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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。
8 f- ^( B( I3 i. Q- x: H; L  onetlogo自带的social science--traffic grid这一例子当中,' \4 d# w5 d* H0 j( q- m
globals
, ~' A5 C# ~0 }  t: L8 c[
- a# }: Z7 Q$ q+ N5 b: {  s  grid-x-inc               ;; the amount of patches in between two roads in the x direction
6 p+ _# a( R  h/ ?, q  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) z* x9 ^% ^! d7 C* `  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
& I; U- v! b/ y                           ;; it is to accelerate or decelerate
) W1 `' e) r# d/ d/ I  phase                    ;; keeps track of the phase" |2 y+ f( N+ h6 L% ?- a! q
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure0 B7 }# R' c! C9 Y/ N
  current-light            ;; the currently selected light
4 I% L- G  k) Q- z! b" r4 U- q$ C
" a, v& V2 m- b( f. m! `2 Z5 \1 v  ;; patch agentsets
8 m/ x. ^& E8 F8 M9 {  intersections ;; agentset containing the patches that are intersections
2 M& A# A3 I3 t9 t  roads         ;; agentset containing the patches that are roads( q3 v; l* E- Q4 ~$ V
]6 Y+ H4 u9 o5 {8 l% M3 |

% T3 q: V3 v$ f' M) b' Z! sturtles-own2 ^* E6 d( y# _
[9 f6 R0 s) o, |& R% x4 Y
  speed     ;; the speed of the turtle: X. T, H% T% C  x# e
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right3 s, i. R# f9 A+ {
  wait-time ;; the amount of time since the last time a turtle has moved
/ q1 v. ^8 O9 T]
% O, E& m, }1 B/ H4 q5 A& k9 \2 Y
4 d' T8 |% c% a( W& m5 hpatches-own9 l! v: G: ~3 u/ P& A
[  o( s5 u4 X) i7 Z* _" W
  intersection?   ;; true if the patch is at the intersection of two roads8 p- o' e/ ^  D$ y. j3 r$ N
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.( l2 |5 l' d- I* \
                  ;; false for a non-intersection patches.
) M7 F' E: ?7 `  y7 ?& f8 b  my-row          ;; the row of the intersection counting from the upper left corner of the* n* P% l$ w+ S
                  ;; world.  -1 for non-intersection patches.
5 e9 I9 m" o1 R; C  my-column       ;; the column of the intersection counting from the upper left corner of the
* f+ x7 K1 O5 z2 {/ I                  ;; world.  -1 for non-intersection patches.
+ H1 n0 Z* p& T) u: S' J  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.( N0 s. u+ w! ]$ g! E+ n4 r
  auto?           ;; whether or not this intersection will switch automatically.
" O8 F  c2 q7 Q9 [& s& I  i                  ;; false for non-intersection patches.
% B! [6 ?1 j6 w# L4 E" Z. H]# `) Z/ P) A) y- j( c. K

" n! z% O( ?: \3 T( D: ~6 I7 k- v6 J* q3 }/ ]( t4 Y. l( [; L9 I/ r- ^; n- Z
;;;;;;;;;;;;;;;;;;;;;;! u* h) |4 H9 t% C) G( x8 w
;; Setup Procedures ;;5 Z& h" D2 d7 B' h( T& a
;;;;;;;;;;;;;;;;;;;;;;
, B" i. w2 c4 e
3 C/ _% L7 L7 }; b. q;; Initialize the display by giving the global and patch variables initial values.
# e. G8 q6 J& f) U- ~;; Create num-cars of turtles if there are enough road patches for one turtle to
& U* Z# P. B: I2 w! h8 e;; be created per road patch. Set up the plots.; v' g, Z, N. b& h9 H; |
to setup
7 K  e  _/ H- {/ K  ca
/ b  R' h  Z& w7 i& W' D  setup-globals
5 h% c1 p" w3 V, Y  `1 b+ ?6 _- P2 R7 l2 r; z( }/ V
  ;; First we ask the patches to draw themselves and set up a few variables
/ n+ F9 X. p% J  q' u  setup-patches
6 y! I0 r8 z! I) `' b  make-current one-of intersections, ?$ C: {# S* L0 n; ]2 |# v
  label-current
; b/ @8 R0 `, I/ Z) E- `
# y( c3 `) u. T  set-default-shape turtles "car"8 ?2 w# i0 r& W  s8 [

