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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。
" o1 b& v  L' g! Anetlogo自带的social science--traffic grid这一例子当中,
, d8 J! _: j0 `" O/ F, Y5 @% nglobals
% k) |: N" b2 o: G; f[5 P* V* _4 c% \
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
3 t7 e9 S; r4 q  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! `+ m) u; _( j9 K  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
+ |, O4 ~3 u& l, w' }7 [7 v2 r                           ;; it is to accelerate or decelerate
! `, u% ?& h, P  phase                    ;; keeps track of the phase! D, g- x# o8 F. i) d; p9 o
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure- n/ w3 F1 n$ F* _( P
  current-light            ;; the currently selected light- i# S' \- H( A6 B% q8 [
' d9 x1 x) W8 u8 B
  ;; patch agentsets3 S/ _$ R6 c6 G& X+ `* G
  intersections ;; agentset containing the patches that are intersections
+ @# T  v0 k) t+ ^5 [  roads         ;; agentset containing the patches that are roads
1 v+ j3 i4 W0 c]: o( I0 l0 D5 D5 h
# N+ M. j" y$ s
turtles-own8 ]+ d+ t1 s& t
[
# {! x; x# G+ [! w+ x+ m  speed     ;; the speed of the turtle
- J. ]4 ^- \& I1 c, L  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
4 E! B* x1 w! q" x3 G  wait-time ;; the amount of time since the last time a turtle has moved$ f( x1 \3 ?( W( Q6 B) {
]
& q0 |" L# S/ y9 z$ L% M) \
$ l0 x' W7 `' A2 _patches-own
* m" C/ {5 t' c& L5 ?3 H2 |[
! X! }( `" h5 f/ q- B% N# }  intersection?   ;; true if the patch is at the intersection of two roads
" Q$ N8 D+ G# v1 y) {, W  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.1 }& f8 u$ Q" ]6 t* L$ ?  f5 I
                  ;; false for a non-intersection patches.8 {( p( c5 V% u  ^& x! S6 t) R
  my-row          ;; the row of the intersection counting from the upper left corner of the
) ?# A* z6 `) x5 a. q/ P6 E% w                  ;; world.  -1 for non-intersection patches.. c( `/ _3 u& v8 W8 B
  my-column       ;; the column of the intersection counting from the upper left corner of the
4 Q! m) K8 M  @8 C/ @                  ;; world.  -1 for non-intersection patches.
; V: s  o: ~* Y: h  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.3 E7 O4 [6 X) g" Q- I( `8 f
  auto?           ;; whether or not this intersection will switch automatically.8 o% Q! _! E: c% y, b9 u3 O* }
                  ;; false for non-intersection patches.& u( x* E' u! K* `
]! h9 ]5 z$ A+ E1 q
9 K0 p$ }* \/ X' N6 w

  C9 V( l; d! B$ b. u$ a9 @;;;;;;;;;;;;;;;;;;;;;;- ^, a9 R9 B6 s
;; Setup Procedures ;;
4 j. ^4 i1 R4 _6 Z4 @* X) P;;;;;;;;;;;;;;;;;;;;;;
" e+ y2 ~) n2 r$ ?) V; p( y' T* x4 Q+ E/ a# v0 B: c5 D5 T! L
;; Initialize the display by giving the global and patch variables initial values.
4 d/ ^- R1 O" ]! v: M  @;; Create num-cars of turtles if there are enough road patches for one turtle to
3 x. _6 F6 n+ }4 l7 e;; be created per road patch. Set up the plots.
9 y' \3 w1 I0 c. ?; }. |to setup* a1 R: S. I! u3 l; n5 B
  ca
6 f9 J/ g( v% z3 X/ ?. W6 [' X/ }  setup-globals! C3 }: ?$ J1 B/ q. N; W' c4 c2 |
. K4 K3 |' Z( t2 h$ z6 K4 H) n
  ;; First we ask the patches to draw themselves and set up a few variables8 ]7 X  L0 u2 @8 p
  setup-patches
) v& p/ l. r' [0 u2 y  make-current one-of intersections  ]5 P! T, b4 m; H% b, y
  label-current7 ~3 J3 l. Y+ B; _2 U! d7 U  j: T
, S, X  p+ x. \
  set-default-shape turtles "car"
$ `+ M( I; p$ B$ c
$ L5 e2 X# Z8 |3 Q  if (num-cars > count roads)) _- a- M4 D4 i! W5 M7 l
  [
' C1 S; @( X5 g+ J( }) \! M" K) j    user-message (word "There are too many cars for the amount of "9 j8 P% r3 P& P/ F
                       "road.  Either increase the amount of roads ", L" `$ v7 F+ n9 v
                       "by increasing the GRID-SIZE-X or "  l. ^/ D+ g* N
                       "GRID-SIZE-Y sliders, or decrease the "
" `! C+ {+ X! T/ {! J                       "number of cars by lowering the NUMBER slider.\n"
$ ~/ H( h1 d) Q$ r                       "The setup has stopped.")2 V" o+ X1 |/ I2 [6 p
    stop0 Y- X) h. o* ?2 Z/ G
  ]
8 N( z# g4 I4 T5 C* T# E
4 p0 n, x; Q+ c' Y# d/ _  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color' Y2 H- {/ v1 L( {7 @/ }4 X
  crt num-cars
  d& t8 m5 \# y& J6 e+ I  [
% F2 l! B( |' h. l, Z    setup-cars
3 y' S# D- X# F$ a    set-car-color
6 g6 Y8 w! m  s& S7 {7 d% j    record-data& V, N/ G- U+ q
  ]3 M6 o, W9 `- d+ O, H

