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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。5 K9 k, S0 ?9 W/ I; }* m
netlogo自带的social science--traffic grid这一例子当中,: b1 k1 G1 U. |+ M1 b, b
globals, o/ w5 ~) T/ x' Q: i- E$ n
[: H) \! z6 p# O
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
5 s3 L+ }# B( Z  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 W+ @9 Q7 [( e0 |, R  Y' U& h
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
" t! W) f/ a/ M2 W                           ;; it is to accelerate or decelerate
% F: J. g6 v% Q- y* R$ z* ?: F, y  phase                    ;; keeps track of the phase" T) n; D3 m( Q& z# x' P
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure5 R2 ~( \- W9 E5 {$ R
  current-light            ;; the currently selected light
& s, r$ s! i5 P+ a, F: N  Q5 j1 t& W' V* F" p
  ;; patch agentsets! l' u" @: b2 W3 C
  intersections ;; agentset containing the patches that are intersections4 [+ E5 d6 Z7 X/ |$ T9 B- {; U$ w
  roads         ;; agentset containing the patches that are roads
0 k, _' k3 W3 r% l8 c$ N]# N  v5 }0 B+ t+ n7 }, V. k% M

: z$ ~5 M6 [. n6 ]: m$ Qturtles-own; n* I7 V/ Q; K- m
[
& [5 t% j* h' ^4 f) ~0 d7 c  speed     ;; the speed of the turtle
' X% w, l5 s* j  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
" R6 K( N1 L$ ?; n& {; r  wait-time ;; the amount of time since the last time a turtle has moved
& M9 I. D; }' `& W]
, R( z/ S6 R4 l$ `7 U3 x& ]
: S. m2 J& {  `patches-own1 Y- G3 ^0 j; R! S2 h% I
[) {" @  I3 T4 U& D( M4 y) q
  intersection?   ;; true if the patch is at the intersection of two roads! f/ Y2 [3 e3 y8 U# y% Y! \6 _3 E) O
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
" x. E6 U( d3 w& d) v) ^                  ;; false for a non-intersection patches.
. Q9 \: U- C; V- A, s  my-row          ;; the row of the intersection counting from the upper left corner of the
. l4 F# b2 F0 W1 D" w: p                  ;; world.  -1 for non-intersection patches.
' O" \# J0 z& D  my-column       ;; the column of the intersection counting from the upper left corner of the
+ Z. s. I1 e- Z1 R, V                  ;; world.  -1 for non-intersection patches.
% {/ o+ _0 C9 D0 d! q0 i  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
6 g4 X( w# `# r! i! P  auto?           ;; whether or not this intersection will switch automatically.: i; ?' K: n% C( r  B7 z
                  ;; false for non-intersection patches.: q) V5 H% [1 N! H( Y( l$ E7 O
]
3 q+ Y6 }4 [* R( ?9 F' n" g0 ]0 O6 Q: e% U
+ |  x; [" f: _" q* [7 X& `
;;;;;;;;;;;;;;;;;;;;;;) q0 _& U- ^4 ^8 ~
;; Setup Procedures ;;
* z/ r0 @2 ?2 ]* V! I! j( ^7 t6 f;;;;;;;;;;;;;;;;;;;;;;
7 h' N3 p$ k- k- Y0 c
3 {6 j, C' b  ^8 I;; Initialize the display by giving the global and patch variables initial values.
" P2 }5 T' ]. i' `: M9 O; F9 h;; Create num-cars of turtles if there are enough road patches for one turtle to1 C  G  L+ U  L' u0 y- ~+ f$ c
;; be created per road patch. Set up the plots.
- s1 o6 K0 H5 ^1 P0 Eto setup8 ]) ]0 |! `1 b, r
  ca
% a% Y: ^' s+ U. m) u! ]  setup-globals. n. H2 }  j3 v; n# |( n: Z

