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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。# d; ^- Y  l+ u
netlogo自带的social science--traffic grid这一例子当中,# h6 N$ U1 z) \: N3 ?3 b1 Y
globals
' R7 W1 |& A+ b) @3 O/ H3 r$ s[4 k, X3 O1 s( [+ f3 O* x
  grid-x-inc               ;; the amount of patches in between two roads in the x direction  M! P! {9 J& |6 ?4 R+ r
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
+ k1 M7 R  I9 g  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
- N, m2 Q  {& g  [' Z  X! G8 U% X* y/ T                           ;; it is to accelerate or decelerate
2 A/ f% K5 B( k" S8 M- k5 G! }  phase                    ;; keeps track of the phase
! c% z* {1 b8 t& D8 {  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
3 e8 `4 J( R2 I" d  current-light            ;; the currently selected light) F  `0 |1 Y* q, L, y- I  g' D- b

. X" i7 k8 x$ f* V  ;; patch agentsets
) _# A. L% P( V* R5 I  intersections ;; agentset containing the patches that are intersections1 `0 O- |; M; }" y# T% T# S
  roads         ;; agentset containing the patches that are roads
, Z& Z! B9 M' G7 i4 R% J]5 Y5 \& b; A2 v3 y7 D. a8 K

  \* @; O/ I6 U$ Nturtles-own
6 y8 X5 o4 l( R9 [[" @+ t1 U( T# \: d4 \. D( Y
  speed     ;; the speed of the turtle
4 ?' G3 I$ I& E. Z" B# @  up-car?   ;; true if the turtle moves downwards and false if it moves to the right6 ^" g% ]7 Z$ v4 P% A9 F
  wait-time ;; the amount of time since the last time a turtle has moved7 N# o( S, A) ^
]& o1 ?/ G' \* `; k# S; W

" l/ {" a1 i7 l; d# t* L: d. Lpatches-own6 K% F6 Y" i6 r5 N
[
& D7 |0 e% d6 R: ?' G$ P  intersection?   ;; true if the patch is at the intersection of two roads% E! r7 o+ o) A! n
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 k& m4 t% v. B2 J# e                  ;; false for a non-intersection patches.
- J* X. D+ c) {. r5 e  my-row          ;; the row of the intersection counting from the upper left corner of the
. k  j. v! Z' Q" T% U                  ;; world.  -1 for non-intersection patches.
' V4 B, E2 C- ^$ B; P  my-column       ;; the column of the intersection counting from the upper left corner of the
* v1 v: F* u( S& J( H& r. m                  ;; world.  -1 for non-intersection patches.' M$ m0 C/ N- {& n6 r: b
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.( M9 y: @/ O) M
  auto?           ;; whether or not this intersection will switch automatically.
9 _2 j5 E' f. t4 M) E( r. W                  ;; false for non-intersection patches.
: K% m4 a' n+ @]5 t0 j) F# p, r
3 |  m) S1 O7 V
* V2 ]: R7 U4 G' V, G3 ?
;;;;;;;;;;;;;;;;;;;;;;
8 j9 I, S7 J" X. a5 m;; Setup Procedures ;;* v2 m% _- `& c8 n
;;;;;;;;;;;;;;;;;;;;;;2 I" F) F4 `$ N, _) s+ n: h
0 N1 Q2 V# ]( P6 ]; K1 a
;; Initialize the display by giving the global and patch variables initial values.5 P0 P8 Q- K; J7 n
;; Create num-cars of turtles if there are enough road patches for one turtle to
+ X" X! H) R4 J& I; };; be created per road patch. Set up the plots.
$ y- x9 ~6 B% E6 N( k: n; Cto setup
  q; r+ y% g* }6 d: p- c  ca
7 x# b& b- k3 ^5 z4 Z( E  setup-globals+ a3 W0 ?1 a0 `1 U
' m9 o) x% u+ b
  ;; First we ask the patches to draw themselves and set up a few variables+ a( z) u$ ?" C9 Q3 d/ n3 V% s
  setup-patches; V8 o7 T0 S9 c: }: J. b) r! A2 @
  make-current one-of intersections
- [; L2 \; m  e; y/ W  label-current
' X: q' M4 J& x7 R( k9 |  X5 u" P  }4 q
  set-default-shape turtles "car"( d' r) h% x( y$ F5 N8 f* O

