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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。
  q; z0 g/ S& i3 Onetlogo自带的social science--traffic grid这一例子当中,8 N$ b1 X( l: s4 H) B9 n3 j! L
globals
% L+ ~' M! C1 O- b[
0 Q9 S) F2 u4 _2 F  grid-x-inc               ;; the amount of patches in between two roads in the x direction) ]! {$ G* `( L3 `! n
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
# Y+ k0 Q5 @) V% |' ~* \  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 H2 [+ ]3 s+ p+ O
                           ;; it is to accelerate or decelerate. _: v- M  @0 K
  phase                    ;; keeps track of the phase
/ j1 s9 e2 [. ?2 C  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# f7 q( q! A7 J, p
  current-light            ;; the currently selected light" L. i- G+ D" M7 Y: @+ S8 H/ U6 w: r

; Q" C, K5 p/ \8 e$ I  ;; patch agentsets2 }, O. W5 l2 I- s% U) {+ S- h' {
  intersections ;; agentset containing the patches that are intersections
0 Z( [9 h8 x# N; h  roads         ;; agentset containing the patches that are roads6 \5 v; g& F0 }
]- J+ {6 o; R! D
/ D  {9 ]3 u8 G" J
turtles-own
+ G: t3 K9 {$ u( B5 R4 w) i# |8 l[# \9 p6 N& s5 I) E6 V0 k/ B8 i
  speed     ;; the speed of the turtle
: Z' m0 V( I0 C  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
, D  U% h  |7 A6 T# M  wait-time ;; the amount of time since the last time a turtle has moved
# I' x' {; M1 E% _# Y5 l]3 o. {* h$ I5 O+ @. o
; k" `; t5 Y$ X% p4 ?
patches-own
# ~4 p: n! ~0 |  x2 B! r4 o[" {& l* z  h! {6 n8 ]% ?
  intersection?   ;; true if the patch is at the intersection of two roads4 g" R7 i: }, W$ n0 d
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.! @9 ]0 Q7 i6 c% }1 l$ T
                  ;; false for a non-intersection patches.
  ~' f% I7 `: ^) [  my-row          ;; the row of the intersection counting from the upper left corner of the
: K6 C( P) |7 B7 Z0 m+ b7 V- J. i                  ;; world.  -1 for non-intersection patches.
9 o8 {! S6 O6 V' L3 ^* o9 {  my-column       ;; the column of the intersection counting from the upper left corner of the
! |* H5 H; K7 O/ {( e& `8 a                  ;; world.  -1 for non-intersection patches.
# h1 S, Y3 O, Q" ]# u7 i  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.; z- n+ G) B$ J" F
  auto?           ;; whether or not this intersection will switch automatically.
- a- p. V0 n$ O                  ;; false for non-intersection patches.
) R" l' J2 E4 R7 X' T]
  O: j- u6 N6 m! f( D% M! d6 [0 W) j. m# \) J; P& c0 x

. f" _) W, K8 ^$ i1 q# P;;;;;;;;;;;;;;;;;;;;;;
7 o3 P8 q6 m* S;; Setup Procedures ;;
' A1 |2 R4 y+ ?( y( w' W2 v;;;;;;;;;;;;;;;;;;;;;;
9 o9 t) B) q( b) C% L" z) t6 j1 Y1 @5 N3 w0 Q; X( v
;; Initialize the display by giving the global and patch variables initial values.# [; r8 n; J4 E8 T$ ?1 @$ }+ Z
;; Create num-cars of turtles if there are enough road patches for one turtle to  E2 N6 J  H  ?
;; be created per road patch. Set up the plots.% m. Y" r$ U, U3 ]( T* a) c7 I
to setup- u6 [' [$ Z1 _8 A" X) n! P
  ca/ g, \, g3 B4 q5 f
  setup-globals/ V4 [: D0 P( v+ y" T7 U5 p+ x

3 b8 o- j: Y9 G; X" g  ;; First we ask the patches to draw themselves and set up a few variables& [3 T9 ?! ^& P8 k+ A+ ]1 y- j+ ?
  setup-patches
+ W+ h5 ^2 a0 i" ]$ [( `  make-current one-of intersections/ C! b  j+ M! \" G
  label-current
" e1 q0 I4 B; d4 J& }+ h# u! {+ O4 t+ T# `0 }7 n" }: |3 n3 d
  set-default-shape turtles "car"& {2 Z7 u5 m. N, C

