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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。
- W9 S2 w/ ~4 K+ I( anetlogo自带的social science--traffic grid这一例子当中,* _2 m. l1 ?) D& H
globals
4 f/ C7 Z/ Q' Z. d: @  D) b0 k5 m[
( O1 K( J: k) }. W  grid-x-inc               ;; the amount of patches in between two roads in the x direction& y7 ^1 I0 j' p! f
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
7 b. m. U& _# g; x" t  m; b6 u  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
! l$ L8 o! `) d: w. a4 V1 n6 u' L                           ;; it is to accelerate or decelerate1 O% A) e: V+ n* i* q
  phase                    ;; keeps track of the phase
, P) p3 v* C' w  K& B: Y  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ S: o, v) |( F1 x  current-light            ;; the currently selected light; V$ u( N$ v0 g; a) c

/ N0 H! R% _+ {0 S0 H  ;; patch agentsets/ I3 L7 ?& Y; W; N
  intersections ;; agentset containing the patches that are intersections
: S+ m+ K3 o4 O5 C7 k' B2 }  roads         ;; agentset containing the patches that are roads
9 G: K  A9 X  x- G# F# m) V]5 A* Z9 P' `0 H  f( C) `

+ n8 S" z& |* j& ^7 {& Yturtles-own7 J8 `1 J% E; a) w7 x
[
1 X4 O, W" q/ I, h$ {  f  speed     ;; the speed of the turtle. M# w: z4 P/ r& E: D. d$ q
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
. E+ ?2 ~/ }; K  y0 B  wait-time ;; the amount of time since the last time a turtle has moved
) o9 ^: q& y! _2 I- e' H]9 _6 Y" [' d, @. x

  c7 z: y! K- b1 H$ Q2 ^patches-own
+ ?" H7 W8 L$ E/ F- F4 l; ~& c[
( [, q& C* Q& ]/ H3 |% R  intersection?   ;; true if the patch is at the intersection of two roads" w/ C6 r. [' G; z9 @3 B; l
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- Y0 ?# D& g. h0 |% E3 M# y
                  ;; false for a non-intersection patches.2 m' L2 c$ E" C% t5 O, v3 P
  my-row          ;; the row of the intersection counting from the upper left corner of the2 q% _+ b' T( S$ m$ v' Q* W# \
                  ;; world.  -1 for non-intersection patches.! S) M! t1 w5 Q' \* d
  my-column       ;; the column of the intersection counting from the upper left corner of the" I3 u" [. B* R- ]4 ^" L. z% V
                  ;; world.  -1 for non-intersection patches.! a' \$ ^  g4 O' |7 f- u3 m
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
3 _" L) t# i1 l1 {3 S+ R  auto?           ;; whether or not this intersection will switch automatically.; A, ~: a: D% f4 E6 v
                  ;; false for non-intersection patches.
6 l  P2 ^% b* B* d! B/ y]7 d! O: C; }4 ?) r
9 u& D4 j# R4 V: y0 l5 S3 a8 S# X" h' a

" t3 v' W' d6 e1 S1 }& f: E8 @;;;;;;;;;;;;;;;;;;;;;;/ g) E& l# w4 n; `: R8 F2 N
;; Setup Procedures ;;: \: k' W  w  V6 ]. r
;;;;;;;;;;;;;;;;;;;;;;
7 e7 ^% S$ C2 ?, O, \6 r; C
$ _3 G/ ?' v6 `8 U% D;; Initialize the display by giving the global and patch variables initial values.8 N6 R3 f6 @% P  ^  U
;; Create num-cars of turtles if there are enough road patches for one turtle to
2 Z: h/ R4 m$ |" ]1 ];; be created per road patch. Set up the plots.
. T5 V( D+ p  m2 f8 Q' Ato setup# d/ e- |8 K( i( l+ Z( \7 K
  ca
6 L( k, H+ ~: z9 g, b0 O/ j  setup-globals  I3 F8 b7 e! T) H, _

4 Y2 o+ N+ S0 T% k4 E. H& u+ Z% i  ;; First we ask the patches to draw themselves and set up a few variables
8 R$ y+ [3 t: O& s  setup-patches
2 s, z; M0 G7 e$ X$ ~* k! E  make-current one-of intersections! d* m: Y6 }9 Y  z0 c/ N; n
  label-current; x" N( v0 ~/ r/ k