! H/ @/ ~# M0 U; F1 d. c  if (num-cars > count roads)
" L# H; v* ~1 W+ i7 u  [
+ l! Y- d* J7 A; |1 D& \4 ~# f    user-message (word "There are too many cars for the amount of "; s5 u+ r3 U0 O0 E2 J+ ?" G, ]
                       "road.  Either increase the amount of roads "
' n6 C/ P& e0 q3 `0 j$ N                       "by increasing the GRID-SIZE-X or "
0 z) G1 `' Z' U( t6 f( O% ~                       "GRID-SIZE-Y sliders, or decrease the "6 E" x5 J& n0 T4 ?, P7 ~. R
                       "number of cars by lowering the NUMBER slider.\n"; B9 _# W& B4 w# q) {' `
                       "The setup has stopped.")
9 Y& S0 m! F# f' S& @1 Q2 Q- z) [* O    stop
0 R1 Y8 ~  G/ r- a2 B" b  ]
! l7 m% S  ^1 M4 J+ b0 @% s) Y+ Y! v
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color4 i  z2 F) j3 ?' {  @" D
  crt num-cars$ A3 P7 W8 f- H, Z: a
  [! }# ]5 l. U! ^! d
    setup-cars+ y! V# M) t, `6 Z
    set-car-color2 B; C* s0 o; a: D* q( A7 t
    record-data
+ S7 w& c. T* w% v  ]6 q( ~" n; E7 e2 p  n: P

, b9 s  C6 O; s3 L  ;; give the turtles an initial speed3 d  u4 V( j9 ?$ k7 E: T& N
  ask turtles [ set-car-speed ]3 r& x6 m% K% `$ b3 v% ?$ P# l7 e
' u4 x1 x2 {; [7 i- U
  reset-ticks
4 ~- `3 T9 \/ F: u2 N; \4 b( Lend" D4 d2 L4 K* w7 [1 M
7 O% f' e8 f" g9 g
;; Initialize the global variables to appropriate values
5 X; \) T) i6 D- I! P6 |/ oto setup-globals3 `; Y( h2 Z# h* N4 N
  set current-light nobody ;; just for now, since there are no lights yet) z& n# _4 e8 a* _7 q4 b8 x+ X
  set phase 05 j" U7 g5 @6 m; q
  set num-cars-stopped 03 m& m7 D% X$ _6 g- e% c* I' r
  set grid-x-inc world-width / grid-size-x
% q9 X6 f: J3 ^) z2 L0 v' n  set grid-y-inc world-height / grid-size-y
9 i8 e% J- g2 `: `$ a
/ t! ^. T: j9 [( ^+ P  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary4 n. Z, z; {. q( L+ s' ]
  set acceleration 0.099( Q7 S/ j7 R1 W. v0 E8 Z8 b
end$ u( g. l. l# _9 R

: _, m5 K+ J- [;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 p( L) P( Y$ @+ J2 V
;; and initialize the traffic lights to one setting
  d% K1 t& n* {+ A* E+ n5 Vto setup-patches
: Z+ r5 T  v2 p) Y9 e( {# w  ;; initialize the patch-owned variables and color the patches to a base-color0 ?" k, b  x- c& o" l/ m* {# ^
  ask patches
7 o" F2 z$ M( N$ f$ i7 M& ]  [' H2 A  T& Q# T( Q& `5 q3 O
    set intersection? false" D# o6 g! s/ l- k  K7 {& t3 `
    set auto? false
, }2 n8 s6 a3 b* X; X7 _    set green-light-up? true
* u. g0 l% ~6 h. r- Q5 o* j4 ]    set my-row -1! Q! ]0 n  z, M; s' X% ~5 N4 ]8 L- ], f2 A
    set my-column -1) }* C, S0 ~% X7 k
    set my-phase -1$ F5 c5 O7 R% l# t6 @) ~
    set pcolor brown + 3
, d( I: o& O5 Y; a% ]  ]( w) k2 C! J! R5 b
' y8 }1 D/ Q1 y- B4 v+ x
  ;; initialize the global variables that hold patch agentsets
" i& s+ ]/ t8 Q9 M  E( d5 R% r; d4 L  set roads patches with
, Q" K1 y; [; _% ]2 X8 y4 ~" E' \    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% o9 k( d6 E. q* ~( p" ?2 G6 u
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 n3 ]) B& T, i  a/ b  set intersections roads with* ~( y4 C4 b/ T) n: W! {; j
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
6 j  o  d3 d2 M; |& O$ w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ v5 ~0 e" G9 b  X. w0 U- R9 g0 C

) O* z0 ^! _' ^. r! q$ o8 B1 H  ask roads [ set pcolor white ], X* f4 p6 P2 Y+ n) T
    setup-intersections
+ e! C7 m1 j3 i; v, hend
. H- _2 _- \  r6 a  k  J其中定义道路的句子,如下所示,是什么意思啊?/ W! \: v1 f! q  b* v3 ^
set roads patches with
9 f* u( g7 f& i  I6 o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 x2 ?8 R/ l( C9 ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 b4 B2 [  p2 v5 a% u* ]! u. U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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