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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。- F) Q: B# e, `$ m3 ~# l6 Q
netlogo自带的social science--traffic grid这一例子当中,; M4 J( C+ p0 V. W- B% y: m$ u  s
globals& k" R; U+ d/ \1 A. q
[
- ]1 _6 M: f2 n9 L" `+ w8 @: ~  grid-x-inc               ;; the amount of patches in between two roads in the x direction
& y8 l- V7 L/ y% o( C  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: ]9 d% c" H" i: E0 \  acceleration             ;; the constant that controls how much a car speeds up or slows down by if/ V7 F* t# j6 ^) y7 K. {
                           ;; it is to accelerate or decelerate; E1 q1 s$ m* ^, L
  phase                    ;; keeps track of the phase( x5 R( u4 ?: h: x4 N8 k2 @: U
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
* X- G( C  L% p  A' `  current-light            ;; the currently selected light9 i/ Y# w) x  k+ b6 a1 i4 Y1 f, _0 |" I: z

" B- x+ B8 i* c7 a  ;; patch agentsets# o6 l0 i- J# r! ^2 a
  intersections ;; agentset containing the patches that are intersections
" z8 c# n; D2 Q9 Q& `0 G  roads         ;; agentset containing the patches that are roads
4 q7 w# q% [. h]8 _* P6 @: J0 e4 ]  |2 N

: S- r. v* C% C" B8 M& P- Uturtles-own
2 S! I# _, k  V, @2 Q% B[
) b1 H7 i- z& o  S2 J4 L2 l& w  speed     ;; the speed of the turtle
8 P# s) ^) C' V5 q5 r) N) u  up-car?   ;; true if the turtle moves downwards and false if it moves to the right9 z2 S+ b+ Z' P2 W% M7 ^' n
  wait-time ;; the amount of time since the last time a turtle has moved# F! U) v1 d6 o. x1 J/ y
]  P3 x; ^/ d& n, j8 Q. Q" Z
, c! B% T# a/ g2 G
patches-own
0 W$ V% g* E% J0 B! f( j6 n4 C[) @- w$ G0 h1 y% t. G- R$ x
  intersection?   ;; true if the patch is at the intersection of two roads8 O$ ?  j" u: p. ^! H% y  N. v
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false./ F. V' f) t) [' G2 y9 j6 U
                  ;; false for a non-intersection patches.
- }! P* ~' E5 Z* R2 ?  D1 t# a' H  my-row          ;; the row of the intersection counting from the upper left corner of the3 w" m8 e" K% P0 Q+ E
                  ;; world.  -1 for non-intersection patches.1 A; O( J4 t( g2 v: g+ l. T
  my-column       ;; the column of the intersection counting from the upper left corner of the6 w3 f' N- _% g+ X
                  ;; world.  -1 for non-intersection patches.( w0 Y6 m4 W: h8 _
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
) s/ C/ x5 l6 @: }4 R0 [9 e/ r  auto?           ;; whether or not this intersection will switch automatically.+ t$ F7 B; N9 B2 N* s9 H3 f
                  ;; false for non-intersection patches.
! T3 l) s' Z9 g& {]
) I/ J, }. q5 O: C% t+ R1 k7 y/ `) d5 m& x( l

