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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。' I$ I  ]$ {4 }7 {1 t6 ^. P1 |2 l
netlogo自带的social science--traffic grid这一例子当中,& l7 Y# _1 ~- u* t
globals7 |1 n9 V7 `5 u+ n4 v' N4 L
[& h8 s0 a0 p  r7 C
  grid-x-inc               ;; the amount of patches in between two roads in the x direction/ e2 H" ]* [, w! s4 @2 D
  grid-y-inc               ;; the amount of patches in between two roads in the y direction, f! |: ^2 k6 c! K0 m
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
( y) s  E0 {' U- S8 _8 H                           ;; it is to accelerate or decelerate  s: W. P: k7 v9 o* y
  phase                    ;; keeps track of the phase- y. @' M" d  _: u4 c
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
) @* F: S9 ~# J  p* b! @  current-light            ;; the currently selected light& Z! y% C) ?6 i) c

7 D/ |5 G# r/ a: H. D7 T  ;; patch agentsets8 f5 m0 u8 |) S5 a! P. t( V
  intersections ;; agentset containing the patches that are intersections% \8 ~  i3 y' H$ G6 h0 [
  roads         ;; agentset containing the patches that are roads
3 j& {% D& m( H! O( M5 ~]
7 _/ V4 u% s: K4 S$ i5 P  i' l
2 T: G+ @, z. \- zturtles-own2 Y& K% \. e; v  M
[& ]/ m1 }0 S( u$ l5 b; {; t
  speed     ;; the speed of the turtle( s8 z( J5 b) ~; z& T5 V
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right- Z7 e, ]3 |9 R5 x
  wait-time ;; the amount of time since the last time a turtle has moved7 b" G. }  |$ P" _* j' F
]7 D: c- q+ K" k. G% r2 D. Z5 ^

, o. e" \5 A9 c4 p- h7 C# i# Bpatches-own
) s0 {( }+ F# L9 P[$ r3 q; Z' [- S- O1 p7 b
  intersection?   ;; true if the patch is at the intersection of two roads
0 M9 j# L( ^: h6 C0 k& f( i" V  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( x! d) _+ _$ l# h& X, d4 b& w                  ;; false for a non-intersection patches.: A4 K- T, i0 U
  my-row          ;; the row of the intersection counting from the upper left corner of the& A) h) q3 a$ [  x8 B' o
                  ;; world.  -1 for non-intersection patches.1 M  c! z) A0 u3 }
  my-column       ;; the column of the intersection counting from the upper left corner of the$ E4 x$ C* I, O$ X$ u
                  ;; world.  -1 for non-intersection patches., P/ x! l# x0 F* \5 o, x: D. [+ t5 |
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
5 I1 w: e4 r# t( A+ ?4 @1 P: Z4 [  auto?           ;; whether or not this intersection will switch automatically.
0 g4 J( w/ [. o5 N                  ;; false for non-intersection patches.
1 u' |! {/ C; t* n]4 i8 }4 s. Y, @2 j
$ m8 i! X: r1 ~
" K4 j' j1 ?! P0 o9 y' }) F
;;;;;;;;;;;;;;;;;;;;;;  |3 C7 H7 F3 k6 c! Y) t& w7 t
;; Setup Procedures ;;
8 i- `, E' `; v9 m3 m;;;;;;;;;;;;;;;;;;;;;;8 {" T& x" z& a* P5 u% n
1 `6 @/ X7 E+ y
;; Initialize the display by giving the global and patch variables initial values.: V! o  O  ]% ~. U" s* Y
;; Create num-cars of turtles if there are enough road patches for one turtle to: I+ {; o3 e- I6 p2 e6 w( m
;; be created per road patch. Set up the plots.; m) g6 ~4 t8 S% _
to setup
4 R, ?: X9 A, f- Y7 N, l  ca
" t% N8 p& ^' f& n, F$ Y  setup-globals
9 g' q/ D; _8 I' \  L/ w6 \) g7 m3 {3 u. H0 l* A
  ;; First we ask the patches to draw themselves and set up a few variables
( N! A6 T2 l. Z3 ]( j  setup-patches
7 i+ R- j" `) u* z  make-current one-of intersections  l* D4 s0 i3 R& T2 R
  label-current! J1 |, t, ^- q
, J8 ]; p# q+ ?! s, k
  set-default-shape turtles "car"  `" }+ o* s1 j" E& o" J2 N
& k0 b7 V2 V/ R( W+ k
  if (num-cars > count roads)+ O4 G; s5 m3 k  d/ a+ l% \5 ~: O
  [
! L- s+ K* Y1 x0 y0 T    user-message (word "There are too many cars for the amount of "; @8 E: T* ~; X+ O+ W2 v+ j- i/ v' H3 p3 G
                       "road.  Either increase the amount of roads "
, _0 C8 A4 i* o0 |* B0 j- P                       "by increasing the GRID-SIZE-X or "4 V3 t3 A# e; ?/ Z6 n" r3 Q4 h
                       "GRID-SIZE-Y sliders, or decrease the ", w3 s1 @# C( i% e& ?0 G  C
                       "number of cars by lowering the NUMBER slider.\n"1 `9 l) u) c+ G! Y! J8 @7 D: `
                       "The setup has stopped.")" x& X( k+ I/ t: m
    stop* l0 I$ x$ j+ b( ^$ H
  ]
9 q2 c; A/ g& I* M
" ^0 d" L& A% a' b* s. a6 l4 n  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
, {1 E# b) f- |7 ~  crt num-cars
6 D' H, e5 G* a' U; C- ~1 h  [
; i# o. Q+ e4 f+ O8 c- q    setup-cars0 ~  R0 H* n$ {
    set-car-color
# g0 o' E# _- b0 l# R    record-data
% R* V1 {0 x/ p0 p$ ]0 ~" v; a  ]
( [5 k1 @' |  c- s" S
. x% f& V8 s8 q  ;; give the turtles an initial speed
* y3 `! R# h; U9 y, H  ask turtles [ set-car-speed ]1 X9 x, r9 A1 j! R& P, N
4 j; W, N5 `! N4 D+ H9 {0 f
  reset-ticks- D. ~: F3 E1 h. o! Q/ ^- v5 l7 J
end
3 U& }: n+ N# o  I( {
* M6 ~. G7 U$ l3 A6 a;; Initialize the global variables to appropriate values4 `: c( z" W1 U: d' k' D
to setup-globals
: e7 g1 Q( C2 _  set current-light nobody ;; just for now, since there are no lights yet
, l3 W  q: v* D; s9 Y+ {  set phase 0
9 [' {+ Y$ m) L( g7 Y' F  set num-cars-stopped 0- U5 c, N" k5 I3 @; q+ B
  set grid-x-inc world-width / grid-size-x- g( Z% Q+ ~' }; Q0 ]4 B; ^+ [
  set grid-y-inc world-height / grid-size-y6 y! }4 k% O) e