) r" f* P5 n, P( y5 j: U  ;; give the turtles an initial speed1 S3 i: K# K1 \+ c2 a
  ask turtles [ set-car-speed ]
  y3 W9 c% r& J; d5 J5 U& G4 Q( ]! q% B: I% y3 x4 _( `* _# y/ R' v
  reset-ticks
/ ~, B! Q5 ~% D: u% I2 [end
; ]. T3 G4 s. w1 f; e2 P! S
) l. q( ~$ A9 p$ T5 x# `) P2 s: O- ^;; Initialize the global variables to appropriate values
0 u6 }' P1 Z2 Y6 u! J) Dto setup-globals) i5 t( W0 \8 U  X# T: T
  set current-light nobody ;; just for now, since there are no lights yet+ B- Z2 }) V% L( E2 o1 d( V
  set phase 0) J. u. h* }* I# o* s' J8 D6 h
  set num-cars-stopped 0
6 n$ S2 B  c: T% g/ U  set grid-x-inc world-width / grid-size-x
2 s% |( Y; O7 V, s$ P' m  set grid-y-inc world-height / grid-size-y
! D* R* m" R3 l- R" V  [9 @' }1 g1 d* z. X
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, {, a( e  _& L5 f  `/ d" `! R
  set acceleration 0.099
4 n4 j  m/ J( Y; g; @3 Oend
1 [5 |& b3 h% E' B% H9 H0 ?. s6 |9 H2 T; c3 n  a
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,2 H9 z' ]4 A0 h+ J$ S8 b8 `7 A
;; and initialize the traffic lights to one setting
. V  G% j* U/ c& `: x6 E& @to setup-patches1 I- j( ^! J% t, I0 B3 S- ^
  ;; initialize the patch-owned variables and color the patches to a base-color, Z$ `, I8 R- M* j
  ask patches
/ i9 R5 ?4 O, Z/ G  [1 a1 Z& T8 p+ V+ y
    set intersection? false
$ n( z- L. R& w( G# G$ V) i6 b    set auto? false
' e$ ?; C! y3 c2 _& N- k6 a    set green-light-up? true
" d* t- I  W. J    set my-row -1" ?5 @, g" l/ v0 h2 k) ?; _
    set my-column -15 j, ~; O! ~; o
    set my-phase -1
& z2 V. Y3 p9 C# G7 u, S9 g    set pcolor brown + 3) }# l2 C, t1 X( s9 Q( e4 N
  ]
7 y/ t7 S  F6 g0 F  }  t1 r6 K9 x" |
; d; h1 k5 K  ]1 Q  ;; initialize the global variables that hold patch agentsets4 U* S# C. ~1 H1 P
  set roads patches with
. t3 X. T2 e4 m: N    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  K( }; M# p0 a1 Z3 h1 D( C7 x
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 k0 U4 h9 E% p2 h: E  set intersections roads with0 `) r" q- B5 d9 u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
9 _) e9 C/ L1 v( u/ r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# ^! c, d- k4 k

6 v$ |1 i- i+ T* f4 }) @$ @  ask roads [ set pcolor white ]8 a7 }3 x) Z2 D- R( e3 X
    setup-intersections
1 k. ^9 P1 G! c) J/ }1 _0 [" g  p( Qend
2 t) G) W/ K" q( ]6 e其中定义道路的句子,如下所示,是什么意思啊?
1 h! \% B+ t$ V/ C- M set roads patches with7 f/ ]8 H) F6 w' ]( m: [1 d; K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- F2 L0 L& x' u, d7 t  E; {% M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- e; d0 `: T: C8 w+ T% y+ 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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