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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。
$ ]# E+ f( w. _netlogo自带的social science--traffic grid这一例子当中,, m4 Y; G, ~+ m9 T( A
globals
. V6 p' p7 X, Q$ P% r6 X) z[
2 F+ L9 I! H  x6 _0 i- h2 n4 e  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, `! P- z% K9 i) V" E  grid-y-inc               ;; the amount of patches in between two roads in the y direction
( P& I8 Q  j2 @2 Q5 c2 {  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
- @) H: Y& H3 C                           ;; it is to accelerate or decelerate: f9 J% [! ^/ y$ s9 N( V* d: z8 R: I
  phase                    ;; keeps track of the phase
2 [% w$ x6 |/ _3 R9 q- V. P  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; j1 f1 u% O% ?/ Z8 L/ e, V  current-light            ;; the currently selected light& I# B, i4 e& T4 o1 c' F1 e

% P( E% ~) }/ c; E% x  ;; patch agentsets
, S9 |  t9 e8 P. M# H& Y$ v+ c  intersections ;; agentset containing the patches that are intersections
2 r: A2 i: `# [7 o7 r  roads         ;; agentset containing the patches that are roads$ \( Z" k% a; T9 B$ v
]7 a2 ?2 o; m; p1 h& y; C  V- H" ]" L
: B" ^  ]! _( L3 V
turtles-own4 g8 _& K  g# w/ [0 O/ t
[! a" h8 I4 K/ A9 \
  speed     ;; the speed of the turtle
# o6 E) X: K- M0 m- f5 `$ F0 S  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
! _" Y* ^+ O2 \  wait-time ;; the amount of time since the last time a turtle has moved
/ \% Y& r- l8 g, U]# H9 a* H) C8 S

/ W  [; s, q( spatches-own
, B' O6 `7 c7 o- P, b. Y[
1 E/ w0 s2 Y. v+ t4 o  intersection?   ;; true if the patch is at the intersection of two roads
, S, ~1 P5 L6 \  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.7 h0 {: J3 |" L8 i- ~% A9 t2 y0 H
                  ;; false for a non-intersection patches.
3 T. [; g) Y" D: `  my-row          ;; the row of the intersection counting from the upper left corner of the
. \9 e# m1 `+ @+ F, \) l                  ;; world.  -1 for non-intersection patches./ r  n: f8 u9 K' \, w: X6 O
  my-column       ;; the column of the intersection counting from the upper left corner of the
( S! t" e$ }) H  [+ }2 B, a0 U6 S& j                  ;; world.  -1 for non-intersection patches.
  ~1 ~9 z; |7 v& f  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; b( H) d5 \* O* D1 J  auto?           ;; whether or not this intersection will switch automatically.
$ f4 u4 i7 Q  U4 B9 H                  ;; false for non-intersection patches.
4 X3 P! I# Z$ |  @]
! H5 m) H1 B, b( r" l; u( @& G$ t0 I) j2 V

9 \. P) H+ T7 L! }! C6 k4 ^9 N, S;;;;;;;;;;;;;;;;;;;;;;
% A3 @1 E1 R! F/ I% Z+ G9 G;; Setup Procedures ;;
) f) t, k6 q) C: o# O( L;;;;;;;;;;;;;;;;;;;;;;, \2 m: g& N9 @% S+ b
) |, k( s0 S' D! n! [, ^' @, H; C
;; Initialize the display by giving the global and patch variables initial values.
- u5 L$ |6 w$ o1 _" @;; Create num-cars of turtles if there are enough road patches for one turtle to
$ E  N1 `9 o9 ?1 t; d# L;; be created per road patch. Set up the plots.
+ ]' q. k% U7 i0 R- F* a, n4 Kto setup5 d; T* j' I+ ~8 {# Z: f
  ca
9 b$ S  g, U# @) V9 A6 b  setup-globals
# n1 C( |! |8 T* d4 Y
) h% D( l$ `! U, g8 Q5 j  ;; First we ask the patches to draw themselves and set up a few variables
& C; u9 g% R7 f. j+ l  setup-patches
9 l/ o9 t" P. w: y( D  make-current one-of intersections
/ O1 @( d$ ]  Y& \+ u1 y6 j( c  label-current
6 }$ h9 V: v; h+ q( R+ V$ |- x. R. D3 G
  set-default-shape turtles "car"
. G; Z! _9 D! M
3 [: r4 I6 m+ |  if (num-cars > count roads)6 q  q- u. h2 ?4 e
  [
8 m4 H' ]1 G, U; q    user-message (word "There are too many cars for the amount of "- R& m& D7 q& l# ]# E- V5 `
                       "road.  Either increase the amount of roads "- [, R; M8 `9 h( @" a
                       "by increasing the GRID-SIZE-X or "
: f6 e2 R9 _2 }; ]2 F8 `; {- f                       "GRID-SIZE-Y sliders, or decrease the "0 ~" H* e$ S; R6 @; E- j8 u0 P
                       "number of cars by lowering the NUMBER slider.\n"
1 u; M; r! Y: N  b                       "The setup has stopped.")
% H; [% ?( m8 @7 p% a/ B    stop
! w9 Y: |: S0 ?% X) {! H* u1 A, P  ]$ _  l3 @0 b3 d: j2 C' I4 R

