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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。+ b% u8 ]; ?( C: J$ n* K
netlogo自带的social science--traffic grid这一例子当中,1 a/ d  L! c. O7 `
globals. u! g. U  o# u2 g( H, t
[; n) ~0 Z3 t. Y2 ~
  grid-x-inc               ;; the amount of patches in between two roads in the x direction7 f+ R& Z" x$ x, D( ^" r. O, i3 [
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
& [& R) l5 T9 s6 x: v' I& Y  acceleration             ;; the constant that controls how much a car speeds up or slows down by if! t8 m+ y' T: S$ _- k. t) f
                           ;; it is to accelerate or decelerate
+ a6 I  U, E3 q, f) F3 B3 a, ^3 K( e& ]  phase                    ;; keeps track of the phase
( ]% t3 w; a' \4 n4 z. Y+ e4 h$ s  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 _' j6 A8 O& H9 O
  current-light            ;; the currently selected light
; z4 ]  Z0 q/ O$ L+ x8 y. x% L. W6 F
  ;; patch agentsets; C5 O( `' u: F$ o- t, K$ c  c0 U
  intersections ;; agentset containing the patches that are intersections
4 [/ ?! F- _! q) Z  roads         ;; agentset containing the patches that are roads
. z  s, d# `4 T: B0 Z]2 Z' f" @  Y( u  E# K

, n$ I4 V5 U: N/ V* J% mturtles-own
' O9 {$ ?2 |. D$ h- ?[$ Z: _) ~/ A; U$ f
  speed     ;; the speed of the turtle. v# [, p9 o$ c
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
0 I  B: f; I; C2 L  wait-time ;; the amount of time since the last time a turtle has moved
% ]7 {- H2 e* ?" Y  t( n% [  }]
- W# l: F- E* r  e# [6 z
3 q$ W5 ?9 }+ J9 p9 \) I9 o: Lpatches-own
/ P$ A. O" O% K' D% z! z: @! y[: D7 {" a, U, b9 |7 i' X; t
  intersection?   ;; true if the patch is at the intersection of two roads4 r3 a1 u: m5 b( [: f
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.# X$ O4 s/ O6 ]) v( Z2 O2 G6 M
                  ;; false for a non-intersection patches.; k. G% Z6 k/ z- ~4 w3 Q' h3 T
  my-row          ;; the row of the intersection counting from the upper left corner of the0 z6 |" }6 ~/ |4 h0 ~; o; ~
                  ;; world.  -1 for non-intersection patches.
7 X$ m: I" Z2 n- f" ]$ o  my-column       ;; the column of the intersection counting from the upper left corner of the
0 k& T1 N7 G9 V1 H6 h5 T! y/ K' x                  ;; world.  -1 for non-intersection patches.
# r) U) q4 W1 B. J) X* L  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.1 ?. Z6 R2 ?9 j2 R( T$ q! u
  auto?           ;; whether or not this intersection will switch automatically.1 S0 [9 O3 z/ A% n5 |) e( S
                  ;; false for non-intersection patches.& x5 F8 J7 H, N
]( y- ?& h9 W, A/ _0 M* c% b1 k
: s/ Q5 x8 F! X( d9 |
+ O+ c2 I7 F( G
;;;;;;;;;;;;;;;;;;;;;;+ I, Z  `" M) E* P
;; Setup Procedures ;;
- S. W$ i% L  Q3 N! S6 A;;;;;;;;;;;;;;;;;;;;;;/ d/ m7 T+ r+ W/ ]/ e

% \. M. W% c* m! I' }% c;; Initialize the display by giving the global and patch variables initial values.- v5 g3 C) N% Q* U, R  g
;; Create num-cars of turtles if there are enough road patches for one turtle to/ k& L6 Z2 J* |
;; be created per road patch. Set up the plots.$ z, F# C! _% L% G' n% |
to setup
1 e9 t& C" S6 t: m, U$ `- b  ca. z7 y, T0 _4 |2 O" Q# J
  setup-globals; B; v0 B5 H% u

