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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。2 }" y! L- O. v
netlogo自带的social science--traffic grid这一例子当中,
4 k; }, p$ h3 b$ kglobals
5 Z+ |2 _5 o. K/ B  Y[
% ], ]% q' ^1 k# F2 i  grid-x-inc               ;; the amount of patches in between two roads in the x direction
) X' Z4 ^, [9 G+ G  grid-y-inc               ;; the amount of patches in between two roads in the y direction
" I4 p1 C6 Y  C  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
# g. V' }- q, k" a  k                           ;; it is to accelerate or decelerate9 `1 o+ F* ?" }2 l" W
  phase                    ;; keeps track of the phase
$ n& d4 o" B/ R/ \1 w5 k! s( N, s  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure% S  ^5 _3 B) l% |
  current-light            ;; the currently selected light
8 c$ i( n7 X* d6 t# s
- S  A  ?( ]3 Y" o  ;; patch agentsets
6 t. d: G6 O( A. H9 J3 p$ }7 \4 ?5 E  intersections ;; agentset containing the patches that are intersections2 l# o" }! s8 Q) a9 N1 z
  roads         ;; agentset containing the patches that are roads
6 c, }, G) ~% L. t% Z]& s5 L' a) Q. G7 s+ U
. ]. L1 n3 X8 C* @
turtles-own2 I( a7 w& S9 t8 V2 J6 G5 T
[
, [7 r  N, R! M; S/ f- g/ H  speed     ;; the speed of the turtle
. v2 x+ ]3 k. A. |# _  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: }- ?2 v' i0 z  wait-time ;; the amount of time since the last time a turtle has moved4 M  e- F' V9 c8 q% n9 B# O
]
0 w2 u1 ~4 i8 g0 D% \3 |& Q8 l& V" I" {2 r
patches-own
0 [2 S' m( n5 X% E9 G0 f7 P# r[
$ S9 o) z. R* m  intersection?   ;; true if the patch is at the intersection of two roads. n% G' J$ {$ v+ e# @6 z
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.' q9 y/ m6 v' u" h+ i  q& ~
                  ;; false for a non-intersection patches.
7 l! w- Z! f1 k7 J7 \& w" o, `. M  my-row          ;; the row of the intersection counting from the upper left corner of the
8 R( @) ]# h! w% _( w                  ;; world.  -1 for non-intersection patches.
( Z4 @' v" D+ J! J1 {  my-column       ;; the column of the intersection counting from the upper left corner of the' S- a+ M( I; p! [0 w2 V, B
                  ;; world.  -1 for non-intersection patches." D# {2 @5 z' ^+ @: Y9 C; K
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.6 M+ \! ^% r0 L0 }7 i# X! y
  auto?           ;; whether or not this intersection will switch automatically., p2 @( v5 l' G3 M$ g
                  ;; false for non-intersection patches.2 B- J1 y* w6 }
]
, p3 Q% c6 V6 x; L' r6 {' I$ S* K7 V; R

- O% \: ^  G0 O. N;;;;;;;;;;;;;;;;;;;;;;! }% _6 H4 u9 Y( N# \- }$ ?
;; Setup Procedures ;;; X6 V: L" ?* P& A$ f( t7 g
;;;;;;;;;;;;;;;;;;;;;;
  N' L- J: ]3 r- {) I8 p; {' n. o
;; Initialize the display by giving the global and patch variables initial values.7 y- l; Q, U: a% Q# w
;; Create num-cars of turtles if there are enough road patches for one turtle to
7 ^! N: ^1 j$ h. ^% j* f;; be created per road patch. Set up the plots.
4 w( p1 o6 l! |( I1 p- W1 vto setup- d; S0 Y8 m6 C" A% z" l
  ca
# x9 W! M" {7 A: h% ]  setup-globals! C# }& }" I) a: G; E
  Z" c, P5 I# G6 l
  ;; First we ask the patches to draw themselves and set up a few variables) U. r. ?& o1 H0 l: y
  setup-patches% H/ r# _3 N+ m5 B) _. O/ h. L
  make-current one-of intersections
8 m# M* I& Y0 }, i; j. U  label-current/ V  `* x& w  s3 ~$ r( C

' D( [2 J7 F7 R% I0 j2 j. x  set-default-shape turtles "car"( I5 A3 |0 R0 c  p, b7 L- X# _

