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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。
1 U' ]2 D1 p% h1 V+ \netlogo自带的social science--traffic grid这一例子当中,
5 Y  T" r: s  _globals
- ^+ l# z) }  w2 G[5 J  j: M  @0 b: X! E
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
7 x' r8 F1 q. I: b' t/ B2 f' h  grid-y-inc               ;; the amount of patches in between two roads in the y direction6 {; N: v, W) }1 X4 U
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if3 u( r! o9 u1 W1 H9 z
                           ;; it is to accelerate or decelerate
! e3 R2 q+ C; X+ e" A  phase                    ;; keeps track of the phase. |1 G( ?, x" D" }- S
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure& M8 y" g' i& |, n/ H% r
  current-light            ;; the currently selected light
: ~- W) O" n8 z  m+ n8 Z9 j7 s- R- E* |! z$ C8 F, Q( o6 \4 \
  ;; patch agentsets0 Z6 m4 S9 a2 ~- b2 l$ J
  intersections ;; agentset containing the patches that are intersections
+ F3 g" t0 u" x$ ]* h9 y  roads         ;; agentset containing the patches that are roads
  A' @8 S; S# t; G+ |]7 F1 n4 S6 T5 D. D! I
- C( J- u( I& t# Y: Z! C& X' M( U
turtles-own
; f# Y4 {& |" {- O' G) i" `, n[' o' i! w% t# i
  speed     ;; the speed of the turtle! L! S( `# w0 ~5 b! H
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
  a; v9 b# l8 W$ L4 t6 }. V  wait-time ;; the amount of time since the last time a turtle has moved
- S; }. i. B/ G]$ x# v: H$ L+ N; W: C5 q' U" P' `- p
0 V0 p+ F5 H! m4 l1 I$ j) P# X
patches-own
) t/ e' `- H6 u' k0 W* f7 \[* s. j3 A. h6 Y4 C3 s0 i
  intersection?   ;; true if the patch is at the intersection of two roads
& ^/ |% \$ z% j( ^2 l. n2 Y: ^  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.8 y& `" @3 m, @$ R8 V$ d
                  ;; false for a non-intersection patches.+ X4 T2 \/ x+ q
  my-row          ;; the row of the intersection counting from the upper left corner of the
4 F; {: |! z4 Y2 r. f. \# P6 q                  ;; world.  -1 for non-intersection patches.7 c) q: _7 u  ?3 Z, C
  my-column       ;; the column of the intersection counting from the upper left corner of the
5 ]1 A0 S3 X0 z                  ;; world.  -1 for non-intersection patches.
+ j( X1 |% c* W1 P+ ^- @- J  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
8 ~1 t3 x. y6 M- J& l  auto?           ;; whether or not this intersection will switch automatically.0 I  g8 P4 K; ?3 l1 v- o
                  ;; false for non-intersection patches.
- \& x* \$ r' N8 ~]+ \, q" W/ `" J# p) r) W
" X! G/ `2 |. s7 O6 P

& Y# ?1 U& c( ?2 f) G- Y;;;;;;;;;;;;;;;;;;;;;;6 B& a( \& j7 g- d+ T9 Z
;; Setup Procedures ;;
0 H; ]( X, q1 |3 {; }/ O4 L+ T;;;;;;;;;;;;;;;;;;;;;;4 j6 w  m$ i5 u- S5 z3 t

: ~  S9 [3 E: H2 M$ i4 ~. @+ v' z;; Initialize the display by giving the global and patch variables initial values.
4 s- w  B8 O. G7 H5 g' J: n9 d;; Create num-cars of turtles if there are enough road patches for one turtle to
% l# H7 Q. U9 z9 p;; be created per road patch. Set up the plots.* Y) ~, n% Z, P* E" |' D
to setup- n- y' o- B: a2 J7 F& A" m
  ca
$ q9 X5 V6 C2 I0 i! }' T) P( v  setup-globals
0 I& r( x! W2 x9 u0 D4 ]  x
/ M! q0 F+ |5 t$ w4 b7 M: `0 a  ;; First we ask the patches to draw themselves and set up a few variables
8 M1 q( _' P3 j* @4 y* L4 b* |, I7 o  setup-patches
" ]4 C7 @2 }, g: M* D& T  make-current one-of intersections
+ V4 m# H$ b- x/ J) g2 W- n" I  label-current
- Q' u# R: ]) W6 }' k' t6 T) Y( v! [" a
  set-default-shape turtles "car"
6 z7 f# V1 {; n/ V2 b& t/ @6 Q: L8 n. T; a* Z8 j
  if (num-cars > count roads)* x% e3 Z6 x9 X" s% X. U
  [0 B6 K2 X/ C2 p. o4 j+ p" V0 s
    user-message (word "There are too many cars for the amount of ") A4 _  y( E+ {9 ]; T# u
                       "road.  Either increase the amount of roads "
# X$ O. w' Y4 D- t2 G: J                       "by increasing the GRID-SIZE-X or "
. |+ l+ Q6 R7 C* B                       "GRID-SIZE-Y sliders, or decrease the "
0 L: v4 f0 O$ m! J, G- K: G                       "number of cars by lowering the NUMBER slider.\n"1 B& B  x8 \# F- c$ O0 ^9 ~
                       "The setup has stopped.")
. Q! M* V+ r) [- ]  G    stop: G4 S/ a+ e$ k( `- F5 W! C
  ]
$ q* ^: F; Q/ v" F! |# k8 S) N9 E: a8 r- K# U" {9 t' J
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
) b6 F. \2 F4 ?! U( o; a  crt num-cars
) V& t  k  m5 C2 s4 ~, t  [1 t2 J& T" g7 R  S% T9 B. Q" p
    setup-cars* ^6 Z# p6 ~- ]4 |* P
    set-car-color
9 A$ k4 q$ |. R    record-data: D3 y6 _) U4 D" F
  ]' S* w+ M3 s; O

