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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。$ y) I8 T+ m: z: g, A+ `
netlogo自带的social science--traffic grid这一例子当中,
4 K8 U* N$ z1 H( `: m+ X0 wglobals
: Q! w" n  ?5 P! p( T8 ^- S1 Q[/ ~, m$ P- o0 [
  grid-x-inc               ;; the amount of patches in between two roads in the x direction' u. z! z2 ?# t' `
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
4 W, O! A. ]: e. h8 l7 J  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
0 i) K- }3 e9 l% p$ ^+ t                           ;; it is to accelerate or decelerate
0 L* |' @+ l! k6 E- F  phase                    ;; keeps track of the phase# |% e$ t0 o6 d1 e( g4 R* N
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
% J/ G1 m+ ?; a+ L5 q  current-light            ;; the currently selected light/ m; `( W% K3 [1 T% g2 p

( r. v, \3 j) e" Z0 r) l) W  ;; patch agentsets- G" S5 t: F/ ~
  intersections ;; agentset containing the patches that are intersections2 r. I/ T/ \( n% o1 c/ X
  roads         ;; agentset containing the patches that are roads4 V( {9 d! r/ B" S" x0 q
]
# F) S- b$ {) ]- i. \/ n3 r) P0 Q' N; r
turtles-own* ]* x7 D* m% F7 e  D
[% A( z! x! x7 o/ A
  speed     ;; the speed of the turtle3 y+ ^6 }( Y# O0 A* P
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
0 G; c) G- f( h; G  wait-time ;; the amount of time since the last time a turtle has moved
8 s9 h# D7 m8 A+ j$ Q]
( r* ?$ H; ~8 p+ q
% L$ T- q+ \9 V/ m/ n5 g. opatches-own
; k( r" j+ {' Y- h; m$ ^% M, }[
6 r  F7 O; E* d6 g: r  intersection?   ;; true if the patch is at the intersection of two roads3 K: ~+ X% Q0 D
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.. K8 g6 `2 L& B7 Y
                  ;; false for a non-intersection patches.
2 F2 D5 f- Q5 j' }" W6 R9 Y  my-row          ;; the row of the intersection counting from the upper left corner of the
! f9 d# R; Y  l) U" q# ^                  ;; world.  -1 for non-intersection patches.
6 G- @. t9 a) Y* d  my-column       ;; the column of the intersection counting from the upper left corner of the
9 ]# O( U- @! z* q" P! @                  ;; world.  -1 for non-intersection patches.
2 D9 a: f9 V1 |, i8 N  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; t" S& n8 P8 Q: Q4 y  f  auto?           ;; whether or not this intersection will switch automatically.
7 J! f. z- e% L- v                  ;; false for non-intersection patches.
1 x% c% K9 L) t- ?5 U]3 }+ I% y: h3 \1 c3 D5 e& v5 J* s
: {9 G: C# b3 n* _& `% W' y
: Q0 C$ y  f: L+ S& M
;;;;;;;;;;;;;;;;;;;;;;8 a- x7 ~) I7 O; p
;; Setup Procedures ;;: p3 V1 k8 U! V  t/ `: I
;;;;;;;;;;;;;;;;;;;;;;
/ v, K- J" b) d; w0 e, I+ B8 r
* w/ q, N: P6 M  I1 |;; Initialize the display by giving the global and patch variables initial values.
/ }, t2 g. f0 R/ |! S9 J2 };; Create num-cars of turtles if there are enough road patches for one turtle to
& @, n8 I7 T. |/ n! V;; be created per road patch. Set up the plots., l0 S; F1 X& `+ _; @
to setup
4 Z4 ^7 R8 z8 q  ca
% W2 h# x3 `4 H9 d. p2 N+ W2 O  Q  setup-globals2 o- D0 G. k$ \
/ f( R/ K2 p4 r7 V. }' c) E3 V- Z
  ;; First we ask the patches to draw themselves and set up a few variables, W% d7 G2 {5 I  n
  setup-patches! w" N% z( h7 J5 Z6 V/ h1 X
  make-current one-of intersections7 p! y" t% i7 \& l$ C1 w" p, U' g( ]
  label-current
/ @) C6 {+ G- A, w
( b( W( @( Q1 {, O/ \$ F% x  set-default-shape turtles "car"/ i, e$ w% x9 W

