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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。
! _" b, f' X6 ?0 R  L1 M' y) Dnetlogo自带的social science--traffic grid这一例子当中,
* G, d$ v- @# z  ^1 W( Iglobals- f4 A$ l  g/ Z0 W
[+ l* S( c+ ?* d) K8 C2 l1 r
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
# m( u. B$ x$ i1 _" q  grid-y-inc               ;; the amount of patches in between two roads in the y direction& d# {/ Y  L; m9 R, @
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if  L4 g4 k7 y6 N* j: q) N+ q
                           ;; it is to accelerate or decelerate$ @2 m) \, T6 K/ ]
  phase                    ;; keeps track of the phase
- ^) t4 p9 g, A  e! n9 q  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure. G- z+ I. P. |+ x: E( P' V5 Y6 O
  current-light            ;; the currently selected light; Q. y. E; }- @% a0 |) `

0 I) _( I) h6 v" o  ;; patch agentsets) f1 m2 {4 o9 @, Y6 N8 G# m2 z
  intersections ;; agentset containing the patches that are intersections
) b" A% `8 r4 ?/ m! C  roads         ;; agentset containing the patches that are roads' ?- ^8 L8 }# K  D3 ~" s
]( Y* q* }4 @6 x' c  T5 ?( |/ l% W

3 S% G0 F8 \4 g; H- oturtles-own
, k, U* f9 e8 ?; M; K, t[
0 ^; t0 k7 x" I7 D  speed     ;; the speed of the turtle
+ E+ O, A+ }' j5 t2 G6 x( q  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
, ^5 E9 x! j0 W: s/ y  wait-time ;; the amount of time since the last time a turtle has moved$ U5 g/ I$ ]& s. c  }
]
4 K" e2 G4 M# P4 m
3 d7 b# a" ^8 s6 f# |& D( C+ q. }8 B" }patches-own* m+ s7 h- q  M" S* |* f
[* M% T8 k# I" K" ^' ^2 _( @
  intersection?   ;; true if the patch is at the intersection of two roads
2 d$ t( B+ R$ X# \# T  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 L* t- E! H: C) X! W! _3 K
                  ;; false for a non-intersection patches.
& v7 y& R  `, A3 m; |  my-row          ;; the row of the intersection counting from the upper left corner of the
! t5 K: ]: c. c" Y' \; S) \                  ;; world.  -1 for non-intersection patches.9 V2 S7 L4 D5 h7 ?) n) E% }( ~0 X4 ^
  my-column       ;; the column of the intersection counting from the upper left corner of the
/ O! z0 i6 c8 G3 I4 n1 d1 {  \+ }                  ;; world.  -1 for non-intersection patches.
2 s" L( {. |+ K( }1 B8 F  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.3 @% F( C6 }& }( i
  auto?           ;; whether or not this intersection will switch automatically.
. W* |5 t+ X& i6 T  `                  ;; false for non-intersection patches.* P" Y+ p3 Q9 ~. B& S' z
]+ `+ m& d( a" u7 S# J+ p

* ~; i8 L: x. Q5 h2 l
0 G9 n. P3 l  O5 s4 m;;;;;;;;;;;;;;;;;;;;;;
; e' p8 @  U8 Z! E* ~" G5 n;; Setup Procedures ;;
: K7 z) X/ d" o$ \& `$ y;;;;;;;;;;;;;;;;;;;;;;
: w# d8 E& a/ |
8 W- ^  k2 {9 J, m;; Initialize the display by giving the global and patch variables initial values.
' v& O" W4 g7 A2 }: f0 `% @+ ^$ t9 Z;; Create num-cars of turtles if there are enough road patches for one turtle to
$ ^* X1 F9 V9 T0 t, X. C# {2 e' N;; be created per road patch. Set up the plots.
( K  a- V: X. Wto setup+ t# z; Q& Y6 q8 Y9 E. `* R, e0 t
  ca
( r& o2 j: k) ]. R  setup-globals7 h; f5 \" n/ P+ i

% Z( ?4 O( o) G3 F8 Y  ;; First we ask the patches to draw themselves and set up a few variables
/ t! P: ^3 F( r  c( |  setup-patches
" @6 K/ J4 }  {" N/ B3 ^  I) A  make-current one-of intersections
+ {/ b1 x- f5 O% v& j* O1 j* b  label-current
9 t8 M$ F7 k4 g9 ]
2 Z% V2 d6 G9 [& q8 h; h  set-default-shape turtles "car": o5 E, ~/ q% g: A

