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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。: z# J6 J5 o+ R
netlogo自带的social science--traffic grid这一例子当中,
7 z- F0 }  @- H+ ?) l! Eglobals7 a/ N# ]0 G/ a  h" O
[( F4 U$ u. x1 ^  h# }! h  M* W
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
& ]# ?. J6 t7 [) ~2 j! [  grid-y-inc               ;; the amount of patches in between two roads in the y direction
( D. D7 L+ y* |  acceleration             ;; the constant that controls how much a car speeds up or slows down by if/ e& P, v2 I8 f* R
                           ;; it is to accelerate or decelerate6 L9 ?! N& `0 E6 u0 o. ]/ E$ k* W4 f
  phase                    ;; keeps track of the phase
4 w9 z- {. o0 ^3 v3 c  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
  ]: _5 y( c" N2 r4 N2 q& X  current-light            ;; the currently selected light
' P5 ~7 H( y2 O+ C0 w* G0 w6 |# h8 y% M4 v3 }* o' f0 N
  ;; patch agentsets
$ U3 g! i3 Y& K+ Q% _- r  intersections ;; agentset containing the patches that are intersections
; r3 j4 k" N& C0 G# H9 b  roads         ;; agentset containing the patches that are roads( d. @# l: v2 ^- f, S+ K! s2 ?8 B
]/ Q1 i9 ^* U" G6 R( k

. X  K7 C: p% _7 B6 z5 oturtles-own, s" Y) e$ _' n; B6 B1 k
[
5 I! L0 q+ c: ]' d, V! L0 r5 n  speed     ;; the speed of the turtle# _# t! r" ?9 t" {- l
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
0 }7 j2 j# Y& f4 V" r" }2 i  wait-time ;; the amount of time since the last time a turtle has moved
  @8 M3 e0 D: P! r5 q" e]
, g! n* V6 m! s, m  R
! ]: v6 ?* ]7 e" r5 f6 X5 E% W/ s2 Upatches-own
8 g$ W2 r# a! V$ T2 t& I[+ y" B2 b8 |0 z1 Y, O0 q
  intersection?   ;; true if the patch is at the intersection of two roads
: L3 v" }- e6 P2 J5 u8 a  j  green-light-up? ;; true if the green light is above the intersection.  otherwise, false., Z/ F; ?/ x" g, S; Q( l
                  ;; false for a non-intersection patches.& b% t0 R0 U2 d: T
  my-row          ;; the row of the intersection counting from the upper left corner of the
; k/ M) h% i- v; h+ L0 m- T                  ;; world.  -1 for non-intersection patches.) f; |4 c. h5 m5 c" T, y8 i
  my-column       ;; the column of the intersection counting from the upper left corner of the' q9 O; J' z3 ]0 p
                  ;; world.  -1 for non-intersection patches.
: y: q# Y# O& o( t1 t  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
7 T! b: U) i) ~! |1 {5 G2 t2 G  auto?           ;; whether or not this intersection will switch automatically., {5 h% I( K* k' t( c
                  ;; false for non-intersection patches.7 `7 }9 D% e! v
]
% X) j" Q$ e; Z% \7 _( m8 N2 U- q  l& x6 J
8 q2 `$ a3 f" L0 B" p; h0 d
;;;;;;;;;;;;;;;;;;;;;;
* l! K5 l9 k0 m8 P& T& V;; Setup Procedures ;;
! D, W2 M8 f6 D/ J;;;;;;;;;;;;;;;;;;;;;;" x  Q  G$ r. T* [1 _7 A9 I7 M
5 Z/ U  D& u1 }" C1 h
;; Initialize the display by giving the global and patch variables initial values.0 }- I$ z# x, Q  I! S5 L- ^
;; Create num-cars of turtles if there are enough road patches for one turtle to' {0 V8 }9 D/ X9 ?
;; be created per road patch. Set up the plots.
& r5 r: l+ G! d8 Z/ O$ @to setup
& G; J: h2 O7 S( J  ca
7 z0 A3 S% o& k- V( r: K  setup-globals
. a0 M. Q! X  m5 N1 N+ Q9 N; b
6 n# |' X, ?  B  ;; First we ask the patches to draw themselves and set up a few variables
  j/ y1 k+ A$ [# n7 y, J5 Q& T  setup-patches  s/ `/ h  c6 H  ^8 o1 @. ?$ X" w+ a
  make-current one-of intersections2 c3 T( x  h0 Q6 L0 A; C
  label-current8 N+ ^7 C( t$ c. w; E- H  [& ~
8 u8 ]  y6 Z6 B' }/ o+ r. P, m
  set-default-shape turtles "car"
1 r  x$ C; T$ A6 x
+ E+ _5 R! ?4 z. S- L2 P3 A* i  if (num-cars > count roads)# Z/ }9 a% u8 \0 V2 i2 q
  [2 z8 h; v% E5 E( f0 f! `0 Z
    user-message (word "There are too many cars for the amount of "
) j; f- {( r. i; t, V7 f4 T                       "road.  Either increase the amount of roads "
1 X: ~, F5 ^* X                       "by increasing the GRID-SIZE-X or "
# Z' D* i# L* I" e/ h9 l                       "GRID-SIZE-Y sliders, or decrease the "# b- Z/ K5 o! n; K, u% i
                       "number of cars by lowering the NUMBER slider.\n": Q7 f9 q5 l0 p5 G1 @$ V
                       "The setup has stopped.")- k; J+ T6 Q' m' e  v$ S& ]: o
    stop
- @+ C. c3 j$ {, x  ]
  c3 f4 _0 f) o/ e( c( f! \+ W( n7 E- D; N( R" W0 R& v
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color  @! u  P, k: V0 i0 N6 [9 H
  crt num-cars; Q# `- H0 E0 c" ^
  [
& n1 @( ]1 C" V6 @7 d! n    setup-cars- E+ K8 M+ K$ i! y
    set-car-color3 M: e7 S: q" ~. h5 y
    record-data
4 W$ P7 [  s( l& J9 o: M0 m  ]
% Y. ~1 Y9 w" l$ g. ]( q) F, o9 F( r1 N' X" S# O3 p
  ;; give the turtles an initial speed
! b) J2 T9 K- H  ask turtles [ set-car-speed ]5 Q- A# I5 j0 ?1 K) f$ H: @& s