( i) L% D1 i6 {" F( g  if (num-cars > count roads)
- s/ o9 o+ R% ~) `0 y3 F  [, \9 ?& C* t/ @( q
    user-message (word "There are too many cars for the amount of "
" y  n) z9 l  P% J6 y3 L                       "road.  Either increase the amount of roads "
; L. N5 z6 l. ~                       "by increasing the GRID-SIZE-X or "8 P0 x4 k" V2 s- J+ o! M2 g1 l
                       "GRID-SIZE-Y sliders, or decrease the "
$ |7 p8 f( k3 S. u! b" X                       "number of cars by lowering the NUMBER slider.\n". u& p' g, t# Y3 ~
                       "The setup has stopped.")
8 d0 M( X5 c* Y- R    stop$ a$ [6 ~0 I/ @3 C3 {: H
  ]$ a% k6 `! Q* \( X/ e+ q9 r
2 r8 Z8 x0 x2 [& Q# F% i1 ~( e
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  |4 H$ L- i1 G/ l  crt num-cars
9 V. C, }' ?6 W) s  [
2 ~7 }& R# b( X' t" ~7 Z0 y6 h7 E    setup-cars; _% j4 Y; ]1 |) B8 O( L# g
    set-car-color
$ u7 t9 l5 V6 p) n    record-data
+ @8 N8 R) }, |8 q8 m  ]
) Y: O) n% I, A6 q! }
. {+ u% W4 K4 O7 j  w  ;; give the turtles an initial speed
" y3 m! \  u1 H; N  ask turtles [ set-car-speed ]
) L5 e, r+ K" x% y
/ T% r7 U5 V  l& m! t  ~  reset-ticks
+ x9 g' o/ z2 m+ L. c+ L9 pend
6 k, _( ~  }, \* r/ u. a( ~9 n3 I
* K8 b9 T! O  K1 j$ r; r' G;; Initialize the global variables to appropriate values: z% z4 q" _& E$ L
to setup-globals
9 w# n- {1 v, X' u: m' G  set current-light nobody ;; just for now, since there are no lights yet( x. s: E7 Q4 W
  set phase 0
+ Q: m9 e/ Q$ a: m$ k. K  set num-cars-stopped 0
( m, Z4 g" K8 S* {  set grid-x-inc world-width / grid-size-x
' d8 Y$ z. X- k9 R' q" P& c0 u- A  set grid-y-inc world-height / grid-size-y/ w. U& Y4 W/ T* P5 n+ L) f
! f  d4 s3 X9 k/ E
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
0 e' [" N# o8 }/ Y& H" a) l( Z  set acceleration 0.099# O/ q8 m0 L9 ~7 X3 z7 Z
end1 i  Q7 z3 X8 q! v

9 Z/ e4 b4 f2 T' h3 T' ^;; Make the patches have appropriate colors, set up the roads and intersections agentsets,2 P/ T- x9 t4 }/ t" [* V0 Z. K
;; and initialize the traffic lights to one setting0 T! P& r! D8 W% u& J6 g1 m5 u$ B
to setup-patches+ G) O. d$ a& L# g  |
  ;; initialize the patch-owned variables and color the patches to a base-color
: t) L( S1 O6 f  ask patches
6 |& i7 r# o/ a. p  [
, r0 m3 e0 G5 U& N7 [5 t( B# B    set intersection? false: |. l6 R5 F0 l5 V2 \2 X8 ]  a
    set auto? false! U" Y  j! I% T- S3 q3 b% l) ]
    set green-light-up? true0 I; I8 `2 j8 }, y
    set my-row -1: B: A2 D9 g9 x3 ^8 f) s: C+ ?
    set my-column -17 x, E7 c- e8 F, g* f
    set my-phase -1
9 x" J% P9 }! L! i" q) ^    set pcolor brown + 3' L0 W0 L/ R/ R% _
  ]0 X7 f- _3 w' f4 ]
, p; A6 c' ^4 ^
  ;; initialize the global variables that hold patch agentsets. b8 B9 I& W8 t( D
  set roads patches with
; u& w: `1 w( K4 o, ~  u3 O4 E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 S* q. D/ H7 y3 F/ r" \5 d7 S7 |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- d$ \9 N) \4 B* d$ J
  set intersections roads with
3 Y* ~( m2 f1 R* u6 _( ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and; r0 ~) @+ \; S" Q3 J1 X: `3 X6 t
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& w" ?( Z3 E0 {# W$ ]' J

, ]. M# ^# C6 ^! k5 r% M% T  ask roads [ set pcolor white ]
. y; W9 R& @3 q7 k    setup-intersections
0 r9 H2 b/ l  X3 u2 w9 Jend
0 `! F1 ~: j4 K* X% o  q8 D其中定义道路的句子,如下所示,是什么意思啊?
$ h8 W: g2 e" L- @# o- [1 U. S set roads patches with
6 j1 X) l% ~# x2 A1 w% `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  i5 X( M, k1 {+ y7 d4 `
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# L/ U) R8 B3 F* X# s$ X- y6 d
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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