7 `0 A% B# v* k. u  a5 E  ;; First we ask the patches to draw themselves and set up a few variables
8 p+ @* S3 P9 o) T3 e  setup-patches
1 I: s' |6 D* ?0 o- x! B  O; \" ~$ i9 D  make-current one-of intersections/ b! d0 r4 S& q8 b1 }1 o: @
  label-current
  _4 m: H4 \0 r, Z2 p
: {3 A; P6 k, T1 Q, Y& ]) R' p3 _  set-default-shape turtles "car"( Y( q4 m# O( a" c
& F, s  C# s3 i: A
  if (num-cars > count roads): ~9 s, Y  D  i6 w& O% `# B
  [/ q" o1 y/ [5 \% I: F  j
    user-message (word "There are too many cars for the amount of "
6 B/ C. A0 R. E- p& B3 L+ ~, [                       "road.  Either increase the amount of roads "; I1 V6 i* T* f! v* ^
                       "by increasing the GRID-SIZE-X or "% ~" x, b0 S% v  O, ^' E6 K$ L
                       "GRID-SIZE-Y sliders, or decrease the "- {" O" V% S- R. ]; O5 \% D3 N) s2 \2 D
                       "number of cars by lowering the NUMBER slider.\n"* o, O% F* g8 j! d7 k3 Q) r. T
                       "The setup has stopped.")9 o! _9 t4 b7 U
    stop# p, N$ f3 ]6 @; ^5 v
  ]
( Q9 K2 L# ?* p& z- ~6 P- t; W  X/ j# I8 Z# }6 T) T
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
7 q0 X3 `& S! W% O2 H  crt num-cars$ k: P, D$ W6 g& Q
  [
6 I6 D0 v& F' a$ e/ X! T2 U5 R0 Y    setup-cars  |) Q0 f- M" ]/ S, n4 k' b
    set-car-color9 S, K! s4 y# E" q& S$ W
    record-data* Z) n3 q- T. e0 Z& B
  ]
, M8 y; G" m  l
- z4 C" v. C" w! t2 p. a  ;; give the turtles an initial speed- K& `- y; h, C. n6 w/ {
  ask turtles [ set-car-speed ]% Z/ Q- H9 c8 [

! R, P, [3 y: e3 y$ s/ J  reset-ticks
9 o2 d- n) ]( R1 |9 _7 xend
8 I4 c+ J9 P6 o1 H! |! j! ~7 m, v2 [5 P* Y2 u  U
;; Initialize the global variables to appropriate values9 ]2 p/ m% P" p0 s4 I. o3 P
to setup-globals
! {0 \) }( J0 r% @  set current-light nobody ;; just for now, since there are no lights yet
  x+ {# v% ~2 _& Q. A( v9 j  set phase 0
/ m6 C7 `# V0 `2 K  set num-cars-stopped 0' J* h. d5 r9 x" G" n* p
  set grid-x-inc world-width / grid-size-x
) v" M% F; R; J7 {$ O* L  set grid-y-inc world-height / grid-size-y+ C! g) L3 A$ X9 ^& Y

9 e$ X$ m+ _$ z1 k  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary8 t! m; B/ p9 a8 `0 v' i  Y+ p
  set acceleration 0.099% @: a$ W0 Y4 M8 T! I! h6 J7 \4 K- [
end/ b+ r" q1 R# [) B. P
; _2 F( Q" j% V. g
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,; J; ?  V- S7 J9 v
;; and initialize the traffic lights to one setting6 `) D$ S: Q# m& m. E" e- t
to setup-patches) i3 X# N' f7 S0 ]6 U
  ;; initialize the patch-owned variables and color the patches to a base-color
5 `; L  u: w- G& e  ask patches0 R( s  G0 u: Z; ]8 {' U- ?
  [
$ L3 m+ p8 b; ^7 g    set intersection? false( h) K& \0 Z6 G
    set auto? false
. `8 a* b/ Z7 o% n8 e) \    set green-light-up? true# r- b$ @' L" A! _
    set my-row -19 C2 B$ y! O9 e; Z$ ~
    set my-column -1! l  m6 Y) }' A( J
    set my-phase -1' r4 w$ F% Y$ G6 |' W
    set pcolor brown + 3( ?: e, h$ V, j/ S' O' i3 P+ r% b
  ]/ r2 \) u9 b& K/ H$ o1 C

3 p3 ]  W5 L6 T( _: x. p  ;; initialize the global variables that hold patch agentsets8 H  D  W9 U, t  R# ~& ]
  set roads patches with7 s/ g2 R* e. a  @1 Q8 ?" f
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 ~. ^. T& _5 s/ Z  q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% {7 r' U0 T; f+ y$ u& m1 {! i
  set intersections roads with! ?( j% G! w6 L% d/ l  G, p6 t8 j
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
& V* k7 F) @, R/ M3 D7 r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( d( D. Y2 k" L- b% V# f7 t. _+ I

" J2 a" _; X1 w# j. d; I  ask roads [ set pcolor white ]6 t# x+ G1 {6 x/ q1 ~
    setup-intersections
) B! n: [3 w+ r, z9 L+ l/ lend
4 ^4 e& h& u( P. \) M, O  a其中定义道路的句子,如下所示,是什么意思啊?
( P0 N. S" M# x- e set roads patches with
1 }3 G) E; F8 C# M7 R1 r6 ~9 ~    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! U' z* l3 k- e& ~* G2 k0 R    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 G0 z% F2 E# i: S! v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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