$ y9 w' z9 ?2 a" m8 Z  if (num-cars > count roads)
3 D2 ]/ H0 M8 X! c7 |! v" S  [0 n: ]: ?. L0 j* E. u
    user-message (word "There are too many cars for the amount of ", M6 E/ q3 Z* I8 H' @) R! {3 o# r& G
                       "road.  Either increase the amount of roads "6 P+ q8 l& w- z
                       "by increasing the GRID-SIZE-X or "
# Z+ l5 ~2 k, \; G                       "GRID-SIZE-Y sliders, or decrease the "" B9 V$ `" C/ q: a$ p1 C
                       "number of cars by lowering the NUMBER slider.\n", r6 o9 G7 ~' `* W- Z
                       "The setup has stopped.")
& E! \- }: U. z    stop3 l9 [& ~: R0 b$ _
  ]
4 D7 x- X$ L. l0 `0 X" v$ r4 C
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color" E& f9 ^. x7 N. F& p
  crt num-cars" x# C4 y. M1 Y3 f* [& ^
  [
9 }' y% Z' J5 a( H. M    setup-cars
! a1 M) v. g0 r  b9 g    set-car-color2 D$ ]9 h/ A/ {; A/ p% ]7 L
    record-data) R" l- G# Q1 r4 H, K) }6 F
  ]
2 u1 G1 D: {4 p) ~6 h) \+ y$ u9 S3 ?8 x8 g1 l  D1 I) B( I3 L* ?$ L. U
  ;; give the turtles an initial speed
8 V+ b9 h$ U3 B( |- O( Z5 i! B  ask turtles [ set-car-speed ]1 z( |8 h/ V4 r
4 a0 Y' G1 J; z
  reset-ticks
# p- B: y  K, M0 }( v; uend
2 N) Q1 l+ N9 x, K, N$ U% e, t; t% C7 d- N
;; Initialize the global variables to appropriate values
: F4 L' L3 @5 o/ p) ^to setup-globals% F* Y/ ~/ _& }  g
  set current-light nobody ;; just for now, since there are no lights yet
) O7 g9 v# y$ H0 }$ Z' \/ ]  set phase 0
5 Z- p/ }  _: Y# T- p- W  set num-cars-stopped 0' q$ M3 [: u( _5 R# \2 J
  set grid-x-inc world-width / grid-size-x
  K; @+ \8 \) B1 ]2 n  A  set grid-y-inc world-height / grid-size-y
" x& b* ?+ P- N" w3 `8 S' x! E8 X6 o$ o( w  D: l
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% I; q) x7 w* u; F  set acceleration 0.099; d0 |8 J3 Q8 t$ I
end7 _* `# k4 S. `8 m  M+ V. Q
! z2 H4 g* O) G) k
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,. ]" u* e( ?, V3 v2 [
;; and initialize the traffic lights to one setting0 v, e* Y& T/ @; f: z
to setup-patches0 {, ]' k% S# P" k& O
  ;; initialize the patch-owned variables and color the patches to a base-color
, w% i3 `+ J$ _: {  ask patches; T$ s) O5 w- x$ y& ^" y4 z! c
  [
. r! U* Z3 y5 X0 V    set intersection? false
' [" _7 U2 S* K8 z! Y, O9 r    set auto? false- p' N/ D  S; p) R
    set green-light-up? true
7 ^- `$ o* E. O. r% \8 k6 n% x    set my-row -1+ P( \/ @: d$ E7 F* e1 E+ h
    set my-column -1
6 J. I# b( j8 d    set my-phase -18 I; H3 o) b0 C5 M, _) `
    set pcolor brown + 30 U1 r1 G9 Z. t+ }6 ]% C8 m3 u2 U
  ]0 G' [5 o3 g2 ]$ J

+ k/ i* W1 ^, N% [  ;; initialize the global variables that hold patch agentsets
# `! Y6 `+ y" R* r. x& e  set roads patches with
5 A+ G  _/ s6 P1 o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; E4 c+ Y) {% ^) ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  C. i5 d1 [+ o2 \
  set intersections roads with
9 M: v+ ^3 _1 {* p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and5 o- s  }2 U+ R" \" T$ _* o4 h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* |' O* i. M+ G! W  w, h0 S( F, S8 e' P4 h; [  w& G& ~6 ?0 g
  ask roads [ set pcolor white ]
3 R( X  Y2 l; n- r    setup-intersections
$ p# M# x5 ~8 c1 Q7 f" X. A( a3 s1 nend" ~# Y2 i( t. D  f
其中定义道路的句子,如下所示,是什么意思啊?: q+ D3 y. k5 ~" F/ C: r
set roads patches with8 K2 j# h8 }% ?0 s( j& W' i
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" u) x) r/ Q3 d! K- l3 X$ ~" {3 M- P7 q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% e4 S* ]3 o! J6 }$ R
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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