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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。1 f+ Y2 Z) l* i- a: H/ t4 S; K4 s
netlogo自带的social science--traffic grid这一例子当中,3 }: x0 S! ~6 h& \
globals
8 ?7 H1 |/ h1 K9 X[* m$ O" I( ]3 [: F8 ?/ L
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
$ J7 j, M( e$ c1 C* D7 Z# S- ]  grid-y-inc               ;; the amount of patches in between two roads in the y direction
& M( h) K9 M! i# q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if4 f) w5 [  z0 h( |2 y
                           ;; it is to accelerate or decelerate4 i* U. C7 ]% i5 d* x. J; m) Q
  phase                    ;; keeps track of the phase
1 F, f* O6 x( h6 B* j( U; @0 O7 ~  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure- S! }, T8 n2 d" J& H2 W. y
  current-light            ;; the currently selected light- r/ W, f( E( @) c

# P: `2 p$ d5 u  ;; patch agentsets8 ^+ E3 G' y+ R; [
  intersections ;; agentset containing the patches that are intersections
, f/ f, V$ ~2 N- C  roads         ;; agentset containing the patches that are roads" D; \! z+ _6 Z$ j% }5 X# t
]2 e" k4 E! T' W' S0 ~5 C" e: ?

; ~! n/ F7 c9 w0 v/ Jturtles-own+ G6 X+ y* a1 J. d
[, o8 B* G+ \5 @9 O, l
  speed     ;; the speed of the turtle% o5 F& P) V; ?
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right; H: A/ m1 @0 G1 U# q
  wait-time ;; the amount of time since the last time a turtle has moved7 E$ d& {# V4 Z1 z& V) c
]
. G: X6 P5 e1 ~; k7 k5 S& H
+ Z( e- U' C; p( }& R- e" b9 Qpatches-own
1 `" y& v% H. y# g[8 p- o+ ~2 P: z
  intersection?   ;; true if the patch is at the intersection of two roads- B% k% o) H" u: n1 M. x
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
5 K& i$ r4 `) n2 @' [                  ;; false for a non-intersection patches.
4 l/ E% u4 F5 i1 z: ^$ \  my-row          ;; the row of the intersection counting from the upper left corner of the1 L' K5 o: `" }3 }
                  ;; world.  -1 for non-intersection patches.
$ p, S9 q4 v6 y8 I! O( C  my-column       ;; the column of the intersection counting from the upper left corner of the+ @. n: D9 O2 G
                  ;; world.  -1 for non-intersection patches.
+ J" p8 \2 z$ C  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
3 w% Y" u  ^7 h  auto?           ;; whether or not this intersection will switch automatically.
6 Z! X, m$ b" P3 z4 P* Y+ J* s1 u                  ;; false for non-intersection patches.3 T6 h3 p* O# M" h( r8 w$ e
]: N! a! o! Q+ M! x8 a

7 q7 }: K& G$ x: u, W; M. m4 _) S2 F9 ^1 M8 V+ C4 N
;;;;;;;;;;;;;;;;;;;;;;
$ k# j+ L2 d. ?$ e3 d;; Setup Procedures ;;
0 H( \- H3 h2 a( O7 y: z& B;;;;;;;;;;;;;;;;;;;;;;
1 T) p9 X0 }1 ^8 g& G: G
1 G3 q' U, B3 j: f* k;; Initialize the display by giving the global and patch variables initial values.  x8 x$ X, H, E& C) \. c% S
;; Create num-cars of turtles if there are enough road patches for one turtle to
; e: K: c6 D, E1 u, ~& ];; be created per road patch. Set up the plots.3 G8 g/ A& j$ _+ I) q* }# w
to setup
0 W6 C2 L: G0 b1 w) J  ca
& g2 t( [  m  x6 X- F- m0 e8 x  setup-globals  H0 r# `5 \- z" q, e
0 b5 w# e1 ^: b1 c
  ;; First we ask the patches to draw themselves and set up a few variables( M/ f( L$ [# U* ?- ^
  setup-patches3 C: `  \4 b6 }& k, o/ ^9 L* ?
  make-current one-of intersections4 W% n- A7 f' s1 G$ X: Z
  label-current
* \$ s( c8 }, l1 _; v" R/ {+ @0 w2 `. ?
  set-default-shape turtles "car"
2 Q3 @( \) H% I8 w% c( }- j( K
6 M( F/ O+ e8 d3 \, e) p+ {. F, o  if (num-cars > count roads)3 U6 G; M- p& U5 v! C: b
  [6 r3 a' R5 J0 I9 t3 V* C
    user-message (word "There are too many cars for the amount of "7 B; X* C0 I! C1 W0 V
                       "road.  Either increase the amount of roads "7 l: z7 k. _; N( G: \9 R
                       "by increasing the GRID-SIZE-X or "3 n, i+ n8 r( x; d3 M4 }
                       "GRID-SIZE-Y sliders, or decrease the "7 H& D: P' n* f% {, T
                       "number of cars by lowering the NUMBER slider.\n"; R9 a: W/ E; F8 e) M/ E
                       "The setup has stopped.")9 L9 M/ {4 q' J, N. v+ ?! p. W9 o
    stop
4 m# y$ i8 Z- @8 m" D' V  ]0 y. U8 B, s- H

