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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。& n* Q* G! ?5 z" j2 Q" x
netlogo自带的social science--traffic grid这一例子当中,4 x3 ]$ i- L! t, @
globals
3 }- L$ ~" y' [! x[
4 x/ N6 T  J" I3 ~' C  grid-x-inc               ;; the amount of patches in between two roads in the x direction
6 o3 z* q. K/ M. o7 h  grid-y-inc               ;; the amount of patches in between two roads in the y direction* x  ]* b# [$ \
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if  r$ z) M( l% z; m) M8 N* X4 Z
                           ;; it is to accelerate or decelerate( v, V2 O- U0 f1 r/ d8 v. u
  phase                    ;; keeps track of the phase
! a: P6 H) U8 r1 Y3 N1 z  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure' O4 h2 Q4 i# l" L, w- `2 F) z
  current-light            ;; the currently selected light$ h4 q9 d: y3 e) W% W- h4 I0 V

! G. c) m* a% \/ V' N( h  c8 s  ;; patch agentsets
; j4 M6 \# ~, r. E  intersections ;; agentset containing the patches that are intersections% j$ q% N- x0 q& l1 _2 e
  roads         ;; agentset containing the patches that are roads9 v& c5 j: h0 r
]
. e$ L" l: `5 Q1 w' A+ u8 I! @1 |
turtles-own
: }# h1 x- _" V! ^7 j1 F; v, J+ g[* |( K. K7 `  `$ K/ M! c% I
  speed     ;; the speed of the turtle
3 P, N2 B* u! Y  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
4 l  p" \' ]/ \+ [* I  wait-time ;; the amount of time since the last time a turtle has moved
6 m% m# S8 s- T3 L! T]) w! K$ u4 Z9 M4 b% G' i( {
- N% n+ w$ P2 `' b9 w% U
patches-own
' Z* v4 t2 x9 i  l[
! k3 i* g1 A' Y/ F- W  intersection?   ;; true if the patch is at the intersection of two roads
) s& N9 Y5 w1 ~) g  f% L  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( d% [! b( V1 B& A) `                  ;; false for a non-intersection patches.
. l$ L1 M- H/ f( d  my-row          ;; the row of the intersection counting from the upper left corner of the
) q. b8 q, B- [# {! s# B                  ;; world.  -1 for non-intersection patches.8 \: m( W$ U# Z1 q9 H/ C, A
  my-column       ;; the column of the intersection counting from the upper left corner of the5 O& S$ l% m( n( ^/ o
                  ;; world.  -1 for non-intersection patches.. o7 ]5 l! @1 z% E0 E
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.( Y0 n) f3 |4 Y) N
  auto?           ;; whether or not this intersection will switch automatically.1 \% I: |4 V5 y+ M3 y5 ^: A
                  ;; false for non-intersection patches.+ m$ d9 u4 t6 x& M
]
- {% X9 `0 q3 k, L/ \
0 W( \  V, t) A1 `
0 Z8 u7 P/ _5 v6 K6 _1 x;;;;;;;;;;;;;;;;;;;;;;( c! H2 ?' ~# Y- [* Y. @6 {6 X; W
;; Setup Procedures ;;
0 i: `. O& V2 m& k( S5 B;;;;;;;;;;;;;;;;;;;;;;
; y3 U  e2 W7 E4 m
* g" l" a! A- N' \# u;; Initialize the display by giving the global and patch variables initial values.8 W* h+ R1 ~$ a/ p
;; Create num-cars of turtles if there are enough road patches for one turtle to  l% e* d4 x  x- w
;; be created per road patch. Set up the plots.7 F, H8 Z; K8 M+ n( U; Q/ a
to setup7 Y6 h( Q" O" Q$ f
  ca" J$ Y" I' J4 {3 d* L/ P  E
  setup-globals" ^: C0 [' d' `7 N. f

! u) f, K( q8 ~  ;; First we ask the patches to draw themselves and set up a few variables& ~( {$ N5 v: I& I! t7 v
  setup-patches" l  N  C/ h5 U' R
  make-current one-of intersections
& K" F. q! k& c# _* }  q8 b  label-current: ~2 n7 E# b& X% }, f
; X. G6 u8 b6 B" }% z  Q' ^
  set-default-shape turtles "car"9 J- R3 O/ l9 w' \( @+ U& q3 W4 F
: g% D4 Z7 ~, _0 b: t5 C5 \! C
  if (num-cars > count roads)2 A1 [1 i7 f2 \; U; w
  [
! W# d! \9 G8 D" ?% m    user-message (word "There are too many cars for the amount of "
  I% O* @6 ]" s- i                       "road.  Either increase the amount of roads "
7 M( a1 S! n( B& g1 y. S+ s# J                       "by increasing the GRID-SIZE-X or "$ u) o  }  V. S! _
                       "GRID-SIZE-Y sliders, or decrease the "
& v1 p2 a+ Z3 Y  I* z8 [                       "number of cars by lowering the NUMBER slider.\n"" U$ ]' p: ?5 g$ K+ S" p8 M
                       "The setup has stopped.")0 t  w+ c4 f. z3 r3 e3 k; n! T# O% x
    stop' l' q# W8 q# z0 m  ]
  ]. ?' x3 y" Q, `# D. b" C( I1 X: q4 J3 n

