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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。* |9 e+ L5 o. K5 Q
netlogo自带的social science--traffic grid这一例子当中,
: N: ]9 B2 }" ?- Eglobals$ P% \( p2 [. _
[
: g0 t! C$ L5 E( h% E  grid-x-inc               ;; the amount of patches in between two roads in the x direction
( P8 i( W7 B( Q, i: ^  grid-y-inc               ;; the amount of patches in between two roads in the y direction% _0 W9 _- i% n  }
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' c6 h* x6 d1 B" S                           ;; it is to accelerate or decelerate
0 Q8 |' Z/ u4 V: @: F; {2 D  phase                    ;; keeps track of the phase
4 z* z' ?- |/ C. C. z5 T  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure1 [% e8 x% n$ B( v
  current-light            ;; the currently selected light
: M4 T9 n& _8 n# l( }" P6 A0 j( z4 R( T$ q: l
  ;; patch agentsets
7 `& {2 u5 l) x7 i, {" i& m9 j8 R  intersections ;; agentset containing the patches that are intersections
: F" @6 }0 ^9 S! @* r  roads         ;; agentset containing the patches that are roads6 [3 R/ I+ H  Y3 U7 P/ h
]
& ?7 l  @! F) N; p& [
3 N& k% d7 J- H4 m$ Kturtles-own; Y1 Q1 `- ^* e8 l9 s
[* y. r3 g6 n, x' K0 T3 g$ y4 W
  speed     ;; the speed of the turtle( u! ~1 G& a$ t: i* X
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
4 {# f5 S  v" p+ }+ n* x9 o  wait-time ;; the amount of time since the last time a turtle has moved
2 |# H- S* J/ R( x* B( x% j* v! ?. p]
* F. X" b3 N0 p1 \# M% I# M2 V3 d, K1 K: @
patches-own" t. p( L7 T, _( j* Z
[
# k0 W: c+ J# N  intersection?   ;; true if the patch is at the intersection of two roads
/ x, v# x6 X: B4 p  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
+ V; \" w& c4 [2 R  d9 Z                  ;; false for a non-intersection patches.
$ }: E3 H+ x# ^1 o  my-row          ;; the row of the intersection counting from the upper left corner of the- x, F) X, l- n& p  X# V
                  ;; world.  -1 for non-intersection patches.+ s1 Y: f* D2 V5 s0 W
  my-column       ;; the column of the intersection counting from the upper left corner of the% ?+ D: d& i' u, z
                  ;; world.  -1 for non-intersection patches.
& C, @/ e( m  N* L) \; r7 S  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.* f& n' E( n4 k
  auto?           ;; whether or not this intersection will switch automatically.: x8 h5 x0 ]4 |) v5 e8 |+ v
                  ;; false for non-intersection patches.
; ]0 `+ ]! ]0 w6 X8 R]$ y- j# a: i4 p! f/ [6 X4 A

0 d; p9 C' v- ?5 o: a/ |* m  Z5 \; m
;;;;;;;;;;;;;;;;;;;;;;: {" \) e3 P7 y7 n) s$ G
;; Setup Procedures ;;4 ~! O3 v# J, w4 H, \; t3 f5 ]
;;;;;;;;;;;;;;;;;;;;;;
* T9 h, ^" \3 B: M& L; L
: J4 z; c" D( }: f5 P" A) P( A% ^- g& x;; Initialize the display by giving the global and patch variables initial values.! l8 |2 [, Y" F% s/ m8 k# p
;; Create num-cars of turtles if there are enough road patches for one turtle to0 |+ t$ A+ q2 ^  z& c# G4 G
;; be created per road patch. Set up the plots.7 u9 d0 P2 M  l% l
to setup
, i9 w0 s' w# E; N! K- x+ I) G  ca
$ d1 e$ v6 Q5 G  setup-globals. ^/ Q% W" h4 H. \0 @8 W8 Y

( }2 D/ k  v2 a/ L# Q, m  ;; First we ask the patches to draw themselves and set up a few variables& q9 B5 {8 {0 W3 H6 K
  setup-patches/ n9 d* H2 q) S1 t% f
  make-current one-of intersections
6 l6 a# h+ r/ x$ u  label-current
  D" J" ?  ^5 L# p$ ^& Y6 X
  |5 h. j6 |( ~0 T5 l! B8 S2 N  set-default-shape turtles "car"- t" X4 y- i! s+ H( D" y  W$ w# s

