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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。
& `& q& {1 F5 B# Bnetlogo自带的social science--traffic grid这一例子当中,, {+ i  t, e- n* A( H1 k( U
globals
; q7 s4 ^7 e/ X8 J3 u[
: p+ i( _/ Z# V! \8 g  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 _6 ]0 x1 I5 n, a3 G
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
  x( M% R' I& d8 Y  b, F$ D  acceleration             ;; the constant that controls how much a car speeds up or slows down by if' v5 L0 h2 v5 j/ f+ \# l1 `0 G0 \
                           ;; it is to accelerate or decelerate
3 h, |$ m" I  C& a  phase                    ;; keeps track of the phase
) k/ ?4 h5 I* X  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
% N6 s) ^) a5 }0 p  current-light            ;; the currently selected light/ v8 c, a1 V$ q
+ U  q( m$ Q5 l5 X, O% I
  ;; patch agentsets7 I- Z/ ^! A3 T: o3 D
  intersections ;; agentset containing the patches that are intersections0 K$ ?: c7 X! D# K' q9 r6 f; A0 w
  roads         ;; agentset containing the patches that are roads# |# m$ O; \  f# C: s: K1 g
]
' g3 q$ @8 F. s2 k. k
  F- i$ Q6 p$ e) L* u, Qturtles-own
7 _- m0 Y6 \% q1 U" ]/ H3 A- Q2 O. d[1 p# A/ u  k: H- q! C
  speed     ;; the speed of the turtle% F# L# E( n" ^; ~/ U5 b2 t( d+ k
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
- U* v: {* O5 g* V( ^! w4 w8 V  wait-time ;; the amount of time since the last time a turtle has moved' b( R$ C3 k9 T8 K/ J
]& U) U0 U1 W( `2 k9 M
+ o  `. T3 x: J
patches-own6 X' t4 S: c4 T
[
0 n! l  I5 N1 ~* b1 s8 T, h  intersection?   ;; true if the patch is at the intersection of two roads/ X+ L/ {3 {: [3 J3 z1 @# U5 I
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
: l: J/ f- p; i                  ;; false for a non-intersection patches.
3 R6 j  r8 r+ Z, l  my-row          ;; the row of the intersection counting from the upper left corner of the
6 ?6 ?. k, g6 k$ v; m; ]                  ;; world.  -1 for non-intersection patches.
; |" F! p: Q/ O8 H8 b( r" n6 I- ~  my-column       ;; the column of the intersection counting from the upper left corner of the/ p3 E; o7 r& ?+ X, Z# k
                  ;; world.  -1 for non-intersection patches./ M/ w! n+ l5 r* r
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.8 f$ r0 D; X1 Z! h1 m3 Z1 k; d
  auto?           ;; whether or not this intersection will switch automatically.
- n! \! o: x7 n                  ;; false for non-intersection patches.8 \$ a0 P  H6 P+ D, l# Z
]; g: t6 B/ R' l. E& H1 N

6 d$ A- j0 f" i3 e
! [0 R2 t* y/ j1 p3 R7 w;;;;;;;;;;;;;;;;;;;;;;0 ~' X6 Z) K+ v1 e% c8 w
;; Setup Procedures ;;
- ]; r+ b$ `# m  J, \3 G% r! z;;;;;;;;;;;;;;;;;;;;;;
* w  T- U+ Z6 O0 h# E
' _+ i+ y) @2 m0 k" ~' x; m0 P;; Initialize the display by giving the global and patch variables initial values.
5 K8 F' v1 f1 _;; Create num-cars of turtles if there are enough road patches for one turtle to! [/ t  M" h( z2 k
;; be created per road patch. Set up the plots.0 q3 `8 q) q" ]/ m
to setup" j- K# ]8 V' n5 B) J6 [7 C
  ca
3 E' B* M3 {0 p. f8 @) a  setup-globals8 T: v. f3 P" c0 E/ E

