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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 t( s+ ^, l$ B# V- h0 G$ ?- B3 T
netlogo自带的social science--traffic grid这一例子当中,
. s' |0 C# F, c6 p& `" ^$ Jglobals
5 O; ~" ^( O) _% {% _[, X/ s4 N8 h( y3 f) n
  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ S5 `7 Q, E% W0 f, H! S4 G' Q
  grid-y-inc               ;; the amount of patches in between two roads in the y direction# x8 j4 ^6 `1 A6 E9 k. Q3 e
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
5 g3 N9 d% p( e$ D' Z                           ;; it is to accelerate or decelerate
) K8 _5 z; q+ S4 f& u  phase                    ;; keeps track of the phase
. }. F, G6 j. s  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
( P( C7 I+ G# `0 s; g& a" Y  current-light            ;; the currently selected light% u4 I8 H; Z$ k: {5 [$ k. M' d1 h

  @$ O( Z4 w$ e4 b" w  ;; patch agentsets2 g7 A2 Q# }* x; L9 h
  intersections ;; agentset containing the patches that are intersections/ S5 r" U& L1 T; A/ n+ q/ A
  roads         ;; agentset containing the patches that are roads: Z# w6 X8 F  D8 f3 t: Z& O
]
( P: i+ L% ]/ e' e  m% O
% M# l! X- o, X1 |4 `5 g  `turtles-own
3 k5 }, i7 o7 y3 E1 c; y; g* d/ ?. ][
5 v- t1 g+ {+ ~$ E# c1 ^  speed     ;; the speed of the turtle
' C2 Z. j6 i- R2 c! H  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
) L9 {  a- z: M+ L# O) K0 R: G: i! V  wait-time ;; the amount of time since the last time a turtle has moved% }* s( ^8 p# l2 L2 B% S  K$ s
]3 n1 x) E  t: U) v! G: J

% ]0 o' j, K: |+ S; r8 Ipatches-own, c3 P3 ~: f* j3 g0 b2 g' {
[
( j* X# l) D9 S/ G/ D0 A  intersection?   ;; true if the patch is at the intersection of two roads( f* q& O  o* @& `* i
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.. x7 H& n# Q) L' y
                  ;; false for a non-intersection patches., j5 U; _) F4 X8 n) o
  my-row          ;; the row of the intersection counting from the upper left corner of the0 o6 B$ K. K0 n; ^" Y) Z7 R
                  ;; world.  -1 for non-intersection patches.
8 i. ~& I$ @) t9 C# [1 s: d  my-column       ;; the column of the intersection counting from the upper left corner of the
2 h! u* [* o( M& l' ~5 M. [                  ;; world.  -1 for non-intersection patches.5 i* h$ i& A0 \+ e/ [
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.2 t0 m% L6 d6 c, W2 g
  auto?           ;; whether or not this intersection will switch automatically.% h1 g" U# d4 |$ a0 _' `
                  ;; false for non-intersection patches.6 K. p# V9 W" S; `5 T
]
4 {& b/ t8 E0 ]5 `9 @
1 s7 O) r% ^5 s1 {: C& V  W  c6 I  _6 ^  B+ ^; N5 M6 L. y
;;;;;;;;;;;;;;;;;;;;;;5 Z- B% X+ }3 s- J
;; Setup Procedures ;;& t+ L" l) H. [! j* `" q! T' N
;;;;;;;;;;;;;;;;;;;;;;' T# [8 {3 L( C& W# `- g

" o9 Y! l; @- P  V/ P;; Initialize the display by giving the global and patch variables initial values.
4 O( o. u! n+ L& A: v;; Create num-cars of turtles if there are enough road patches for one turtle to- s! |0 N: U( c) }. E
;; be created per road patch. Set up the plots.! {0 o! d0 c# _+ h8 f  y& a: X& b
to setup& Q1 ]; r0 e4 z0 e
  ca$ `4 }+ ^! \3 h: S) E. V+ s9 @
  setup-globals/ c% I% r6 u- O6 N7 o
3 B: ?" P4 X6 }; ^
  ;; First we ask the patches to draw themselves and set up a few variables
8 ?& F! l: |6 A4 {. M5 v  setup-patches
% |: S$ p$ _4 k9 E* ^( }  make-current one-of intersections: M6 c0 E+ K& V9 Q0 T
  label-current) N0 O/ v; k% u0 b7 O# `5 w, }

