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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。
( }! g9 e% W8 S) e+ [8 hnetlogo自带的social science--traffic grid这一例子当中,- ]7 a; L3 [9 A; G2 H% p
globals
* u1 q5 d* @! X  v, D% `' j[4 v+ B- v4 c9 `
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% Y0 t, }" ?- f  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) y0 i% \" M- P! t1 ~  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
. D( Y1 J6 S4 X' [+ M1 c( B* S                           ;; it is to accelerate or decelerate
" p' N2 }! J) y  phase                    ;; keeps track of the phase9 r: S: e( w$ k2 P" Q0 M  w
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ A+ I# r8 c) h6 k: V/ Z9 o  current-light            ;; the currently selected light* h$ R; g9 |, p8 A" E9 Y' S- }; ^, c
  b9 U" t6 v& v' }+ M* Y1 M
  ;; patch agentsets
  Z! G3 A6 S: D  C& J  intersections ;; agentset containing the patches that are intersections- l8 O3 q" \6 a8 B
  roads         ;; agentset containing the patches that are roads6 n' F+ x% @7 d( ^  @
]; ~( _" I% h" ]3 D

) i8 k5 l8 S' O: ]: V, [turtles-own9 d" H: s& o! e+ Q
[
9 G! M  `3 F4 K) Y7 V& }  F  O  speed     ;; the speed of the turtle& `+ U; D% e$ `; f
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
) I) s8 s; X$ n/ z0 E, w2 O9 e  wait-time ;; the amount of time since the last time a turtle has moved
: [" m& M. O' Q7 W/ |]/ a% K0 u$ J$ l8 w0 E: i  y
  f2 A% E$ f8 E- P' ~0 Q, i
patches-own1 I( x# I- \9 _5 T  O: Y
[
( u& m4 H! O" N; z' p3 U' a2 t1 a  intersection?   ;; true if the patch is at the intersection of two roads
! |; Q& ]; c5 Q, X% ^! _" j: _/ ^  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.1 o3 @& [. U) H- n
                  ;; false for a non-intersection patches.5 y1 U0 q1 l8 u
  my-row          ;; the row of the intersection counting from the upper left corner of the
6 t8 j- \3 M- {* r                  ;; world.  -1 for non-intersection patches.3 d9 B4 s& X3 i. A4 Z
  my-column       ;; the column of the intersection counting from the upper left corner of the/ N2 C+ J* d0 U6 }( T- B# }
                  ;; world.  -1 for non-intersection patches./ ~5 Y8 G3 M. R2 I3 \
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
* g0 g2 ?5 `1 [+ C  auto?           ;; whether or not this intersection will switch automatically.. p% @; y' e( z* A; L7 u, z
                  ;; false for non-intersection patches.. l' P9 t' h2 o
]
1 f$ j) I# C2 {+ H7 t* r/ I9 v
1 k, d$ x0 W. X# w; I  f6 X; b' ]* W
;;;;;;;;;;;;;;;;;;;;;;
5 N* A9 N5 _; m6 [. X) o; j;; Setup Procedures ;;
. Y+ j, K6 D* o6 P' Q, ?4 b;;;;;;;;;;;;;;;;;;;;;;
3 \( M! L$ Q  \6 S
2 S6 Q+ k5 e$ L) d- Z3 o$ ];; Initialize the display by giving the global and patch variables initial values.
( O/ G6 x& t! ?+ E;; Create num-cars of turtles if there are enough road patches for one turtle to
$ m4 }* X  W7 Z% i! G3 L;; be created per road patch. Set up the plots.