4 w8 ?' \" J5 q1 a5 l" Z  reset-ticks
; C$ g7 x) z  Tend& ~7 d0 U2 |. D6 E' `) K

' g6 g$ o8 F: C4 W;; Initialize the global variables to appropriate values& A/ A. [2 N- a- y6 {
to setup-globals
1 }; d& p7 |& A" e  set current-light nobody ;; just for now, since there are no lights yet& t7 E# a8 m/ j
  set phase 0
1 C8 U! M  F: X2 Z; c  set num-cars-stopped 0
# g: ?, m* _- H  set grid-x-inc world-width / grid-size-x
  Z! B* i4 m' O5 G& B  set grid-y-inc world-height / grid-size-y7 N6 M' s6 |# L

& s" p  y+ u2 T1 l) ]. U2 k/ i  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary$ f- `1 W+ o6 `! ?: A7 y# c1 P0 e
  set acceleration 0.099
. p* b: M$ m# o4 v9 ]end6 [, f2 A: L2 M) I: g

% x* O& ?1 ^1 c3 R1 w2 J0 };; Make the patches have appropriate colors, set up the roads and intersections agentsets,2 y5 b8 P% \  Q2 c7 N3 K
;; and initialize the traffic lights to one setting
) W$ L  w7 F( Uto setup-patches! {* a+ o- S# c' r5 @; B7 Y
  ;; initialize the patch-owned variables and color the patches to a base-color, q* m! i; _4 ]( n
  ask patches
6 e% s1 ?# M$ p3 ?  [
* E& Y- H! a# R0 w' e. Q  a    set intersection? false
* ~& B0 t8 d' J/ P& E8 t* q    set auto? false; r# y9 {  X4 R/ N9 P. ^$ Z
    set green-light-up? true
$ i0 F3 N/ D8 b1 i/ A6 q    set my-row -16 A# ^- j+ k6 B2 u. p2 ]! M& w
    set my-column -1
" m- v5 u! N; `    set my-phase -17 h. y# L0 J" M# ?$ q% r1 ]1 O
    set pcolor brown + 38 E: k! A; h' @, n
  ]* q' E8 h  Q5 P) J  I+ h" I

: X% x, R1 u* _) {$ X  ;; initialize the global variables that hold patch agentsets
7 o7 y  S- M# b& C6 F6 J) V  set roads patches with% l/ L1 o( }5 m) A6 n5 P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* v3 B- C) F" N% Y# w% r
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 y  F8 {" S+ o0 ], X0 h0 N
  set intersections roads with
* U3 k; M3 J) c3 d! Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and! T2 P- c, M8 b; W: E& n
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; _  e4 B. u+ Y  \+ I8 M0 P

8 F- Y$ W/ r) Q" f  ask roads [ set pcolor white ]
) z9 _) H7 C& R! X2 v% r  z/ w    setup-intersections+ w2 g5 W; u# C+ o. g  t
end
# D. V  [/ i2 d2 |- }; k) W其中定义道路的句子,如下所示,是什么意思啊?. y; [6 _) @& ]
set roads patches with
2 Y: J5 U. j; r) W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 v+ o$ J5 B: }1 e8 a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' v& o2 `; d- p" i
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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