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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。
6 i* H9 S8 |" p: ^1 dnetlogo自带的social science--traffic grid这一例子当中,
3 \! R9 \5 z% U% x" D; D# I6 Y5 Iglobals
! e, u3 o; Q5 A- J$ Q+ d3 B[" Z, {  q# Y, L. @% q8 A6 j. S% P
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
; |% Y' v% G: g  ]! j4 b9 W8 l  grid-y-inc               ;; the amount of patches in between two roads in the y direction
& D. h1 U& ]1 w% x6 i/ ^2 T  acceleration             ;; the constant that controls how much a car speeds up or slows down by if8 _8 I5 H& u2 @: o9 O" R3 F
                           ;; it is to accelerate or decelerate
, p0 A( S% ?( T  phase                    ;; keeps track of the phase
( j" L1 O% h) v# M6 n: P5 }& I  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure' E: C% @) \. I/ R
  current-light            ;; the currently selected light; A, t! \& B( K2 `; _2 T
3 K# Y2 P  ?0 p% Z! n
  ;; patch agentsets
) _1 a! O+ r- E. e# ]$ x4 d  intersections ;; agentset containing the patches that are intersections
7 W' `0 d& Z# g. @# M6 x  roads         ;; agentset containing the patches that are roads
% f* L) L! q! n4 i# I% B8 S]' z7 W/ s) t: M3 G3 U( i4 Y% B
% g5 C  Z6 L  D1 b; M3 _8 g& L. B+ R
turtles-own
, U6 D9 ?$ l7 S- w9 w9 x* d. m* c[1 Y  J6 p# p; f- H# l4 p3 c3 x
  speed     ;; the speed of the turtle/ Z& `" N2 q8 D5 E: M- N! {  t
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& Y6 o- L: e8 s, b6 g
  wait-time ;; the amount of time since the last time a turtle has moved
$ n' Z# R# V6 A1 F7 p]( F3 g" _( B9 p, G
7 C+ ]+ u0 i' _& X) E4 K
patches-own
9 x. a$ Z# T- v4 O6 E[
) P- h* x5 d& _; @; Q  intersection?   ;; true if the patch is at the intersection of two roads: q$ [, D, `# u% g$ D: L6 t9 e
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.( L1 }- f0 @/ M) D& o  H2 `
                  ;; false for a non-intersection patches.
3 ?& A- q" {' A% l" @, d* |  my-row          ;; the row of the intersection counting from the upper left corner of the
. @/ y/ g% i! r7 k( c, O% W# \                  ;; world.  -1 for non-intersection patches.; H, r( X( u  c) D
  my-column       ;; the column of the intersection counting from the upper left corner of the
% ^# R. {; z7 t$ r* M7 f, a3 m$ A! u3 j                  ;; world.  -1 for non-intersection patches." L* E  m8 ^, G6 B7 k) t
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
+ u3 j5 F7 u& l  auto?           ;; whether or not this intersection will switch automatically.
* d1 Q) H' `, Y) q* S( [5 J- u                  ;; false for non-intersection patches./ ]& l; L) P1 t8 S
]' v+ U4 k6 f# O7 {7 w1 V2 v/ R

. U2 T% t9 s1 N% z
2 \% d! {% _2 J. t6 I;;;;;;;;;;;;;;;;;;;;;;* R- @# I% U) `1 H
;; Setup Procedures ;;4 u2 o2 j; J/ ]2 ?" F8 Q3 k
;;;;;;;;;;;;;;;;;;;;;;
, Q* v/ f# F6 y
: j9 K3 I' M( s" h3 F;; Initialize the display by giving the global and patch variables initial values.
) @% M' {6 e. u6 B5 j;; Create num-cars of turtles if there are enough road patches for one turtle to
5 t8 A" u! v# H;; be created per road patch. Set up the plots.  {9 ]+ F) j( d0 n7 m
to setup
* B3 {, O" ~7 M  ca# R( @. q2 G: N' _
  setup-globals
6 H* X2 \* U/ {) f0 u: f) U4 b+ a7 L7 A- s( h
  ;; First we ask the patches to draw themselves and set up a few variables% J* t+ q8 T5 m; |
  setup-patches5 e5 M3 j$ c+ }; j5 w
  make-current one-of intersections9 Y9 B: Q! p6 p3 E
  label-current
; O% L* ^" i, `; V( e& I  B" ]
! S7 ]$ p! w2 o- v  set-default-shape turtles "car"
0 K' c6 r) p  p, \! a2 h; B1 }4 @2 r1 w
  if (num-cars > count roads)2 @* k3 `, j. u! w
  [4 p/ [% a: Q) l& }; T1 @7 ^7 r
    user-message (word "There are too many cars for the amount of "
" B! C+ [* D7 C) f& s- }9 {                       "road.  Either increase the amount of roads "2 w9 Y5 |7 M& `  _
                       "by increasing the GRID-SIZE-X or "
" h$ q( Q% b' i                       "GRID-SIZE-Y sliders, or decrease the "0 N! A. _# |" T# O+ ]
                       "number of cars by lowering the NUMBER slider.\n"; v0 B/ [' _7 h0 i! S
                       "The setup has stopped.")
