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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。9 Y6 S6 G! o  k! Z
netlogo自带的social science--traffic grid这一例子当中,
7 }7 [/ G5 A! {  Z% Yglobals
) D5 K! x( P: l[' l1 y* T% R7 S7 x3 ?  }9 Z
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
* f5 q& u4 D$ R: v  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 b. X2 h/ z8 |. k' i( u! G  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
$ r+ d' N* X( H                           ;; it is to accelerate or decelerate  o" W9 D; `( ~, A8 l' \  o5 A
  phase                    ;; keeps track of the phase. ?& r4 N8 V" C- L
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
" T/ j3 o' p% H. x% l. |  current-light            ;; the currently selected light( u) h! v) ?! J# O4 U/ m- X- H

! Y( u0 B5 S2 S$ Z4 @  ;; patch agentsets) G8 w2 i/ A8 R+ t- h" v
  intersections ;; agentset containing the patches that are intersections
1 i) u! T; m/ {% G( {  roads         ;; agentset containing the patches that are roads1 ^4 ]& u  w( I4 m$ B( @* m7 u
]
8 G5 C/ I! v  A# n2 H7 P" B9 B5 {# Y( t% ?$ K/ O. E
turtles-own
# k' A- c5 R2 r9 y1 t; E[( y& M% U& M6 K/ U5 @# M  l- Z
  speed     ;; the speed of the turtle5 V0 y- P+ L! d, w2 x0 v
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
$ `$ {8 U# l- h* `' L  wait-time ;; the amount of time since the last time a turtle has moved
% @# ~' A- e/ p+ E0 ?]. Y5 ]+ o. [! h) d5 o' s
" A" b2 K+ t/ T1 ]1 M% V! v
patches-own# s& Z2 U) n# ?
[
! l) i+ L# b- n8 _( L6 O  C6 e  intersection?   ;; true if the patch is at the intersection of two roads8 n. T# {8 J2 J$ m3 P/ J, ]
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( E' S' h( i  |0 b, p; i$ e                  ;; false for a non-intersection patches.6 B6 Z; _3 c/ n6 N6 f6 ~8 `
  my-row          ;; the row of the intersection counting from the upper left corner of the% C# ]% q2 d9 p9 t8 u7 S, Q
                  ;; world.  -1 for non-intersection patches.% a9 w' H" v2 r% ?/ z. [2 x
  my-column       ;; the column of the intersection counting from the upper left corner of the
- T' L: Y% c! A* J0 n                  ;; world.  -1 for non-intersection patches." u, c3 t, N4 M
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
: `; E( C* m$ k8 L2 i  ?& \  auto?           ;; whether or not this intersection will switch automatically.! Q' o) O4 Y3 L9 ?& l* n0 ~. G9 |
                  ;; false for non-intersection patches.3 @7 R, y! p  M. D2 g
]9 X+ C, B) U* O& L& D3 l8 n+ S
& s# Z" l9 p/ W

" P( J8 m4 {! J9 g* {1 i1 c;;;;;;;;;;;;;;;;;;;;;;# S$ p! e. M( ]+ P/ _: X4 p) I2 G
;; Setup Procedures ;;
- u7 O2 o0 g4 @+ k9 ?;;;;;;;;;;;;;;;;;;;;;;
1 S& F% b0 v7 v! c: r3 S, q: u; S; Y1 I( C; N- ~3 a4 i: r  }' A
;; Initialize the display by giving the global and patch variables initial values.
5 [, z4 R1 V! B4 f2 E;; Create num-cars of turtles if there are enough road patches for one turtle to
6 L- S" @: e! }; {2 L;; be created per road patch. Set up the plots.8 U6 R$ m9 c  [2 E; j; C* B" k
to setup
8 q6 d" L( r0 o# V% j  ca
# m" d( D) [8 v( {1 e$ m8 J& z& X. |  setup-globals; @0 i* N9 v' z
2 V" K) S9 ?% }. n+ f+ R
  ;; First we ask the patches to draw themselves and set up a few variables# ^7 u9 z9 ^( J
  setup-patches
2 j. ~/ }) A* X: F/ O  make-current one-of intersections3 r8 P) i0 a- O' \
  label-current
, {, Z3 X$ {2 w; R8 C$ o9 g% H5 f9 W
  set-default-shape turtles "car"3 }3 Z4 C# o9 f! \$ |: O
# \) a% P, ^/ h0 \
  if (num-cars > count roads)
% y! V+ y1 j- G7 V9 O( T  [
* x( G, p; B* E0 {$ K% Z    user-message (word "There are too many cars for the amount of "
5 a0 b5 W1 v; [2 S) T1 h                       "road.  Either increase the amount of roads "6 Y5 e! k% h* X; Z4 P% r
                       "by increasing the GRID-SIZE-X or "
+ n9 S3 f! ]( E                       "GRID-SIZE-Y sliders, or decrease the "9 M# f& r( ^0 S. ~/ `
                       "number of cars by lowering the NUMBER slider.\n"
) K+ W) N6 k+ r4 w                       "The setup has stopped.")" U* t/ L+ `! N( a/ N2 D3 q! ?
    stop
, h# C1 N+ x% u) f' r  ]4 r1 x2 O( _$ P8 p% t1 Y+ r( I

