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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。
! p% P: |2 O9 I7 h7 Znetlogo自带的social science--traffic grid这一例子当中,# G/ H; {- Q4 l
globals
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/ A3 v' x% v$ \7 O7 t  grid-x-inc               ;; the amount of patches in between two roads in the x direction# D  l4 v: B3 M( c1 {" S
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 G8 m& d" w. y& g( ]  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
7 ~6 E) Y: r, ?( L                           ;; it is to accelerate or decelerate% s. ]; o! {# \" W7 A
  phase                    ;; keeps track of the phase4 V3 J* O' }7 ?/ g* z! c
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ C1 {& G7 K* p$ }" ~1 r2 G  current-light            ;; the currently selected light
5 [9 ?/ {( h9 T0 s! w, Q5 [- m  T2 s0 _3 b
  ;; patch agentsets* ]7 E5 L3 m. F+ v6 o, p8 g9 J8 n
  intersections ;; agentset containing the patches that are intersections$ L1 f" P* n, P8 k2 @/ j
  roads         ;; agentset containing the patches that are roads6 I3 X1 M  e& D, P$ v
]
9 @8 |, H4 x3 T$ I$ c7 K
* F/ F( [$ P6 Aturtles-own
9 p! _8 a: O! t4 O) U0 r[0 n0 z4 D+ J4 Z0 {+ G+ E
  speed     ;; the speed of the turtle
$ n# G- y% ]: e6 u  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
' |- `& h  t) t  wait-time ;; the amount of time since the last time a turtle has moved
1 K: S" `' x$ x0 K( {]
$ j3 t5 d6 c8 G5 r
' r& X4 W7 h' `) opatches-own
8 b' n" x; F2 u  p[1 G+ v- A  J. r
  intersection?   ;; true if the patch is at the intersection of two roads
/ t2 f5 u" O  a" E" e  B  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.$ J# t7 U! L# p( s8 g0 H1 A
                  ;; false for a non-intersection patches.! z7 P& m8 |: @  N
  my-row          ;; the row of the intersection counting from the upper left corner of the2 h/ A1 [7 `/ I! O( Q
                  ;; world.  -1 for non-intersection patches.
, I* f1 u9 E. _' c$ V  my-column       ;; the column of the intersection counting from the upper left corner of the
  F5 S5 K7 J/ P+ a$ @                  ;; world.  -1 for non-intersection patches.
( \% z! P. S* u+ B) K) |  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.3 r! w6 T9 w- x( J$ ^
  auto?           ;; whether or not this intersection will switch automatically.
' d/ R; P8 o6 K                  ;; false for non-intersection patches.
% d4 [8 r1 i5 O3 B$ H1 R4 \]6 I& N& ^& ]$ a7 _: A: Q' J- q, K
" G: p( R1 |2 I7 [

2 r% @2 [/ E) b4 I;;;;;;;;;;;;;;;;;;;;;;0 N" I7 K) z+ i% y
;; Setup Procedures ;;
- G) ]2 z3 a& ^$ G* v) o4 ~;;;;;;;;;;;;;;;;;;;;;;
  \# ?; Z- q. w
( Z! g5 z! D9 k6 U;; Initialize the display by giving the global and patch variables initial values.: r! H) m1 z# i6 s& h" e
;; Create num-cars of turtles if there are enough road patches for one turtle to4 ?/ ]3 g5 m) z) h: f  N6 c; e
;; be created per road patch. Set up the plots.& b- x5 _1 @& e  ?5 a' e/ G4 I: {
to setup
5 O6 W; F$ q/ d- h  ca1 I/ f* n  v) y, y5 S3 u5 k2 `
  setup-globals  f; X# ^+ ~3 G! |

% g# }+ J7 y5 s- A3 u  ;; First we ask the patches to draw themselves and set up a few variables- [( w) N7 @. U
  setup-patches
( w9 U6 {. V! ?1 g$ o  make-current one-of intersections. U/ k6 |  K- J3 Y
  label-current* m; V; `1 n3 i' h

