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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 I9 v" Z# Pnetlogo自带的social science--traffic grid这一例子当中,
! o9 B/ e4 e& g; xglobals
9 i& V- k) e. l! q6 a! e% O[
) w; `( q1 k  c% O! X5 h7 t  grid-x-inc               ;; the amount of patches in between two roads in the x direction
$ d& X: U  O7 r; d! N" P4 i& o! n  grid-y-inc               ;; the amount of patches in between two roads in the y direction5 ^: V) f; t+ A/ ~9 r0 b- I% W
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if" g; |5 P) K5 B' K
                           ;; it is to accelerate or decelerate
1 W7 A$ \( ?( e# A  phase                    ;; keeps track of the phase, D( ]0 p+ j. ~$ L
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure; D' t6 v  k" E5 Q! Q
  current-light            ;; the currently selected light
5 d& K6 k6 z6 s% l% i
' @9 L$ V! F( F  {& G$ }& L  ;; patch agentsets+ j/ ~$ \/ O/ {; U; l
  intersections ;; agentset containing the patches that are intersections3 T$ v3 h1 y; O# t" s' m9 b" z
  roads         ;; agentset containing the patches that are roads2 G+ f5 f8 q7 B* A9 y3 M- Z( Y& b6 X
]( K, K  S8 T7 e- g# C- ^1 P
& C3 H6 D' n$ J- U- {  ?" y
turtles-own
6 X0 L" G6 W+ Y+ l+ Q[: m* K1 V: ?' N( ?7 S; k
  speed     ;; the speed of the turtle& s+ }: ]! [& B" ^; `. D; u8 |
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
) C) \! q! Y$ f- r3 z  wait-time ;; the amount of time since the last time a turtle has moved" {, U  q6 w$ `1 ?* E: Z5 V
]7 R! r% d# r( _: W9 ^& p8 h6 K5 _3 Y

: m. k' A5 d' }: npatches-own
* L0 _5 e3 ~/ o" `( N% `5 X/ q0 n; P[) b( T$ C. Y9 P& U% C/ Z
  intersection?   ;; true if the patch is at the intersection of two roads
6 ^* Q1 e: K8 m! V+ {0 z- j  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
; ~% _. c) ~' Q                  ;; false for a non-intersection patches.
5 I) s) v. L( C1 t7 c' |4 ~1 {7 |  my-row          ;; the row of the intersection counting from the upper left corner of the
, _7 c; m5 n0 m' G6 H                  ;; world.  -1 for non-intersection patches.
1 H7 Z7 d/ ?$ i7 @# n  my-column       ;; the column of the intersection counting from the upper left corner of the6 O" X; \6 j. Y& t
                  ;; world.  -1 for non-intersection patches.
, x; ~4 A! h; E7 J' Q9 L  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
9 J" W* y- w- J4 H  auto?           ;; whether or not this intersection will switch automatically.* Z" R, i: ^2 k& I* G/ I4 m8 I" C& d
                  ;; false for non-intersection patches.
8 @$ M! v! }& x9 ]+ g]
+ }0 ?( [) M' _- V5 x. T5 S# O! w! {
; n, ?0 n, u' F3 l6 r
;;;;;;;;;;;;;;;;;;;;;;# F) C# y3 k& g* K! k
;; Setup Procedures ;;* r  z4 H3 p* ?$ }9 F
;;;;;;;;;;;;;;;;;;;;;;
4 j9 `; x5 T  @6 }1 F
9 Y% b! Y/ T$ C& ];; Initialize the display by giving the global and patch variables initial values.
" w8 Q9 @2 g8 b+ f2 Y;; Create num-cars of turtles if there are enough road patches for one turtle to  f1 F. o, e& [- y9 z& H* |
;; be created per road patch. Set up the plots.% E# s3 I2 A$ H1 a" h) n8 `
to setup" ^: V8 C" G: {" h1 {& @
  ca
" ?, [, T/ k$ v/ k9 [% _  setup-globals$ h. M3 K# v8 q' B$ j5 _$ g

