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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。/ a' O- ?8 u2 ~1 t4 ~
netlogo自带的social science--traffic grid这一例子当中,
9 O' f+ D$ t) y, vglobals2 j6 O/ q: Z, Y5 \9 d3 q1 l
[6 Q2 G+ p, B2 L
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
! J% \* z' I7 V7 ~  grid-y-inc               ;; the amount of patches in between two roads in the y direction
' F" N$ Q! [6 ]0 v( m' R  acceleration             ;; the constant that controls how much a car speeds up or slows down by if- }0 s* b0 _& O0 k& ]$ l
                           ;; it is to accelerate or decelerate/ S/ e2 c$ c6 B+ {" R' e6 U
  phase                    ;; keeps track of the phase8 S- g& ?, I$ b. ]/ C% H  n
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ K0 F. y( t0 S4 L; B+ k4 T& o  current-light            ;; the currently selected light9 q0 n, \* J' R+ ?

4 l' i) K: K7 C  ;; patch agentsets
1 J+ |" _# Y! P, O' y  t, {4 O& w  intersections ;; agentset containing the patches that are intersections
  o8 U5 {5 f7 W0 l  roads         ;; agentset containing the patches that are roads3 }4 S- q$ G+ F' c: ^; ^
]1 N! F. J6 i; b0 H8 }) l7 y9 V
8 e1 E0 {% L1 c
turtles-own5 ?& D3 L* _7 D( j2 t0 u& n% q5 R. H
[
6 M! X8 ^" w& @  speed     ;; the speed of the turtle
! x6 {( `  n- K  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: n# H% I- d& G$ M  wait-time ;; the amount of time since the last time a turtle has moved
& J* b- h) [  i  M* f]
! g, ]8 j0 i- d: [# I. m3 U" j' x+ f) R2 Q+ @
patches-own
' \3 N4 x+ f% c& [) }0 ^[- Q! g" I5 q( p) Y# z2 L
  intersection?   ;; true if the patch is at the intersection of two roads. l% l/ o4 g4 ^9 R" X
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
& U. b9 u5 @& V3 D                  ;; false for a non-intersection patches.. ~; i" |5 q4 k. m' D" ~9 ^# y) q+ c
  my-row          ;; the row of the intersection counting from the upper left corner of the
! _2 O7 I$ H0 W8 ^1 j                  ;; world.  -1 for non-intersection patches.
4 M( q, o' U; x) ], |& y; y* m  my-column       ;; the column of the intersection counting from the upper left corner of the# F. e) K) Z( J0 ^
                  ;; world.  -1 for non-intersection patches.* r- v# n+ o" B* _/ d
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  E3 z2 Z9 x2 o- P6 P7 a9 X  auto?           ;; whether or not this intersection will switch automatically.
- e6 c# r$ I- W7 R9 C8 J; w                  ;; false for non-intersection patches.( C! s- c) n: g# X; s% U9 Y
]
- L& ^& {- s: b' p' y
! P# I0 d2 }7 H* X" _6 w) `0 T: \
8 z  A! k+ l; o;;;;;;;;;;;;;;;;;;;;;;
* C; v; A; A0 B, Y. y;; Setup Procedures ;;
; K2 `9 n  U; V4 E) t) A) K0 a7 [;;;;;;;;;;;;;;;;;;;;;;
$ M/ r) B* b: ~$ c8 \! t9 Y0 m) B: v0 L* }! B) v6 b3 g& f
;; Initialize the display by giving the global and patch variables initial values.
$ Y) i) J7 \) {;; Create num-cars of turtles if there are enough road patches for one turtle to
9 s6 e9 q5 y! Q& b8 N9 H;; be created per road patch. Set up the plots.- J  ]; }( Y6 L! H7 u9 J7 r
to setup& X. ~" C' `0 h/ `' j
  ca3 l7 D( d; l+ n3 r
  setup-globals
1 q$ o, r1 S( Z" Y
( d" c7 j7 B( c  ;; First we ask the patches to draw themselves and set up a few variables" G% i( O& |5 p* f
  setup-patches+ P, j1 R2 Q9 ?
  make-current one-of intersections& L  b) Q& d. k: Z8 W/ i! N; J
  label-current+ ?$ S1 W( h. b! ~# n( b1 r9 E

