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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。
: w6 F' g. J% j# qnetlogo自带的social science--traffic grid这一例子当中,8 Y9 g0 E& l& v/ p: j
globals
6 G6 F  y1 S4 Y5 H[6 g- L% y0 x. S6 H0 J
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
" i3 X4 P2 A: L, X  grid-y-inc               ;; the amount of patches in between two roads in the y direction. ^! i" Y; y6 K& }
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if( w: I% S0 j8 b4 r6 X6 _* P9 u
                           ;; it is to accelerate or decelerate2 x2 W: R3 n2 d  p
  phase                    ;; keeps track of the phase
( l. n. D" p3 w1 N  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, p, U, ~" F6 R( y' L% j
  current-light            ;; the currently selected light
8 x- {  `$ E! M( f: L1 n1 j' f
( p' O9 H8 Y" c( i+ [% a# E4 x  ;; patch agentsets
5 g7 k& w) d8 P, q0 W9 z! Z6 O  intersections ;; agentset containing the patches that are intersections
" R0 V$ v/ G3 b, v+ g9 h0 N  roads         ;; agentset containing the patches that are roads* @; Z" w8 D0 {* y7 C
]3 Z6 A% ^. O2 l/ g+ p
0 r, C5 a- c( {& K. T$ f. n) Z+ f
turtles-own" K+ s3 V; ]: K4 ]* X4 W, [
[
5 _" {: D* ~1 X# c% N: o5 E  speed     ;; the speed of the turtle0 J# C: P1 R: s$ X4 e( n+ N: [6 y
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right2 `1 n- Y" L6 @6 {! G, ~  H. l9 o: H
  wait-time ;; the amount of time since the last time a turtle has moved
- E! \! \0 e8 K9 r4 h]
; D$ \4 `2 _' m4 ^( j
) f; n7 U/ {  \4 o" o2 M$ Qpatches-own
- F' ~/ D; Q& W[0 K, G* J8 A1 R+ d# ?
  intersection?   ;; true if the patch is at the intersection of two roads
" t9 Y: _5 q/ e1 Z* G& h  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% [' c3 i" f1 Q                  ;; false for a non-intersection patches.
) `" l* g( b: }% Z  my-row          ;; the row of the intersection counting from the upper left corner of the
% o- S0 m% p6 t$ b4 E: F                  ;; world.  -1 for non-intersection patches.
0 q, `* K& u" B9 m( u" Z0 x  my-column       ;; the column of the intersection counting from the upper left corner of the
3 Z7 U* w+ o# `                  ;; world.  -1 for non-intersection patches.
. R, j# V5 A+ X  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.. a' C8 a0 x9 \4 m
  auto?           ;; whether or not this intersection will switch automatically.
$ y+ E) P) x% w) Z, Z0 [9 m                  ;; false for non-intersection patches.
$ }: J/ V: p: t( q6 D! O: [9 }' q* q]
5 I0 I) ]# h" `( x2 j
' y# e7 A; p* h3 G2 r4 c. w6 H8 H# y6 f
;;;;;;;;;;;;;;;;;;;;;;/ G( P9 O" t! _+ u4 R' o
;; Setup Procedures ;;' ^* h# v% U: B0 l3 Y# w$ q
;;;;;;;;;;;;;;;;;;;;;;2 o) {8 `$ S. @: X

* D) t; V2 `# z/ w' i# [2 J, i5 q;; Initialize the display by giving the global and patch variables initial values.. m( l( @0 _  X) ^# ]
;; Create num-cars of turtles if there are enough road patches for one turtle to2 M  {  p1 A4 c! B/ x/ S- O! L3 R
;; be created per road patch. Set up the plots.
8 e& E8 A! R+ |" T  e; ~to setup5 L7 |% q+ D0 M5 `2 f# P
  ca
% \/ g4 s% _: L2 p9 i3 T+ I+ Q  setup-globals
% S* ~! p- u! C- Y, T
1 f+ V0 t* s. K" ]$ {! S4 y$ X  ;; First we ask the patches to draw themselves and set up a few variables+ @/ Z+ m2 Y; A5 }  P( e! N
  setup-patches5 Z$ i$ x5 K+ c- i8 Q* u% u3 o
  make-current one-of intersections
1 o" R6 d7 a$ r, {( H  label-current
, U) r) \& H" q5 V6 T8 j* \# s$ s' N0 w7 @6 I  c
  set-default-shape turtles "car"
, y4 }* Q% n& d3 s+ J. w
+ q0 x# |  q. a- K: C. Z8 G  if (num-cars > count roads)
! \, h, V- V) Z0 I  F2 M  [
; T- X1 y0 n8 Z# {$ Q8 o: K    user-message (word "There are too many cars for the amount of "6 O) F8 I. n  @5 U! e; b
                       "road.  Either increase the amount of roads "5 U- A, r% v: K% g
                       "by increasing the GRID-SIZE-X or "& S/ o8 T: N3 |" ]9 k9 E3 v9 X, v. a
                       "GRID-SIZE-Y sliders, or decrease the "+ Z/ M+ I- ~% }0 u; X% y. M
                       "number of cars by lowering the NUMBER slider.\n"
" r$ r+ Q& D! R5 }  L" w                       "The setup has stopped.")
