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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。5 h1 l; Y3 ]& H
netlogo自带的social science--traffic grid这一例子当中,
! r2 }% ?# V# a8 K, N3 W- b, t- `" hglobals9 Y. K3 I  ~3 s, @: B6 p' t
[% g, t8 \+ F7 H, \
  grid-x-inc               ;; the amount of patches in between two roads in the x direction% h5 F% R: p7 g. w% v9 M8 t. Q
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
  Q( ?/ K. ?; W6 w  acceleration             ;; the constant that controls how much a car speeds up or slows down by if1 E& `0 z7 F1 d* n: E* ~
                           ;; it is to accelerate or decelerate
+ w2 F5 G+ [3 S& F( u& v. G6 ?  phase                    ;; keeps track of the phase% G+ F6 F5 `/ h; H; c
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
& X, F+ @- @0 ^" i( r7 V, t  current-light            ;; the currently selected light( W1 m3 t* N% i" o

2 r! j- D7 [4 C8 r! w) G  ;; patch agentsets
! v' ?; f4 ~, f+ V6 M( ~7 u) V  intersections ;; agentset containing the patches that are intersections' h- V  s! A! T  d
  roads         ;; agentset containing the patches that are roads
9 O# u  W9 {/ e3 H& V3 W% d, }5 |]
6 f3 a: [4 W- P' I* l& B# K
4 N! X: o+ L: Iturtles-own4 f8 Z$ G0 o, Y: n7 z* X1 H" S
[. M! E, t  z( \
  speed     ;; the speed of the turtle
$ g3 x2 {- ^9 i  F6 G% @% H  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
% {6 \2 K, b$ i  wait-time ;; the amount of time since the last time a turtle has moved4 h9 A+ x9 i0 o4 u" }
]& R" G$ ^8 I9 @9 Z. G- C! u
8 @+ V2 B+ z" N4 [
patches-own
4 d: M. F# i  h1 E[7 _: O" E; w1 L- `
  intersection?   ;; true if the patch is at the intersection of two roads
* c, A8 I+ O, M+ ^: B  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 I; S' t6 Z" ?& _, s' i, O) c
                  ;; false for a non-intersection patches.; y& R/ h; K4 G: r
  my-row          ;; the row of the intersection counting from the upper left corner of the
/ O) {4 u( T( P# b3 _                  ;; world.  -1 for non-intersection patches.
, W/ ~, |  g( g& I# I* p. Y  my-column       ;; the column of the intersection counting from the upper left corner of the
0 Z9 a/ N  ?3 {# g: w3 I" c: G# `: X                  ;; world.  -1 for non-intersection patches.2 Q$ A5 S) I) \( W) s7 i
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
1 n) u* x$ N( B# Y6 p3 M0 }  auto?           ;; whether or not this intersection will switch automatically.
- x- Q) N( r# F% W, q7 u                  ;; false for non-intersection patches.
6 `" B  g$ [7 J& {]
2 h7 G& y. K( L; n+ [' A
8 H1 k9 }5 R% H* z7 |8 O
  ?! d5 f2 z& };;;;;;;;;;;;;;;;;;;;;;8 y: m% G- U0 e4 P8 l3 o
;; Setup Procedures ;;
. Y' R2 h5 J" A+ {5 A7 ^;;;;;;;;;;;;;;;;;;;;;;
8 d" I% I; O! t: g& ^
( _0 W# q* o) {;; Initialize the display by giving the global and patch variables initial values.
* ~' I; k! T: s0 j0 l6 n* F! u;; Create num-cars of turtles if there are enough road patches for one turtle to5 m2 i; j& B+ A' E# V
;; be created per road patch. Set up the plots.7 H& M& m: x2 z+ h: c; P2 }0 \
to setup7 A( X* P% Z3 N% }/ Z6 O
  ca
9 ~$ {- k+ G0 G* ]5 R7 m: P, J  Q  setup-globals
* Z$ G9 c9 f& |* l: j2 w% W7 a5 _8 Q7 b  X8 C. n+ r: i
  ;; First we ask the patches to draw themselves and set up a few variables
# z6 }6 H& A% N$ k  setup-patches
* H6 p: O4 k2 X: e" W% W& v- _  make-current one-of intersections
4 S1 P  _! i4 Y  M  label-current0 p7 d7 ^. V: g/ Z