! {! m  e; A8 r! M  set-default-shape turtles "car"
: }$ \- q+ p. R% |0 o' f/ _: S# `  d3 x/ }  p& D1 @- y( _
  if (num-cars > count roads)$ C* h  k4 K8 f  p' D9 E
  [
  {! q* i6 x6 T% j) n. S$ `    user-message (word "There are too many cars for the amount of ". c" ~# a  v. h) I
                       "road.  Either increase the amount of roads "
9 s# o' d- M0 z- x7 T                       "by increasing the GRID-SIZE-X or ". T6 P" I& z4 L# O" f) q8 f# ?
                       "GRID-SIZE-Y sliders, or decrease the "
# z* N' F# R: }, N* L$ _+ U3 d                       "number of cars by lowering the NUMBER slider.\n"7 k4 k; \& |! e( r  u6 m  b% Q9 a
                       "The setup has stopped.")- ?' _+ c4 k0 ^; l1 O* d4 J
    stop  z) ~+ }8 N+ U' H, M4 S$ @
  ]
& G5 [/ A% [. }0 r% p/ M! N+ S4 a/ @  E! a6 m/ o
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
7 J/ r0 R0 q! @5 Z2 b5 ]  crt num-cars
+ I0 w9 e4 g4 p3 i6 D5 J) @  [; T2 |$ d: ?: L+ @7 r
    setup-cars  \- q5 l7 u7 R% M) l/ h
    set-car-color
9 ]/ i& H! M! O& [, h2 g  W& w    record-data& ]6 C) K  m6 X' W; c7 E$ r7 {
  ]
3 t& A9 Z6 A0 f  O5 }7 m( l5 m! r
  \; x7 W9 O* t, n$ ^  ;; give the turtles an initial speed
$ d3 t) K4 R, x1 g6 J( J! G  ask turtles [ set-car-speed ]
9 l1 d! [) ?, g" V1 K3 U- i
( M' B$ x6 p) [' {  K7 ^  reset-ticks
# l9 R1 q9 ]. J4 Dend
( J, \$ I9 `; w7 w
* S0 A8 D0 m8 i  {+ c, u;; Initialize the global variables to appropriate values
4 Y+ m0 A3 B! c& V: \to setup-globals* ?/ r: A  J5 H9 S- U) ~$ D
  set current-light nobody ;; just for now, since there are no lights yet' H9 c+ F1 y3 S, B
  set phase 0
0 a* Z8 u: a. m( Q6 N) l  set num-cars-stopped 0
+ u7 n2 ^4 P% L4 \) K* U  set grid-x-inc world-width / grid-size-x
3 K5 E- X9 K' Q: X' W  set grid-y-inc world-height / grid-size-y# d+ ?/ m; A8 O/ r0 ^# d5 G
8 v1 _  \+ g6 e4 _2 z
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 n3 x: ^3 X9 F6 W* F, q5 K  set acceleration 0.099  c( ~5 s6 e( T2 S3 W
end
2 l) ~: X9 I8 f! S( [, g* X% \1 x& f, \6 {
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
" t( J" M  g9 V% U! h& e;; and initialize the traffic lights to one setting! m$ `9 @9 v0 Y1 C
to setup-patches
* A, i1 i9 \9 P/ C- s5 x$ t3 |5 ^2 b  ;; initialize the patch-owned variables and color the patches to a base-color
, x, y; k  R# ?4 s# i; g2 n8 f  ask patches
* o  z) \' s( u' r0 O9 j9 i2 y  [& z8 ]! ]0 W9 v* b; M" M
    set intersection? false+ o, ^( g& ], ?2 z' j7 c# _
    set auto? false
# z8 w' S4 u. }! `" b2 j& a    set green-light-up? true( V+ Q! F1 c& V0 f5 A
    set my-row -1
) A. G- G( T# W# y, Y. w    set my-column -1( ~% Z4 ]. H6 k0 f$ t4 j
    set my-phase -15 U# E! t' C& i( M  s$ X# @
    set pcolor brown + 3
! D! u8 W: V5 ]2 ~  ]( _9 I; l, x- c0 o, `$ o' [7 T. }

5 p3 ~) s* P* u3 g! R: n7 M  ;; initialize the global variables that hold patch agentsets* S3 _/ C" F% `: H  m
  set roads patches with9 B5 \9 [+ E' e, M% L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' i! l0 n  w2 F3 \. h  R" `6 U
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) P# h  M5 u/ \- r3 b, S  U  set intersections roads with
4 F  S4 C6 Z+ `4 V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and$ ?1 y  o3 e, C4 Z! S
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 i! f! w* \/ }% B6 p" r  e/ w- ~

6 _+ O' k% s/ p- m) M( h, u  ask roads [ set pcolor white ]& \3 h3 j2 f& w
    setup-intersections. s# q* g# f' u5 F) Y# T- Q
end
% A8 f1 t0 w) S/ ?2 o: _( u其中定义道路的句子,如下所示,是什么意思啊?
' Y! V% a) F! ` set roads patches with) U3 b' W9 u4 S5 |0 i  k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) k" [5 q6 x& [0 e    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], p0 ?* S" T0 Y. q( ?+ X
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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