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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。; e) e; X8 f6 @
netlogo自带的social science--traffic grid这一例子当中,! l' p) X; E% r. x# l9 s0 @
globals! J3 s% @. t* v4 C6 ^1 W8 U, R, ]
[
; O! L$ t1 z* d2 ~5 F  grid-x-inc               ;; the amount of patches in between two roads in the x direction
6 k. C- n+ P8 a  grid-y-inc               ;; the amount of patches in between two roads in the y direction9 D$ q/ J+ c7 r, P7 K! y/ U
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
  r, m4 g. N4 V' }6 q1 g3 t                           ;; it is to accelerate or decelerate
$ E2 N; D5 Q4 F  K' d. y  phase                    ;; keeps track of the phase5 k( O. C4 v1 q# U# J
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ J6 {2 \/ f* ]1 t8 \' r  current-light            ;; the currently selected light
( O* ], S$ P: B4 f" a; ^% ~: Q. K" S- c' o. \" j
  ;; patch agentsets
/ \8 b6 F& J, z4 D# x: Z  intersections ;; agentset containing the patches that are intersections
, p9 K. ]: @* u2 w3 x5 G  roads         ;; agentset containing the patches that are roads6 X! g3 v& z( [2 z1 D/ s
]  s8 _1 M+ l9 Q( K
: x, E' k. z5 {
turtles-own
! }, {6 M& t; F+ `[
/ z/ q" U, M9 y4 f% q, C% V% A  speed     ;; the speed of the turtle( ?" k, s& T. i+ y9 `) c! q) ^
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right- d* R, I" y; c; S5 a  a9 d( g$ H5 z
  wait-time ;; the amount of time since the last time a turtle has moved
) D% U0 Q# I) A5 ]  F1 E: ^]
! Z  n% d, H4 F4 [" `' V
; ^- K, \2 \1 K6 K6 npatches-own
# s) X* _; @# X/ X: f[
8 q1 F" d" A$ g  intersection?   ;; true if the patch is at the intersection of two roads3 w: [! ?- A% |& ^) b- \
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.1 a6 W+ u3 S) n% V
                  ;; false for a non-intersection patches.
% L& g3 R7 e- C0 B, u* s  my-row          ;; the row of the intersection counting from the upper left corner of the
! K( Z/ Z3 E. s: i( q$ Z% Y6 `                  ;; world.  -1 for non-intersection patches.
  c) b( \/ P& J8 x8 o' `  my-column       ;; the column of the intersection counting from the upper left corner of the
& r# p2 N4 d; G: w* c; a& K3 l                  ;; world.  -1 for non-intersection patches.9 o# A3 J( k) X% m, o' a9 p' k
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.+ R5 N: T* i( C$ C4 A  p% }
  auto?           ;; whether or not this intersection will switch automatically.
8 C( }, l9 Q: P                  ;; false for non-intersection patches.$ a9 l# A0 m) i" K' S; P% {! q
]
) i$ O2 e1 w$ }! h+ E8 D* J$ K! L" P8 F9 }4 M" S# e9 {, }

9 R( V' @4 k' w# v;;;;;;;;;;;;;;;;;;;;;;7 E2 c( e: f& ]  R  L/ J) U8 q$ Q, a3 e
;; Setup Procedures ;;! ]! O4 H& a) t2 n6 M- S
;;;;;;;;;;;;;;;;;;;;;;6 q# J8 H/ P" E3 O3 ^

: C# o6 L: K2 y* `0 Q* z+ F;; Initialize the display by giving the global and patch variables initial values.4 ^) ~" ?8 F2 {
;; Create num-cars of turtles if there are enough road patches for one turtle to9 k+ p' E" n/ l. Q
;; be created per road patch. Set up the plots.
, I# t4 x: c" M1 U, cto setup
8 U% ~' o% x2 N4 O# P  ca
2 z# z' z# F* S  setup-globals
; E3 P. X0 E; z. [8 I; f
( ^/ B: O& D( B. u  ;; First we ask the patches to draw themselves and set up a few variables
& t0 P4 u. }$ \  setup-patches
2 g- s* I) P! o) V: c" W  make-current one-of intersections) u7 ^7 ^7 _( p5 ~( ]1 x) o  A+ Z/ l
  label-current
; K- C8 M  n2 t; Q5 m: C3 Z0 {
# i8 G. G5 |+ B0 p1 v, L  set-default-shape turtles "car"! S( t, M7 f! E- `4 I: v
& d7 l5 K( t2 }4 K2 w
  if (num-cars > count roads)
+ C) E" P# ?( B2 m* k  [
, B! \& i% A4 X5 E8 Z# }8 i    user-message (word "There are too many cars for the amount of "
8 [' Y+ \& l# i/ B: V  S/ d                       "road.  Either increase the amount of roads "
0 p. }9 v; L1 g5 }1 `/ c8 f! p1 j; {                       "by increasing the GRID-SIZE-X or "6 I4 L! Q6 A  o, v1 t' Q4 n+ ~; `' ?  h
                       "GRID-SIZE-Y sliders, or decrease the "
- W% s: ?9 P( x+ g3 D' l. E* D                       "number of cars by lowering the NUMBER slider.\n"
+ ]- k* K% L- }7 \  ?3 r                       "The setup has stopped."): |! {+ I$ ?9 A& A! \& K2 U
    stop, G5 B3 l, _7 s% d4 r& h3 o6 `- P
  ]/ [" G1 Z6 S  a" O5 F

