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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。! ^. @1 ^# E6 o# c% `% a9 d1 S
netlogo自带的social science--traffic grid这一例子当中,
+ W/ M. f$ \. }: G, J, pglobals
6 X0 i* U7 W  p: }[
6 A0 |& `. j: x! K! B  grid-x-inc               ;; the amount of patches in between two roads in the x direction& j# W6 v) F2 y6 @
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
" L' e6 h+ ?5 R% l  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* o( \7 L1 p- a0 r8 q
                           ;; it is to accelerate or decelerate. ]5 ]& K* s& m( E2 w
  phase                    ;; keeps track of the phase
* Y% }" i7 X/ I- {4 ?: `7 ^  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure3 B9 T1 X; r+ N9 S2 _
  current-light            ;; the currently selected light7 M' e: ^- Y) }0 R+ k

' |( G/ ?! Q2 d- J+ X9 V  H: ?1 t  ;; patch agentsets
+ z+ w2 v8 E2 E, h9 g- Q7 Q2 E  intersections ;; agentset containing the patches that are intersections. A8 ~! G6 e+ _
  roads         ;; agentset containing the patches that are roads
; D% g$ X" {# w: L3 q]  T2 `6 Y& e6 c" U* w0 i

4 R7 S8 u6 y3 f. a: b# S9 a) Bturtles-own  F) O* V3 A1 t% X  M
[
8 Z" J- a& L8 w, x9 R7 E  speed     ;; the speed of the turtle  ?, a4 ?9 P9 m7 o+ C
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
$ F$ o5 w, c0 F8 c, G7 C  wait-time ;; the amount of time since the last time a turtle has moved
8 s! g: Y# Q; m; A]
3 T! m9 K7 w% W% l
2 q  y5 s1 ~" N- j1 `3 Xpatches-own
( J$ y, e7 @" R7 x. e+ Z; }[
+ b6 F9 V7 m) l9 S1 `6 R. t  intersection?   ;; true if the patch is at the intersection of two roads
; c! R) n8 h  u* w/ y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
  V* D- t, B) K) s                  ;; false for a non-intersection patches.' q5 O+ L$ e4 u0 k
  my-row          ;; the row of the intersection counting from the upper left corner of the
2 p1 g' E7 ^3 T4 r4 N5 }, N2 e                  ;; world.  -1 for non-intersection patches.+ y; l& P$ V5 T( z4 _1 E$ r3 ^
  my-column       ;; the column of the intersection counting from the upper left corner of the
0 Z9 ^4 m* X9 [' V  z                  ;; world.  -1 for non-intersection patches.& ]+ y% a7 {" K2 O2 _3 ~
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
8 U+ I* l8 u8 ^/ f% ?  auto?           ;; whether or not this intersection will switch automatically.
( v- X# O% Z; e9 @- a6 s, W                  ;; false for non-intersection patches.
; |! ]& x/ ?3 B]
. H# ?+ G5 O3 N2 S2 X$ d$ ~  O3 r' c+ c0 `, S/ x, X

. g0 r( S1 O2 J3 Y;;;;;;;;;;;;;;;;;;;;;;
" S- t; l& C  E;; Setup Procedures ;;
2 J8 `9 E2 R" F  o* u9 O;;;;;;;;;;;;;;;;;;;;;;3 o( g8 a. _( q$ F% e# d' m: G

! }& [# J' O  i0 Z7 ~0 D. Q# P4 Z;; Initialize the display by giving the global and patch variables initial values.
/ X3 h6 u5 R% Q6 v% A;; Create num-cars of turtles if there are enough road patches for one turtle to
' U- V$ I8 E  Z( m7 h, O" K4 T;; be created per road patch. Set up the plots.
' Y- _/ U4 q& F6 u/ C7 ^to setup1 C( x5 b: G0 g/ B" y- p1 e1 ~9 {
  ca
: }5 D' |; H1 k2 S3 t" |- h1 k  setup-globals7 B0 q% M! n+ Z

: A: h9 X0 r0 E  ;; First we ask the patches to draw themselves and set up a few variables
! ]. S; Y# K% r& d  setup-patches2 A# M) Z6 I- ~; o  K
  make-current one-of intersections; A5 }, ?, }* ~  n; i6 Y
  label-current" N$ W( D1 F8 [9 S$ f

