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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。
$ v& K6 S9 G5 q6 J/ ?netlogo自带的social science--traffic grid这一例子当中,* _* n$ B! ~+ ~
globals' g5 i4 x% p7 ]
[
' l+ A/ f; F6 V+ E! x' D& u% ~- t* D  grid-x-inc               ;; the amount of patches in between two roads in the x direction9 n8 J0 Z7 O) E6 y( h* N: o
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 y: d9 [2 z! ]7 Z% }; U  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
# m, C  \2 w8 t6 W4 Z' l                           ;; it is to accelerate or decelerate
# J# j' A6 I, l  phase                    ;; keeps track of the phase
7 d3 j; }5 W9 k& h& \  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure( G7 j2 M7 I5 ^1 c# Y
  current-light            ;; the currently selected light
  n( D5 O+ F. C( B5 i+ c( q0 S( v6 [3 |7 u
  ;; patch agentsets
8 q% z) g3 d' m+ X  T5 j  intersections ;; agentset containing the patches that are intersections
$ M' m6 T/ S; v9 o7 t  roads         ;; agentset containing the patches that are roads/ l" l  A' {5 Y0 b
]
# w3 R- k3 O1 J; D5 l1 b* T* W( o$ [) }4 G) @  P
turtles-own5 F. J# f) a( Q' S1 H
[
3 _! v$ X) E! I# v  speed     ;; the speed of the turtle/ K+ Q" i! Z3 g( d5 K+ G* Q
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
" t- R/ s" I+ w# _5 u/ D( p  wait-time ;; the amount of time since the last time a turtle has moved
" m: k$ D0 |8 f  z2 a0 O]" w+ W  Y: `% K& c
+ a4 F4 J& X3 M
patches-own9 E8 H/ N/ p9 ^( X: ~( a4 @
[& v" s! g4 d6 N6 M9 m0 I. X( @
  intersection?   ;; true if the patch is at the intersection of two roads8 S  ]0 g/ Y) Z( J( b, y3 B! J9 _
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
- {, _. G; K3 [' N: _                  ;; false for a non-intersection patches.  n" z% n- `. \7 v# y, ]
  my-row          ;; the row of the intersection counting from the upper left corner of the
: F/ p% ^8 _" c  E                  ;; world.  -1 for non-intersection patches.% f  V  o' K+ `; P
  my-column       ;; the column of the intersection counting from the upper left corner of the, Z1 O+ `; [+ A% t
                  ;; world.  -1 for non-intersection patches.
+ o  V9 D7 p* m: {; R  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
4 ]1 p, m5 p+ ]$ Q  auto?           ;; whether or not this intersection will switch automatically.
; K" B8 L- n, l9 e2 s                  ;; false for non-intersection patches.* {2 Y  l- l" V# H8 s
]
5 Z0 v5 F% X& u4 o% c1 a
. S0 X5 J8 s2 |, I% w% g, [8 i$ _% E& L) \4 F/ O# ^1 F
;;;;;;;;;;;;;;;;;;;;;;3 B6 A. y4 X8 q7 I: X
;; Setup Procedures ;;
" P( {* {" ?0 ~% p/ O;;;;;;;;;;;;;;;;;;;;;;- G; d) r# M9 I5 w0 X
+ @; M. H/ m% T+ B$ e6 H
;; Initialize the display by giving the global and patch variables initial values.
1 d( ^- j3 M0 C2 G) P8 d9 y;; Create num-cars of turtles if there are enough road patches for one turtle to
% R! O! l$ f$ D; W;; be created per road patch. Set up the plots.
2 e$ p3 w4 _' ^/ oto setup1 Q9 k0 _- \/ @& J, `" \7 R4 g5 H
  ca' R0 z! P6 r6 R, T  k4 L& U
  setup-globals
+ F, @' P4 |! g" _9 f# p" f! }/ R8 ]& p
  ;; First we ask the patches to draw themselves and set up a few variables
, H- T" M# j% e7 Y( n  e6 U  setup-patches( R- o( c1 U9 g7 y+ G+ i3 x
  make-current one-of intersections' x  U- V2 U; M) q
  label-current6 p7 F3 y" j( b' r+ A* {" _: u, ^

