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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* U. ]4 H+ V0 znetlogo自带的social science--traffic grid这一例子当中,% X6 B+ X" y: \" t% M, z+ ]9 G# }) k
globals
- g1 B7 G+ l) J' D: N3 _$ R1 x4 g8 w2 M" }$ I[
/ b' m2 u* s" |: |4 \" K0 F& q  grid-x-inc               ;; the amount of patches in between two roads in the x direction
" a& g% v2 @/ u6 l  grid-y-inc               ;; the amount of patches in between two roads in the y direction: z3 @. s* A, X
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if4 `2 f5 S( f$ H9 B' [
                           ;; it is to accelerate or decelerate
/ f( e( K5 f( H% `3 n2 m3 e0 m  phase                    ;; keeps track of the phase
7 w3 s, ^* o) }9 ~! B  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
8 Z, c0 r& Z: ^4 \* C* J; p& w/ \9 ^2 J  current-light            ;; the currently selected light
4 s: G% @" e: C# Y) L* `5 `2 P5 O: h4 T, S) f
  ;; patch agentsets- e7 E  G* s6 V+ g! p' J' Y  i" ]6 I
  intersections ;; agentset containing the patches that are intersections
( \" t$ p0 {  l) S1 l7 W  roads         ;; agentset containing the patches that are roads0 M# ~8 n# F6 ^$ S* s
]+ |0 F9 m  R9 Z+ E( n0 y
7 u4 L- o( _9 U. G
turtles-own
! u; Z4 m( x8 o2 C) I2 }* r7 [[
4 Q3 T8 _3 m7 ~3 y  speed     ;; the speed of the turtle
8 p4 \& ?3 \8 W2 J2 t* B, K  up-car?   ;; true if the turtle moves downwards and false if it moves to the right- `# H* ~3 }8 i, `( `$ ~( L
  wait-time ;; the amount of time since the last time a turtle has moved
" k5 ]: A7 T* C]0 g+ C+ I" v/ N) b: k' G
; ?. h5 l2 o- M! A0 Y* G% A
patches-own! P# w* d% Q1 l, ~& v' I5 b5 g/ l6 [
[
# x9 ?) X4 W9 O% T4 w! Y  intersection?   ;; true if the patch is at the intersection of two roads
" r; Q9 b4 G3 i  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% i" o: G1 K5 h/ R' d8 A                  ;; false for a non-intersection patches./ x6 Z  l% p+ p6 b9 C, s) f
  my-row          ;; the row of the intersection counting from the upper left corner of the
: U9 R0 o5 Z: {5 R( s2 |" G                  ;; world.  -1 for non-intersection patches.
  F! k$ {' z& m2 f  my-column       ;; the column of the intersection counting from the upper left corner of the
" C  U9 ^* P# j3 x" x                  ;; world.  -1 for non-intersection patches.' A( @6 h6 s1 N4 }/ e- n. Q/ c7 Q
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
8 {6 W: |+ b: F% i& T8 t* o: m( g  auto?           ;; whether or not this intersection will switch automatically.
. c! q5 r# g. \. H5 T# F                  ;; false for non-intersection patches.+ _7 E$ n9 U2 z, E; a! A9 m
]
$ R* I; ?# Q+ Y# U3 ?5 Y5 l2 S, W% w. v. b2 j; K# }' S
3 n1 P( B% \7 T" K
;;;;;;;;;;;;;;;;;;;;;;
$ ?: ^, o3 E0 }) I;; Setup Procedures ;;8 J9 o5 v4 K" u" N
;;;;;;;;;;;;;;;;;;;;;;
3 _  L$ g8 b* ?0 ?$ \
! E* E! b3 h, q$ F9 `;; Initialize the display by giving the global and patch variables initial values.
, @# Y" `1 ~3 `# O;; Create num-cars of turtles if there are enough road patches for one turtle to
* N  l2 t4 h5 K8 x4 p  x;; be created per road patch. Set up the plots.
$ ]4 A! Z) m# k* y' nto setup
- y8 ~5 H$ L: A2 n+ O6 `  ca
* W6 H; n  B( h- Q9 Q( a5 Q  setup-globals
- C7 _$ h) q. P
* O/ A- P& z) U" d' Q) h. X  ;; First we ask the patches to draw themselves and set up a few variables% g$ p& j0 [# ~
  setup-patches: C5 Q% F: {" ^2 [* [8 V- [8 w8 V4 \
  make-current one-of intersections6 l9 P2 T+ A" ?' g2 a% L0 D
  label-current
4 }  {: B0 t. c) k  U# E
: v: R2 A& x' Z% s) f  {+ Z; I. p  set-default-shape turtles "car"
8 F9 s& g$ {+ v) N( d, K4 |" J7 @- E8 T) F- ]1 t4 U
  if (num-cars > count roads)
4 X# R4 w( n; ?  j  [' r! g9 o& B/ J
    user-message (word "There are too many cars for the amount of "
) v0 P! a  U, b- M9 ]                       "road.  Either increase the amount of roads "
% o5 n4 s! U$ y, i                       "by increasing the GRID-SIZE-X or "" g" J+ G7 w4 J% Q
                       "GRID-SIZE-Y sliders, or decrease the "
3 U3 U2 ?* E5 k8 ^, {. ?& C                       "number of cars by lowering the NUMBER slider.\n"# C+ q+ d( @+ e5 z
                       "The setup has stopped.")