2 e, y, T7 N: N* K1 B/ J+ h6 Z" k  set-default-shape turtles "car"
7 M& H( ]$ Q2 a3 R
, a9 U& ]3 k& b  if (num-cars > count roads)) G& A; G! L! n6 G2 F
  [
& Z, b* I0 L, a' G    user-message (word "There are too many cars for the amount of "6 ~3 I* f$ l8 F5 y6 P
                       "road.  Either increase the amount of roads "& V* m3 P, p% r
                       "by increasing the GRID-SIZE-X or "
+ ^7 H0 U; |* N% x0 \6 F3 {                       "GRID-SIZE-Y sliders, or decrease the "
3 z1 l. H! [7 j1 y* L6 Z* ~                       "number of cars by lowering the NUMBER slider.\n"
7 R2 ?/ t& c& a, u& I                       "The setup has stopped.")
7 s7 l; h8 V( u9 {2 B0 b/ s    stop7 {3 K1 c" S# c
  ]. ?9 L9 q- s0 Y& D  K

4 j) m& |# v. ]& H  |; g( w* P  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% ]7 R6 k; m1 T
  crt num-cars$ Y& d* |3 r5 s+ \* `
  [6 f8 L0 H3 t* `" E
    setup-cars, \4 C4 D5 |! s, d# Q" F8 e
    set-car-color
- B) w7 h0 D! J& I6 e    record-data6 u' d: {# z% @3 ~3 h2 d
  ]
8 p  ?* x, c; I$ I% {6 R( Z6 R4 m  y4 N( e2 H
  ;; give the turtles an initial speed
3 N" |& d( H" |+ f: B  ask turtles [ set-car-speed ]/ O( m2 D8 \" I

  w. o- {& ]$ c+ E% F. e  reset-ticks
! O8 ~. B3 h' g' }end  c  q* [. y2 e6 W$ d

4 q1 F, p/ A5 T; u( e;; Initialize the global variables to appropriate values
8 l! F" {2 Y2 U% S- E* M( T. vto setup-globals
; F1 [" s6 i/ r  set current-light nobody ;; just for now, since there are no lights yet- m! j( B( F; {
  set phase 0
! O" _* O* T4 b0 d  set num-cars-stopped 0: z0 d0 C" ?! e% `: D2 e) Q2 Y. T  y3 ?
  set grid-x-inc world-width / grid-size-x3 a, O6 N! o5 W( M1 z
  set grid-y-inc world-height / grid-size-y
% P* d  k/ y" M% I+ E' D' D( M( J, p1 T: k9 f
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
) o! x, y* i& O4 L, V  set acceleration 0.0990 g% P& v% `5 x# V# C, \5 f# P
end: L7 B) \5 T1 c7 x' s! ?# l

" a' K( U9 A8 k) E;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
5 z9 z4 ^+ F7 T/ ?: l;; and initialize the traffic lights to one setting& E* I5 I, T5 h. I0 ~9 w( c; C8 \
to setup-patches
' p1 H3 q, E" v5 {  K  ;; initialize the patch-owned variables and color the patches to a base-color
( _2 V! M* i# m) ?; N& S  ask patches
# a6 W9 ~7 D9 W& ^9 L  [3 y! h: k$ ?2 {: a) ?
    set intersection? false
5 D( d* I. A) M6 L; Z    set auto? false6 p) Z* S' h! O, T
    set green-light-up? true
& j. ^2 i& m$ Y  q3 \, ~$ Y0 d4 D    set my-row -1
% b) F7 |/ p8 _9 m    set my-column -1
! Q# z& G6 K1 `/ _! e    set my-phase -1
  A' y8 u! K/ e: d5 g* h    set pcolor brown + 36 r& A3 s4 D4 J6 b. D
  ]
3 ]2 u3 e/ j: a! [
0 d$ o, I3 P8 q  ;; initialize the global variables that hold patch agentsets! U4 ]% Y% Q% Y; z7 `
  set roads patches with' _6 M# e: V4 a! T+ F9 D: R, t
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- L) `! K4 U; s( i3 X4 Q& h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; K! H, B3 k" i  B3 @  set intersections roads with
) T+ r( `- s5 ]9 l$ ?    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and  l' P( S# X$ e7 p5 v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 w" ~, ^) a6 E& S% {5 R+ [
9 b, h4 n& W" N; L- p$ c4 _2 {  ask roads [ set pcolor white ]
9 V" q0 w  {1 w1 {    setup-intersections
0 Z9 b+ X9 G: y! B* Oend0 Q, c/ y" e, x$ R, ^  Y
其中定义道路的句子,如下所示,是什么意思啊?6 ?: f9 \' t0 b: @$ x
set roads patches with
* w8 D! a% X3 z: O9 f9 n    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* P4 H  p8 U9 s) b! N
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 t2 H- d7 v+ |" t
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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