, |  b& H8 |8 g  ;; First we ask the patches to draw themselves and set up a few variables+ n$ E, [- N2 S+ H& \$ F' r6 b9 V: P
  setup-patches" Y$ F# i1 s3 p  }2 \
  make-current one-of intersections
. H/ v4 p3 n! P+ ?4 i  [9 _  label-current, o% a$ @/ D8 u$ x+ _
0 U0 N6 N* A5 i+ h. a. X2 {7 n2 _1 q
  set-default-shape turtles "car"8 ^" k1 Z+ e- b' S9 i9 z. p
8 x# {7 I( g2 x9 n8 H- O. h
  if (num-cars > count roads)
7 O* {' l1 L4 g9 O9 L* u  [
$ h+ T1 {) G. y& s    user-message (word "There are too many cars for the amount of "
( |4 L- }. j) V& z7 q                       "road.  Either increase the amount of roads "
1 Y( T9 E' y4 M5 l  ~                       "by increasing the GRID-SIZE-X or "7 u' ]' I. u1 a- d; r
                       "GRID-SIZE-Y sliders, or decrease the "3 @) q0 [# \! b" P  `) x4 \
                       "number of cars by lowering the NUMBER slider.\n"
- t! I, h8 V3 d3 a% f                       "The setup has stopped.")) z7 Z* u- t, X; s5 M2 Q7 P; U! `! k9 N
    stop
: ~- a: C% E8 Q( L6 U+ ?; J  ]+ M- {4 R. p- Q2 F( I# M% q+ t
5 s$ e5 D- S2 t; ]8 x1 V
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
3 u4 |6 G# G# H  crt num-cars
6 n9 U/ r7 ?4 o  _4 `9 L4 Z, w0 P  [7 f5 C( Y2 C. ]1 n* }) L
    setup-cars
$ o: p3 u6 o; Q# P$ f    set-car-color
5 ?. A- y- [* ^% _* U0 @6 S6 K# g    record-data
1 ?& x1 i& k; Z9 ~* ^  ]* L* M9 j: z1 E) [

0 C1 O. V6 I7 b& [6 G% T  ;; give the turtles an initial speed
: A' g" }2 y& A, f/ j" k+ _, s  ask turtles [ set-car-speed ]
: t8 T* h; A( F/ g
7 o8 F, c# a. y- c9 R  reset-ticks- n6 V0 A. G4 z
end, s5 Y7 Q; ?, r

$ C( i' o+ Q7 @- J0 X% p;; Initialize the global variables to appropriate values5 O+ Z" l) N* [9 U& h2 k
to setup-globals
& T/ [+ p! @3 W$ U0 s3 c  set current-light nobody ;; just for now, since there are no lights yet. i" r) `0 s" T- M; e) |5 Q
  set phase 0
5 R& f# m# ~, ^7 i8 ?- [  set num-cars-stopped 0
1 f8 P  x- U- y3 M: V9 B  set grid-x-inc world-width / grid-size-x" e; m+ x* J. ^$ m$ ?
  set grid-y-inc world-height / grid-size-y
# B& Q; L4 x# Y- x( [! u) ^" Z' A" b, P5 X5 t# n/ ?  S
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
2 K( d! F& q; R2 b( r' g  set acceleration 0.099
. Y; r6 Y0 x0 f8 N9 _6 }2 L3 Vend* {6 x: {; p3 {9 }! W
/ T5 p* c, F2 }
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,# r$ L. s; P/ b9 m
;; and initialize the traffic lights to one setting8 t+ x  c2 a1 |4 A9 W
to setup-patches
" M$ T+ b0 H% l) j, c0 h+ K  ;; initialize the patch-owned variables and color the patches to a base-color7 ~% g9 E* ], p& z% w
  ask patches: e1 X0 f# H' o# f7 N
  [
" x  @% k9 h/ x* S5 y9 M    set intersection? false8 b+ A* K! O3 J3 m& H5 I
    set auto? false
$ K7 d0 l5 B- z, M/ b    set green-light-up? true
" N+ Y( Y- f5 k+ I" j5 u% L    set my-row -1. _) ]' x. `4 R
    set my-column -1- a+ S' b" \4 N6 }; B& X1 G
    set my-phase -1- [) d" a- F6 G9 r7 \
    set pcolor brown + 3& [4 f2 K% M1 q
  ]" A8 v4 Q8 {" j' @

# A- I# d" d/ D9 I  ;; initialize the global variables that hold patch agentsets
; a( G/ P7 T0 Y6 I) O  set roads patches with
! M0 r+ z+ T# I1 `& G3 s) }    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; ^. i- c; E2 H: s+ x8 C+ G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( x$ g' r5 U/ u! ^# h1 N3 p$ f" A
  set intersections roads with
8 [& P/ [4 m3 x% Z! L  q, W$ I* V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and. m) B2 J$ u1 Q) V, q2 L" D4 q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# S. q% a! X0 q! L; D2 M7 E% v& P  j4 @0 @& ~
  ask roads [ set pcolor white ]4 Y5 |+ j4 x, k- B8 w/ t0 @! f
    setup-intersections
- i" ~' W1 G! g: y' pend
) ]6 {# w# _! _1 v* V3 X其中定义道路的句子,如下所示,是什么意思啊?
" Z' S$ a, H: f4 Z. w- g! t# C set roads patches with
) s7 T8 ~& t. c3 @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- G; v7 l2 K+ N( ?1 u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; M8 @5 T- H4 K, k) \: a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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