) ^. C8 M( j9 f" Q;;;;;;;;;;;;;;;;;;;;;;) r7 N/ G9 F. y5 f( E& }6 @' H
;; Setup Procedures ;;
" O/ }& r  {/ M. G: f6 C( E;;;;;;;;;;;;;;;;;;;;;;
" C$ S# Q; `$ F5 Z9 v$ I8 e1 [1 `
;; Initialize the display by giving the global and patch variables initial values.9 G6 A  k* @% _3 ?
;; Create num-cars of turtles if there are enough road patches for one turtle to
; b! ]' T7 q" \% M1 n+ F% q;; be created per road patch. Set up the plots.0 T1 I) C- T) k4 f
to setup
" G" l" v* r0 x! x' M2 @  ca
# T7 W% @2 S" E7 v: S  setup-globals7 j: A9 x( R0 ]1 U# \0 e( E# C
* E) S2 E# l; c5 {( ~* d
  ;; First we ask the patches to draw themselves and set up a few variables
: W8 B6 c( }8 B  setup-patches+ N: \0 O! s5 {/ U* {
  make-current one-of intersections+ D* [+ s6 e, k4 B# [2 S
  label-current
) G. n. L' z; U. V& F
9 R9 N3 ?2 @6 [2 {+ ?  set-default-shape turtles "car"
# ?% M2 o- d% _& e5 z2 l& s" p" e' t3 I7 X3 y0 S/ j- ^/ C
  if (num-cars > count roads)2 ^# c" v  m1 W! B6 n. m+ w
  [: a, L3 Q8 n6 B! g+ u3 A' L
    user-message (word "There are too many cars for the amount of "
/ o* h! [* n6 S, s7 Y                       "road.  Either increase the amount of roads "
# |+ s+ E3 d1 U$ W& I                       "by increasing the GRID-SIZE-X or "
$ H: G  C+ x- R: |  o                       "GRID-SIZE-Y sliders, or decrease the "1 f4 D' z& m4 S5 N* \3 s+ E
                       "number of cars by lowering the NUMBER slider.\n"( g/ o* |6 t: j+ R0 z" o8 l' \4 E* b, Z
                       "The setup has stopped.")  P& {% i8 H! S2 ], [
    stop
: e! E  R3 q1 j! ^: Z3 U! d  ]
8 h& \$ {" E5 P- j& E7 [$ S
5 \. S, ~6 z9 W1 q2 O9 J1 G  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color) f0 j; F6 ~$ g" \1 T
  crt num-cars
0 E  J+ B9 Q0 k8 d) H& x  [; H% D# [# q& _; t, E
    setup-cars
; x# f5 _% c! X2 I4 ~, s) Q    set-car-color0 U  p% a% Q! i) }- y
    record-data
; P2 ^9 }+ c2 ^  ]5 a$ \* O- f- G
9 u! _5 V2 N* A% T1 j
  ;; give the turtles an initial speed5 ~$ J+ t1 s4 ?: X+ t" W
  ask turtles [ set-car-speed ]
, G/ Q4 o  ~6 n& H( J" v7 R0 \/ u2 I: F6 y/ @. i7 h( G
  reset-ticks
, b* x, H  R( {, C6 a. |end# p2 Z  O: s( X& L+ y! C5 L) F
6 s* b6 }  [7 M( C; D
;; Initialize the global variables to appropriate values" {3 ]: u. K3 Y
to setup-globals
, N+ z8 l# L! T  set current-light nobody ;; just for now, since there are no lights yet9 @! v/ D3 q. G4 D
  set phase 0" b; Y4 P* u% L- H# k
  set num-cars-stopped 0
7 \4 \* l6 i4 t& Q7 o6 J" E; [: D  set grid-x-inc world-width / grid-size-x
, l/ y& f( Y9 O- h  set grid-y-inc world-height / grid-size-y5 j2 U1 `7 _# {
4 _, }2 n7 ]2 S& ]3 ?
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
2 c. a: m# h, Q' A& p  set acceleration 0.099
# x- e9 n8 c: n) T. `" Qend
9 B, e6 W  s- D* V* ]/ V% [' k* d) X) }9 P
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
+ I4 Y* |6 k# |. L8 {;; and initialize the traffic lights to one setting
7 d$ p3 q6 D( h& Eto setup-patches6 F# A# k, D! n* |( _
  ;; initialize the patch-owned variables and color the patches to a base-color
! u2 k1 X: W$ _2 {: w1 z  ask patches
- t; f4 \9 u% @' p! k( F) I  [
4 R' Q/ a5 T8 f( `& F    set intersection? false
+ }$ ~7 \# A; _) O1 H. M    set auto? false
  o# ]  O* j3 K4 C+ S% [- {    set green-light-up? true, Z8 d/ q0 ?: J: |5 z7 H, _$ }
    set my-row -1
" P. T3 _5 B* e7 e5 i/ A    set my-column -19 ^1 }: i6 o: n- b8 m5 ?1 B
    set my-phase -11 m0 R9 P, z, W0 F
    set pcolor brown + 3
0 x' c, {: Z" R" Q( l. H  ]0 Y4 B2 J3 z6 L' q+ o
7 W/ h+ p& F1 @& F4 y  X
  ;; initialize the global variables that hold patch agentsets! b$ {. v7 v( k0 G) ?/ S+ b* R
  set roads patches with4 R" x7 u- }! A4 `4 K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 j& {: b1 f7 M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 _! K9 {6 a: Z
  set intersections roads with4 k& J/ t  i% X# y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 _1 j# A2 U3 K" q( a1 A: w
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 t  j3 F8 I3 T) T* N) J+ ]1 B7 R, }& D
  ask roads [ set pcolor white ]# B# e+ j: e4 t+ n0 Z3 M) E# O
    setup-intersections
5 d; G/ ]5 F) A  j! kend8 Z/ ^. S/ }! l9 q+ k
其中定义道路的句子,如下所示,是什么意思啊?6 V2 x0 b- ^; M: ?- K8 b! J
set roads patches with
0 Z* ^) z% \6 V) `9 S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  I  z; U0 q( V2 Y3 u9 {! L1 c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) S  b9 u/ K4 f$ t
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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