) m9 G5 T/ c. {' c9 J% n  ;; First we ask the patches to draw themselves and set up a few variables% ~# j# g. K5 ~: n
  setup-patches0 U" n# k. D5 ~; {. W
  make-current one-of intersections$ Y' c% E% L1 s0 z: u
  label-current
- f4 i3 G* s/ l. O7 q" }0 N/ e
4 U* i8 g) C8 B6 H* K  set-default-shape turtles "car". m6 N3 y  \; M; T4 }8 V1 M
, [$ V5 [  ]2 J% O6 n, s
  if (num-cars > count roads), d# F- L/ X* d) h& j( I, ^
  [
( n* r; D, W5 I$ a$ ?    user-message (word "There are too many cars for the amount of "
, ~- B: n5 z9 J8 u7 |                       "road.  Either increase the amount of roads "
! X6 T* u. b, H- E! t+ [9 E                       "by increasing the GRID-SIZE-X or "
  h% g) K8 R9 w7 J% `+ {) I                       "GRID-SIZE-Y sliders, or decrease the "; p" n) U- A* q8 B
                       "number of cars by lowering the NUMBER slider.\n"$ g) L3 J' H+ _" e( E
                       "The setup has stopped.")4 ^2 w2 y. c% _3 k" n; \. _; r: l/ i
    stop
) ?: U) v+ c5 d' G0 }  ]
2 Z1 x; {2 n4 B' o5 A4 u8 G! T6 t0 N; d: j! T# A
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 F# d1 _6 P3 i8 L$ }8 u+ E& E9 }9 h
  crt num-cars6 s9 P0 _  ]+ v" j8 O. B0 x' T# i' z. v# A
  [+ F# X% h+ L$ {7 t3 M, A
    setup-cars
; ]4 u5 Y7 c: G% T* w- d% I: J2 p( Q9 f    set-car-color* O" @# o* T5 _; ?5 g
    record-data4 X* k5 s  F" q! c0 d( Z
  ]
  i2 C) U+ y: e4 o* z" |. E; U- [" b) }
  ;; give the turtles an initial speed
. |0 }( w  e- q' D  ask turtles [ set-car-speed ]
; w! e1 X* B* A7 z6 W& Q; o, T5 r
8 @  L4 K: s! ^. n5 y3 @  reset-ticks
  A: @* k' u7 g1 u0 `end! O2 q! t& p/ m) E/ _
) x$ \/ l/ v* g& [
;; Initialize the global variables to appropriate values. W8 z0 A+ T  L1 @9 I9 }
to setup-globals
& q8 ~0 s; x4 o- S) ^  set current-light nobody ;; just for now, since there are no lights yet3 A/ |5 G# H- }8 v
  set phase 0# ~  ^* Z% e( \9 c# X
  set num-cars-stopped 0
! X; G) O  d" v! }, F) f1 j* W" j- _  set grid-x-inc world-width / grid-size-x
- B1 C# e2 B3 T  set grid-y-inc world-height / grid-size-y/ A, ^! E: X* \; u5 z3 C6 S( c

+ _2 _- x% B* Y  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary6 e) i$ h% o- L: Q' [; ^; N  u7 \
  set acceleration 0.0992 x9 b& o4 @( B
end6 p, O- T  [: x7 _! W9 m! [6 T

: V$ o  ~  F4 W6 u- \;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
' e- u, C4 J' q# V7 H- J+ D;; and initialize the traffic lights to one setting' j$ B3 a" r6 I
to setup-patches
( `" R& O" s$ g, _- S6 D. a3 l* o  ;; initialize the patch-owned variables and color the patches to a base-color
% y  {9 {& @0 R! @  ask patches1 p( M1 N# z* ^8 ^
  [
0 L; y# w2 A# @! y    set intersection? false! l' e; Q8 f2 v# Q2 I3 M( |
    set auto? false2 m# }9 ?$ n& z: H# x* c
    set green-light-up? true" F3 |0 D( f+ l6 o4 e3 ~
    set my-row -1
$ m$ S% V. t2 e0 E$ u    set my-column -1" [, @3 s2 V' I5 ^  V9 s! b' d5 m
    set my-phase -14 H+ n& O$ H+ \0 ~0 o# F
    set pcolor brown + 3! A1 P% J3 c: A
  ]
% B5 E  @/ y6 P
+ r5 ~2 i3 r) y, Z( Z2 t  ;; initialize the global variables that hold patch agentsets+ H1 N& ]8 T) ^! H$ ~& V
  set roads patches with5 h! ]4 |5 l9 @$ D. \/ n  R" f) ~. e8 R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 Z' G) K4 T5 u" E. X, v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* K- v% _9 d9 G& l8 N  y. A4 ?
  set intersections roads with7 q2 j& Y: L! v% z. \& T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ g5 ^1 D5 n& P. b- |/ h. P$ w* }
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ a7 w% ]0 [& ^- i
3 n2 V' O# h9 p2 x
  ask roads [ set pcolor white ]$ Q+ D) u. o) b' ?; `2 C
    setup-intersections
% k: r7 ^+ Q" ~8 fend3 G& ]1 B5 J( e0 F+ G
其中定义道路的句子,如下所示,是什么意思啊?
( h+ r% c6 A( U set roads patches with% C6 k% ^/ J6 i  E- A
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 p2 i+ ^9 [, U2 @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: D4 i- Q  t$ N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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