( L% [! U9 y6 X4 a/ ^  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color6 a* j2 I3 K: i* G! O2 b- Q  d* |! o6 ]
  crt num-cars$ l, L) l8 N! h3 t$ y0 q
  [/ n+ L9 n( C' ^' A6 U
    setup-cars
% n5 K/ m) W" j& w3 t# s    set-car-color4 p2 c( Y9 [& m6 E
    record-data* y* Q2 b: e8 \, j. S
  ]4 E6 y5 f+ R( ?' I  ]
8 }, a4 D# F* S4 u/ y* [
  ;; give the turtles an initial speed
& _2 f# P9 |* w0 b  ask turtles [ set-car-speed ]% ?3 Q& Q. Z5 ?) @# I9 e( Q
* Z6 y: ?8 D8 Z3 W7 o
  reset-ticks
; Q+ r8 v1 i" l7 \$ H0 \4 Pend2 _/ z# }% b. w  C

  l! ^! g4 A8 {3 x; M" |7 s;; Initialize the global variables to appropriate values+ E6 t+ W5 U, ^+ G2 Y$ i' S
to setup-globals* Z8 b5 m! S# _+ S
  set current-light nobody ;; just for now, since there are no lights yet
# K7 j/ M7 y' Y% {% j9 e4 {  set phase 03 E4 D/ B0 i; V
  set num-cars-stopped 0( z4 r1 B/ [, ?2 v6 c
  set grid-x-inc world-width / grid-size-x
" A% w# _) l) ]* t: i5 U1 O  set grid-y-inc world-height / grid-size-y3 I; ~! w* Q0 E4 o9 Y5 c  g
' o* q3 e1 i8 x0 r
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary! D' I' i/ F/ q: O- N8 E* o
  set acceleration 0.099
8 x$ n) d/ m5 m" `end
& E  f0 E5 k: K0 j
. A/ K) \0 d* X; u+ `, \$ w# o;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
' g7 E, ]6 m4 w7 _;; and initialize the traffic lights to one setting) t# c6 b1 I1 j1 c; W
to setup-patches
, M2 n4 ~% [$ Y+ g. y" r. R( d  ;; initialize the patch-owned variables and color the patches to a base-color% B4 i7 }- h0 y# W
  ask patches1 L+ @8 O' q9 w8 }
  [4 y# _' c4 k0 P9 o4 ?" Y6 W  x$ p
    set intersection? false
5 S8 t' k, F* X3 }' P" R5 p    set auto? false/ [+ p/ q+ |( _' |
    set green-light-up? true: L& x! i% G; o7 a. f
    set my-row -1. J& d4 A% T- K1 p
    set my-column -11 v. c3 l6 V" N. {# }' Q5 p
    set my-phase -1  `7 e9 _  f4 o9 }0 H4 g
    set pcolor brown + 3
5 g1 `$ L) J! X+ Z  ]
# B# w+ W$ k8 }0 X! A- M7 X! {3 U* W
  ;; initialize the global variables that hold patch agentsets3 S; _6 Y1 j! @, v1 Q2 S
  set roads patches with0 l" c( v9 o: H8 O% L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& m. Y$ V0 Y2 z' b' p
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- [" c8 v0 g, ~) \2 `  set intersections roads with% d( |0 o8 n* B9 _1 T( W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
; z8 R! _+ A: q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; t8 u5 o- ]- p
) B2 i" S# k/ I  ask roads [ set pcolor white ]
; V6 u* h& c7 `- o    setup-intersections7 |! C- c( n: y, `
end
- r) f! s) o2 e. U( j其中定义道路的句子,如下所示,是什么意思啊?
4 w7 [- K9 l" p$ }) D! g set roads patches with
( ]& y, Q) n0 |& N6 {    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% u. S$ c, Q/ _4 Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 c7 Y: X: }2 v- Z( x' h1 }
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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