: P5 q  h' b2 ]: h: T) T    stop" Z1 c4 B% q- G* k
  ]: ]0 Z. l' ~  M  o9 V
0 v/ t- i5 Q* W7 S5 l7 I$ b
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color) m3 f* R5 L( U. q8 C
  crt num-cars
9 c5 m# d( S! K' y. S6 I  [9 R. E3 D& C1 z
    setup-cars
5 T: v" Z3 r  R1 A" a* f    set-car-color
6 c8 F3 z$ C1 V4 b5 ~8 @" D5 X  m    record-data
: D' e1 k& \. \, P$ ^  ]
; E7 `" K7 ^/ g. C7 ~$ X" K* g, Q+ v
  ;; give the turtles an initial speed
4 ?2 x; g9 G0 j4 z! Y8 }# T4 ]- d  ask turtles [ set-car-speed ]
' C2 @0 |8 U- ^. E3 P9 E, m9 y% T5 t
9 O5 C: ~, `# E  C" @) [  reset-ticks9 R6 E0 q/ o( |5 M) s
end+ Q6 F) q1 i0 D
7 [: K; j, t2 y
;; Initialize the global variables to appropriate values) q- ^" u6 y; M1 }; q5 e, a, s
to setup-globals
+ C& [1 P2 P0 X  set current-light nobody ;; just for now, since there are no lights yet  o- [) H: E" V& O: P" d: F6 c
  set phase 0
- z3 Y8 |; U5 G# i) {, p& a  set num-cars-stopped 0
% X# s- x5 }& T, b' L8 A  set grid-x-inc world-width / grid-size-x
  i" C7 w" t' K. j9 Y  r5 ]  set grid-y-inc world-height / grid-size-y
# i% T1 ~, D8 Z, k/ P# T
+ T! _3 X7 k5 u  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
1 K$ V$ {6 J- n  t' B$ t  set acceleration 0.0990 Z, i! s6 Y# G0 \  A: B: Y
end
4 w2 q- j$ h+ `7 Y7 V$ }; a( Y0 {/ Q8 G+ A
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 L9 H, p* s+ }, Z& [+ W& E1 _4 S! c' T
;; and initialize the traffic lights to one setting% v. O3 F' d: r6 U
to setup-patches4 `) [7 B/ R0 ?* U" L3 h
  ;; initialize the patch-owned variables and color the patches to a base-color; h& B+ ?3 ?& X% {# c3 [
  ask patches
0 F0 ?5 {8 L9 V2 K9 t  [" u+ K6 N& H2 u  m, G; D, G( U
    set intersection? false
3 X# a' F0 b, r* R4 s    set auto? false
, ]$ K3 G1 s1 ^/ I- J/ z% P) x    set green-light-up? true
) N& i8 T2 B' C+ F    set my-row -1
  o, p8 N8 C$ N    set my-column -1" O# u+ D$ y/ H, e
    set my-phase -1
- b( i2 C) H; i' l+ t+ c    set pcolor brown + 3
! }% c$ A3 n" o" a0 a  ]
% H  i2 h* |( t" M% T% y
2 m7 ]" {# C1 a  ;; initialize the global variables that hold patch agentsets. t4 t; ~4 [  G7 l6 R, R4 Z) U
  set roads patches with0 V5 W6 U" h& C1 ?* E5 g$ r% H+ Y8 ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 d" @$ ^7 y/ v# y; z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& _) X* r' f! E) ^; u: {
  set intersections roads with' o( w* [; |. \, @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
$ z  D1 {6 d- L    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: ~# q" A' ~3 j

) E1 h  T6 b6 A; `9 y  ask roads [ set pcolor white ]9 t! Y8 y  D# |% A* d0 ~
    setup-intersections( ]% w# T7 Q$ D6 n- A
end! ~- S. R  j0 {. ?( k
其中定义道路的句子,如下所示,是什么意思啊?$ w# }5 |; }, G  m5 l8 T/ s
set roads patches with0 L& ~( s/ a* B" m& L9 @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 @7 q0 [$ u$ X; w
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; C0 s+ I) s) S2 n' T* O$ 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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