; M/ D; g0 C$ `8 m+ D  if (num-cars > count roads)
7 J* V/ Q3 t8 {/ P, h" l* _  [
+ D  B( c, [0 H# t3 |    user-message (word "There are too many cars for the amount of "# j" w( N5 Y- A$ t7 M
                       "road.  Either increase the amount of roads "
# t: K. S- ?  m. `+ U, }                       "by increasing the GRID-SIZE-X or ": m% v+ X0 ^0 Q1 l9 p& |) y
                       "GRID-SIZE-Y sliders, or decrease the "6 E. e6 F& ?! u2 `+ B+ U
                       "number of cars by lowering the NUMBER slider.\n"
8 S% d, H4 _, a$ i& h                       "The setup has stopped.")! w' }  b  T* }  I8 G6 f
    stop
) K' K8 g- a4 @4 d9 p' b  K  ]
3 D( p6 |- T" S% l
% K0 p( |$ y+ \& X, W% x( t6 J  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: g+ F- o/ }% C3 a8 F
  crt num-cars
; Z/ Z/ u# y( x9 @4 L8 B  [, A& S- k$ I6 Z- @
    setup-cars: S0 C, ]) l# u$ J' J1 @+ Q; `6 y! k
    set-car-color
4 \# J7 M4 J; J0 k/ _2 ?8 G    record-data
7 x1 j2 ?1 ?8 S0 t3 x7 ~& O  ]
; e. C' e+ U# l$ n& G7 e! X0 i$ z. g7 e4 D+ T% P  A% Z/ e
  ;; give the turtles an initial speed& h7 L" u: Q8 s# ^
  ask turtles [ set-car-speed ]" h8 F$ L0 M1 C0 O1 N

1 |+ b) f& i. h# W, `  reset-ticks) I: n  f: D  B! e
end( \7 W* V  W, y+ G+ O+ ~1 J

# |. m2 ^8 `: }1 k, w) c& G;; Initialize the global variables to appropriate values
1 u2 [! T' t1 z# ato setup-globals8 t! |% j) X, A! @
  set current-light nobody ;; just for now, since there are no lights yet; l% h: j  U- N; [' y% g# q. s$ T9 x
  set phase 00 Q! |$ c3 N' b& l1 E: f* t
  set num-cars-stopped 0
1 f0 P7 [6 m3 H% B- D* e  set grid-x-inc world-width / grid-size-x7 E% U/ x0 u9 I$ I
  set grid-y-inc world-height / grid-size-y
  Z. K" F* F* ~9 t7 E1 V% P2 g9 H+ ?5 F/ B5 S: l9 a4 [
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
- n. U4 l0 {. V0 g; S6 A4 N  set acceleration 0.0992 l, S4 G; ?6 p. l' q
end3 I7 ^* R6 n/ Q( K  J, W
7 o* Z, Q+ l. |
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
! R) N) {+ c" v- g6 j& ^& w, H;; and initialize the traffic lights to one setting0 Y) b9 l2 f4 I: n& G
to setup-patches
4 Z' E" q* R/ C8 }8 m) g& z  ;; initialize the patch-owned variables and color the patches to a base-color
; i5 [! p! M: e1 \/ i  ask patches
; [  {8 D' X% }2 k6 q7 V, q8 E' m  [; Y, D) C. @7 l' ~2 p& c
    set intersection? false7 L4 H5 b) S; }# y9 b" b+ P' y1 [8 h4 g
    set auto? false
, D% i* ?# Z, y) _7 c: Y! Q( I    set green-light-up? true5 l! F2 h9 a: k8 T+ r5 C$ w& x, K
    set my-row -1
( |2 Y& D! \9 M0 p% V% P) C( }% n    set my-column -1
, q9 o- d1 X! w4 O6 N# y" D! u    set my-phase -1
1 _! t. @7 \& r& @; a7 K    set pcolor brown + 3& N* }) z4 r/ D3 [) I
  ]
" ^$ T* _2 m# e. N" ?! j$ \5 j! C7 L6 q- Z3 h- k
  ;; initialize the global variables that hold patch agentsets" k! {" N# g3 D9 n: p. Q  w% ?
  set roads patches with
! r; f1 m, U- i- l1 C  N9 O    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( I3 Z8 O' w9 m1 w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 H8 _$ m* G) @
  set intersections roads with
/ @# {: l- p0 _8 \8 G! z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and. i) [* }1 p: V- _; Y( D
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& |4 g& k. J' w3 \3 N& F+ N7 ~% o+ K
+ `. J8 a$ }$ i+ ?* {) E
  ask roads [ set pcolor white ]
1 P4 M/ r4 {2 T2 g. D) r. d( o4 `    setup-intersections$ K  ^0 B$ v% Q% `2 Z1 @5 D
end
* T: D, \2 K  k2 v, p- |: g7 D其中定义道路的句子,如下所示,是什么意思啊?, k& d( x2 o7 a
set roads patches with
* a* T( F5 a" b. _$ t2 F0 Z% I/ a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ \- e0 R2 m8 d) L( D* p& ]! I0 y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' y1 @4 A! M; p1 o7 ?
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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