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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。
. K+ l2 o' O4 o: U: b% r/ I* Vnetlogo自带的social science--traffic grid这一例子当中,
0 U; H) B1 V! @% z- J$ S* tglobals
9 p6 ], I9 G9 j[
0 W/ j$ j( i0 j# f/ o0 M' J% ?  C0 w5 _  grid-x-inc               ;; the amount of patches in between two roads in the x direction" D. b* w  N+ Z( p% ]( X" V
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
; {1 F7 `2 Y. @  acceleration             ;; the constant that controls how much a car speeds up or slows down by if( i/ T$ w( h' k/ R
                           ;; it is to accelerate or decelerate$ e, ], J& z8 T4 C# K, m
  phase                    ;; keeps track of the phase  B, M8 ~3 x0 ]' O
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
- y' c8 k! t' y0 D1 t+ n% d& M  current-light            ;; the currently selected light
- l- w" e! X+ n8 h7 P) |5 H, y, F3 n" c1 n6 M# o* v
  ;; patch agentsets# e( g8 F1 @' k8 H' l3 U
  intersections ;; agentset containing the patches that are intersections
) Z! K# |' d% @) q; _6 n' B  roads         ;; agentset containing the patches that are roads
6 q5 \8 T  D; N1 S1 Z% X, H]9 J) _  M* Z# ?5 b9 m: K
2 W+ Q  j2 V  a0 G# K+ u- d
turtles-own
' W( d" f7 Q5 J: X7 k2 x: g0 D[
4 O) I+ }; p- ?% R; }  speed     ;; the speed of the turtle. ]& u. d7 K: O7 X# u/ C$ O
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right: [3 ?% a, A  }. X/ e# ]4 a
  wait-time ;; the amount of time since the last time a turtle has moved
# \4 Z/ d1 A! G" S  q; _]
, d: Y$ F0 k& i2 {! B  q; c+ u/ c$ [' D; n1 G
patches-own0 Y4 ^% c2 ?. E. Q- O/ p8 v6 y
[  @/ M3 }: @2 X; S2 ]& T  W* ^- C
  intersection?   ;; true if the patch is at the intersection of two roads6 k1 e9 |* S/ \. I3 m$ k- b+ H6 U; a4 }
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.5 \. N3 v' b( }8 b
                  ;; false for a non-intersection patches." s4 Q* T  U( h- r9 C
  my-row          ;; the row of the intersection counting from the upper left corner of the! l4 `! u$ j2 a) Y# ]
                  ;; world.  -1 for non-intersection patches.9 z. B* L4 D  v& O
  my-column       ;; the column of the intersection counting from the upper left corner of the
, X% L/ a3 C5 A% H% W                  ;; world.  -1 for non-intersection patches.9 d3 P1 B2 b1 E
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
3 v' [9 l5 {+ C* f. F  auto?           ;; whether or not this intersection will switch automatically." ~$ E/ f0 S& {3 `, e% c- M
                  ;; false for non-intersection patches.
5 ]4 d' e$ |& E]8 B3 z. U6 b0 B/ D' K. F" |! ~" q

. Z4 G( p, K7 i8 b3 Q$ l( y2 c* J# l8 _% Z( `, _" |
;;;;;;;;;;;;;;;;;;;;;;
% e3 _& S, P) W$ d;; Setup Procedures ;;
, a4 ~1 ?0 ^/ V+ Z" b0 x8 ?;;;;;;;;;;;;;;;;;;;;;;
9 [+ r1 V$ L# f7 a, u' h" M1 ]% O2 W, f
;; Initialize the display by giving the global and patch variables initial values.9 H) g5 a- @- D0 P- D, e
;; Create num-cars of turtles if there are enough road patches for one turtle to2 h2 e' O: w" w  `5 E
;; be created per road patch. Set up the plots.9 W3 }. }( |8 l- a. K
to setup
5 W  H5 C  a8 F5 P/ S& M' K! k  ca
0 }/ E3 Z  k9 C3 ~  setup-globals4 f' X. b1 Z0 z$ d
) a% |( J# i' \5 d3 c8 O- W/ w: t
  ;; First we ask the patches to draw themselves and set up a few variables
2 n4 d" C- p9 m1 s' u0 j$ \  setup-patches9 E" a! r; z" M4 {  f
  make-current one-of intersections0 E. J$ Z. w4 G4 T' u6 G6 v  P7 Q
  label-current
3 b& |! a6 e, [+ z8 |; _# B" g
  Y+ i" B& I2 ^8 H  set-default-shape turtles "car"9 t$ W- j4 `# t; d/ X