5 Z% _1 {2 J! ?7 ?% i/ u: J9 v- y7 Y2 I  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color/ N% e$ b' d+ b" P
  crt num-cars
) @3 x% y2 S9 j+ g  [
" N4 w# Z8 n. Z1 D+ p; H: I; P    setup-cars; u2 w7 M4 l1 g1 g& p" w! D) J' w
    set-car-color
( F  I9 r1 ?% q$ c( {    record-data
/ g9 W& M' {( {  ]
% }& {4 e3 C9 t4 p$ h( R7 |
2 r+ @: k/ G; q9 w; G/ V2 |  ;; give the turtles an initial speed4 s# h1 L7 `8 i
  ask turtles [ set-car-speed ]
) P$ i! ]1 }% f5 \1 m
2 W$ C# h9 t$ C' S( X' P  reset-ticks. \6 ^1 W1 K3 Q& ]6 X* D
end% ~& }. p& n4 m4 K, Y0 O
5 c  e. g+ Y: O9 q/ F7 T) B
;; Initialize the global variables to appropriate values
. l6 p) I  p9 i) C& i( Jto setup-globals% M5 G* F% r% G0 N
  set current-light nobody ;; just for now, since there are no lights yet/ R  n6 X! C4 D) T! f- F, T) H
  set phase 0
8 J( l3 R, X. a! J8 l' b; X7 [  set num-cars-stopped 0, C2 M( f" S9 a
  set grid-x-inc world-width / grid-size-x. ]: ~0 B: f# H2 j
  set grid-y-inc world-height / grid-size-y  _( c( O4 O' X* N$ `7 |. d
3 k  J6 x& ?" q  L& L3 q% V1 I
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 N2 `6 e  h2 y7 V0 m  set acceleration 0.0995 Z% d% q! J! y6 i( o( M" v
end- Q; f( U9 R; y

( a) M' Q' ~1 H# a( f;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
4 j& s4 g, {8 O2 P' f;; and initialize the traffic lights to one setting
" k, L, C* p. \4 B, Pto setup-patches6 R" X; I1 d1 T5 i
  ;; initialize the patch-owned variables and color the patches to a base-color" R! r9 r, C; `: [( P
  ask patches1 p$ ]4 d! f. l
  [" C4 [, I, h9 ^6 l4 q% e  D
    set intersection? false
3 u2 N6 A; s3 l' l' E8 e2 F% ~    set auto? false
2 H" C; t# {0 p6 C( T$ q    set green-light-up? true. q5 e( @+ N6 M# E7 x+ D5 f" o
    set my-row -1. t6 r$ A2 }! L9 K* x
    set my-column -1( l/ t8 c" X3 E" b9 K
    set my-phase -1
" r* [6 U: ^: k    set pcolor brown + 3
" K* ]  @1 ^& t  ]! j: d% u+ r1 r$ @% D

5 ~9 @3 _% O6 x/ M  ;; initialize the global variables that hold patch agentsets
" X$ j) L8 W/ U3 `1 U" b5 N7 T  set roads patches with
' w4 x3 C! b) x9 \9 `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* t) o& l# d6 X9 V7 V: V. f    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) C5 W9 q9 S3 B' b8 }. q  set intersections roads with
/ a  G6 W. K! B. L4 K8 u    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. Q$ |2 t* ]! r+ m. t+ ^: p) I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], g! _  W. Y5 J/ e/ {& Y

9 \: {; R3 U) Z$ @& P, E+ @  ask roads [ set pcolor white ]
) J! G, |) g: d3 I    setup-intersections
7 ]8 K9 |5 r" f. e  J- F/ s7 ^6 Nend% F8 Z) C* h) `
其中定义道路的句子,如下所示,是什么意思啊?
( c  s9 m5 D8 D. @7 K* W; C set roads patches with' ]# {/ R: P; I# w& W8 [
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# }; w  T' |1 E4 I/ Q; s
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ m4 s) i* ?" \5 z! y) J1 E5 ^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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