, w* z& r7 ~; T+ t8 C1 d  set-default-shape turtles "car"
! O: {, `; O8 J
5 Z5 D. ?6 B( \$ c) b3 Z7 z  if (num-cars > count roads)
1 h5 r7 ?8 n9 l% o3 r5 t  [- S" M& {) D$ n- b9 t5 m
    user-message (word "There are too many cars for the amount of "4 |, ?, y+ L7 F6 J! \/ @
                       "road.  Either increase the amount of roads "
. N" l6 `& x% R6 M* ]" ~5 z" W                       "by increasing the GRID-SIZE-X or "
' ^8 _3 Y1 o& j  c6 f" H* b                       "GRID-SIZE-Y sliders, or decrease the "
. e- o% Y# i" N                       "number of cars by lowering the NUMBER slider.\n"0 o' Z5 U: O7 p$ i
                       "The setup has stopped.")
3 P+ ~. E9 C1 C; E; y8 V7 ]    stop
- }% h0 `7 K! E! Q, f+ v% Z  ]0 u4 S7 J/ O0 L: o$ p7 ]& ]* V

5 Q0 P+ s; C/ p1 u7 k+ o- [+ ?  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' `7 o& {: U( y3 A2 o  crt num-cars1 ?) J. s0 u) v0 [2 @
  [, b1 m# T: {/ |, ^, I) d3 V
    setup-cars6 ]- m8 J4 X3 }3 z. N- g! d
    set-car-color" K! U; T! P- g3 y
    record-data
. N; a" T/ Z+ A5 a2 @  ]7 K2 x0 R( Z3 ^3 N

8 N. f+ n0 u2 G) V7 A2 T3 H4 r  ;; give the turtles an initial speed) ^1 s- u0 h6 ]8 d0 h+ e8 e
  ask turtles [ set-car-speed ]& u# G# z$ |5 E1 Y/ l% z$ I% t. r

* z: l& E& D( ~  reset-ticks0 P  R1 U( `$ l' ]
end7 d# h1 A) ^9 W5 ?* t6 h
9 T. Y6 b, R" i
;; Initialize the global variables to appropriate values2 ^0 j7 }/ z) x
to setup-globals
0 ]- h  l5 O. f! f  set current-light nobody ;; just for now, since there are no lights yet
$ C  _  k2 w( V9 x9 F& }  set phase 00 T, f7 {& o; W! @7 s
  set num-cars-stopped 05 `/ {7 P) G+ ]6 }0 d* T$ d
  set grid-x-inc world-width / grid-size-x
; O: s' E+ Q, m  set grid-y-inc world-height / grid-size-y
) R# p7 Q9 b: t% m# G/ I# v; [$ v$ u/ Q- }) c
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
/ F. s( }( E9 g7 [8 u" y  set acceleration 0.099
4 ~  G2 `! v0 o. _8 dend' O# O! c: ~! y( M2 f4 ?

0 m! F7 t2 t4 [8 K) W;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
3 H9 N5 n3 J7 l3 \/ x$ f;; and initialize the traffic lights to one setting
8 @/ L7 c5 d6 |7 f, _to setup-patches  V9 w) \. a2 \) f+ f
  ;; initialize the patch-owned variables and color the patches to a base-color
% R8 s, h' y/ k3 a  ask patches" ~' G% Q! i$ r; m+ L% m) C
  [
# N% \1 y6 N. z: h- Q" J: F3 A    set intersection? false
1 C) J2 o% y6 {; Y. j  B. J+ x    set auto? false5 x0 F$ v8 I3 \
    set green-light-up? true
( X6 D# K' |+ p3 c    set my-row -1+ Q6 t! r( h! v- O. M' e
    set my-column -13 N% s# D7 Y7 n& c
    set my-phase -18 U: y  Q/ [2 H* E, s
    set pcolor brown + 3
# s5 j: K, S( \  ]& D, u! R0 C) [
+ V" [* H9 V4 [2 A' l/ M$ j
  ;; initialize the global variables that hold patch agentsets7 t' j8 {4 z, K, t5 ~
  set roads patches with
3 b0 ]0 {& A# {. x, `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' K4 e* s6 d: B+ T( O    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], o; d, k, e8 G6 u; f# y. ]0 O
  set intersections roads with! _5 J* N5 K0 t; l1 q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and3 x. _6 Q1 s- a3 b- U# i* Z; s. A& E* z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 m3 k% t1 x0 \6 I* @1 f+ ?3 j. G

# ]2 d+ u" N# ^( p$ B4 ^  ask roads [ set pcolor white ]
% C6 M* C) {, {; }- R' u9 ^& i    setup-intersections. t8 w4 s, }9 p$ }
end. ]. g3 Y4 _% n
其中定义道路的句子,如下所示,是什么意思啊?  C, b9 T: M4 n, H( e
set roads patches with2 M, j) A5 j+ B% `1 ~+ c
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( e& Z1 u8 f3 A) ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; s% D' b0 q, g2 d3 }
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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