& {) {5 U$ c4 \6 F3 k6 z. Y, t  ;; give the turtles an initial speed6 d  k5 `0 [: f7 V
  ask turtles [ set-car-speed ]
$ h5 v+ [: t/ r6 U! w5 W( _) r* I
  reset-ticks
1 ]5 N' j: c. m; i3 ^end* y0 U5 I3 q4 w

4 |3 R8 I% Y: P9 R5 K+ d3 ^;; Initialize the global variables to appropriate values4 z, E7 X5 [: N9 k- w
to setup-globals1 m4 W! q# [9 z4 m, e- V; U# G' K% D
  set current-light nobody ;; just for now, since there are no lights yet& m. e; j2 [. w6 L0 D7 I6 O
  set phase 0
7 c1 _5 M% T& D" M! h  set num-cars-stopped 0
, V/ b0 K- u& |  @- ?# _) z3 s  set grid-x-inc world-width / grid-size-x" t0 o# [0 H1 ?' P, u
  set grid-y-inc world-height / grid-size-y
6 v& `, P* z# g8 q2 V) i3 U/ N/ [
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary2 P; J9 i( j5 H( \$ z: R4 O
  set acceleration 0.0991 D& q7 c. x7 M( x8 @# I1 c6 s0 h
end! }$ y3 c6 }1 h( B
! U3 H( _' D6 m/ n0 G
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,) s% h2 y5 B9 o1 W
;; and initialize the traffic lights to one setting, @; E. e) q1 J, y# L, C
to setup-patches
' Y7 p0 V2 |( a  ;; initialize the patch-owned variables and color the patches to a base-color9 {# V" t* C5 M. p
  ask patches
4 V' |! M: w* u, b8 H7 f. T  y  [
5 O) W5 T0 v. ?- ^% L    set intersection? false" s/ _8 @  G! L" U- Z9 c( S
    set auto? false
7 U! y5 t& j6 q4 y2 b/ T    set green-light-up? true
& N& D, W2 d8 h* U0 V0 ?4 G' ^    set my-row -18 U2 ~6 @. d9 r7 n0 \1 |
    set my-column -1
3 Z- q* y: e' _& G, U4 f    set my-phase -1
( y4 W0 o  ^7 S( r1 p* O9 e    set pcolor brown + 3  B5 H) v& s6 Z1 `7 F8 L  S' U
  ]
! {$ E7 c  F8 B) d4 _
6 t# ~+ b" O: O7 `' H7 M* E% J  ;; initialize the global variables that hold patch agentsets
' r8 ^4 X( c: ]. V. j) ?9 A/ x  set roads patches with; G+ O. x  l7 h# [. T6 ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- t; D& O' }. W, a" W5 l$ S* @$ W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 N+ T  M# c# k) k  set intersections roads with
# {# B- t6 S2 D; [/ @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
+ I& r, H& T% f; d! r' @& ^6 o- ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 z2 t8 m+ J/ o6 _5 e7 U/ \
& b% l$ g  L7 e6 ^( q
  ask roads [ set pcolor white ]
1 Z2 D' I$ t  |, D9 Z6 _7 g    setup-intersections) q" n+ j- O+ H
end, b. k) B+ @/ L4 H3 H
其中定义道路的句子,如下所示,是什么意思啊?
  a* x3 Y% L2 [- x8 Z" @% c set roads patches with
. l  z! K7 G5 _2 D: {8 z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 u# j4 [1 N' v1 [7 n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- z$ E( M) w) K/ s9 ]2 v* P
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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