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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。: k, e. D6 ?+ }) v
netlogo自带的social science--traffic grid这一例子当中,+ ?" J: B$ W* E- o
globals
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- A8 o+ `+ L+ P  B) G  grid-x-inc               ;; the amount of patches in between two roads in the x direction' s# V, a; t. v! b8 ]; o
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
3 X- C7 A4 u; f: k  acceleration             ;; the constant that controls how much a car speeds up or slows down by if6 ~5 J! z3 g1 Y/ I9 v+ ^5 o
                           ;; it is to accelerate or decelerate
1 v6 l4 O! }3 R+ ]  phase                    ;; keeps track of the phase
9 f, x$ X# P5 M  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
- D4 @4 h- M. }6 t1 {) d2 s. w  current-light            ;; the currently selected light
6 ?7 f8 u8 q3 X7 g: _+ l
4 y; E% r! t1 A$ v6 O# L  ;; patch agentsets
! M! X, x: O, p" O2 o6 Y  intersections ;; agentset containing the patches that are intersections" B; D# h7 U7 d' u
  roads         ;; agentset containing the patches that are roads
5 A( @% A* o1 l; ?) u]
$ b9 U- X" G: q0 V6 g2 r
  l. ~( b* ?5 A5 `turtles-own: F# u: G& _; m: H
[- u, @1 q* R  W2 d0 a
  speed     ;; the speed of the turtle# T1 E- ?( ^0 u& C
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right4 B8 f2 A' t0 W# s
  wait-time ;; the amount of time since the last time a turtle has moved
  |( p  j, T2 A& E]9 _! k) o# d- k& D  [
' K4 K8 |; H+ n: i
patches-own) v- h8 V  b% ]
[2 G# H1 X% p4 ^8 [
  intersection?   ;; true if the patch is at the intersection of two roads7 _. c. U" A* O
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
/ h' T4 D# E. H& j                  ;; false for a non-intersection patches.
5 o( G! x5 ~& N  my-row          ;; the row of the intersection counting from the upper left corner of the
2 Z  G0 P4 p, }  M; e7 i                  ;; world.  -1 for non-intersection patches.+ K0 Z' B" M( a; `8 o! z
  my-column       ;; the column of the intersection counting from the upper left corner of the
7 u+ e9 F9 E$ w% g) @                  ;; world.  -1 for non-intersection patches.
$ l$ P4 T: Y& T: C" m- l0 z  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
$ O! z6 p  p( d) j  auto?           ;; whether or not this intersection will switch automatically.
' a3 D7 ~$ ]6 N+ u                  ;; false for non-intersection patches.
2 p- Z8 Q* a. W4 G2 s" \% r; N]: z" Q- c/ _; i/ _* v
) S6 F- B6 `5 [' U* X! E  n

6 ^4 p; Q1 V! F9 @4 Y;;;;;;;;;;;;;;;;;;;;;;6 [: C; O. ~0 a3 p0 [! i7 t
;; Setup Procedures ;;7 \6 X& A4 F" V7 Z+ n9 P2 L
;;;;;;;;;;;;;;;;;;;;;;2 n) z" i0 Z: z( {6 K2 K

. Y; b2 N, i+ t;; Initialize the display by giving the global and patch variables initial values.0 p5 [# Y4 r* V. P& o, H( }
;; Create num-cars of turtles if there are enough road patches for one turtle to
1 i" f9 G7 Z) t;; be created per road patch. Set up the plots.) y9 T0 c0 t1 C0 i6 h
to setup
  [2 g% P' r8 c0 f& I- p7 H- }! v  ca
  r/ R# B4 L: K/ O; j1 [; w  setup-globals+ L; j# j; l* B4 z- ~

& m2 }5 A3 Z- v5 |* K% y6 C6 ]  ;; First we ask the patches to draw themselves and set up a few variables
  {% g! J$ i* x5 E( q0 }  setup-patches. K7 b$ I7 m4 ~0 N
  make-current one-of intersections
) `2 ]' `: h" @( @; |, \  label-current/ v( B2 b$ d8 i7 L  H
0 S: Z. d, Z2 ^* c
  set-default-shape turtles "car"; L+ x9 t$ _% e5 S' q' Q7 }  p" i

