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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。
; `- I$ o: O! Q7 F% o# fnetlogo自带的social science--traffic grid这一例子当中,  W5 v" M! Z9 w4 _' A5 ]7 @
globals1 L* \' N" o: H( D; @
[- f' V4 z3 |5 z7 t' H+ K6 c
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
& {* X, U  |2 A! T  grid-y-inc               ;; the amount of patches in between two roads in the y direction
9 G2 X) D- A$ ^7 t' X$ T8 U& f  acceleration             ;; the constant that controls how much a car speeds up or slows down by if# E8 D) w- X8 [1 x' [% m$ w6 Q' P
                           ;; it is to accelerate or decelerate4 i7 a7 j$ }4 w. B
  phase                    ;; keeps track of the phase
1 n5 J4 _, V  U( T. q  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure2 u$ V$ Z. U) Z0 y+ M; P" N6 v
  current-light            ;; the currently selected light
4 P. ]; M7 ?( [" d8 t) x' I- q" D4 B+ h. N& w
  ;; patch agentsets4 M( R9 ^) [+ o" v% f6 m
  intersections ;; agentset containing the patches that are intersections
6 m* e  e1 I! E& i, z+ P5 u  roads         ;; agentset containing the patches that are roads
, q  O, B& G6 J! b# p]' l7 A# R0 h# ]1 f$ ]

9 w8 c1 J2 c+ I. K% Jturtles-own
6 e7 a. Y$ m2 L! }( i# P( c+ W[
% o0 s: w* a( r% j  speed     ;; the speed of the turtle  U% b! m, h4 s3 v' r
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
3 Q% L1 X; I( g3 h  n  wait-time ;; the amount of time since the last time a turtle has moved$ [2 `" S0 f) ]9 b: K& |2 N* _! }
]
+ d: M; S2 f8 y, K" y1 U( S9 Z3 y; B0 s1 J5 o( X% a
patches-own) ?4 O) L- N6 ^& s: @, D) S
[6 }  Y% m' t/ J' e! z( L+ S
  intersection?   ;; true if the patch is at the intersection of two roads
* S9 m# T1 J# j$ b  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.5 {' A5 ?' U3 G- [1 \
                  ;; false for a non-intersection patches.9 i6 {! d9 ]) w  u  V' s* c7 ?: O
  my-row          ;; the row of the intersection counting from the upper left corner of the
0 }# }2 D% I, s2 v; F) e5 y7 C                  ;; world.  -1 for non-intersection patches.1 Y% J( E+ R) `! @, J
  my-column       ;; the column of the intersection counting from the upper left corner of the; C/ X: @( {) ]6 u8 K, d4 U
                  ;; world.  -1 for non-intersection patches.
: @8 ?' l# I- `  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  I. U! p. c% Y) n% P2 L! g
  auto?           ;; whether or not this intersection will switch automatically.
1 i1 e/ ]1 B* j' H$ m7 B) R+ g                  ;; false for non-intersection patches.1 N2 h( ^0 J% L+ D$ Q
]3 l. o2 `' }2 u, A* c, p4 q

+ F$ r+ c! a% G, m7 j0 _5 Z) n; F+ v0 ~6 `( \9 U( L
;;;;;;;;;;;;;;;;;;;;;;
: N8 m$ r  i" l& |* l. A5 \;; Setup Procedures ;;; @( J( |5 G4 }5 ?' Z9 A; }6 Q
;;;;;;;;;;;;;;;;;;;;;;! ~) P# ?! }; K" U: o/ Q! C
! T- C, U9 ?1 }' Y3 E+ c* X
;; Initialize the display by giving the global and patch variables initial values., [, `% m" U4 X4 Q; i. [9 b* J) T
;; Create num-cars of turtles if there are enough road patches for one turtle to
0 e# P8 J6 g$ w; ]. P8 Q2 \8 k! P2 ^. b2 y;; be created per road patch. Set up the plots.9 T! ^+ H/ ]% y8 P4 G8 B% z. ~8 h
to setup
( I: p# }$ R% @$ ^# t! ?6 B  ca; _# z6 k$ F+ g. R5 i9 f, M
  setup-globals1 }. h8 L. O8 n$ G4 E! h
0 z, t" P9 ?$ v- g& C% O# a+ n
  ;; First we ask the patches to draw themselves and set up a few variables
7 B/ m/ n5 C  b  setup-patches
8 D" F6 ]5 K; g# {! M; l  make-current one-of intersections) z, k0 n+ d( `
  label-current
. d+ |- [0 y, V- d$ m; u, ?0 D
  set-default-shape turtles "car"! i! U5 d& t' @

