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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 F# w; i2 [( E% a$ i/ C0 r
netlogo自带的social science--traffic grid这一例子当中,
% Y2 y' d: a1 p1 Pglobals: u- q2 a( y* M" U
[
4 Z: ^9 v2 ~! M6 H# i0 P' j  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% m5 q' s0 L- y, x  R! C  grid-y-inc               ;; the amount of patches in between two roads in the y direction
( P) d! t9 T7 G. `  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 U! A' _+ }! L
                           ;; it is to accelerate or decelerate
( o, y& t6 N7 b5 R2 F! q. s; j2 {  phase                    ;; keeps track of the phase' _( {; b( j+ F4 U6 S; ^+ c# b
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
. u8 E. f- B' y# x; Y! k, ]. `  current-light            ;; the currently selected light
! d7 u: U' `& P9 E4 z: c
5 y" q5 w% w9 Q, [  P/ _  ;; patch agentsets
1 ]) W- n# x- U4 [( d% r  Q0 d  intersections ;; agentset containing the patches that are intersections
: W, G4 J; Y/ O+ K  roads         ;; agentset containing the patches that are roads6 T9 F- M, @; f
]' O4 u. |4 _  ^% j( j) o

8 S5 E* o/ p) l7 W' {: s' mturtles-own
* O$ ?% Y# }( C; u[- v" @6 m5 t1 ?# h
  speed     ;; the speed of the turtle
% i3 w  L7 C! ?  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
9 g  [& Q) q6 @$ l  wait-time ;; the amount of time since the last time a turtle has moved& k/ N! M6 V; s- O* }$ D
]
2 L5 l2 n* l; R
( q, Q. ~0 M" I6 \0 F, Opatches-own
* n, t0 v; {) }/ V# }[- B. L% ?( @2 R" g/ s% n
  intersection?   ;; true if the patch is at the intersection of two roads; x; a% Z* F. m6 y. ?! K. E# L9 F) u
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.! ]  i8 G6 P( A5 J
                  ;; false for a non-intersection patches.
+ U8 b8 D9 r& y- e3 |5 S9 w& S  my-row          ;; the row of the intersection counting from the upper left corner of the. x& [& Y: v, p1 w  K8 W: W( l
                  ;; world.  -1 for non-intersection patches.
% r. G6 A( o, M. s% p# ]  my-column       ;; the column of the intersection counting from the upper left corner of the
& O& r( ]! a) r                  ;; world.  -1 for non-intersection patches.
! p: K& {3 N. o' Q  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.7 }8 L* T5 @2 n( O/ P( t8 W
  auto?           ;; whether or not this intersection will switch automatically.# B* d! [  I( `) G8 f) T& R( N
                  ;; false for non-intersection patches.
) f  E  ]+ i% i5 W7 x]
; q$ V+ q. c' v: K* M: V
/ a9 P! V1 n7 |2 K  A5 P  N. p. d: d$ K
;;;;;;;;;;;;;;;;;;;;;;
( a6 V& S/ t  I9 d& U;; Setup Procedures ;;
: |# L2 S; ?0 q- j" s;;;;;;;;;;;;;;;;;;;;;;) a1 i4 \* I. z% Q$ M

3 M2 H4 O0 E& f! s& ~7 w9 X;; Initialize the display by giving the global and patch variables initial values.
3 _" r2 K5 F: B5 u9 P4 m;; Create num-cars of turtles if there are enough road patches for one turtle to+ r! z5 x7 n3 W
;; be created per road patch. Set up the plots.0 S! T$ |/ F. ?9 I
to setup/ h6 ^7 I! }& l7 |  h6 \' s, F9 J
  ca$ g* u2 T$ r9 G- S# b& L7 _
  setup-globals
. x9 [8 f( Z' x! Y5 W+ M; V3 F
+ ^; T" j; \' @2 K' u- w  ;; First we ask the patches to draw themselves and set up a few variables% W4 I5 V5 F5 y- T# s
  setup-patches! B' \0 s7 N& t
  make-current one-of intersections
) h2 R8 `% ~. y; T. d  label-current! ?/ V, Z; `4 Z! T