* l' p. I& }+ R3 ]  if (num-cars > count roads)- X4 Q# Q4 r9 Q. j. `5 }
  [
) q6 r+ e* y# G/ A( c6 H    user-message (word "There are too many cars for the amount of "
. o4 ]3 w: r& H& O  m                       "road.  Either increase the amount of roads "
& j* m5 R# r8 Z+ g" f3 M                       "by increasing the GRID-SIZE-X or "
8 r1 q7 ^( ]% q2 j$ \- Q                       "GRID-SIZE-Y sliders, or decrease the "" I2 v4 q7 }2 e
                       "number of cars by lowering the NUMBER slider.\n"; D( X6 s, f; u* Q8 {2 e# Y
                       "The setup has stopped.")( S8 m, \$ P9 q( Z! [" u# G, g
    stop
4 r, Y1 s# M7 ^  ]0 I. w) \7 D; i1 a5 H
: Y/ o2 Q: h: r) j+ G7 \8 _
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 \' `/ L8 m, S( n7 t
  crt num-cars+ s3 P; u7 o1 ?7 f8 \( y
  [9 w( q9 Y' s1 `
    setup-cars' x( ~) H$ m) D6 W+ Z( q
    set-car-color
3 U! N7 n; w2 j" V  K) O    record-data( @* S9 Y: m6 F- Z. w
  ]: {) A' [) I3 M8 ]+ @6 K

/ E3 @5 ?7 l7 L$ Q: T0 R( ]1 a  ;; give the turtles an initial speed
2 A$ h+ R+ _+ l  M' Y8 S# g5 F0 D  ask turtles [ set-car-speed ]
) i: f$ Q" ~9 K3 V" E, q
0 J! B: B* k; t2 A( t  reset-ticks
& I& Y- H. @+ ^* Wend+ ~: ~& ~. h" U4 N  `! {

( T: D+ G* o* x;; Initialize the global variables to appropriate values# w$ u" j0 m5 r( `# j0 @( c
to setup-globals$ I- C9 ^6 S/ d3 Z1 Q0 E
  set current-light nobody ;; just for now, since there are no lights yet2 H$ R% ^5 y& s
  set phase 01 _- V1 R. p3 W- `1 f" |- r3 {6 _
  set num-cars-stopped 0& I6 |! l# N0 n9 I4 h8 N2 k  F
  set grid-x-inc world-width / grid-size-x
) A+ ~# B1 b& [$ X  set grid-y-inc world-height / grid-size-y
# u# A7 _' M% \; ?9 ]6 r9 M
; w, U/ N% B* A4 J. a  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
# e- |9 A+ t+ N  set acceleration 0.099$ {$ N7 G* {# x# L/ Q
end! t6 Y( h4 f# a4 s

. J% G+ X- q$ r# e% K; \  Z;; Make the patches have appropriate colors, set up the roads and intersections agentsets,; `( K7 b, o* E0 y$ J& ]
;; and initialize the traffic lights to one setting9 K9 T! i* [! y6 i0 m8 p
to setup-patches# b0 B( |) h7 G1 t
  ;; initialize the patch-owned variables and color the patches to a base-color6 [$ x" I4 G# [! ]8 ?" N; @
  ask patches
' {5 O$ N: ^: X* K! s$ d  [; j6 ^( g$ R/ x4 j. o
    set intersection? false
1 w; E+ `8 q& K$ L1 M) r    set auto? false7 n3 g) X, N/ |
    set green-light-up? true4 a! |6 o1 Q& R% p; R3 [6 l/ K- Z
    set my-row -1
* f% Z% d+ ~! h; ~+ e9 P! Y    set my-column -1
" `& z7 T% S6 s* T) W, }    set my-phase -1
  N2 o3 ]7 K" x( T& r& M    set pcolor brown + 3, G0 N' \: }# T' {! ?& {% w7 ]
  ]
: s# m/ v$ h& B" J: o' `5 I: C
, _; w, K  z9 Q6 o+ {# v0 ~; F  ;; initialize the global variables that hold patch agentsets  N& D" m5 H5 v
  set roads patches with! ~, _& c3 J3 }+ I7 I) c4 V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) u: j# P8 [, w, D6 F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 M2 d8 o5 O) U( L
  set intersections roads with* i% l& b/ C8 n4 ^  W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
8 }/ ~( O& g* K! y4 Z+ n& g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% p: _4 x$ W- m5 |" u0 {
* K9 o* G. ?0 ~5 @4 I  ask roads [ set pcolor white ]8 L+ L+ S+ k& S& A8 [% ]
    setup-intersections
* t8 [2 q0 ?/ g. J" ~end
9 p) h, o3 I' q其中定义道路的句子,如下所示,是什么意思啊?
0 m% w3 V$ I+ N% Y set roads patches with( L7 S# `8 z5 N- z/ c+ I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  T6 D$ Z6 r  w4 t$ B  Z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 T  k4 s# u, \+ b! S4 {" I) k
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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