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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。3 j, w0 D, `, u0 R3 l
netlogo自带的social science--traffic grid这一例子当中,1 K: w5 R! e/ z1 m6 D3 T7 f* I
globals
: j9 E  E: f: u/ `, q[. }  f; Q: H7 a: x( g
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
1 d# Z! [) }2 k0 |  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) |: Z& q5 {) B( [" F5 M' z  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
. U" [. ^4 ]$ g+ h9 [3 y0 D                           ;; it is to accelerate or decelerate9 C3 |# s  K7 B+ w8 I# \; E
  phase                    ;; keeps track of the phase
( ^3 B3 k. _1 y% A3 D' w  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ F& Q7 x: n/ _
  current-light            ;; the currently selected light- e/ n$ V& q; k$ P% g9 R
4 B2 {) `% ]- {% _* x& T  u& Y
  ;; patch agentsets9 K' a3 w9 G; V) c% T+ {
  intersections ;; agentset containing the patches that are intersections3 Q. f4 T) Z: R: O
  roads         ;; agentset containing the patches that are roads
* s0 {4 z' q; t- J, y( x( t, W]" F7 b+ k/ O3 w/ U/ I# d

2 }, m/ _2 {4 n' l! R- s3 xturtles-own1 |2 X1 P) d- P2 r2 R: N% k
[/ x9 L; Y* c: {* ~* q2 O: _
  speed     ;; the speed of the turtle) q% q: V0 e- T9 @$ L5 {8 K& `
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
+ e3 ]7 s3 h% P1 m2 @2 B  wait-time ;; the amount of time since the last time a turtle has moved0 D$ e" j3 O1 `" d+ X2 I
]
! e9 i& A6 y$ k: g0 p7 s
! C, r9 \1 G: W% E3 m2 Opatches-own) J' i4 G. i1 L0 T4 P
[
% r5 h/ E4 e+ J1 C1 \4 C  intersection?   ;; true if the patch is at the intersection of two roads
! A" o! }4 J' r) ]6 x  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.  z! u/ Y7 [/ i+ k7 s% |$ C
                  ;; false for a non-intersection patches.' }3 b& J2 S# e9 g+ ^* w) L3 G
  my-row          ;; the row of the intersection counting from the upper left corner of the6 _- U8 q5 h0 }
                  ;; world.  -1 for non-intersection patches.
: E$ Q( O) w8 ?$ x- _  my-column       ;; the column of the intersection counting from the upper left corner of the
' Z; M3 X! ], p0 E% j+ R                  ;; world.  -1 for non-intersection patches.
3 `3 ]" d- P$ k4 x/ I9 W% x/ b  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
! D# N4 p; |& C+ j( v( L! n  auto?           ;; whether or not this intersection will switch automatically.% W/ h. I$ Y4 }
                  ;; false for non-intersection patches.
: D+ j7 H: K$ h& B1 A1 G7 u]
/ e$ ?! F7 D6 w' z
; x2 c; r0 x5 r+ c( E9 G5 _  ]8 ~6 M+ X9 I4 Q+ x8 f$ B
;;;;;;;;;;;;;;;;;;;;;;
  w6 D+ l1 O& @3 q1 \;; Setup Procedures ;;: b' l3 I5 j5 {- J) C+ I
;;;;;;;;;;;;;;;;;;;;;;
$ `# v; Q! k& T$ N! F- H! Z' B1 [4 H( ^
;; Initialize the display by giving the global and patch variables initial values.
  a; c  G9 V4 K. u) C. M;; Create num-cars of turtles if there are enough road patches for one turtle to
' J; Z4 Q9 A6 r6 `7 Y6 b+ g;; be created per road patch. Set up the plots.
; a+ W% w8 `5 Oto setup
+ ~; A) G4 ?5 L7 ^" R  e  ca
" i  g( C( g- F8 j  setup-globals$ E8 x! v, a+ }9 b* [! m6 A0 a. U3 e6 U; I
' g- N) P5 V4 o% N
  ;; First we ask the patches to draw themselves and set up a few variables% h; [  O( Q, a( K* ?  s
  setup-patches- U9 L' G  b7 L* V6 w, i) A- v# b
  make-current one-of intersections
* ?+ Y/ `( d% R  o  label-current+ t" ]% n, L8 Q8 l# b3 z' O
3 I- O. E3 {# G/ M5 y6 V
  set-default-shape turtles "car"2 u* b) Q! T* {9 S& G! l7 O, A