  |1 E# K- Y8 s# R$ X4 F1 ~  f1 ?" t  if (num-cars > count roads)5 {$ O6 T! I9 h& @! l0 H4 w; d1 `
  [
0 e8 z1 C2 f$ G  t) w3 D. s    user-message (word "There are too many cars for the amount of "8 j8 S) [# ]( v9 T2 D. d/ f: g
                       "road.  Either increase the amount of roads ". v2 z0 j; n$ e  f' d9 U
                       "by increasing the GRID-SIZE-X or "
  f& R6 ^! R, K( ^3 j& `                       "GRID-SIZE-Y sliders, or decrease the "
1 I* d5 \/ n$ k/ B/ _                       "number of cars by lowering the NUMBER slider.\n"; x% |9 _% B- w6 N1 J3 I6 o- T
                       "The setup has stopped.")  A3 s  i! X  h
    stop
! o2 l( ?/ ?* M  ]
9 J. m, l4 m7 N/ ]3 u0 }0 W! w1 Y8 _
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color. @! `, h8 Q( Y' f8 ~/ `
  crt num-cars
1 N: Q& E8 z9 w! R6 Z/ ]+ h+ l  [7 B+ J, h# |( v
    setup-cars% W/ q& g6 j; v0 f
    set-car-color; I$ B  C4 g. m6 D7 h1 I
    record-data1 R8 u+ G- n2 z* R8 H) u* H
  ]
$ O+ Q) d) E7 O' q8 |% ]0 F* a. k! u
  ;; give the turtles an initial speed
8 [: |7 Y2 \  ]6 K/ A  ask turtles [ set-car-speed ]! ~2 K" V& U  @2 Z- R+ q
# Z6 C2 r  x, j- C. Q- o4 @
  reset-ticks. H3 Z( g/ l. B$ {+ x
end1 n# Z: T' K% ^7 h6 ~8 f

  i' s0 {+ |. I5 [* K;; Initialize the global variables to appropriate values1 t' u; h/ p. p5 k. i5 u" J" H
to setup-globals
* |9 Z* N% E6 v4 Z4 @$ }1 x  set current-light nobody ;; just for now, since there are no lights yet
% e' l; [4 h4 B3 W" E* `  set phase 0
4 c, q5 f: U, v  set num-cars-stopped 0
7 K  C3 U6 d7 A( w5 Y! s  set grid-x-inc world-width / grid-size-x
3 n! z6 Q8 W  p4 d( E8 D1 N  set grid-y-inc world-height / grid-size-y, `) h# ?8 U% d" }

7 s" ~" `& Q9 q6 P: w5 @& B  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary: ?; F$ s; Y! G7 o- D1 b3 k0 g
  set acceleration 0.099
6 O4 f. g% n, n# X! S( Aend
8 T4 n: O& T, T! Z4 t' @
% w0 p1 v3 N- X) V7 _' e;; Make the patches have appropriate colors, set up the roads and intersections agentsets,6 C1 I5 d' ~4 n" Q
;; and initialize the traffic lights to one setting
8 }+ i" V$ o7 G2 r' D2 Xto setup-patches! T% R( M8 d6 D; ^" U
  ;; initialize the patch-owned variables and color the patches to a base-color
1 v8 @) t8 ?( n4 e  ask patches' O- u: ~' ^1 I% Q/ w
  [2 Z) p2 H: u( t+ ?
    set intersection? false) C% S! y& H2 {- y" q. `, X  _
    set auto? false* }9 B7 Y  |: F# b
    set green-light-up? true
0 |. U6 k+ Q0 V7 j    set my-row -1% p# J1 j9 `% J: h* L0 X6 n# A
    set my-column -1
$ T% h' E. Z0 Y- G    set my-phase -1
: y6 k( j* T) h; m2 G    set pcolor brown + 30 r9 E( e$ V  v/ j7 V4 o
  ]( s; t  L5 I& w
& R# j, N8 R& u* ]! S' c
  ;; initialize the global variables that hold patch agentsets
  I# ~- F1 l- u) m( c' e1 R- z  set roads patches with
# V" A2 I1 m6 M  r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, d$ z0 b0 b3 c0 R) b. J, I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 I. g* t* ]/ c  set intersections roads with+ W6 V, m. I7 }0 b1 X: V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ w; x* I' a, a- A, ?$ N
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; r8 D. k; D% h! o+ [) k7 {( q. G

/ g+ z; }' \) g& C7 M; [9 f  ask roads [ set pcolor white ]5 D, Z3 s  a& X( q
    setup-intersections7 Y1 l8 w7 _6 O  Y( @
end
1 D( N! R4 ]* Y' r: O/ [, x, [) k其中定义道路的句子,如下所示,是什么意思啊?
% y4 ~2 [" l, D6 Y/ y6 U5 \0 ] set roads patches with+ h2 \! k2 \5 ]4 s
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! f7 S1 D; g' a. M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" j0 `# t" M! H
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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