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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。$ }$ e4 q% P7 u5 Z. Z
netlogo自带的social science--traffic grid这一例子当中,
+ I0 E- t" A6 a) z. _1 _globals5 q8 Q; e9 ?2 A: `' p
[
* ?8 ^5 I. H9 a0 j& W, g  grid-x-inc               ;; the amount of patches in between two roads in the x direction, ]1 O. O7 l6 f7 }* [! H
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
% L2 G4 |1 m, @$ @  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
7 J% X0 D1 F5 t; {* v+ N7 Q- C                           ;; it is to accelerate or decelerate2 v$ `$ ?4 p8 a* e& K
  phase                    ;; keeps track of the phase
# L" i1 m+ u0 d5 h6 h( i  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
8 l3 i& q4 `# {  D  current-light            ;; the currently selected light3 k) g* Q' s1 W7 m  ^

4 B9 F0 Z* {( l4 [: \8 C) W, R  ;; patch agentsets
6 h, V! R! @$ ~  t  intersections ;; agentset containing the patches that are intersections
3 Z) e. G$ J  I  roads         ;; agentset containing the patches that are roads7 y- h. V; p$ `0 L/ F
]
5 N' h+ w# I) A# v7 [% f0 t+ W3 c$ d* I7 H- H4 f& k6 v
turtles-own( E" r1 i7 K( _& S
[
  a0 d  ~7 S1 L  speed     ;; the speed of the turtle6 g- w- n7 \# i, ?8 k0 M
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right! I$ y9 v  S- e8 b. k% k7 n
  wait-time ;; the amount of time since the last time a turtle has moved; q3 K- [4 n( D
]" m) o5 h; T) r2 U% P
0 k0 n% T) M" O1 n# D# Q! Y
patches-own
; ?  V0 x* L) r9 M/ w- i7 Z+ q[
) V0 z3 T* S6 x8 q  G  intersection?   ;; true if the patch is at the intersection of two roads8 |& u/ U' S- T5 O7 n
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.1 s& a( b* i$ q8 `7 h: u6 C
                  ;; false for a non-intersection patches.
1 P7 B. k* X- }* l  my-row          ;; the row of the intersection counting from the upper left corner of the
  ]# `& [+ t) ?/ S                  ;; world.  -1 for non-intersection patches.
+ O1 [+ J& C4 Z& p  my-column       ;; the column of the intersection counting from the upper left corner of the- A* _+ A! q, o) u/ }$ L
                  ;; world.  -1 for non-intersection patches.+ L: k5 F$ f5 H' a
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% ^7 `; ]. w* d. X5 k# y0 F  G  auto?           ;; whether or not this intersection will switch automatically., _6 q: b$ g0 Z( ^" w) x
                  ;; false for non-intersection patches.
( |+ F5 g, B3 ~" J( n' I4 X# |# `]
+ ~, F. J+ Z. |" }, b' u# X6 A+ r5 W+ B8 U4 \2 m