/ a) N  T5 N. ]/ y6 _: Q/ Z  if (num-cars > count roads)
5 s5 v; t, \) Q0 _* e" L  [2 L( t& }6 ]9 t
    user-message (word "There are too many cars for the amount of "
& r  p: C4 T" T0 V                       "road.  Either increase the amount of roads "
" o5 }: z( P& ^$ H  i                       "by increasing the GRID-SIZE-X or "
$ Q% ^% D9 }0 w8 L; B/ [                       "GRID-SIZE-Y sliders, or decrease the "* [! J/ ^* Z0 Z5 ^
                       "number of cars by lowering the NUMBER slider.\n"
5 p% j0 w9 U# j$ X2 W' g* }8 I% y1 O& t                       "The setup has stopped.")
0 S! Y% B# B( Y. m8 @, T+ L& R    stop
$ M: ~; C# T  ]  B- t* ?0 ?  ]# K2 W. `  L: k& F

/ W" f. h) V% A7 [/ J6 P+ Z  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% [! n* J. k0 n: ?6 F2 ]& i0 _
  crt num-cars
' \3 Q- Q6 A- {" N- }, ]  [) u8 [/ J& I3 Y  P  \, j. E
    setup-cars
, o2 v' {9 j6 Y- d+ J7 Q$ a    set-car-color
- h1 Y' f1 q" q    record-data
4 i3 d) U& ~( `8 C1 Q0 L  ]
0 u" s8 l  N/ s% X. d8 k
. g7 e" Z' B6 i8 H% U  ;; give the turtles an initial speed3 c' n- I" N! d1 k- |+ }
  ask turtles [ set-car-speed ]- I( R1 I  ?, l+ S! ~4 @
. _( |6 J" [9 `- h
  reset-ticks& s" J' X: X/ P/ z& y) i
end
: a# u; g' Y, V
3 I. T% @; e3 l1 p& d) B# \;; Initialize the global variables to appropriate values
% @  K$ C$ D$ }' sto setup-globals
, p0 P$ x" U5 J& X" k# i3 @  set current-light nobody ;; just for now, since there are no lights yet
8 ~/ L. @* @. m2 R1 t  set phase 0
! J6 \" u. q9 q# J* [% |) q  set num-cars-stopped 0
  C# l+ r/ h2 j* a2 x! X4 d$ H- f3 t& v  set grid-x-inc world-width / grid-size-x
% I; x8 A6 b2 u( _  set grid-y-inc world-height / grid-size-y0 n# k  F/ `* [& t& a7 P5 L" m1 P

. {  c  x7 l$ R. m( b( Y( N0 S  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary: p3 T$ x: @) I
  set acceleration 0.0991 l& P0 n9 [+ d" e$ V, d( l5 |9 j
end& J; U& A/ c$ U) _% O
, ?0 w: p2 ^( k& s1 K1 r, p
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
4 ?7 q* s+ K  h; Z* d;; and initialize the traffic lights to one setting" W6 r: F# s% u1 Y+ T, L
to setup-patches- I$ S/ F, G# ]% d/ v, x
  ;; initialize the patch-owned variables and color the patches to a base-color6 L9 Z' |- J( @. x) X; l+ W5 {' H' g
  ask patches/ r- P" D" \/ A5 m
  [6 Q' P$ t$ \  T5 K3 R. w/ ^  i
    set intersection? false0 R  G/ n/ R, V7 l/ f" x
    set auto? false
: X. Q, E7 o' _/ U0 v% y1 q+ u    set green-light-up? true
; n2 D8 K& [& d7 s, w3 j    set my-row -1/ a! ^, y  X. ~& |
    set my-column -1
. j  p( M+ P2 p( v: \4 a8 D2 _    set my-phase -1+ p& \5 A- R& J' |9 U
    set pcolor brown + 33 A, _; q3 W8 K& F# j5 ^8 Z1 A
  ]
5 a# x* K! d3 T8 ~+ @+ n: f* u3 s
5 z9 p  l# k& C: q  ;; initialize the global variables that hold patch agentsets
/ r# [: J1 Z* ^' h  set roads patches with
5 N/ d) {" @5 X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. O! a8 R" x! o5 t; I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 G; S+ c& B/ `8 F  set intersections roads with
4 y8 p, L2 A$ v. W) @; G" `' q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and% @8 j7 r3 u4 L
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- z: D/ }/ h! w! L. F5 Q

) J( z8 {2 Y9 A0 ^4 L7 `  ask roads [ set pcolor white ]
! {" M1 k9 [. I3 [) \& m" _' y* s    setup-intersections7 }) A$ t( V+ ?/ h
end
5 G& {- e3 R5 N9 e8 G# @其中定义道路的句子,如下所示,是什么意思啊?
5 c0 n1 y* ~' k- ^+ Q set roads patches with2 q* r) v; K( q8 C% A  ?
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ E) B# x' M( T% o. A% p* s
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% w& S4 z' w; ~! X' n: K, _5 g: ~
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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