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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/ m8 u# l3 n  V# {9 c8 B" e
netlogo自带的social science--traffic grid这一例子当中,
. k) o% C8 Y& ~8 `2 O9 j! dglobals
, e) q7 q8 N$ x7 {9 Q[
  E7 Q$ D" R' A1 U3 R' `  grid-x-inc               ;; the amount of patches in between two roads in the x direction9 y2 H9 N  |4 x" f* [' v
  grid-y-inc               ;; the amount of patches in between two roads in the y direction' `7 r1 _9 y8 l; R
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
! T( w. z2 Q3 K, L. A. ~                           ;; it is to accelerate or decelerate
: Z4 }$ K5 s2 E$ v: a& g* p! R  phase                    ;; keeps track of the phase3 r( ]! S( [4 v& i
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
( v& h2 x6 x* K) ?+ s0 ~. O  current-light            ;; the currently selected light. g8 ]. b: \3 b1 N2 \: @; I
) o5 W6 r( W4 }) \8 P9 j# }7 L
  ;; patch agentsets1 Z+ Z% @8 n" d# x* K
  intersections ;; agentset containing the patches that are intersections
0 o. X$ e5 r% |" p8 u: y3 c  roads         ;; agentset containing the patches that are roads3 ?% q' @4 |8 b8 U; H" e
]9 S" R3 F4 C( z4 |' _7 @# e

3 |7 _) j4 e' [0 ^$ hturtles-own
7 t0 X+ ?( y2 k8 n: C7 G7 p; |[' H6 p( t  b1 y
  speed     ;; the speed of the turtle% N5 g! O6 z3 O% t) o
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& b# f6 e; ^% u6 c) `8 Z
  wait-time ;; the amount of time since the last time a turtle has moved) U; m  t) w" R" K' }' `7 q
]
0 d0 e1 l1 `$ o+ v% O$ R; L# m, @  C4 s
patches-own2 q/ [) Z- i( G
[0 n9 I: m" P) x& h1 ~
  intersection?   ;; true if the patch is at the intersection of two roads, w$ {/ v  v9 |
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% K1 h; ?' ?2 J5 Y" r                  ;; false for a non-intersection patches.
- x" o7 y$ b- L& B: d# h1 Z3 E  my-row          ;; the row of the intersection counting from the upper left corner of the4 p; I5 B2 ]* {, `8 G
                  ;; world.  -1 for non-intersection patches.
" K8 v8 u$ M% O  my-column       ;; the column of the intersection counting from the upper left corner of the
/ o! j9 c5 }( o# x) F, G                  ;; world.  -1 for non-intersection patches.0 n0 X$ v% |# J$ ~! q4 s
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.& \- o0 w  }* G; e" y# G% @. `4 @
  auto?           ;; whether or not this intersection will switch automatically.! N; G; {- M- B- k5 \  l
                  ;; false for non-intersection patches.
; P& U9 J' u" D  k3 w" J]9 B  P# j$ u. f  J. ^  j
/ \; t6 ~$ D& v5 {; W6 ?