6 S+ M) h; J( @- H' |5 x7 m;;;;;;;;;;;;;;;;;;;;;;
- J1 _  r! O$ {: M4 R7 B/ s;; Setup Procedures ;;4 P: z% s( N; ^
;;;;;;;;;;;;;;;;;;;;;;
. I+ m' |& k$ Q( _- A/ j. _" ~
;; Initialize the display by giving the global and patch variables initial values." W, K& y) k# e
;; Create num-cars of turtles if there are enough road patches for one turtle to; |$ V# r6 K- Q( E- c
;; be created per road patch. Set up the plots.
  a0 d1 e: K0 Vto setup
9 n3 ^2 _, [- Y7 g  L  ca3 \9 K0 K- F% A6 U( `6 M, u8 X% r
  setup-globals, y& T( q+ f# c: a1 r" _2 [
! V3 f) ?: `# y$ `3 G( V. ^* `. G
  ;; First we ask the patches to draw themselves and set up a few variables
# P2 l& Z7 H, v& w! ?  setup-patches, M7 B. {# D1 {5 y: ]
  make-current one-of intersections$ r9 ^1 Y) X- V) q. N
  label-current
5 O2 a1 l3 z" q2 e( S3 R9 y0 b8 K1 m+ V9 M: O* w
  set-default-shape turtles "car"
2 ^6 G% _" f& w' g( c9 ]; ?% L, ]- g. r( Z! }
  if (num-cars > count roads)0 J6 P" i: H" q9 Z3 \
  [; a; N1 i6 k! ?3 A& }' W
    user-message (word "There are too many cars for the amount of "
% K9 e  f( s8 n+ f: W' t  }4 H                       "road.  Either increase the amount of roads "4 P7 Z* Q! w" Y; r
                       "by increasing the GRID-SIZE-X or ") S6 }7 A7 s" w+ s$ x3 O  g
                       "GRID-SIZE-Y sliders, or decrease the "
/ b( w; I6 ^$ ^7 w% M5 [5 A" ]                       "number of cars by lowering the NUMBER slider.\n"
" g9 L( A; l6 J) r                       "The setup has stopped.")
0 k1 @' M6 D! [+ [! A8 n# I    stop
% F2 G$ `" v8 Q8 H: C2 e7 H% y- o; K  ]
5 h1 C, v7 b  }& P& K, M& J
( O. R" ^1 M3 \: E& V+ R; i  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color, f* A5 r4 I# {
  crt num-cars
* f- u; E6 X8 m  [# M+ K6 o' _- }( g, U3 L" K& y
    setup-cars
; K, f$ \( Q: U2 F8 E' ~: o    set-car-color( H! E5 x- e9 c* J9 V  ~6 n6 R" `
    record-data
' c; L$ y; n/ `& I& ~" r  ]: `$ W" A: u7 Q3 a; s. n
+ R5 I! L3 p- i0 `3 W; k& R& R
  ;; give the turtles an initial speed% G) S+ q; M$ _! g/ f5 |* }
  ask turtles [ set-car-speed ]
- J1 \! |1 m, d( ~* ]2 T
+ s- F' Z4 V8 Y+ ]" ]0 G  reset-ticks
4 G% P% C7 r; d/ pend* J: C: l' c$ X# m" h) m
0 Y0 v4 C: z9 t9 N
;; Initialize the global variables to appropriate values
0 r  H! H# ^9 g8 i! y9 b' P: Xto setup-globals
' G& H' }! T+ }; K! _+ X, d- ~6 n  set current-light nobody ;; just for now, since there are no lights yet  N5 E& v2 c( z! [; Y' D/ e
  set phase 0
% @2 y2 Z9 g% X/ s6 d  set num-cars-stopped 06 E: k$ h5 ^$ E. J4 z
  set grid-x-inc world-width / grid-size-x0 N, P9 b/ b5 m* r6 Y
  set grid-y-inc world-height / grid-size-y8 x/ |. E+ k' j& o: {( v9 O5 O( X3 l2 _
8 g8 v0 ?) F" P* U
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
9 m- P6 F0 b& l! E4 f  set acceleration 0.099
: J7 y7 b: _* `  C# a' d0 rend! `: V: X; e) W; S3 @

& `( v# W" m% L) p9 B3 c1 y" R;; Make the patches have appropriate colors, set up the roads and intersections agentsets,' n2 _# `3 z/ f7 Q4 T6 E& R
;; and initialize the traffic lights to one setting" n: b) E7 ^: O8 o! w
to setup-patches4 C# w1 e9 K9 \& ]% p5 }( d
  ;; initialize the patch-owned variables and color the patches to a base-color# X0 \: o: ~$ X# w/ C
  ask patches
+ S! ]) @* V. k, r; v" c  [9 N1 Q% p9 J7 t; J3 h8 Z* F3 r
    set intersection? false8 H/ g5 c; E* @6 i) {( v/ S
    set auto? false
( m( S5 h( p4 Z* n7 P9 X    set green-light-up? true8 E$ \0 J/ T7 @" K
    set my-row -1
0 b6 m) c+ F! a8 v) {0 e2 G    set my-column -19 Z  ~! ~  X: r. X9 C# I
    set my-phase -1( P% S* `: K( G3 E" p
    set pcolor brown + 38 R3 |) N" e. e% `6 D5 W
  ]
" j5 V* w$ ]" W. j; e$ a, u" L" [  `  W% ]
  ;; initialize the global variables that hold patch agentsets; z' w) k, @. q7 ^4 U6 W* O
  set roads patches with1 {% H% F5 N' k; i
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! M  Q4 o3 g1 n$ G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  Y1 I. T& X( f: ^/ d4 W
  set intersections roads with$ B4 Z4 l$ e/ j! O) C7 v  U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ a. c' H3 r( P% J% ?/ m
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- Y- i. g% Q* j2 Q& A( \7 H3 v8 D$ O/ ~# {
  ask roads [ set pcolor white ]" ?+ u1 C2 V/ h# G% X: \
    setup-intersections- e# s  w7 E* Z' J' [* x
end
/ S2 P* f) q" w8 Z) P' c/ T其中定义道路的句子,如下所示,是什么意思啊?
2 L9 V: H# a3 n" L; z# H1 ] set roads patches with. M: ~) T5 \% o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 o4 H. U* N: L    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! f9 f4 r0 t, d/ R3 O: 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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