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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。  f. ?$ v6 M& ^
netlogo自带的social science--traffic grid这一例子当中,6 n0 x2 S& G  G. x; X
globals
: }% k. g% y/ L9 a8 L& n4 r. X) E[' Y( n7 G% u( H. u* a
  grid-x-inc               ;; the amount of patches in between two roads in the x direction* }( _" B8 k9 y9 I4 J6 m9 o0 H
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 ^3 J/ r  v5 }0 ^$ o/ L5 a6 g  acceleration             ;; the constant that controls how much a car speeds up or slows down by if' t5 P$ O( G' n6 h
                           ;; it is to accelerate or decelerate" N3 l. J. y" S+ e% q- z% q
  phase                    ;; keeps track of the phase
, ^& B) ~: L4 o* @* G  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure  q+ f  J* e0 c( v2 [  a+ O
  current-light            ;; the currently selected light3 Z% b# }; a; E% f
' g" w( a& M1 M: P, J8 B
  ;; patch agentsets
' C8 E. y9 [, c% k, ^& v$ N( Q  intersections ;; agentset containing the patches that are intersections
; _& l2 W" q" u2 j; W* f2 j  roads         ;; agentset containing the patches that are roads
- ^; N3 ~: C* m, s! b' C/ W5 b- x]( ^! ^4 ]. q2 M& k  x) y  ]

- S' ~" p2 K5 y  _+ a, k( k, ]: cturtles-own
8 h2 `! `7 K' d[4 b1 \, b4 A- {: i" Y' m
  speed     ;; the speed of the turtle9 ]4 ~. Y/ F5 \9 w% T1 X0 K% ^+ ?
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
  n$ m$ [/ u, m: C8 K; B  wait-time ;; the amount of time since the last time a turtle has moved. O( ^$ [% o" R* k% N& K) `% d
]6 T7 c! W) ^' W; z3 s! J& S

' E$ S& c- I! Cpatches-own1 F# A  T. @, [( i) Z- s* z- {
[
6 P" d% ~9 V) h+ B0 _% ?& }( H  intersection?   ;; true if the patch is at the intersection of two roads5 a: y# R" G5 w3 y& ~
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.; w- T1 A: ?0 X
                  ;; false for a non-intersection patches.
- H6 g% c4 q. E8 M0 M/ _4 ]/ l  L* ^; h  my-row          ;; the row of the intersection counting from the upper left corner of the& A% f% y2 M% Q3 J8 E0 r5 T% K
                  ;; world.  -1 for non-intersection patches.
/ }2 ?' q8 g) N8 n8 y3 {  my-column       ;; the column of the intersection counting from the upper left corner of the$ ^4 A4 l% T: Q& W* ~* B
                  ;; world.  -1 for non-intersection patches.3 g$ z4 [: z# {: Z! {* \
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
) u. Z0 z: g8 P: N& k: ?  auto?           ;; whether or not this intersection will switch automatically.
4 O- }% R2 ~+ l/ Y; S  W' p  e                  ;; false for non-intersection patches.
2 u  ~3 t- V+ C8 O9 I]
4 l* o/ g/ X" f8 s: {+ t2 a% e3 e
1 ^, {0 F. ?1 M2 P3 ?/ p8 l1 \2 k  P8 @
;;;;;;;;;;;;;;;;;;;;;;1 n$ ~/ L! c8 W* ?8 R. X% V
;; Setup Procedures ;;& c  u6 C/ u+ U% d5 l
;;;;;;;;;;;;;;;;;;;;;;
2 Z$ l& W0 ^) g) N! Y- C: |4 d$ G! i3 N" e2 ^' O/ [1 K: X: |1 d
;; Initialize the display by giving the global and patch variables initial values., H8 s/ _9 P5 X) i/ `
;; Create num-cars of turtles if there are enough road patches for one turtle to' y6 ?$ ^' y4 y7 g  W6 C1 M! h
;; be created per road patch. Set up the plots.
8 W, k5 b, _8 E8 O' F1 Zto setup
3 V5 w" w9 o; C. F( {: |" X" l# X  ca
) T2 o8 x* }7 W4 n" E  setup-globals/ K& z( ^+ E7 l9 D: l* G! c* y% k
1 ]! y7 w6 N, |+ I' r4 C/ o. v" z
  ;; First we ask the patches to draw themselves and set up a few variables5 |3 w9 r# {2 i  h
  setup-patches8 _5 h  q8 m$ J6 w$ }* u; I: _7 P
  make-current one-of intersections
+ L0 p4 a8 F" n' u. U% k  label-current
9 a! v3 p5 i% v; @& v  Z. t
/ `* e* e6 y) k+ e+ X  set-default-shape turtles "car"
/ \9 W, ?' C- Y+ ^6 D1 s# K
; g0 V( w/ ~) _5 m% d  if (num-cars > count roads)
% k5 P2 d( U8 O3 k% h  [7 q: H: n0 u. C& g
    user-message (word "There are too many cars for the amount of "
( ~# |+ e# v$ G: x% N6 Z' n                       "road.  Either increase the amount of roads "
( q/ }. o- q5 D% k+ I                       "by increasing the GRID-SIZE-X or "/ V2 A, q/ r. N4 W& z
                       "GRID-SIZE-Y sliders, or decrease the "
0 V+ K5 D8 \8 t0 a% ^                       "number of cars by lowering the NUMBER slider.\n"2 {2 }4 d! q0 y' I. ~0 ~5 K
                       "The setup has stopped.")
& o1 E9 e& w. V/ n( w0 G    stop4 }, r. w$ k% C# L$ R2 R/ r$ Q
  ]/ o4 H# A5 ^6 e) o