% Z5 K9 w) z  s+ K  set-default-shape turtles "car"
% M! t' a: ~& e( ?  s3 S( z6 D* s5 R1 Y3 ?* }$ L
  if (num-cars > count roads)
/ _2 @6 x/ C2 k0 S  [
* ^) z) E/ P' |, b; ^  E    user-message (word "There are too many cars for the amount of ", p3 y4 O' N5 S9 w8 X. w9 a; |
                       "road.  Either increase the amount of roads "/ a" A' q. P" e
                       "by increasing the GRID-SIZE-X or "6 C# \. H6 Z6 M/ v$ {* `
                       "GRID-SIZE-Y sliders, or decrease the "
) G% F/ s6 _; I! Y) w9 }2 b, x                       "number of cars by lowering the NUMBER slider.\n"
2 k: }, b) G3 K: Y6 x3 m+ q. D                       "The setup has stopped.")( k# ~! ~0 J0 l" B( D9 a4 _3 m
    stop# w" U0 K# c  x4 H3 w
  ]0 ~) |# C: [7 T2 \

) E, ^: n  `# I2 I8 J9 u3 I3 i5 x  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' |# O5 r! O  Z5 k$ b4 Q8 e  crt num-cars" u1 P: u, x$ c1 L
  [
9 B1 g6 d+ B  N- Y# [" c* d    setup-cars
/ o/ z. {  o" h3 E    set-car-color$ c- C; K$ H/ a2 @4 e* H
    record-data
' k5 J! n5 V! g; ^' G  ]
6 Q2 B2 M. q8 u/ u) {! T' m( o1 o2 p5 `! A3 R2 l# L' F; W
  ;; give the turtles an initial speed! G0 h6 [# T) s: [- _
  ask turtles [ set-car-speed ]6 ~. w+ A6 l* x+ s' |' Y
" |* |+ g0 ^7 ~" {' M
  reset-ticks9 y; S. H8 R. |  X
end
  w9 v) X0 b: M- q- x, m
1 g- K' p. Y) b( V;; Initialize the global variables to appropriate values: H8 O0 p" m: c, b0 A! C
to setup-globals4 M& F7 A$ d# |( I' B9 Z; x
  set current-light nobody ;; just for now, since there are no lights yet
9 R! m' b# r5 ~# I  set phase 0
4 Z/ [, B3 ^- E" t  set num-cars-stopped 0; h4 s- ?0 s, }6 T
  set grid-x-inc world-width / grid-size-x; d- t7 e+ j8 r1 a) y! z8 z6 i
  set grid-y-inc world-height / grid-size-y
6 C( E/ A- h3 d- X
: T6 _: X6 h$ V6 }& N  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% R8 z8 H) _, g5 r6 ~1 X  f  `  set acceleration 0.099
8 H" |3 f2 ?6 Cend
7 R- ?4 y; \5 @' t2 |# y3 M3 g& o3 t" z& b$ {+ x
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
. {! o8 z' k+ q0 X# @. ?2 t;; and initialize the traffic lights to one setting
; }* W- x$ U2 _9 M. l+ M/ h% mto setup-patches
: i7 \. f, l$ r. j# i  ;; initialize the patch-owned variables and color the patches to a base-color' o/ ?; w' j) }" [' a# E
  ask patches! h. X; y& u, I0 e/ j: `
  [" ~3 S- ?$ S# |+ z
    set intersection? false2 d2 A9 C* }/ y4 A7 z2 o! z
    set auto? false# {; Z: R8 l) F. B  d+ q6 `  R4 E4 Y
    set green-light-up? true
) G, i! n2 X5 m    set my-row -1# x9 @9 f0 k; m) {! q) W. r
    set my-column -1
- z5 A7 o! w5 c8 _3 d    set my-phase -18 M( A4 G4 Z" z' a' b
    set pcolor brown + 3( i6 n& O: W6 O0 c7 N, W2 b1 y
  ]
# h* ^4 p% M0 g- Y) r# W: G4 @5 _/ z# Q' L! \
  ;; initialize the global variables that hold patch agentsets) |0 h5 z& V9 Y, P
  set roads patches with
: B1 G( A( ?1 Q5 @" F$ V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 j$ n+ }/ L* W- _    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 F- r1 B6 t$ m4 a4 M
  set intersections roads with! e3 e5 M5 h& W& w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and* ?- e! ?) w: @* ^$ J* U9 p5 l; L3 @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 l  @9 @9 [) u! b) c. ?5 Q+ F
5 Q% q0 k2 H" B5 {8 ?( e: A2 o. I
  ask roads [ set pcolor white ]' w$ E3 Y" P1 T1 d% ?+ x9 U
    setup-intersections
& l: z8 k" I9 I" V& i; Gend
- u# p" ^! h8 C其中定义道路的句子,如下所示,是什么意思啊?8 d! R/ K  Y) E; I- p" d4 O
set roads patches with# H) }9 f8 W& W, P+ k$ X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. o6 @0 N$ C6 _$ X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 |7 f; i0 R5 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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