patches with& C% L" t. N! {% a7 Y# c, Q# T# l. W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ V! a! K2 J$ E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 n7 Q2 B; T7 y7 M  set intersections roads with3 O5 v( N& M  ?) m4 T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
# W7 B1 C2 X2 ~; G2 z+ B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# H' ]8 D: L/ I3 @  U4 S
# Z3 }, b2 u& V+ o  ask roads [ set pcolor white ]
. s% L, U% O; m, w    setup-intersections* ]- o7 p5 Z/ f  T# Y" U
end9 z& ~& @5 H7 b+ R- D
其中定义道路的句子,如下所示,是什么意思啊?
4 P( F5 H" m4 w- E' g set roads patches with
% Q$ l( d9 y. z1 D3 i( e2 q" q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 n) K5 j' ], m% H& w" M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  j9 n  f: v  F( U7 Z* f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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