; V9 I0 K' n6 g8 I/ G6 b  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
- N1 H! x# R! V, C! \  ^  crt num-cars
7 R$ ]$ C% j* e8 F2 }  [, W8 t3 c; h$ _  v! h
    setup-cars7 k. H7 L' S, T, |, k  F# d2 ]
    set-car-color
7 ^  i# R5 J7 {) F& z3 U    record-data
( s# ]6 W! F! G1 J5 l8 @7 g  ]0 N( ]  x5 p; |

3 M: I2 E: p' M( O) h2 u  ;; give the turtles an initial speed8 S4 [9 R8 k: e7 h( M% S
  ask turtles [ set-car-speed ]
8 t- j! O: @. E; i! g* N' t, A4 W6 W) ^+ M
  reset-ticks5 S2 D$ w% Y( A
end
. Q% d9 q  h# u2 D2 G
' Y' c1 u( A, a) F- a( v# J& Y; h- d;; Initialize the global variables to appropriate values: \+ S6 X7 c- n+ e  I" t$ {
to setup-globals  q* a: c+ y) ?* ~
  set current-light nobody ;; just for now, since there are no lights yet3 l8 t7 ~) @$ r6 g$ f4 i+ P
  set phase 0; y) U: a- _% d- W' G5 u. g% ~" G, N
  set num-cars-stopped 0$ I/ H' ~, O/ p1 C# x# g
  set grid-x-inc world-width / grid-size-x7 q( S3 L) q4 s! }% [
  set grid-y-inc world-height / grid-size-y
1 }, B/ s" C5 a( R9 {0 E- h! @& j: c6 a3 K
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary. V* |! A6 {) S' r; z. D2 C
  set acceleration 0.0993 s( F" p, F" v% s( i. n# H
end1 [  C" q1 E" R& f. o

7 y6 n. U6 i6 z/ A;; Make the patches have appropriate colors, set up the roads and intersections agentsets,! E; Y! k' Q$ o1 h) Y) n& S
;; and initialize the traffic lights to one setting2 [3 a, N- s( f% H( l  n
to setup-patches
8 @3 W+ a) ^1 @7 _  ;; initialize the patch-owned variables and color the patches to a base-color  Z- a2 U" ~' C9 b
  ask patches
* N$ t' A' |: L3 e  [
. p' [3 n' ?! f6 J* V3 v    set intersection? false
5 I4 |1 Z7 ~- @: R* l! M    set auto? false
0 S. q# s$ ^$ ^    set green-light-up? true  p& Z& |  H. p. A* M2 ]
    set my-row -1. C# j& a: B. K5 X! ?7 u' J6 c
    set my-column -1& b+ L# \0 V6 e! Z/ @$ p% F( y+ d. T
    set my-phase -1
3 J" b% K- x7 {- w    set pcolor brown + 3( l1 C9 O: i7 j- g- X
  ]
# K$ p3 u% U& X$ E$ G& A6 ^5 {! Z6 p4 d5 {0 D
  ;; initialize the global variables that hold patch agentsets: ~% @8 O' M+ I9 q3 N
  set roads patches with
" j& B1 h% V, m3 J, H8 [) u4 {, \$ C    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( v* b6 @, n) K3 w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& M4 N  X  @" q  H" k- K2 _  set intersections roads with/ m2 v8 S! H7 w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and: Z: Q# U  I7 M+ b4 F" R0 I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& o; e& D; i2 r9 E8 n; I
. U. q) {: {" ^. p% e+ f0 h
  ask roads [ set pcolor white ]
, H7 A/ T9 c) G3 D3 q    setup-intersections
8 w/ K  I! l2 Q8 \: @) Uend7 K% d# u7 `$ a9 p7 v
其中定义道路的句子,如下所示,是什么意思啊?
# P) u) s9 I: @/ |; S% t% p) o set roads patches with
; E- W+ Q# h3 C    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ v. s5 ?3 |) c# p' S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 G( c0 s4 q2 z0 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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