# W' c- q) k1 @8 A9 x$ t, S8 p  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 i8 e+ d4 E5 N) ?- k2 v2 _; R6 p
  set acceleration 0.099
* T# V! j6 Q* Oend
! e3 X( l( ^- M2 a2 `! X+ P3 ?4 ?6 U; h5 @/ p! I
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,) ~" H# T5 ~( s( a; S% H0 f8 s
;; and initialize the traffic lights to one setting. E0 P  n1 b7 r7 |; G
to setup-patches
* g: P$ {* a( O  ;; initialize the patch-owned variables and color the patches to a base-color1 Z  U$ ~: e) @; O% r/ z
  ask patches2 i# T9 g4 F3 ~
  [2 _- r" y! H! I9 D1 @  d! F) C1 V
    set intersection? false
9 k! s" M& j1 N# p& k    set auto? false
$ ?- q; \- Q( ]  t    set green-light-up? true
% p0 ?  c! V* ~+ Q6 D* L% |    set my-row -1$ L3 a' B( S8 B: x0 R$ d8 d
    set my-column -1* T! ]* n: l  t! ], t
    set my-phase -1
1 `1 T  r6 Z6 a" Q/ r9 A    set pcolor brown + 3) W/ u- G3 n/ r* \# i  M
  ]0 o! H4 u* X7 z4 W/ R3 Y

7 ]1 j" c  G, \$ R% u) J  ;; initialize the global variables that hold patch agentsets; S' t/ B# G" J& I! x
  set roads patches with1 f- c  Q8 @6 U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* H- P4 ?9 n- J3 H- g/ ?    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. Q$ ]+ W0 E* I+ g
  set intersections roads with, ]: J/ d' b  {7 H% L& I8 |" P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" n4 x* W9 ?/ U4 ~. ~+ y7 f: Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 N! [+ r9 _6 K" [' P
3 r* r! t/ L) s2 b2 E3 |
  ask roads [ set pcolor white ]
! S6 |8 L1 ]4 k: Q9 y; R/ N    setup-intersections
6 E5 P! w4 t: q& V5 aend. k. }4 S( ~- z6 _  }
其中定义道路的句子,如下所示,是什么意思啊?
" ?7 F; y. s! P; y set roads patches with
) _) G, B& N9 `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) k# f3 I* _7 N! R
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. c+ ^% L8 b% y' p) J2 O5 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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