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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。
3 g7 j1 W! y7 m+ t% ^: [" @netlogo自带的social science--traffic grid这一例子当中,4 i1 B  M, I) W4 n, i1 j, Q
globals" q; s, R  ]8 _, x' Y+ ^( l
[
- L1 y" p! V# o  Y& t$ D  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 V& [' ~% _! D% Y4 F; _% b
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) N0 q. h  B9 q, b: b9 r  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 o2 D. @( k* k, [                           ;; it is to accelerate or decelerate  o: ]$ w# m, x
  phase                    ;; keeps track of the phase6 W9 ]5 f, \4 H7 C8 i
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure; y" N) e% q) n& R
  current-light            ;; the currently selected light
% W4 V5 G4 t# f: E, p+ T" R1 j( T" |
  ;; patch agentsets
/ ^( o/ {1 L5 |1 l  intersections ;; agentset containing the patches that are intersections
( [4 |" n" d: J4 g# E7 J  roads         ;; agentset containing the patches that are roads$ O) H0 X" ]0 ^: H8 o) |1 T1 W( L. t
]/ H2 }: t- [3 N6 S" m8 v
9 t$ L' G$ H! ^
turtles-own
7 n6 a1 h% C" C* G& H[7 j) X+ F* N+ p8 }9 j; x/ f9 k
  speed     ;; the speed of the turtle
# \  c3 p/ g2 d- \8 K3 I7 v  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
2 \5 }! n' {6 j) P: V  wait-time ;; the amount of time since the last time a turtle has moved( d& g  b5 ]. j
]
4 T& v- w9 K6 S  M
+ S+ O9 e  h) k( s% lpatches-own  M' y5 A8 E$ M# C! G3 N
[8 a& r+ `$ v  U! A
  intersection?   ;; true if the patch is at the intersection of two roads
4 Z0 O: ?. s: z4 F% q# c  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.' H+ |. L# w' j- B
                  ;; false for a non-intersection patches.) J, g! w$ ~+ Y+ Q0 V, O1 J0 v
  my-row          ;; the row of the intersection counting from the upper left corner of the/ C8 V5 y; f8 a
                  ;; world.  -1 for non-intersection patches.
4 M5 u. q2 [+ C1 }  my-column       ;; the column of the intersection counting from the upper left corner of the
. r/ C/ K$ C4 J% F$ h" R                  ;; world.  -1 for non-intersection patches./ K. ?7 W+ q0 Y1 E1 z
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
" p: s  G3 J* X; c5 V. F  auto?           ;; whether or not this intersection will switch automatically.5 w  I5 t3 I( J- d9 J/ c% O1 n5 t
                  ;; false for non-intersection patches.' T3 [3 t* Z- s/ a& x- \
]2 e- I  _: ^2 q' @

  T/ G$ z6 |/ @) P( u# [
8 b# {) N0 j; o! v+ s;;;;;;;;;;;;;;;;;;;;;;
* \$ {4 `: _4 {, w7 t6 _8 `- I+ x8 n;; Setup Procedures ;;% I9 F9 T( P: g- H' x& W: B7 e* x5 d
;;;;;;;;;;;;;;;;;;;;;;
9 [; \4 \( P; n' V; e- Y0 b  r. Y* c( K7 r+ X
;; Initialize the display by giving the global and patch variables initial values.: l( }% }. j) c) b' Y" J5 ~
;; Create num-cars of turtles if there are enough road patches for one turtle to  S1 T- l( [8 R
;; be created per road patch. Set up the plots.) w. d& _* |" B8 _
to setup' t* I) }+ {! p1 ]( A) P
  ca
5 ^6 C8 A* P7 P  setup-globals
, X! V7 U$ t5 g' ?! B* |. F) I4 c" K- M
  ;; First we ask the patches to draw themselves and set up a few variables* H. r1 ~8 s  D- a5 U7 C
  setup-patches
5 f/ N& {$ b) Z! ?9 J7 ]+ v  make-current one-of intersections5 V0 e1 a2 [# ^6 \
  label-current/ Q6 s5 B7 S% q/ ^6 u" W, `