7 ?- n; K- D; b( \  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
+ w" w) ?" `# o% t) N, _# q  crt num-cars
: r) i; D+ ]8 V) K' A  [
/ ]  M9 L# G& _& W3 `8 e, u    setup-cars
& u7 G0 h& N! i# |3 ~+ v    set-car-color
( V3 L9 h* h+ d+ e" P+ j    record-data
$ p! p* p  c& g! J7 A  ]. r; f- ]* X+ f/ Q: e
3 A+ L5 H/ ?3 T  c/ a! [& L% @
  ;; give the turtles an initial speed
% Q+ d0 b( n2 g8 K( c. U& l  ask turtles [ set-car-speed ]
7 n% E* Z6 w) S' k+ `+ D
% T6 j" y3 e' A2 p: s7 \' Q7 h* ^  reset-ticks  e" l( o  ^& I8 p% c
end. h, j0 x- G* |9 ]6 Y
: c; t- O7 L! D' D
;; Initialize the global variables to appropriate values4 D0 V4 d3 V* y& X  `
to setup-globals
* T4 B1 A4 W. O  set current-light nobody ;; just for now, since there are no lights yet
0 F& K7 h6 |) L  set phase 0, t+ v6 v* W& d( }0 ]
  set num-cars-stopped 0
2 i" A, q* \2 y+ E! y  set grid-x-inc world-width / grid-size-x. `& C4 P) j& A% G; x* s3 A
  set grid-y-inc world-height / grid-size-y
, ?( D" h1 F9 I: Y; B0 X" K4 C8 y' s5 N: a, C9 y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
1 s+ W  g* t: L9 u7 c; [8 A  set acceleration 0.099
+ ~4 F# }1 i4 l9 e; j7 @7 Oend
: |$ W0 ~& ?# F! S7 n! g) Q) f8 p
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
" E) Q  S" ~5 d3 ], Z# d- ];; and initialize the traffic lights to one setting
; l! w- B  Z& N' B; b! Sto setup-patches
6 ^; @+ @# v' m! c# N  ;; initialize the patch-owned variables and color the patches to a base-color$ D4 {% f7 d  y
  ask patches
+ R6 o, _/ G" H6 ^  [, W9 t/ U5 r, C4 r0 I( ?% h, @
    set intersection? false
8 m* v* G7 ~7 R+ |3 F7 {    set auto? false2 v3 A" D$ C5 m5 }9 Y' |
    set green-light-up? true
, F# k6 o. G9 q9 h6 F    set my-row -1
$ N. g! p% Z6 G# T& c4 m    set my-column -1/ O0 N. A9 k* o5 E2 s8 ?# Q
    set my-phase -1
! P* D4 C  D: N3 [* [  p5 t    set pcolor brown + 3
& \) Z! P- Z/ s# m  ]. m) E$ f7 V2 M; G* I7 p! w5 B* x

. z  ?9 V3 y+ {  o$ ]  ;; initialize the global variables that hold patch agentsets* z$ X) M2 h6 d
  set roads patches with
$ [0 h3 q; m  K) ]) F0 C9 ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' t1 C) l. u3 S! r5 N7 _0 p# l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], ?0 S/ d3 d& T2 r" r
  set intersections roads with$ P4 O' B. V* ~1 B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
2 W3 a# c2 ?& p4 A    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' \# T! K4 R  @% x3 z1 [7 j* o' |4 W! @0 R* P& d% M
  ask roads [ set pcolor white ]
7 d9 F3 j0 y: a. [0 G# ^# ?    setup-intersections1 y2 w% H* s1 r& v
end
4 i- W& n; w7 n/ k" E其中定义道路的句子,如下所示,是什么意思啊?4 Z; ^. L; G) I, M2 ~( G/ u4 m: |/ ]
set roads patches with
* J. K: O1 V" v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 g& _* w( j6 W2 J/ N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' t, u$ u0 V! d5 Z/ A0 C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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