5 E4 x3 I3 S, O0 m2 I! L  set-default-shape turtles "car"
7 e" _! Y1 e2 i& X
! v6 q. x; X5 Q* S/ h( q# m: h  if (num-cars > count roads)
1 C- N& _1 b, T& ]4 {  [
- }) O1 m8 T* ]1 k1 z/ ^: Z# I( _0 W) m" `    user-message (word "There are too many cars for the amount of "- L' Y/ \# R' X5 d
                       "road.  Either increase the amount of roads "
, J7 q6 {& k" a7 w9 z                       "by increasing the GRID-SIZE-X or "
1 l) b4 \$ q$ x, ~" i                       "GRID-SIZE-Y sliders, or decrease the "
8 i. n8 R6 b. Y                       "number of cars by lowering the NUMBER slider.\n", c3 C: v! j1 L) _$ C
                       "The setup has stopped.")
# \+ {# Y4 K" }- a! f    stop8 [  w+ B: m# f6 W4 ^$ p4 P
  ]3 l* [3 H2 a7 G) K% x3 q: N1 p
1 I: T3 m% `8 B2 q4 ]6 r8 J, e% D
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  ?/ S, `- z* @# r; r& P# e  crt num-cars
/ D& X2 p- P4 K( G  B# e3 t0 ?  [. A; ~# ?+ O- n2 s
    setup-cars6 S/ y& @4 D' Q# ]7 h: K, R& C
    set-car-color
8 r' g) Y; O. j0 t1 v- @& b    record-data
; n8 X- d( q: v: @* L* R  ]0 J7 w6 O. Y0 y1 |% ?7 v

5 ?- L& ]$ y# d! r$ |% ]  ;; give the turtles an initial speed
& h1 [4 q1 \) o4 X  ask turtles [ set-car-speed ]$ `2 G6 y+ `0 P: q
' p# L2 h! |, h) r. l- c
  reset-ticks3 k6 a. I* D4 k$ ?! \
end! U, c1 x" U2 @2 T0 [
* d2 B: g- [# n% X2 u3 ]
;; Initialize the global variables to appropriate values
3 ~2 t, n1 j0 B7 |% E$ gto setup-globals
8 n, O, v9 `" [1 h6 b, I  set current-light nobody ;; just for now, since there are no lights yet
: K, Z$ }. G1 g! m3 J  set phase 0
- i  z. C% J5 u4 F  set num-cars-stopped 07 j& S# D3 k  z
  set grid-x-inc world-width / grid-size-x8 X) q* T# ~3 R3 ?3 }& y8 M
  set grid-y-inc world-height / grid-size-y9 p! _- y- r% E; R, K
" N$ C1 P: s! p  m+ Z! d, x! e
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary+ X6 G$ j* K+ \( @5 s" a% Y
  set acceleration 0.099
8 X: M2 v- l* e( v! Q0 kend
% F! _  T3 C1 Y  G9 q
' w+ c9 p& M' D, O6 S0 e$ U. d;; Make the patches have appropriate colors, set up the roads and intersections agentsets,2 x+ l9 g$ e' X2 [! |
;; and initialize the traffic lights to one setting
9 s( }5 t. y: Z; s, d* |  P. t& Rto setup-patches! ^. _, Y' Y! G$ H
  ;; initialize the patch-owned variables and color the patches to a base-color2 E. j: N. @# i+ P
  ask patches
4 k8 j" T8 d$ ?' K; O  [: P; z7 E* l" m
    set intersection? false1 r9 R# X" Q, G6 |
    set auto? false4 w9 u; @$ L8 E
    set green-light-up? true
, b6 t/ d! ]: S% z( i4 G    set my-row -1
' p$ M! ]# F/ j, r) g2 `* d    set my-column -1' R% S. P; {5 O; f- D5 }
    set my-phase -12 _3 y9 d  U* c9 g& z/ V' @9 t; o
    set pcolor brown + 3# `  P9 V' d) k# D0 P
  ]
: ]) e- W; X6 ]; l! n6 A
$ b* T) W1 n- y# q+ s. d  ;; initialize the global variables that hold patch agentsets8 f- m4 L& M& n: j
  set roads patches with
, V( E2 X: j$ T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. `+ t( d# i5 M1 x  Y  I  D1 v  A. h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  z/ E5 y8 W/ ?  set intersections roads with
5 K# e" _8 ?: j' `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and' `# w/ S+ G+ H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 X* R& o( j: d* ?5 K9 ?7 d; F% w4 w: G) g7 K
  ask roads [ set pcolor white ]
$ }6 }, |9 f" N3 o/ F7 v' g    setup-intersections
. m3 r8 x4 U$ B( Nend+ t" M/ _$ m; e) u1 `( m; z) K9 g
其中定义道路的句子,如下所示,是什么意思啊?8 K0 Z. G7 b  V: l, o. C: Z
set roads patches with
3 {9 Q' Y7 \* j( f" ~    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, V* ?7 x5 p5 `6 m( p/ n
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. }. w' n9 o3 `$ s% D3 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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