* w. G# T' u5 t* i" eto setup% y& G; B4 d/ j0 W9 ~% V
  ca
- ?$ F, [6 b/ Y( U" ^+ [  setup-globals1 h* H" {% K& s! Y
" C2 P' N+ o% }
  ;; First we ask the patches to draw themselves and set up a few variables
$ I, X- c2 M4 Z7 D% {- U9 l, l( p1 [  setup-patches! p$ q5 N4 p& t  T% P' _
  make-current one-of intersections/ ]: R- R* i& g& z
  label-current
% g3 C' m8 c& D7 S; ?( B7 R) ^( ^  s2 Z
! Q1 z3 y7 o  L& s4 Z  set-default-shape turtles "car"
8 V3 l0 l: p6 [& E" f! {
5 R- h) o" B( Q# B3 O  if (num-cars > count roads)
; C$ C* C; Y% _  [
( A6 T1 |( Q/ l    user-message (word "There are too many cars for the amount of "
$ z# i- ?6 {. \8 ?$ H                       "road.  Either increase the amount of roads "
( D) S- w4 g% C. l- S' _                       "by increasing the GRID-SIZE-X or "
' g6 {4 n, O* R2 y# |: ~6 Z7 {3 |                       "GRID-SIZE-Y sliders, or decrease the "
  l+ t0 M5 a* B% a+ `, h  L                       "number of cars by lowering the NUMBER slider.\n"
) ?5 ], _, _1 V0 ~! ?                       "The setup has stopped.")- Q/ |9 ^$ K; ]# f- o# Y/ W* [& w
    stop, i6 M  I4 H8 q9 V' Z6 m# U
  ]
# r4 H+ Z, F9 J+ c! b+ i: ^
, Y! K7 @7 e0 H  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
9 q6 f- i* V9 J' Y$ @2 h' `# w  crt num-cars
! V4 k3 j% H+ n8 Z  [
. P; L& O! j4 z* K* w4 V- s, q2 G    setup-cars: a; \( `- Z6 U) Y8 @  S* o
    set-car-color
( `  }  T! W4 n6 q. r1 j  a    record-data3 }. y. b; W! p! g5 j6 e$ z  f
  ]
8 Z$ n# R3 U: r7 ^9 d& [' w2 x$ Z# k/ \0 j( n0 q: d
  ;; give the turtles an initial speed
! }! F" @4 n3 I* K+ `. F  ask turtles [ set-car-speed ]
7 I+ k( Z% A( J7 i1 I' ^! a& X0 }) u5 c
  reset-ticks7 ]  [; o: [% E4 N0 E6 i8 @5 b7 |
end
  ?5 Z; g7 r) }# s0 h2 g
9 S' G5 {. o. L% Z1 q) {;; Initialize the global variables to appropriate values
9 d' O1 `  t. v7 g" p+ lto setup-globals
: v7 @3 m  ]% H( F8 \4 ~% Q5 e; P  set current-light nobody ;; just for now, since there are no lights yet) p, [; n6 {, s( O
  set phase 0
: f% a  [: A$ `1 `# X  set num-cars-stopped 0( I. p/ {( g4 r, w! U7 g+ p
  set grid-x-inc world-width / grid-size-x+ L$ Q2 M! E% p  ]4 ?
  set grid-y-inc world-height / grid-size-y
; k4 O+ B$ h/ ~
; F9 @! I" a2 [" u, b# y  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary" M+ s- Z* G0 r, K# H3 D/ D) o( R5 J
  set acceleration 0.099
" E" N. S$ o! g& U: ~+ rend) ~- d$ @, ~& k$ W

9 h4 L& T; @3 G% W6 }( o;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
8 _9 ~1 t6 ~: D) i3 @2 _;; and initialize the traffic lights to one setting7 S  I. K  V; c3 U
to setup-patches
3 n7 q( p% L7 h3 Q; E  ;; initialize the patch-owned variables and color the patches to a base-color3 G1 d7 r' I+ _$ _$ S2 S7 }; ?1 |- y
  ask patches
1 ?4 O) k4 g: o$ a  [
. \$ T* b( Y: W5 U7 N0 V    set intersection? false3 G% {9 @) p' ~8 m* O) @4 @- O
    set auto? false
4 J' L" S) j9 z    set green-light-up? true
* o$ i1 W& Y/ s5 ?8 q$ Z    set my-row -1
2 A3 o8 y# c! e/ M; a& i7 K    set my-column -1
; H) o+ c+ K% }  c" j    set my-phase -1' ], _. l$ V* b4 ?7 q
    set pcolor brown + 3* R. l+ I0 a& C
  ]
3 U& x# u: X! b4 J. n  K5 G+ Y1 `8 ~9 l/ }
  ;; initialize the global variables that hold patch agentsets
) I( y7 o% j# k6 c  set roads patches with) c- l& Y) j; m+ G8 W: Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# x; i0 K0 ?/ x2 p5 s3 V    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 m" {- \9 v( A: v7 [8 l) K  B
  set intersections roads with
7 b( A! i# Y6 N9 s4 L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and' I6 I6 l% b$ Q3 _4 J( V1 Z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. n7 p- d" O% ?2 j1 P0 q# i/ y
9 K' ]; K' }/ ?# r& P2 J- `  ask roads [ set pcolor white ]
5 C3 A$ Y( g  g- Y( g& A* _    setup-intersections2 ?# G1 n# a5 C7 c6 x6 K
end
+ ]) A8 T) Y3 P" I! D其中定义道路的句子,如下所示,是什么意思啊?' A- ^& r( Z- ~4 X. |2 }* W
set roads patches with
$ Y7 [# `6 t/ D' @1 G& O% o& O+ E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 M- O. I: e" x1 e, d8 {    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 h. t7 R7 r$ x$ ~1 l) h5 d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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