* \2 q4 M) @( F3 p  L  ;; First we ask the patches to draw themselves and set up a few variables  c1 k8 m# X1 T% y/ r9 I
  setup-patches+ _1 n7 T7 n9 |
  make-current one-of intersections4 C( U6 J9 W1 r& I( s( ?9 V# t  p
  label-current
6 o# |) v) Y. f% i) J- H
. t# p# M9 {3 d% P6 |" d- v' q, U  set-default-shape turtles "car"
0 v5 W9 l6 W1 ]
0 E% a- x9 l+ q% Q/ J8 k/ I  if (num-cars > count roads)
/ _" R- X' k$ r6 t& U  [9 f/ _. [! @6 s2 j% X0 @1 q: P7 u# P
    user-message (word "There are too many cars for the amount of "$ K7 ]. G4 `* p9 ]  n
                       "road.  Either increase the amount of roads "
) s) b. _% R4 c                       "by increasing the GRID-SIZE-X or "
3 t' _* B( H4 ]                       "GRID-SIZE-Y sliders, or decrease the "( M" ]; n# _9 A  b$ p
                       "number of cars by lowering the NUMBER slider.\n"$ F0 E6 m7 _: O% k5 z
                       "The setup has stopped.")
( d1 v* Y8 l7 R" m4 F    stop2 o5 A- T' F! t# l" `! j3 |; |2 @
  ]* S4 |% _  l3 m1 c# O+ g- r" z) w
+ [; p5 r6 d' j- S& k) a* P- a& P
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color" s/ j/ F' U7 ?! L. b
  crt num-cars* d1 [8 O" M& i' n
  [# s; E  v: h& }. d
    setup-cars
" F/ d. `% I% `( D2 q; S    set-car-color
" h8 {" C  w" K    record-data
0 F3 E( B; a! e9 U! R  ]: s5 A8 @- o! x- I' [! _

% }( S# T: j9 _" D6 ~  ;; give the turtles an initial speed
2 L' y' u! X3 F( w0 I  ask turtles [ set-car-speed ]' o6 ]9 v( n. O. \
# I/ P/ h6 m! ^( Z4 L" ?
  reset-ticks
1 g5 ~8 l  z6 E* X0 L1 `) X8 Yend
1 g- r' E6 b6 S+ r8 ^
! z. I1 X( S* l* n, n;; Initialize the global variables to appropriate values- c# s" B9 E7 _$ Z9 [* m, Z
to setup-globals  F2 Y. Y6 V* z$ K
  set current-light nobody ;; just for now, since there are no lights yet; @- H4 g. a7 f5 S+ `# V
  set phase 03 z6 T" I6 j( b0 }3 R; p; z+ `
  set num-cars-stopped 0
0 ?8 E8 A. P) P1 n; m9 |2 _  set grid-x-inc world-width / grid-size-x
& a* \/ m( j5 _/ l  set grid-y-inc world-height / grid-size-y( @" K2 |4 U7 h0 O
0 t0 T) i, T# \
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary/ |( _! y$ q0 \5 e/ M- v/ t
  set acceleration 0.0995 \4 K9 ?7 ~5 f1 l' X& G( y
end) a+ v9 t  S. A) p& m7 {0 b

2 k. A0 Y- ?* z$ ^9 U6 x;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
% o  Y0 O' t% Z;; and initialize the traffic lights to one setting: m3 L1 }2 {( f8 r: r
to setup-patches
4 C; W! X& m3 i) H% U. a; g  ;; initialize the patch-owned variables and color the patches to a base-color
2 Q2 B4 J3 a! k! U, x; q1 q( W' W  ask patches
' p- j9 f! M2 X4 f( ^  [- j% ^. `( y: Z% y
    set intersection? false
3 U3 Z# B' s0 ?7 P    set auto? false! l7 P+ a& Q1 F
    set green-light-up? true
1 R% m3 U* C. G  M1 V$ r    set my-row -1
, c# O% t/ d1 W9 l9 z    set my-column -1
* C. q% a) Q( q* |' U. |4 G+ F    set my-phase -10 ~( o5 {" ]! ^. o' E& {9 S0 c
    set pcolor brown + 3
$ e2 O  G2 ?. t1 ]  ]6 u2 O# r: g! R. w2 V6 `  }9 A

8 A5 e* j# U5 U2 j; L9 ~0 |  ;; initialize the global variables that hold patch agentsets
6 p, o0 J, J4 y" }& b7 Q  set roads patches with
; j# x0 V# L) e. L2 r# d& r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 E: T2 p2 j: J& E2 l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ }7 B+ l3 l3 T: C  set intersections roads with+ z( c8 X* b# b0 S4 f
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
1 }) T4 {4 W) h  U& ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- c; o8 K) h! A" p. x% g5 X; G! o9 u" Y4 g) e" E
  ask roads [ set pcolor white ]' s4 A6 Q: r, _" Q8 t- r+ k& n
    setup-intersections# w" h( n: F0 e/ I5 {
end
; F$ R) s6 |2 P6 H其中定义道路的句子,如下所示,是什么意思啊?
' ^. d3 R. o- a( A  \ set roads patches with
  N: Z; z+ J1 r$ |5 r, d! E: W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 X- S1 }* T' K, F; i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- {0 n) X3 P2 D+ Y* 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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