( D8 i# Z0 D& u/ b& J. ~2 _  if (num-cars > count roads); q3 {2 |1 ?7 W: u  M
  [
$ f8 e/ ~  l; p- @" `    user-message (word "There are too many cars for the amount of "
4 M( s' w2 Z) b2 H& H' y8 z3 M8 q                       "road.  Either increase the amount of roads "
7 K3 q' j+ ?3 N3 W  S; u5 a) F                       "by increasing the GRID-SIZE-X or "/ |" T( |, |; }* P$ |
                       "GRID-SIZE-Y sliders, or decrease the "8 B4 ?4 \9 D5 m( Y2 i: m
                       "number of cars by lowering the NUMBER slider.\n"
. B# r5 i5 o$ D6 w: r/ N                       "The setup has stopped.")% I, H! J! w( I8 f
    stop3 f' u# h5 R7 E: q# @9 J
  ]
1 M! G* l6 f8 k$ P6 E; v
+ m$ z/ j) l5 Z% d  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
* x( ~2 m5 @" X6 a  crt num-cars
+ d1 M4 v* B; d% V8 M  [: l; }5 n3 Q: X, ~! `
    setup-cars9 H$ y( a& g1 D! T) b) S
    set-car-color3 d% w( r* w! c
    record-data5 [; a/ l8 p) q: `' {1 d. h( P
  ]; V( p1 z* B) _( p9 }' f7 N. r& `

2 \# V5 S) C2 _0 O  ;; give the turtles an initial speed0 E- o. A% p: Z7 F+ X6 [
  ask turtles [ set-car-speed ]1 i6 C* K/ L/ V. K
- N: \6 ^/ ^% @  d1 X& ~
  reset-ticks4 h; L/ q! A* y$ r; i! z3 L- _
end- [& f9 [) b8 \4 ]7 q# K# L) S
! E+ n2 M8 f( U, p  S% l# \
;; Initialize the global variables to appropriate values: a& n% i8 f. h  q4 a
to setup-globals( g4 F! \0 u1 m2 H
  set current-light nobody ;; just for now, since there are no lights yet
9 r9 V6 Z$ l+ j3 w  set phase 0. W/ H3 g! c, g. N/ E1 A
  set num-cars-stopped 0
. A  r; r8 x+ n2 G  set grid-x-inc world-width / grid-size-x
! D6 N6 `" ^6 N) K  set grid-y-inc world-height / grid-size-y
# q6 r  {' R( n) K+ N9 k5 E9 F' V" C4 M. \% }
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary& h9 H/ A% ]0 v) `7 r  p6 [
  set acceleration 0.099( P4 s) w+ e; U4 A, }/ G$ h0 y
end1 z; c' M- ~/ H) b

: }) |+ q' j9 m/ o% I  X7 Z;; Make the patches have appropriate colors, set up the roads and intersections agentsets,  @7 F$ ~) Z# @% k9 K( v
;; and initialize the traffic lights to one setting
# `' @$ l6 B& @' b# uto setup-patches
1 ]3 g) L2 g3 a/ O3 |  ;; initialize the patch-owned variables and color the patches to a base-color  i+ V9 a# k0 e. `5 n
  ask patches9 F2 p/ Q6 Q* k, P7 x% q
  [: Y6 L2 @9 C/ K$ d  a$ [- I( u
    set intersection? false
5 D% m( M6 @) P2 s) t    set auto? false
/ u1 F* O7 y* f  V: y8 [  X/ ]4 r    set green-light-up? true  ~: V5 E4 y; O. o# R+ ^
    set my-row -1
& P, V4 b1 A( N4 W! U( L    set my-column -1/ @/ G) s3 q5 e# m# @( J
    set my-phase -1' x/ W5 D6 B2 h! }  _& ]
    set pcolor brown + 3
- ^5 n: {( d# j/ X: I: v0 S* U: A  ]
) M1 ?$ t' S$ J& P2 |( _8 D& U/ P
; N6 n- V0 P: k  ;; initialize the global variables that hold patch agentsets  J( h1 }$ L- |7 L. n9 \
  set roads patches with
9 ?4 _8 v; M* i$ X" I& K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# X, |  f/ J7 f2 n7 }3 ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" m! y6 h+ p+ o) r  set intersections roads with
+ Y* p2 D) z! a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and- ^! e1 m. Y# }( j4 c9 u) p
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  H! O1 Z1 ?! N! }$ _1 U  Z& ^7 t8 \0 K0 L- Q& j# q3 \
  ask roads [ set pcolor white ]
8 Z% s# a9 X! i    setup-intersections
! e, T. [3 Y' F, g1 A8 Vend
9 v$ w- d* X, ^1 ?  m其中定义道路的句子,如下所示,是什么意思啊?
8 x& Y1 s9 Y4 \7 @( @( I set roads patches with) S. @" O* T9 Y1 `! G4 ?' w% B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ ?: ]3 W  ~4 u5 \) a7 ^. L
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], J5 u# K4 w5 _; B  c
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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