; a# [: Y; U. u! ]! I7 K  set-default-shape turtles "car", U, Q, k& E+ q2 X2 F
, l% l1 `- z, f/ `* M5 i
  if (num-cars > count roads)  {# q0 t5 |6 H
  [: J5 S2 j  z2 f' y: u$ U" K
    user-message (word "There are too many cars for the amount of "
" \) u( i3 y" o& G$ e                       "road.  Either increase the amount of roads "
; c, A( R: S3 ?# g, P' ^- N                       "by increasing the GRID-SIZE-X or "
& a& ]- Z" L7 _0 p& K. h                       "GRID-SIZE-Y sliders, or decrease the "9 m# Z1 S! x2 ~
                       "number of cars by lowering the NUMBER slider.\n"7 m/ P! }" s" t' {
                       "The setup has stopped."). i  ^! I+ f/ L2 S2 t+ b& u9 C
    stop
& @1 Z0 Q. q( s7 c9 Y, f, T  ]7 L! ], |+ O7 ?* N4 O

% v* n4 f2 v- t- P; u/ o% p  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color# b. D: T2 ?0 t) j. e* `1 J
  crt num-cars
* [+ c& K% ?7 e% j  [$ m4 d1 y5 W; }- u: ]
    setup-cars; {! V. }' t1 b7 m2 f; Y
    set-car-color
% i$ M/ m( S$ B( i: x    record-data
  t% F- H0 P1 M7 t  ]
$ A9 ~: f: @1 `7 F" k8 H% A) T8 _3 @0 ], U
  ;; give the turtles an initial speed4 K' T( O* \) r7 v2 A* M
  ask turtles [ set-car-speed ]
# Y. k( f# n  C: g, U/ l4 `$ w) ?, t# N+ o
  reset-ticks- d( U& s1 k- F1 F$ V
end
- W$ |; X: n; [% t; T' J$ R  ?, z0 ~, r
;; Initialize the global variables to appropriate values( W9 e! P/ N9 G6 G' Z" z
to setup-globals
8 p9 ?( c. v# w1 P  set current-light nobody ;; just for now, since there are no lights yet0 J% o. g' x0 f) I2 {0 h* m+ n
  set phase 0
6 i$ \& _  `, ?  set num-cars-stopped 0/ J8 y  I& h  }; ?
  set grid-x-inc world-width / grid-size-x
, s6 C9 T) ~: R& J4 N1 k. o/ d% D  set grid-y-inc world-height / grid-size-y8 l) ?! C; m" y) ~+ ?4 {- f
& Z, P* @  S* u% Z( M1 g
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
; }4 W& b  f& ^4 M2 C  set acceleration 0.0992 L. n8 s7 I9 v8 S$ z$ f. h
end
/ r$ M( g0 j' e7 C: a6 j; T5 V; R9 U# [$ E0 x
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,+ y5 ?! t' e3 @% M9 q
;; and initialize the traffic lights to one setting( Q5 f0 z2 o, |7 [! L! t; ]+ e
to setup-patches9 J4 r6 h1 w' I( }1 E# d+ ]  p/ I
  ;; initialize the patch-owned variables and color the patches to a base-color
2 Y% D. ?3 M# v' b& m: q  ask patches
0 i$ B% `' R: W  [
) Y; {: H1 i* C# P& q    set intersection? false2 n" j$ |: }6 x8 k
    set auto? false
( j# U6 p' d! J% Z" A    set green-light-up? true: j7 h% f7 @* o5 ?
    set my-row -15 A7 Z0 I: o3 L5 z; h
    set my-column -1
0 d1 y- t: Z# n1 b    set my-phase -1' |& ~& ~) E) ]) w' c+ x+ I
    set pcolor brown + 33 v% ^; g1 c9 }% \& G4 q
  ]
9 ~0 n- P2 N" u9 ?, _, I* V/ }6 y5 f! \$ q/ F
  ;; initialize the global variables that hold patch agentsets
5 U  \& \6 W0 M6 v, {, ?, a  set roads patches with$ Q' n3 ~- |& D9 U& Q% Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) J+ ?7 S- ~+ d
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: ~5 e3 |( `9 d: e( f9 m5 w  set intersections roads with
' A$ V) h3 |4 t8 z! D8 s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
; R4 J& N4 V9 x) \* B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 Z" E! l& Y3 P7 l+ H* b, J2 d( m" f
  ask roads [ set pcolor white ]4 t% n0 V; F3 _' B& v, ~$ [) h! G3 p- e
    setup-intersections
: r) x3 B  V8 F" G% \1 b$ Yend
8 P& B0 k$ s9 V7 t- U+ i其中定义道路的句子,如下所示,是什么意思啊?
* ~4 [8 l% F; _6 M set roads patches with3 D6 i- \! R8 T3 a
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. z+ o; @: k7 d* {5 E0 r( b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' j0 e# M0 D# H. b) b  D1 k# j( t; Q
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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