% T* ]1 k2 F: @  set-default-shape turtles "car"
& z/ `, O" v& [1 [; K: Z0 l1 r# Z6 L
" \$ r. p  `2 D0 r  if (num-cars > count roads)
! A/ W& ?6 z; {: P5 l, p5 v+ g. G  [
# z6 U1 Y% `' Z- b% c% B    user-message (word "There are too many cars for the amount of "1 @3 Q: M8 T- `8 F5 b
                       "road.  Either increase the amount of roads "
$ {2 i9 f5 T9 D( q$ [/ P                       "by increasing the GRID-SIZE-X or "9 `* z6 i- @6 S* N- P5 P
                       "GRID-SIZE-Y sliders, or decrease the "% N# d# ^) T0 g9 t* [. O8 o$ i% W
                       "number of cars by lowering the NUMBER slider.\n"" o. G# r. X9 T5 C' P1 G
                       "The setup has stopped.")
0 U2 L: l, q$ Z0 u    stop; N" {# j# I' K/ A3 d8 v
  ]
6 J( Y  {* G" K- U& H
$ i) _! Z/ P9 |% ~2 u1 h& F( J7 j  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
3 m) U7 R) v- O" ^2 C  crt num-cars
7 f6 D& Q1 y: Z$ _; N9 r1 W  [
- M. ]( Z, ^: @$ P8 p/ f    setup-cars
( x7 A) ^- Y7 B1 O) H    set-car-color
% k9 `' |. P9 t1 |& E) B: m    record-data
/ _  `) L# I, I  ]
" b3 P  @3 `/ \$ [( K( W3 F. s# A2 U$ O5 \4 f) z! X/ o
  ;; give the turtles an initial speed' J; H9 |) o* D1 ^% j1 M
  ask turtles [ set-car-speed ]
; ]- \: l% i" k& {- t" |8 @5 c8 h& I: f8 x. m/ K7 H
  reset-ticks0 c, _- |" ?* r* h6 Y7 i
end8 s9 G1 N4 J  N. j, n
* }4 h  @1 z# _: A/ \5 n( X- h
;; Initialize the global variables to appropriate values& p, E1 y6 V0 l
to setup-globals2 B! C1 j2 H* }6 h. l& k
  set current-light nobody ;; just for now, since there are no lights yet
( ^4 ~) a% r. b6 f  set phase 03 M, }% T, A1 x, ~( e3 d
  set num-cars-stopped 0
- T- y! P' ^& n) W0 m' s  set grid-x-inc world-width / grid-size-x
% B+ T: z% G' z0 U& _, E  set grid-y-inc world-height / grid-size-y
5 d; K6 C8 x9 D& \+ [  N2 L7 |, O$ v' K
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) c) p6 V: K7 X
  set acceleration 0.099, D0 X$ @7 y: f! Q
end
! U5 i' K' I9 x1 p. f' F
; ]* Y6 @, V) W  ?5 _  M0 a;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ ]0 S- r# r5 G, C( K" C! \
;; and initialize the traffic lights to one setting$ a, H3 M( o6 U! @% y% z
to setup-patches
3 y7 k0 u$ v" p' u7 y, a  ;; initialize the patch-owned variables and color the patches to a base-color0 b0 K. G; G5 x, ?% A: a- L
  ask patches/ l2 ~# V7 L, A0 b4 i
  [: Z! y& A4 N2 }" l
    set intersection? false
& J/ p4 p$ Y" Q    set auto? false
8 j8 F9 @) ~  }# K5 j! @: j    set green-light-up? true. G0 g# U3 v7 J* }7 B4 R% B" }
    set my-row -1
0 D  N# f  E8 K# q7 Q    set my-column -1
) C  I( m' T7 `/ P1 ^4 }) p1 U# K    set my-phase -1  p  d- R( P3 z3 x+ e
    set pcolor brown + 3
) I% e3 C) o3 M  ], h' o# L/ V7 S- o
0 k' t3 S" A0 z- G  ]
  ;; initialize the global variables that hold patch agentsets
0 Y# [0 z9 R% r  set roads patches with6 U/ u2 M, y6 _3 L5 x: [  [( p
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 `. R% D7 Y/ k    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: ^8 D5 ~/ ], d' {: p. K
  set intersections roads with( i; j3 H0 B. ]) ]
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
' Q% p1 G1 ], p( H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, G; C  S4 ^* p: v( n7 _' j
' S; z9 D8 ?& q! N; x: u  ask roads [ set pcolor white ]
7 m9 f. @- Z0 ?- y    setup-intersections+ y3 B: N; l# ^# K
end9 O0 s/ h, I5 }- Z/ a5 ~
其中定义道路的句子,如下所示,是什么意思啊?
" h- K9 [& C+ ?; u" V2 O: f$ I2 T set roads patches with
" l$ Z( I8 a! k+ m) O' @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  t+ R( P2 t6 O6 H# \) }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; C, m7 s6 |  J, B) q+ w
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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