0 Q- R* x: A$ a5 k  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
: l! n0 H$ e" l4 _. n  crt num-cars: b1 H$ y% k9 @0 p( j$ e
  [
: }6 c' a& l* L$ }; y1 q$ y    setup-cars3 p# N' f2 v2 D( C7 U" X
    set-car-color: \- d% R% _6 _4 d  F  |$ Q: u' ^
    record-data( q+ q' H* s/ |- [
  ]) ?/ B# @, L4 O- Y) j( B
- }* u0 B+ l' _, A, m. V
  ;; give the turtles an initial speed9 q* [/ s+ m8 h% j# S
  ask turtles [ set-car-speed ]. G& z  O! H- x7 B( X. @( _( k

/ B6 m9 `- G# {- U9 E6 G" @  reset-ticks
8 T0 x) e) m& q$ t! J  [- {, Vend
2 I6 h+ t& D) {- j% X, \: Y5 ]
4 j3 @8 Y9 G. V;; Initialize the global variables to appropriate values0 O' S! q  K- Z) h1 U* d6 |
to setup-globals
, c" l2 I# l# q8 s/ I0 [' r* }( n  set current-light nobody ;; just for now, since there are no lights yet5 D( R, @9 s( I; m* t6 j6 g
  set phase 0
8 c4 ~/ D5 d7 u# `1 v" f' r$ d  set num-cars-stopped 0
# y6 M) B4 e, ^1 }; ?  set grid-x-inc world-width / grid-size-x
7 x. I6 e: A. z8 L  set grid-y-inc world-height / grid-size-y3 R; j( T  W9 ^- G" a8 r
1 B  b- Y+ t( X; _
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary+ N* L! @7 C* R
  set acceleration 0.099
+ k! \2 I% e- [8 R4 Xend
+ ?) G$ L! ^7 X% v. ^+ k' E1 s2 T& X0 J  S& [6 F
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
6 b! W: B1 B4 ]6 m, v;; and initialize the traffic lights to one setting
: d! g+ |: w$ rto setup-patches
% N; G- K) G( W  ;; initialize the patch-owned variables and color the patches to a base-color0 U* u+ t/ M) L8 E
  ask patches2 u9 J6 g+ X2 f* k# Q
  [& d' u3 e9 H& A; @  c/ P
    set intersection? false
! Q/ `1 K9 {) J, a! K    set auto? false
) T! ~# ]5 c2 H" [    set green-light-up? true
0 L9 d2 J# }$ U4 e* e! m# X    set my-row -1$ u& I9 [, s  i
    set my-column -1
/ e% P/ w( X/ v3 }    set my-phase -1
) T7 u* m  ?* G    set pcolor brown + 3
7 m7 `% P! N( m4 `( e% K  ]+ e& G6 P8 n* H* M" R5 n/ x

( @& n! v# g) N$ r" ~  ;; initialize the global variables that hold patch agentsets
- G9 e- b' m0 R  set roads patches with
; T7 D# S% ~- o$ x1 L% z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 E$ A- n9 h4 K7 d4 B. L1 [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 _. J$ p* x2 H; h/ }  set intersections roads with
: ~. \( _, x  z& |6 W) j1 r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
4 V+ ~$ W* V. S# L  G* w8 m7 _: ~5 H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' m2 K3 O% x( q/ p+ Y, X
! k- F4 m* {+ }9 d. B
  ask roads [ set pcolor white ]8 ~! b' ^: r2 @
    setup-intersections
5 l0 |! x: i! h% h3 jend- j7 M; {, J/ F: n. E
其中定义道路的句子,如下所示,是什么意思啊?5 [6 B. f9 I5 {9 @% c4 K- v# l
set roads patches with
6 m( x+ B% L5 U4 N5 v5 ?9 N0 Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 {6 E2 c+ h: G5 [' c1 a+ [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ h2 ]4 w$ Y# `6 j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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