' h( @( a! U. n3 z) Z# A    stop
) E  j' L% d4 ^& w/ P7 Y# k  ]
/ l+ q% X: k2 Y. T( P3 S
$ ]8 ^& I* y! Q3 E  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
5 D& x( L* @, i- O  crt num-cars
  ?; j4 T5 B7 k2 K7 e9 e8 U- ?  [0 B  r7 X* b4 J
    setup-cars
- C- Z6 O5 G; ~- v9 u# M    set-car-color
/ v& R& J" r0 S# d/ l6 e    record-data
; f4 y/ t8 n  D$ a( b0 ?. v  ]
. @# G6 k, z/ s) H( p# N" M& Z& u/ }4 S- }* W
  ;; give the turtles an initial speed
$ x& y1 g. n3 ]  ask turtles [ set-car-speed ]
; [0 U" N5 R9 X# i/ U7 \
. h7 @3 p. P  {% d+ L" Z; v  reset-ticks  P/ ~; w& [, Q  ?
end
  h; e% \" g% X, _; J" Q( K& N2 f) @8 l" L: j6 {1 ?9 Q1 @9 x
;; Initialize the global variables to appropriate values
8 V# B2 Z, _4 E: H7 j1 i7 D. h6 }to setup-globals
; a" j6 @/ J. ~- {# z+ |3 p  set current-light nobody ;; just for now, since there are no lights yet( E/ o1 M! h9 V: k- Q. {
  set phase 0
  W  s; m; j. j- y9 w  set num-cars-stopped 03 N  P  Z* J' b. s3 o3 e1 d3 s
  set grid-x-inc world-width / grid-size-x. Z1 L6 Q- G( A9 _' ?+ O
  set grid-y-inc world-height / grid-size-y0 [" x6 I0 J1 p5 Q9 |5 G; B
3 [8 c7 e$ r8 N
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary' W$ |% H* D& P5 y: l- k+ @7 g
  set acceleration 0.099
1 V1 j! D2 `: j7 t; w3 f! @! }end
  h# _- _% c- f! T! }% U; U, _
' `7 D; z1 T. ^' m' r;; Make the patches have appropriate colors, set up the roads and intersections agentsets,; ^1 K! b) L; J6 Q1 q9 P
;; and initialize the traffic lights to one setting4 j! G) F, F9 ^. F) H
to setup-patches
1 @+ L$ T- s& e3 s) {2 O  ;; initialize the patch-owned variables and color the patches to a base-color
6 P$ z* {. Y6 F/ v6 E  ask patches
5 Z8 p" J4 ]# e5 j# A5 C  _  [
3 V1 J+ U1 ]% p; ]# o; `$ V3 v    set intersection? false; p# S7 [- q! h* c; x
    set auto? false
3 e. v  H7 g+ h    set green-light-up? true! U0 a) d3 \3 Z0 S$ F
    set my-row -1: |7 {- h( d4 e5 ^% I# d* @9 A$ h6 E
    set my-column -16 I* U7 C. |4 i' t9 P' `
    set my-phase -18 J% d; f- G1 ]. E3 f7 O: m+ L
    set pcolor brown + 3
, d# @1 g) t& _2 k  ]
) c; ^9 D2 q6 Y: k. J4 H' j
8 d- o1 M7 i4 O* ~  ;; initialize the global variables that hold patch agentsets; t, w' t" \  S/ G5 m7 ?9 R/ }
  set roads patches with
7 @9 A+ r: K5 B& y9 h7 Z5 l6 f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, P. H" ~+ r( u+ a' P; d0 Q4 v8 `8 v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# H1 n9 ]1 L) F, V
  set intersections roads with& m. Y8 N6 O9 V+ h7 M$ I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
! M" u' l* d: U* N. i* d8 v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* a* Y+ `+ l/ S* x' U+ D9 ?' |' O1 w' Q! Y0 F, S) B, U
  ask roads [ set pcolor white ]1 \# X+ n, d* l2 G2 R
    setup-intersections
& B* Z! D. {: o. `  |( oend
; |( l6 [) y  W( T, _其中定义道路的句子,如下所示,是什么意思啊?) P" w# l* A, T  {& }9 N" P
set roads patches with
' y- O6 E5 J: c% H3 G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 y8 E1 O& ]0 y3 J/ f) D9 Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# V! N8 v- F3 a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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