# O; [( F, ?3 C4 b' ]- j3 F  if (num-cars > count roads)/ [& L/ Z6 E& ^) i7 U
  [: W# \" u- b  G5 {7 k1 s
    user-message (word "There are too many cars for the amount of "
9 v, N& M' |' p, S                       "road.  Either increase the amount of roads "
& H2 o- R4 F# |                       "by increasing the GRID-SIZE-X or "
' D/ R$ K8 ]( N, ]7 l% j' @: ^                       "GRID-SIZE-Y sliders, or decrease the "
3 j, c3 t. |. ?8 ?( K                       "number of cars by lowering the NUMBER slider.\n"
  E; A2 d) x! Z5 w0 b' Q                       "The setup has stopped.")
, |9 l8 P  }- B/ Z+ a    stop3 c5 R2 t( ?# P+ T
  ]
- s$ A1 d. m( z$ w
5 k. e5 W$ B0 }/ |9 E  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color+ B% d9 x# `% D8 q6 A0 \1 y
  crt num-cars
8 x  W3 w- _2 k1 |% ?/ ?  [
3 u6 d/ O* I! N  }/ ~& [; T    setup-cars
/ B/ l6 v; B( d    set-car-color
7 q" x8 ?6 B3 r. }0 h    record-data3 [8 H8 I( r0 I" z& _, ^, R% z
  ]
& j, Q6 U; D: }& o/ ?) K) A: o6 Y
  ;; give the turtles an initial speed
$ X6 g7 g( c6 q; g: K  ask turtles [ set-car-speed ]
) t8 c; h$ y2 [, I. t$ a3 l
2 z, D3 g( s! \# _8 N  reset-ticks
% W1 a4 B' ], [9 q9 Lend
4 M' o% u( S5 {
( X( p" G/ G, s1 \3 ~6 n' X' P5 {, z;; Initialize the global variables to appropriate values6 |: F- V2 e& R  b
to setup-globals, I' R: k% H( Q
  set current-light nobody ;; just for now, since there are no lights yet
) v, ~4 Y* e8 s: ]9 `* l0 P  set phase 0
6 R& o7 a3 b; a: s, x/ ]# m  set num-cars-stopped 0' R2 b( w' k( M  I
  set grid-x-inc world-width / grid-size-x
. t+ [3 K2 Z5 m, F0 c# n  set grid-y-inc world-height / grid-size-y3 j# z: y1 N; _% m0 S9 ^- y
) Z4 J$ D' S# b
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary! J4 q/ h( h3 V" W: J4 C
  set acceleration 0.0994 N: v$ T( d; n2 E1 M( d7 h
end' v/ {+ H# ^1 W  t$ Q6 v1 l0 D
/ X6 c% R8 _2 G9 t, [
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
8 D* B) W; N7 k/ _& f;; and initialize the traffic lights to one setting
7 L* C, ^0 G' _1 X  }to setup-patches
6 w9 q( {9 d7 ^  ;; initialize the patch-owned variables and color the patches to a base-color
% z) N+ R  q/ f* u  ask patches
% z# V9 j: y1 E8 {  F+ n1 y" d  [
! x/ N7 e+ i$ u+ Z    set intersection? false, X) L8 i, A- R6 n4 s: c+ O
    set auto? false
, Q& p6 S+ {& n' E3 p7 `. d    set green-light-up? true" y5 l2 J: r3 h* C' |2 G0 A9 }! N- U0 [
    set my-row -1
. i' O8 n% y6 I: ]1 w- |    set my-column -1
2 O, _: t4 b7 G% D7 i7 g! S    set my-phase -1
& H) Q8 v; d+ }    set pcolor brown + 3
# \7 P0 Y! G& v& S9 ~2 G  ]
+ `4 c1 C2 Q% }" n5 T: h
: ~# C' m- Y1 t6 I! l& v+ ^  ;; initialize the global variables that hold patch agentsets$ I5 v* V- K: P' J6 L& ^4 r
  set roads patches with' ?. h% z7 o# I: S; n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 G  D6 L, ?  O5 v; m# @) ~+ }
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% v( ?' s! L0 c% M! }! `) d8 D  set intersections roads with, I+ }* @. l& O2 ^, |& E3 I+ \
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
3 K5 Y$ @% o5 a7 X5 s( k  t# ?$ {    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], ~# J, H  u' N

' O) W  u9 a  N: Q$ s  ask roads [ set pcolor white ]
8 ~# b1 \4 `+ V+ W4 h9 l    setup-intersections
' i+ a4 }4 V8 Q% b/ C5 Z& W. Mend
7 z2 F$ m+ s) a' A9 F0 X其中定义道路的句子,如下所示,是什么意思啊?/ P+ a% d) K% {2 ^, O5 R6 `2 o, t% `
set roads patches with+ f( S0 D9 I( Q9 p* h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* S+ T5 w2 m* N
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) i/ K) i! O& b' m. w5 _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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