- K6 z0 A! K% F& L3 J$ q  if (num-cars > count roads). t, Y$ M4 p) i8 `
  [* \& U! l! M- I/ |8 D
    user-message (word "There are too many cars for the amount of "$ v+ c  d- m* [+ k. T9 N
                       "road.  Either increase the amount of roads "
0 a% p  u+ W/ D: d  U% ?6 j                       "by increasing the GRID-SIZE-X or "$ ^& W7 t2 V/ B! f1 {
                       "GRID-SIZE-Y sliders, or decrease the "$ d7 ?7 C! g, N1 V# _
                       "number of cars by lowering the NUMBER slider.\n"' P2 n6 x, K& _
                       "The setup has stopped.")
  s+ J& D( ?( a) s# u- }' |    stop7 I0 @, k5 i3 `7 M
  ]; S$ a* g3 r" J1 J
/ \& w" Z$ u; `7 H0 V& B& Y" S
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
0 `; h7 T) c, d4 H$ {  crt num-cars) Q3 ~# F& p* _  e5 s
  [' D. M# ]! }+ p, Y. f, ?  W
    setup-cars* E8 o$ d8 K4 k2 l7 g, j+ l
    set-car-color6 e7 X: _: G* I8 @. e9 Z9 }) O" v5 j
    record-data
0 c; Z. R1 B/ Y! s, ]  ]
, k' i4 L$ t. `; Q, [- D$ T
! O( B" M( v. c% _: \6 o" r5 z+ j  ;; give the turtles an initial speed
9 A& G. S7 L& ~3 [& b2 p  ask turtles [ set-car-speed ]
" v) ~; m, s9 J: q) \! t# b6 M, M2 V( n! o
  reset-ticks, V1 \( i8 ?+ m4 \/ S
end* }3 @8 t& H  z2 L

6 \# s# s. N' j( p) r;; Initialize the global variables to appropriate values/ o) P  `  n+ C
to setup-globals
% s" o: ^/ k5 o+ [  set current-light nobody ;; just for now, since there are no lights yet
3 n8 d# H$ N, g4 Z& f2 Y2 @+ ^* ~  set phase 0; V' P' m/ C/ l( o" ?
  set num-cars-stopped 0
- T7 G, D% e. A2 j- Y3 y) w3 t  set grid-x-inc world-width / grid-size-x. \  W$ G+ Y+ u+ M
  set grid-y-inc world-height / grid-size-y6 M/ s8 J3 Y8 L) f: ]1 s
$ V! j# P: j' v7 I, x, @: J) S" u% {
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
/ O/ ~% X. x8 X% n7 w  set acceleration 0.0995 r0 ^* r" J. Y9 Z9 R8 f
end* [0 C' {9 u4 R( d: j, I

3 B- H4 u1 i: \) k; x) F;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
( a5 R# [; p4 p;; and initialize the traffic lights to one setting
8 F; Z, q) g0 B8 f$ A/ {to setup-patches
% K" Z2 Q' n# i/ N, |! I  ;; initialize the patch-owned variables and color the patches to a base-color
* l: T) a+ U" ~& d. z  ask patches. q$ n1 F, ?  d0 m
  [
6 y5 H. c6 T! _2 |. R  i    set intersection? false' |0 O3 v( k! F( \& O* t
    set auto? false
# j! L, @9 A& p) h* [    set green-light-up? true: F* Z& x1 [7 O+ V
    set my-row -1
: m' D+ C* r+ [, p3 g) k    set my-column -1( @8 U1 J& H. Q/ ]" f; P
    set my-phase -1- G& n! p- _% r2 v  s2 p
    set pcolor brown + 3* P# `2 h8 ^" [6 b5 s2 `
  ]( u. e: L( o( d9 X

% R% H, t$ l. ?) C  ;; initialize the global variables that hold patch agentsets
& c% Z. c6 b5 o  set roads patches with1 y) M& O* f# @' b
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, ]0 Y4 {9 \( O  m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 B) ~0 W5 A& w3 L1 F: |  set intersections roads with$ w3 z9 u8 {( x# M& t: [
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ u* |% N, o! x5 \$ Q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, b0 d3 C/ \7 v2 G/ c4 u% U1 x# N8 S+ d0 D
  ask roads [ set pcolor white ]
% a, y7 K9 @6 {% X7 f" G5 D  x    setup-intersections
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其中定义道路的句子,如下所示,是什么意思啊?  T' O/ B) C# Z1 d. |/ r1 E$ X& C7 v
set roads patches with
/ [" _& X& t: g) M% C    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% m  u3 V9 w, r. D4 v* x    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- u( L, s  c0 C" x1 J
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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