6 z3 l1 O. [" S" |, E# e  set-default-shape turtles "car"
7 P2 x, a# K; k6 V+ X
/ ~" `( ~# N/ `) D- U  if (num-cars > count roads)% I; o2 a! s6 O
  [) U) z+ W9 ?8 E
    user-message (word "There are too many cars for the amount of "( n( W: T3 s3 t
                       "road.  Either increase the amount of roads "
) S0 H4 M% |: G                       "by increasing the GRID-SIZE-X or "5 o7 a) I/ L+ ]/ Z
                       "GRID-SIZE-Y sliders, or decrease the "0 `) Z- u* M% Z
                       "number of cars by lowering the NUMBER slider.\n"
, v3 N. W' v/ h; f! S4 H9 b( `                       "The setup has stopped.")
3 Q, C6 a5 {1 s4 c$ w) w    stop
* x2 C! X* |5 e- p' ], v$ f  ]2 o( H$ Z9 {5 R0 H3 f9 v
1 U7 H" ?% Q" b( s, w2 h' I. [
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color! v) }. I. @$ A- G) N% F
  crt num-cars, `: v# d5 s7 G3 o
  [# w, ]* E2 c( e9 y6 h: J) g
    setup-cars
; N# R) L+ f7 D1 ?% U) Q    set-car-color4 p+ c5 Y: k8 I8 X, s7 B
    record-data
5 W; g1 b9 o/ N9 \  ]
' r$ Q8 Y5 E. Y! ]( F( B" B
4 `. o0 z0 s+ z3 `  ;; give the turtles an initial speed5 N/ o8 x! {5 V8 E
  ask turtles [ set-car-speed ]
4 L7 e( }- L# i  f2 ~: s
. z* Y3 F$ t9 k% W& Z3 ~7 `' X  reset-ticks  c) m0 Y+ h# Q4 G  k  m
end% X, U1 E! L* h
9 A9 P0 \( I- ?; V3 W2 i  T
;; Initialize the global variables to appropriate values" y  D% n9 Q- v
to setup-globals
/ X6 E: q* A/ G! |1 u: N  set current-light nobody ;; just for now, since there are no lights yet
. s' n$ A& B. r% ~  \, d8 B: t  set phase 07 ~1 B, [& `1 C: M
  set num-cars-stopped 0  l8 J& y2 M8 H( [7 I
  set grid-x-inc world-width / grid-size-x2 X) o7 B0 {2 O' E3 I1 |, e
  set grid-y-inc world-height / grid-size-y
' Y& k% H7 W( @/ D( C* H: a7 E, D/ m4 t* H# Y( L# ^2 j) y2 B! D
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary' v5 ~* y, g' y& S$ l' G! B
  set acceleration 0.0990 `1 |  p9 V; W6 Z% P- c
end6 M6 x3 T8 V2 ]3 f$ ~! Y

- ~% K, F& F6 N7 L* o2 o: o9 i. v, G;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
; k9 y$ Q. o* d5 V* F% R  p;; and initialize the traffic lights to one setting3 R% @2 f) ]* F% Y% C5 p- Y9 z# j
to setup-patches
2 [6 o) t) A) L( k; ?2 [, }+ P. f  ;; initialize the patch-owned variables and color the patches to a base-color
6 [: r: G  ~3 h  ask patches" [2 N$ D) t1 L& X
  [
  l6 U( M0 e( O    set intersection? false
6 w: W( }! \- r7 c1 L    set auto? false
0 l, n: r, ^7 r# M, k3 |1 j5 p/ ~    set green-light-up? true
6 w( M* W* P& J- s; d    set my-row -1
, P! T) E8 e6 m  z- w0 j- o/ l    set my-column -1" e5 r9 Z  w& y& ~
    set my-phase -1
) i* Y: E6 _9 e  d    set pcolor brown + 3' m, x# T4 u* y# o
  ]
* z1 N3 [& ]: U8 f& ^# K- Q
- j; t: z( f$ F$ v  K8 B  ;; initialize the global variables that hold patch agentsets- U) l. S' J( @. H& p- H5 B
  set roads patches with
* m4 @( _1 `, c    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' h/ |$ Q( d' B( `4 y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) _) p' x3 }0 Q1 L5 q
  set intersections roads with/ n" o$ b5 Z% t* @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and9 V4 F. V' x) s& T0 A- m6 Q0 ?: W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 k8 u3 D% ~' [; P
4 ]8 @, c% w7 U# i! V% W
  ask roads [ set pcolor white ]
6 O6 h7 S. ]2 j! }, X$ f) A    setup-intersections- V* W$ [$ e3 C& Q7 F
end
3 k9 j; y. Y, m其中定义道路的句子,如下所示,是什么意思啊?
* Z4 j* U& S0 U  h0 a2 z4 ~ set roads patches with8 U* y, v# Z0 C, [2 ?- |1 b2 Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 Q* D% j# @& Q, k4 t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( i7 e$ F9 [& A* z: z: I$ E
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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