6 @8 e2 L% {! y! v! O;;;;;;;;;;;;;;;;;;;;;;
, V( H9 f2 n" k;; Setup Procedures ;;) n, i7 ]3 I4 }$ k% \7 O9 B
;;;;;;;;;;;;;;;;;;;;;;
5 D. M- g, `: F% z" M9 q- I8 V+ S) Z
% u+ r% c$ n  Q# S8 {;; Initialize the display by giving the global and patch variables initial values.2 E! I6 s+ D/ }4 Y6 Q
;; Create num-cars of turtles if there are enough road patches for one turtle to) K' x, y. j. O; b6 _( X$ q1 b
;; be created per road patch. Set up the plots.* C# N( A# S& V( f
to setup6 h) o9 r0 J& m4 C0 I* Y. i$ I
  ca4 x$ w+ U, k( [; y+ L8 b" ?
  setup-globals/ P$ K% o( R- w. n: |
0 F6 L7 n. [3 z! l8 d
  ;; First we ask the patches to draw themselves and set up a few variables0 v3 S3 \: `, |: l; \+ k
  setup-patches6 D! o  T" K, k# o
  make-current one-of intersections
/ d- x1 G1 y2 v  label-current
: M4 X% H4 n$ J  a! B! D! b5 [5 y9 u6 w/ ?+ H" I  J
  set-default-shape turtles "car"
; P0 U8 a3 X0 x  _5 V& E  l3 ~# }! a" p! _  z1 U+ i
  if (num-cars > count roads): L% j5 h3 v( y3 A0 R* Z
  [
9 i8 C, U% u, v7 _; H    user-message (word "There are too many cars for the amount of "' Z" n2 c( K0 k
                       "road.  Either increase the amount of roads "
! k  t, w# a! Q! P) Z. a* X                       "by increasing the GRID-SIZE-X or "+ m$ L+ \- q# I. W- ?0 O# p
                       "GRID-SIZE-Y sliders, or decrease the "
5 P+ F3 ^& d! E) _$ P                       "number of cars by lowering the NUMBER slider.\n"
. q1 J) U- A. [* ~                       "The setup has stopped.")5 E" M" B/ H- ?! w/ A9 b
    stop9 J" D! k8 r* Y5 v9 z! u. V: t$ ]  a& x
  ]+ N* h- U6 ]) W
5 S* B& T; Q" J" K: z
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color. O* ], O( A# v0 K
  crt num-cars
1 V, Q8 Y. d' {9 Y: m  ?  [7 @8 V0 L, i$ F: J% U
    setup-cars
, M& D& i+ B! d( f* A    set-car-color4 v! B" Z! w# n9 y6 O6 O2 g
    record-data+ N' r8 V1 ]! _% t9 S+ [8 W
  ]* o' _4 ?0 l7 I+ ~  q
5 M, e7 _( {1 X( |& \3 a8 Z0 C
  ;; give the turtles an initial speed
; g6 C7 o0 v8 [: d, G/ Q6 V) P  ask turtles [ set-car-speed ]4 X4 i$ u$ Q& |3 b& X4 ]2 F8 ~$ ]
6 \! |3 |9 q# H% H+ z- X+ k
  reset-ticks$ C  y' i; I1 J
end
; r5 T! s, G% p5 f6 z( I. c7 e& n; ]! M% Y3 E
;; Initialize the global variables to appropriate values
* R8 h2 }* I6 F" _7 m+ @to setup-globals
+ s) M1 l, H) s6 p; t2 P  set current-light nobody ;; just for now, since there are no lights yet
0 x& O, ]* h5 Y- F) e* M  set phase 0& n- `' g1 [5 o7 O
  set num-cars-stopped 0$ p- H) D& z& {4 c+ @
  set grid-x-inc world-width / grid-size-x
9 Y7 Q& r  Y# x5 _/ j/ o  set grid-y-inc world-height / grid-size-y
  Q4 v7 k; s( e, P  @7 y- g3 ~0 O( a/ f
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary$ u! R* I! q2 y) T2 e3 ~
  set acceleration 0.099
% Z2 a* h6 J; @- M" Fend
+ |4 E3 o8 z. d' U
# n, |& H, h& @7 s;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# W( r5 c& I: f; g1 K;; and initialize the traffic lights to one setting
5 M" V# i% M! d. Y8 K! U; pto setup-patches% F) j2 B' \- P* X; |; L% i
  ;; initialize the patch-owned variables and color the patches to a base-color
$ B/ R6 U  X, V' U  ask patches* Y, J8 ?  l) m% u) `; s% R
  [
; l7 [% f" B5 U+ ?) Y  m    set intersection? false
; X& p1 D* W9 N* i4 w3 M+ I% S( `    set auto? false
( P$ p0 G( w6 Z    set green-light-up? true
. q% B+ Y; g- f6 A: f    set my-row -1, w- K" s6 g9 ?: a* C1 d* M
    set my-column -1
! n$ S. [3 u% b& f6 \3 e    set my-phase -1( T# n9 Y$ U2 v0 H) f  y
    set pcolor brown + 3/ T" s6 }: |8 r
  ]
- D  s+ A4 H0 U/ s$ ]0 ^1 @7 r: y
  ;; initialize the global variables that hold patch agentsets, ?9 N- @* H. q2 ]9 p* |/ T
  set roads patches with
/ a" k- S7 q& I8 j, T  R3 k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' Y" O4 O& I& o* m  X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( L% p3 p' }1 C  set intersections roads with1 n, |, K! G: T7 R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ e! E6 a/ @; ]- g9 R, b- r! [
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ p8 d8 O9 y8 n6 o

) s9 r3 O* k, M& Z4 s  ask roads [ set pcolor white ]
( V1 g' {) f- D3 x5 U    setup-intersections
. ]2 s5 I0 T; n! w8 M0 _5 t0 Wend
5 V' A7 Y$ Q7 B2 B其中定义道路的句子,如下所示,是什么意思啊?! e9 f; s# _* b9 F$ D
set roads patches with; ]/ a7 T: P; b1 |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, X8 v4 g% Y6 t0 @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& S" L. N! x/ f( d" j5 H* p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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