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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。$ _) C  T9 J. [, T9 u
netlogo自带的social science--traffic grid这一例子当中,
8 A8 |, c; C: _* Y9 k& ?7 hglobals& ]/ j0 ^  N8 b$ k7 b" ^
[3 S5 U9 v6 M# G4 U: U
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% w$ y/ w. t8 t. y$ T  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 |' C. |& L- H) B0 q- `/ _" n  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
/ i3 c) U, r- t0 c                           ;; it is to accelerate or decelerate& `$ A: i' y9 s* g$ }+ t
  phase                    ;; keeps track of the phase
( T1 O2 h. d0 ?+ ~* R  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; s1 W% {( e  F8 f  current-light            ;; the currently selected light
) |" y, B4 W. O- @( n. N, t, I5 {- w( G
  ;; patch agentsets
4 U9 r' a% O  z  L% K$ g2 E9 }  intersections ;; agentset containing the patches that are intersections
/ A( j% G: q. F7 O  roads         ;; agentset containing the patches that are roads
2 U0 s  t% j6 a& V6 a]- ~6 C- {$ y7 ?. T7 S

+ [' |6 K! M5 c# b, G% K; Wturtles-own: N+ N9 `# x7 D
[# D" p) D1 p  k) n0 J
  speed     ;; the speed of the turtle
' w2 y& F! Z. q0 a, T6 N  up-car?   ;; true if the turtle moves downwards and false if it moves to the right! W' H2 l; ~1 x  z, J. u) A
  wait-time ;; the amount of time since the last time a turtle has moved# `3 O1 D# O5 `9 P" c* Z) r2 X* e9 ]
]
5 R1 ?+ R7 ?/ }9 F% k
$ l" k2 {! b9 y- n, Y) Ypatches-own
# R0 t3 v: C5 X( f! \5 d[$ q. \7 s/ b% A1 g
  intersection?   ;; true if the patch is at the intersection of two roads
( v; Q7 U7 v* a' R6 N  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.7 x/ S$ t2 D5 ~6 s. t2 ?
                  ;; false for a non-intersection patches.
3 U( U$ f2 z5 j1 u1 L8 d, A' e  my-row          ;; the row of the intersection counting from the upper left corner of the
$ d+ h4 F. N7 e                  ;; world.  -1 for non-intersection patches.9 X0 L/ B. y0 {! x. [# j4 q
  my-column       ;; the column of the intersection counting from the upper left corner of the  Z6 \0 Z: d$ w9 H( J7 Q% L
                  ;; world.  -1 for non-intersection patches.
! s2 E: v, L  H3 W4 m  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.) {: J4 Q% \; L3 n
  auto?           ;; whether or not this intersection will switch automatically.
2 j' D, J) i6 q7 i                  ;; false for non-intersection patches.. B& C( J  d) `, \+ G( |
]; [; N. q+ X7 G4 ~  P
" ^. }4 W& L! @! A9 X

9 X2 b3 Y- m) Q0 ?. j+ c; t;;;;;;;;;;;;;;;;;;;;;;( W% w2 N! N( s# [8 y% J
;; Setup Procedures ;;' N' \* ]/ W/ t  F' k4 e
;;;;;;;;;;;;;;;;;;;;;;% `0 r4 L: D) t

/ G) C5 g  n0 U;; Initialize the display by giving the global and patch variables initial values.
/ x4 ^; j; |! \7 O5 f; P;; Create num-cars of turtles if there are enough road patches for one turtle to# D- q/ k3 G6 \
;; be created per road patch. Set up the plots.
$ g6 D7 |+ C+ H% R% I1 f, rto setup( {+ W7 x9 p. m. j5 ~5 K9 \" c# c
  ca
3 ]- |( [) y- L( n; q9 i  setup-globals& Q0 h6 O" n5 q/ N0 @& A5 s
0 O$ n; |1 c1 o# F
  ;; First we ask the patches to draw themselves and set up a few variables) A* W/ D- z  R% ~( o( r
  setup-patches. P" @+ b# J1 w# I% a( Y
  make-current one-of intersections
7 T" P9 i, b& M# |) A/ Q  label-current
7 `. L& |1 J& A4 Q" X7 e7 y. W$ u; f9 j  k$ k
  set-default-shape turtles "car"  w; Y8 R: O4 l3 t3 A
7 N% d" {3 q+ c* @  K8 c
  if (num-cars > count roads)& k& L+ ^- {8 l8 c
  [
% d# {( y  r* B) P+ b( O  O" x    user-message (word "There are too many cars for the amount of "6 v1 V4 @! V0 Q0 F* x
                       "road.  Either increase the amount of roads "
, `2 X; G& s  X8 x. @                       "by increasing the GRID-SIZE-X or "
; _! ]$ g" B" T8 q! G4 a5 t                       "GRID-SIZE-Y sliders, or decrease the "
$ @8 J6 t" \( {                       "number of cars by lowering the NUMBER slider.\n"
" N. L- `0 Z7 T5 f. g1 \8 M, N, t                       "The setup has stopped.")
# C: o# J" a4 X- C4 n    stop
( g7 B. M1 ]6 J  M8 P) R  ]/ h/ q0 T$ a' \2 a2 N8 O
1 @& N# J$ T. y& D$ w
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
* A3 V+ \+ Y/ F! X) N" k7 c  crt num-cars$ M% f, q8 z, i1 B0 s5 C2 o4 }
  [% G; c' q; ~5 e, q" b
    setup-cars
' |7 a( Q/ I% W) g    set-car-color, S% |. X; \# b$ k$ T- B- J
    record-data
/ n; M/ B/ V& H- \  ]
! w; T+ E% U8 J2 l( Y5 J
" \; G3 K) `3 D8 G  M; P4 I  ;; give the turtles an initial speed
9 B4 i; N) W  `7 i) K  ask turtles [ set-car-speed ]* _7 }7 D/ h6 x7 D2 h& R