7 w$ b- D2 O3 V* s5 ]  if (num-cars > count roads)5 C! y+ S2 h" V+ a# L9 @
  [
0 h- N3 Z* `; o: P8 h* Y5 z2 |    user-message (word "There are too many cars for the amount of "
3 z! P) y, |: J% r9 z# l                       "road.  Either increase the amount of roads ". h6 `) Z% ^% ~
                       "by increasing the GRID-SIZE-X or "
" B  o, l7 P. N: D0 ~; N                       "GRID-SIZE-Y sliders, or decrease the "
8 ?+ p0 `& l+ H+ S, J( G                       "number of cars by lowering the NUMBER slider.\n"
7 u3 d2 l" _. p; @6 z% B  Y                       "The setup has stopped.")
0 F, S9 w) h9 J% [    stop) l, j: |6 k' F- Y
  ]2 K# ?# C- [/ W9 o# s0 M4 s0 a
8 q( c% s) z7 F/ P
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color8 E) L) s4 l( B$ y
  crt num-cars: l* f8 u! G* F' X6 S' @' Z2 R# Z
  [6 e/ p% U( I7 r2 }% g
    setup-cars! Q$ n9 i8 v, M* A) Q  o' ~- [0 z+ h
    set-car-color
, H+ B$ U3 O8 r6 @6 e    record-data, x# E5 s; N0 S) K$ {! U8 d* _
  ]
2 f  k1 `8 z8 p0 ?' A0 E, r( Y% m8 g2 B% q
  ;; give the turtles an initial speed
) ]6 R' W( p* C) I& }  ask turtles [ set-car-speed ]
5 i+ @6 M8 z* i  b  N0 f# b
; y8 ?) ^* c" @  V% A  reset-ticks
8 a# L9 O/ b( |: R* i& U; {end* t( B1 D1 Q# O( J4 J* E
$ D# w! a( c6 H& }" |- A
;; Initialize the global variables to appropriate values4 S. ~  N% ~( g8 y# F
to setup-globals
' x0 O8 R1 m& l! s/ M8 w7 R7 L  set current-light nobody ;; just for now, since there are no lights yet
& c4 X( l* G# e) v  n% ?4 x  set phase 00 M1 O9 V/ E) T$ I9 u& N
  set num-cars-stopped 0( ^6 q+ J& \/ w1 F; J
  set grid-x-inc world-width / grid-size-x
! i7 W+ s+ }# R  set grid-y-inc world-height / grid-size-y5 Y  J; \" h3 C! K' z% [3 U
* ^- Z% l0 _9 ~+ {# _: X
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) |# G& |$ ^9 S/ C
  set acceleration 0.099
) u$ H5 W0 J! r8 iend
& v" n+ Q2 d4 k6 s3 |/ z9 g5 @+ u; S  q: r
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  ]5 d) ]( r0 J" r/ S  U$ `1 b0 Q+ B;; and initialize the traffic lights to one setting
2 O! @. m0 a% q2 T! p. Nto setup-patches
- j: G4 A. c) S- D" }, j4 U  ;; initialize the patch-owned variables and color the patches to a base-color2 G  {. j4 P$ b: h
  ask patches
, h( a& h1 a3 l  [( X) ^) \3 D4 M6 U  e2 E8 a, Q
    set intersection? false
) X2 d7 T, `0 C) j/ \- r' a: A    set auto? false) ^. x) W6 {7 G2 f
    set green-light-up? true, S0 }& m  o: P, C
    set my-row -1: v* P7 b& }3 ~
    set my-column -1
, ]3 C' r$ |. {    set my-phase -1
. J3 Q3 m' o4 ~. v* Q8 z3 j    set pcolor brown + 3
* V+ d& F# u6 K  ]
. K1 g! {) z8 n# U4 n2 z: |
( d+ N$ r6 i/ J( |1 V  v% d3 N  ;; initialize the global variables that hold patch agentsets& _% B9 f$ t8 B2 W$ P6 s
  set roads patches with" }( s; J3 C# P* T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- W! ?& k3 M  j" o9 Q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% L3 u) U* ^: o% g/ F/ G# I  set intersections roads with
0 a+ Y9 K0 G" f/ ^  N* }% b/ U  Y: [: a$ X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
* |" }* l. `" \6 X2 v- h5 z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 B# f2 W& _- Y: t; L! H- Y3 i9 u: a# f3 r8 M% @
  ask roads [ set pcolor white ]
' l5 n* f0 T/ k4 w0 _+ R    setup-intersections
$ U5 k1 Q, h* A" D; c* I0 @9 U6 `end0 {% W1 R9 ^7 j2 j" C, `" r( W
其中定义道路的句子,如下所示,是什么意思啊?( y% \; ]1 y( p# r' Q+ c! {* f
set roads patches with( }9 Y6 N# c3 R% ^' a. a, b9 q9 B3 d/ S! K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ v! f( ]$ q0 O2 k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; V5 @! I! K( g  @( A6 v+ A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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