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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。
( G7 j9 [, q2 m3 p1 B' J( c; ]netlogo自带的social science--traffic grid这一例子当中,
/ E3 P3 ~  G7 x6 ]+ eglobals
' ^& b; I+ ?1 {2 y[" @6 |1 D* J( D/ J4 ~
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
  e4 K' A9 L, X7 M  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, p+ V5 P; [2 @  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
9 j" X6 g1 _: N9 t                           ;; it is to accelerate or decelerate' t" W7 g$ I3 j3 i! v
  phase                    ;; keeps track of the phase
5 f# h8 Q% X- q! E! |  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure$ B/ O2 w5 B/ I9 ?) \5 G; L. S
  current-light            ;; the currently selected light7 I- J& u# F2 L+ T) o& V: ~

, x2 ?% i9 r' ^- I5 m  ;; patch agentsets
; {2 u/ o8 M7 k8 J4 p  intersections ;; agentset containing the patches that are intersections
+ H( P2 Y( m& C  \* G  roads         ;; agentset containing the patches that are roads! B" d3 c4 G" ?, x) Y1 V3 c
]
" }! M$ n* |* }2 d1 \8 r' v5 Q# A6 Z: B& j
turtles-own
4 E6 q7 S$ ^# e. n[# F: F- f9 _5 P/ \6 R
  speed     ;; the speed of the turtle/ L+ b  V3 U' k* f4 o9 |
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
( R9 d- U) u) G# f' ^  wait-time ;; the amount of time since the last time a turtle has moved0 Y' P4 h& J( _4 R8 }
]  h1 H2 |) M/ O

& }1 h: X9 q( D" z8 rpatches-own6 u% ^) `" [- G
[
8 w; r, T6 \# q! N$ X( ]# \  intersection?   ;; true if the patch is at the intersection of two roads* F& G9 x) @/ D0 r& A& |, B% y! Y
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
* _  H" s: N( ~% Y7 w9 ~( n# X                  ;; false for a non-intersection patches.
. U& ^: }6 m5 C5 {! j/ t! j7 ~  my-row          ;; the row of the intersection counting from the upper left corner of the. d3 I9 a% p- K0 Z- X! r' M9 `
                  ;; world.  -1 for non-intersection patches.( p9 o% S, g$ ~; P4 v4 b* g0 Y
  my-column       ;; the column of the intersection counting from the upper left corner of the; i. d& q4 `. y# v. @( j1 _% @
                  ;; world.  -1 for non-intersection patches.& T; u- A1 D- ^) v
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
5 G) B. |* Y$ }3 n  ?6 S; A* t  auto?           ;; whether or not this intersection will switch automatically.. V% ~) @* |5 T( R
                  ;; false for non-intersection patches.: j5 ~) ]- \! ]- |. ]- x1 Z. C
]. ~( A: ^/ W/ S+ O$ }$ p
# R, ^1 W; W. f. u; M
; F$ a/ b2 F. H: _6 U
;;;;;;;;;;;;;;;;;;;;;;3 M( S4 P1 `3 f
;; Setup Procedures ;;
! L! q& U* W$ O% a: a1 z1 X;;;;;;;;;;;;;;;;;;;;;;
9 s% x  S# Y9 `8 S8 m
2 g. E3 Y# y2 e! a9 E8 j) I3 w  x;; Initialize the display by giving the global and patch variables initial values.
# ]* m+ K7 ^& Y" x) N;; Create num-cars of turtles if there are enough road patches for one turtle to5 X5 n9 h, O5 h  H" L. J9 H
;; be created per road patch. Set up the plots.
5 f3 i; Q5 S+ V. m( j/ ?6 wto setup
* [9 E4 G2 L" D% r  ca; R+ r1 w. j9 N1 ?+ B
  setup-globals5 |# C' e" d, `% U# M: {- R