2 E) D, A: l1 P: i% t4 |  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 J9 u6 `; m  X; G* k
  crt num-cars
1 Q7 r) `5 y# C2 s4 k  [4 f- u8 U0 @, O4 n
    setup-cars
$ g- ?3 t8 V# X% D  i! K9 @; u! l    set-car-color. Q6 y& I1 V4 ?0 S2 m! _6 A9 B
    record-data
7 T5 ^4 t6 \) P. d7 e& _- Y% b4 H  ]# \! B8 `! S; \: D  G) d
- n/ l2 I* ~9 z: p5 h0 d
  ;; give the turtles an initial speed) |! f" a9 Z) L1 a+ H8 r
  ask turtles [ set-car-speed ]; @* r- z5 A( i8 B9 N

' b# T4 g6 d7 u5 k. j$ M  reset-ticks
; Y7 t  N+ J' X  [' k" Zend
# e8 _, l  s2 J' w% G; g  I1 G! c* Q$ `# i: `8 N
;; Initialize the global variables to appropriate values
3 X: _; j$ f- ~! \; M+ X( Hto setup-globals# [6 e% e: r; ~
  set current-light nobody ;; just for now, since there are no lights yet
# A- A* i% k7 e& P; M/ M  set phase 0' _  e; A( a7 V: b" u& O
  set num-cars-stopped 0
( r  _3 D2 b( y2 @+ j# n  set grid-x-inc world-width / grid-size-x( E) Y) G3 a) P% y" `/ P/ e) W0 ]
  set grid-y-inc world-height / grid-size-y5 c+ K3 @( y1 Y$ g9 \: E' n, O6 u) C
6 z& B& n2 ?' S# N5 U
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
# P! ?' D$ e) ~0 d; F' Q  set acceleration 0.099' b/ S* s8 v9 D; t. F$ i
end$ I( i2 t: b& `
# X4 y7 Q8 \, C
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
8 U: r8 z& I. d- t/ T4 F;; and initialize the traffic lights to one setting
* E) b. _. R6 h( B9 pto setup-patches* o9 H- c$ S9 a
  ;; initialize the patch-owned variables and color the patches to a base-color' K1 I+ [2 X# o0 r
  ask patches
. ~  \. E5 y& t* ?4 s1 f  [6 w" @1 ?: \) e2 d( O
    set intersection? false- h9 \- ~1 g$ N$ N3 I7 |
    set auto? false
: S" z) `4 ~4 @, f    set green-light-up? true0 t! X) z& @4 z! ?; Z
    set my-row -1
. n2 l/ N4 T' e( t* P$ z0 _    set my-column -1
4 r( h  Z3 r' |$ t9 ~, B/ G8 F    set my-phase -1/ t8 z8 u. a4 \- H3 P
    set pcolor brown + 3
2 V, q" [* C: r) J' o* A9 E  ]! @! I5 a3 d$ c, l7 M+ ?

# l6 `* ~2 `( m/ E; Y# m  ;; initialize the global variables that hold patch agentsets
* e% r+ n" P' G; p; u+ [9 J  set roads patches with1 X7 i0 v3 J5 p1 s% N9 q; |0 x+ c
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 z  n! |3 D' {: A4 k    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 |, b+ N* U6 R$ ^9 s* P* Q
  set intersections roads with
& i; A( I& w$ s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and$ f% D6 i3 N1 q2 V% U, h9 }
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* F4 s( A6 A& Q. c

% A) v5 I! M# e( Z  ask roads [ set pcolor white ]2 b9 A! }& W% n& |
    setup-intersections$ [. f( i( E+ z! P: A
end
+ L  x2 {- t, n% N1 ^其中定义道路的句子,如下所示,是什么意思啊?
9 k  d+ D  c" {1 a  u5 ?3 Z0 k set roads patches with. `: T/ d+ h% M2 ~
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* ?0 A( ~7 L- i+ s
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" l# a' v0 F( c( I+ g( ~* x: ~+ m! z' y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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