5 q9 C9 E- }& G& l  set-default-shape turtles "car"7 j. u$ t* A+ Y% O: U' i$ o

$ I- h4 J9 t, _: Y" ?3 s  if (num-cars > count roads)
' W, ]$ Y$ R5 t( C  [1 R& V/ V: V" A7 G0 L
    user-message (word "There are too many cars for the amount of "/ U* M& e4 g$ d5 G) F7 P* S
                       "road.  Either increase the amount of roads "
* v$ x! @: e! T; A3 l5 D                       "by increasing the GRID-SIZE-X or "
+ T' I, ~( e# a7 f                       "GRID-SIZE-Y sliders, or decrease the "
: D% K: k" B" S# f) }. S                       "number of cars by lowering the NUMBER slider.\n"1 O+ G+ r  L5 Z! s/ l
                       "The setup has stopped.")/ i3 A# F0 G% m. V8 z
    stop
, M- z# d4 j+ b  ]0 }3 W: G0 d- }! E+ Z
, I" u2 j1 {; Q# X( A( Y* C
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color  ^9 m$ J& B  B: e# y
  crt num-cars
* ^) U! Y( h8 U9 n  [6 r- R7 ?( M( }
    setup-cars# Q4 \6 ?7 o/ H8 {* [5 t
    set-car-color
) ?9 Q2 [4 P* |' ~  a( a& o( q    record-data* L' K' q+ @- n8 z5 d' l4 ]
  ]' ~0 f, Z( ]- b9 ], F  V; e
6 P& v) l) u/ q
  ;; give the turtles an initial speed
* Z( J* b" w. t' N6 m  ask turtles [ set-car-speed ]
- Z4 r! j  A$ U1 N: K6 l
( \4 Q+ O  }- [4 d' G  reset-ticks
, r: B5 q# t8 ~end) |3 l5 e3 @+ @' c9 Z8 Z% g5 e% N

6 `5 r! q6 W5 k8 F1 M;; Initialize the global variables to appropriate values
8 s6 }3 \$ C% h* J) ^to setup-globals
, S( h, W& |) F+ L+ A  set current-light nobody ;; just for now, since there are no lights yet
8 [4 z9 P# ]$ |- d: [3 R+ b$ P  set phase 05 G. w: g! m6 z) {  E, i( p6 P
  set num-cars-stopped 09 R  {7 |: K" [
  set grid-x-inc world-width / grid-size-x$ ]9 x' |2 m, v" j1 j
  set grid-y-inc world-height / grid-size-y; a2 p5 k, C. k( z5 [
! ?# E# L% }' ?7 R" ^  Z" M
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
* |! |, a* }# D8 e- s  set acceleration 0.099
' c9 c- z' D8 Q+ Tend3 D2 H9 |( v5 T+ m1 a

. w0 |# w  G" t) D6 s;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ m7 K+ ~/ R! O, z* ~  \( T* v
;; and initialize the traffic lights to one setting$ ^, W2 x2 P5 i4 z* t# p  G7 K( u
to setup-patches$ V* T# G9 d  A5 Y2 M9 h7 B
  ;; initialize the patch-owned variables and color the patches to a base-color5 V+ }; `8 }+ g* ?
  ask patches
$ I; b' `7 f; |1 q/ M  [
: M+ L, j2 D. {. p9 w    set intersection? false1 K8 P) y: Z- b; a& J! e
    set auto? false! l% X9 Q1 p+ G" |( v6 \) i
    set green-light-up? true
6 I3 P5 s# b& t; a6 T2 Y' }+ d    set my-row -1
8 `- L6 b+ T2 ^: F5 l    set my-column -1; z  C) Y. u2 B( T- m+ g: L- h
    set my-phase -1
( y0 |3 y, r; E! q    set pcolor brown + 3
6 a) t- [: M: A1 C) U  D! U2 k  ]
0 y9 r, H- m7 m  c' L1 O
6 @# {. Z4 U- n# W  ;; initialize the global variables that hold patch agentsets" s8 P) t4 A. A( @6 H6 N
  set roads patches with
' w3 F% E- ~$ q" p7 o. H9 L: O+ {! S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  d  M% V% W# N
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" d( A% n& m! |9 h& p: j% x  set intersections roads with' A- u6 \. A1 y9 I  h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ l% z. S$ U7 s( F5 T1 \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 z6 g: I" v0 C* r6 P1 B
/ T% W$ q3 X3 i2 T
  ask roads [ set pcolor white ]
5 t7 n% p" w5 l    setup-intersections# P" x& V6 L+ {
end. j! h7 ^7 ^! [7 T* u/ g& e# f" ?
其中定义道路的句子,如下所示,是什么意思啊?- |! M8 X2 X" ]! _* _
set roads patches with
9 X; x/ y. H: O, ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  K4 @1 J0 F* ?. U+ l0 W9 B
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 @& M  t! a' Z1 v1 u. M
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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