1 r6 |" b/ R! P+ l5 }% `8 F  ;; First we ask the patches to draw themselves and set up a few variables6 }" S0 J+ }! |8 @  P" O! @
  setup-patches
, l, \+ G  `2 P1 R: g7 U  make-current one-of intersections
. U- [/ E. U) z  label-current
$ r5 E8 G/ }5 V) J% T8 F2 F$ `# B, y4 T/ j! P! Q/ ]
  set-default-shape turtles "car"" T' v; e7 N* v
& V" T* g5 o/ D$ ~3 u! t
  if (num-cars > count roads)5 _, \" J& i1 a0 n! U3 g. k% `5 i) H
  [% y6 G  W7 {4 }) F5 f5 Q
    user-message (word "There are too many cars for the amount of "/ I$ t6 X, u, E
                       "road.  Either increase the amount of roads "
  O4 x+ K) u+ g4 T" Y2 [! I3 t& g                       "by increasing the GRID-SIZE-X or "* B" `- [1 }& ?9 A: X
                       "GRID-SIZE-Y sliders, or decrease the "
' ~; g1 _1 i/ @; C                       "number of cars by lowering the NUMBER slider.\n"# ^8 a/ V1 ~( A3 i7 e, Y5 m
                       "The setup has stopped.")) F1 I2 P; |* z5 \
    stop
! U6 _2 _) V5 E2 G2 n) v1 ^  ]3 n$ H& C! r2 {. F  s
$ T% A- R% M- g1 B+ p8 I  T
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color  p# ^  `, _# Y. g3 @& f( S3 K9 p( {
  crt num-cars
$ E( I3 Y8 a. J4 A: M+ K+ Y! ?  [* R: p1 _9 h: z: }- |) _. T! {7 }
    setup-cars
4 G2 f! h5 Z" z) C0 h    set-car-color# }( L; U) U; h' b
    record-data
( S$ H% R7 E+ p' }  ]) D& w$ ^+ j, l" S, Q4 t% t

5 c: X; V! F3 t  ;; give the turtles an initial speed
' n3 V' B& i0 m; V2 {1 j% W8 I  ask turtles [ set-car-speed ]* }+ ~: U% N- _

. s# [* a) i9 T4 D% d# P' h3 ]  reset-ticks/ L. F( v/ i! {# q9 {9 x1 P2 r
end
8 f7 S! f; c9 d( @" G3 j" M3 o" f/ ~: r  x* @9 |) e+ \
;; Initialize the global variables to appropriate values
% [( m! B+ J# gto setup-globals
  `. C7 |& H" N4 X% ?5 m+ m  set current-light nobody ;; just for now, since there are no lights yet, P" p2 K& e# P# u
  set phase 05 \) ^1 T: t0 J* {# a4 _
  set num-cars-stopped 03 b8 D  v. Z& u+ d$ T
  set grid-x-inc world-width / grid-size-x, `- e4 Z' j  k4 }5 N2 |& g
  set grid-y-inc world-height / grid-size-y
. H. E9 m2 }2 g0 Q. E! [' ~. o
. q3 i* q: q" E7 B9 z4 _  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
' u' V& e; G7 b# i" P) J5 \+ o. Q) j  set acceleration 0.099
% Q% K, _% S' X+ d. f8 S1 _end/ p8 o/ Y) g+ l% H: a" o( p2 M

, \' t+ A7 L) O! v, i- d5 p;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
' y4 N3 Y/ W5 a# ^( P: X; ?! a9 w;; and initialize the traffic lights to one setting
0 W2 c2 Y" E& r) Ato setup-patches
  i2 f; v  h  z  ;; initialize the patch-owned variables and color the patches to a base-color2 ]5 }" s" I! `2 s
  ask patches
1 R. P# N4 B, N9 j2 K+ w3 J  [) ], \8 D: A# o5 f# \! X4 r
    set intersection? false, j( M* c, _/ X# |' B
    set auto? false
3 X$ _/ b8 f+ V8 x4 A9 }; ~/ I    set green-light-up? true0 d2 i6 {& G4 w* h6 P' E( f
    set my-row -1- s* y2 [$ m( q
    set my-column -1
2 h1 c# I1 @5 @4 f5 m& F, i    set my-phase -1& D2 h, l4 y7 e1 J4 J6 m
    set pcolor brown + 31 |4 [5 L% `: c* w
  ]" \' K: c# c1 v  x9 Z- n
+ P: U  I6 |8 X! T* E$ p; F7 ^/ ^$ z4 V
  ;; initialize the global variables that hold patch agentsets( T: v1 k7 s. t/ \
  set roads patches with4 I% D  a4 V! z) N  E6 A4 r
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' v' X* c6 W) d$ L: g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" q% R; Q4 x6 \2 A+ c, I6 [  set intersections roads with
# C$ ]/ A2 `$ P6 H; V# k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
  L: ]$ }$ l- p# h1 @$ O! c# W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- g8 u+ `' K+ B/ a  c/ p  D, ^- X/ d0 K& q- ~1 X) e' F: H
  ask roads [ set pcolor white ]- Z. l9 [* ^! }4 F
    setup-intersections
5 f" e) N6 z3 d7 @end+ P4 y/ F% F% K* F' A
其中定义道路的句子,如下所示,是什么意思啊?4 |) p. g/ \9 Q
set roads patches with( f% U+ Y+ D% l1 G- T( d, N+ X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, h* Y" d4 |; C7 |  E$ r* b6 g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  W& F6 F1 p+ N" p$ m5 k) m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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