. V* T7 L: J- |5 M$ Z/ }- H    stop4 |4 P) ?' m  s+ n
  ]
3 T( G: T3 b5 C6 F/ t6 {. l% T0 n6 X
" ^: H: G; {) z* i/ m  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% D1 ^* P! e' f9 z+ G- e
  crt num-cars0 V- B1 ]( V/ M/ |
  [
. j+ Q# y& M0 f# W/ t& b& K- w    setup-cars
; y5 h# T9 z1 q& i6 Y* y6 C  C# F7 @    set-car-color6 R" H* R+ {0 y: k! s
    record-data
( J$ }$ v: y' |6 `" e$ v  ]! T' M* {& L3 k2 ]! M9 ~! E

$ ^2 p7 ?2 E6 O' z1 l- G. U  ;; give the turtles an initial speed% B3 Z+ l$ f: m3 U: r' R0 d) x
  ask turtles [ set-car-speed ]
7 u, S, q# g' H0 G$ a5 G* ^' p4 y6 Z0 D1 X  l7 ^
  reset-ticks
  n; `, U6 e$ T! d! H5 R3 P6 z3 Zend
2 E1 I" d' ^7 s' J
' g0 C" j! P+ k; t# D8 H;; Initialize the global variables to appropriate values
3 c* h6 h8 c( F& N' N. o. Jto setup-globals
/ D& E* w; x  w' }  set current-light nobody ;; just for now, since there are no lights yet
% j, C4 ]6 }! k4 ]7 ^2 l  set phase 0! y2 J& X+ K. r/ I5 c: V( L! C" t' Z
  set num-cars-stopped 0
  W% D: H7 U. G( X) Q# M  set grid-x-inc world-width / grid-size-x
  o8 h, }* w$ }& m* }, @) g  set grid-y-inc world-height / grid-size-y
" m) |- g! M/ b+ j# ^3 Z- f- e
7 }4 A& s" E* r$ M8 N+ j8 ~  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary: h. ]' F- q! [4 Q4 Z
  set acceleration 0.099
' g2 h. \6 _: @! `8 \end
' [7 N2 Y  i7 n7 U' r, S0 k9 D- V5 Q4 U  ?5 F) j+ I/ C$ v" n
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,) H1 {1 `( x3 E$ I1 L( j
;; and initialize the traffic lights to one setting. q8 |4 x6 |. r( F
to setup-patches
* [' P8 x' O; W. S) d6 D, ?  ;; initialize the patch-owned variables and color the patches to a base-color
' w4 x# g7 Q4 ^6 m7 F  ask patches$ N; {" i5 v& C* @: N
  [% s  h4 [5 H& ]% Z; H2 G/ I# E
    set intersection? false) j0 |% F0 o" N9 Q' S, |% q. Q
    set auto? false
& T& ?" J( ^' n6 [' x    set green-light-up? true' {5 c  ^) B3 Q& S3 Q; a  O2 J
    set my-row -1
" `7 p7 x# H2 z! |% v9 W: [) `    set my-column -1
  M8 t: k  M8 k, A+ H    set my-phase -1& A" t; R0 I" \. M
    set pcolor brown + 3) y" S# j% Z% Y* M
  ]
$ Q, j  J9 f2 S8 u( G2 {: Y# a- p
  ;; initialize the global variables that hold patch agentsets
# n' z$ y: N. u3 d1 j  set roads patches with
0 @+ T2 e. g1 v. C! V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" m3 v; \2 L) A( `) h& e, u
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( T% p8 _  F+ G$ @. B% O5 ?
  set intersections roads with% }7 Y2 B, m% a" {9 b
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and: B* Y2 S4 W. `! D/ D( i6 R+ a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 R8 \7 D# N+ L# ]: Q" N
+ Z) `/ g2 w8 h7 w3 J# N  ask roads [ set pcolor white ]
# Z. `) w7 N. @0 V1 e    setup-intersections2 h) Z; y' @( }0 ?
end  p9 l, f8 y  k0 G' k, e; z
其中定义道路的句子,如下所示,是什么意思啊?
1 \! P5 F. a* n' b set roads patches with
% n- l2 Q8 r9 L$ ]7 a! c    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. u9 [# g7 r. e& n; b1 h8 M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 E- Y( b7 L5 \2 n* 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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