, c3 {/ O  H+ {+ U' Q: L  reset-ticks
8 i! r8 h% o1 {) T5 s8 `/ \( Dend& N, H2 Z% P: e' I- t

2 X+ n& G0 ?6 K9 p% Z;; Initialize the global variables to appropriate values
8 j) I; {3 g/ }2 mto setup-globals4 k( j$ @' I+ y9 g! F% m
  set current-light nobody ;; just for now, since there are no lights yet
2 d, k" n. _7 C0 b* q. k* s  set phase 0
1 H9 _) v. {# \  set num-cars-stopped 0! h# r+ I6 T/ ~. Z5 h
  set grid-x-inc world-width / grid-size-x5 ?) h+ O* ~/ u# L$ L
  set grid-y-inc world-height / grid-size-y
/ r: Z4 t; ?/ @4 C/ {3 h* a( u) p: H' |. B. ~- M$ ~
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
' q3 Y% D, [( E/ A+ ^  K4 S  set acceleration 0.099: d: A& x' U6 [( N2 n2 X
end' `) T. r3 a0 z  k" _6 C

+ q# W( a! }0 c8 g+ @& _# V' @;; Make the patches have appropriate colors, set up the roads and intersections agentsets,: N3 t0 O( Y. }5 E
;; and initialize the traffic lights to one setting
9 j( @, U, u( {  Vto setup-patches
! }# v8 ]& ?; Q! Q. e* J5 q  ;; initialize the patch-owned variables and color the patches to a base-color
) H, C" H  ?# t  ask patches( M/ }7 L3 f+ U7 _3 o
  [
3 Q$ ]! ?3 @, u; P0 l& q    set intersection? false, l9 ]+ z/ y" K( m# i- M4 T
    set auto? false9 E! A' `) l/ b7 c% ^
    set green-light-up? true
2 w3 @  w5 r2 ^( W( |    set my-row -1
6 ^8 r. w+ E, q" u) n9 V  i    set my-column -17 X/ s! v* O6 f5 I
    set my-phase -15 I/ ~* K/ j( M, E; F& D, I: X& Y
    set pcolor brown + 3
5 P4 Z; ]6 O. X/ Z2 W: ^: U# Z6 V  ]
7 X/ K; x8 ^8 U4 V& `" p. E
+ g# `7 r- L( w9 k  ;; initialize the global variables that hold patch agentsets
$ a1 T- x6 I) |9 D; `$ |; J/ ?: k6 x  set roads patches with
6 i1 V) ^2 |( l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) w5 b# l% p) s# [& q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* z2 T6 ^- W8 C9 w1 V, Y* e
  set intersections roads with
  p; E* d% L7 i0 S& t( r6 h- o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
* }+ T% w, C# l" D# }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" S# o7 H4 r$ Q' w
9 c0 u/ i3 b5 w2 L. Z) U  ask roads [ set pcolor white ]
0 _0 z% f- J& I( l( A    setup-intersections
; l$ E( y/ U% }. |( l! M. P! Qend
/ m/ k- S: d( Y6 |, q+ |7 a其中定义道路的句子,如下所示,是什么意思啊?6 h! D$ G& h, l: [) A* Z/ s
set roads patches with
, ~8 |0 u! b6 W6 J    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: i! q9 I) {) q4 E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' o  d) S0 n+ b3 ^" @3 u& n  Y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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