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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。6 c+ r/ I$ y, `4 V. g( T5 U5 Z/ @
netlogo自带的social science--traffic grid这一例子当中," d# ^5 a- V* n
globals3 I/ E6 a3 S$ c1 e) j
[. C( U: F4 ~2 B" {
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
/ x' u/ w4 y! R9 s+ r' R1 `  grid-y-inc               ;; the amount of patches in between two roads in the y direction
4 t% l: U3 a! t* L  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
3 Q& O& R  p6 G7 T                           ;; it is to accelerate or decelerate0 B2 q# E" s& l4 @4 |
  phase                    ;; keeps track of the phase2 w9 E0 E. @# p& [7 F$ z
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure9 k7 L  g: I; T3 {. Y6 E0 `8 }
  current-light            ;; the currently selected light
  G. X* ^, p/ x9 f3 [# S: K, X" w; T7 F  L
  ;; patch agentsets
# L3 |8 S4 O' l) }+ t5 U( d4 R  intersections ;; agentset containing the patches that are intersections
% N3 K8 t1 T( x* C  roads         ;; agentset containing the patches that are roads
, P  `+ A) q/ M/ q3 c]9 B6 I5 t+ {' G  M6 ]" L9 `- O

9 Q- a/ q. x/ t/ e" t- @turtles-own7 \( R  x) R1 E  \4 Y9 I
[0 w2 X' d/ O) [+ X! Y8 B7 {' n$ D
  speed     ;; the speed of the turtle
+ ~$ n, b/ a1 M: v2 R- j  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
0 M0 G: W( W& Y! \% o9 ^1 `4 _# H  wait-time ;; the amount of time since the last time a turtle has moved
: z! _9 U) ]% k) v]  I6 e" U3 q* p+ {) Y% P2 k

% b' L/ ~4 a8 a7 c8 f4 A6 _: `  h( zpatches-own: V# F7 o$ T# L) \% r
[
$ N7 }0 s! T% w, _  intersection?   ;; true if the patch is at the intersection of two roads7 k, t+ h1 s- d4 a3 v
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.9 U; `0 K' |6 q: j1 ^" Q
                  ;; false for a non-intersection patches.
8 R# A7 q9 N, o6 d  my-row          ;; the row of the intersection counting from the upper left corner of the
/ L6 S. a# _! |1 M* m7 m                  ;; world.  -1 for non-intersection patches.
# l6 s  `, b8 q+ a8 J8 |; ~1 x  my-column       ;; the column of the intersection counting from the upper left corner of the, B& b# Q) X6 e& C
                  ;; world.  -1 for non-intersection patches.% v" x* e& f, m2 s- N+ X
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
2 R  n  @! j. I; ?5 X2 Z: x1 K* e) u  auto?           ;; whether or not this intersection will switch automatically.
9 E6 x0 a& m6 f% c3 G. k% S& `                  ;; false for non-intersection patches., V1 V) f/ f2 ?% ~1 b0 C& s6 D) ?
]
  L' f$ w1 j% i. Q0 Y
) ^7 {1 J2 q( B# r8 G
8 ^; N5 e, t& m8 {4 a;;;;;;;;;;;;;;;;;;;;;;
: J7 d" O9 \! Y6 D+ c( u$ p;; Setup Procedures ;;; h$ L( S- J7 C, K
;;;;;;;;;;;;;;;;;;;;;;
$ y! v; q3 }7 K' _
1 u1 f/ i2 a. |& p' g8 ]. P$ T& _;; Initialize the display by giving the global and patch variables initial values.6 J+ i& L, v, ]- e, {& p. C3 R
;; Create num-cars of turtles if there are enough road patches for one turtle to5 D9 B0 Z" p1 U' m3 W
;; be created per road patch. Set up the plots.; i  t( ]" k, Q0 U6 g: N( r
to setup
: A2 Q. s3 V% Z4 w9 q, N3 V  ca
7 ~4 O, N! ~# k9 D  setup-globals$ k# ?# P4 f9 e4 _; a( j% m" Z
: Z) m8 @5 J: Q
  ;; First we ask the patches to draw themselves and set up a few variables% }" H5 Z5 w* N" D8 Z& S
  setup-patches  S% G4 }# p. a' e2 c% B$ e
  make-current one-of intersections
4 J7 f2 i. L; \+ m  label-current4 P, x/ l( A" M1 D! e
5 {- q# h( ]  U& k6 o9 p+ E2 c& l
  set-default-shape turtles "car"
- E& U4 a- B6 K5 V2 v: I% y9 L3 Q1 x
  if (num-cars > count roads)
. P% D% z( \% e* x- f  [  l0 ~1 ^# C6 s' A$ Z% A
    user-message (word "There are too many cars for the amount of "
& `- I& `- b) {' x  E% d                       "road.  Either increase the amount of roads "
1 y+ \' l; b9 f  s                       "by increasing the GRID-SIZE-X or "
) Z' N2 B, F$ b/ r# I' U                       "GRID-SIZE-Y sliders, or decrease the "# C. K+ i. Q( p* Y# t! S; p; x
                       "number of cars by lowering the NUMBER slider.\n"
/ y" [) X" s; K3 G4 Z+ j                       "The setup has stopped.")) M; L  ~# T, O
    stop
" V, k# U9 ]& D" u  ]6 u& r4 L/ r9 e9 T4 }

8 }* \/ h6 r3 E7 w9 w+ {" b1 |  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
5 G4 v% z; L& M5 I7 I5 S; P  crt num-cars! J" L9 X& V6 E+ x. d! A
  [
% z( [% F% D0 j  h" _    setup-cars0 N+ B' g5 K( l  b* i3 E! ]
    set-car-color( r1 _# O9 b; e0 Y. F3 H6 X
    record-data3 O) u* E! {: ^( g' S; s
  ]7 b& Q. m  d" J9 m" u
  V/ M! e) a4 F( D5 z1 [/ \
  ;; give the turtles an initial speed( E3 Y1 c* T( _% t: \
  ask turtles [ set-car-speed ]/ n- w% T* ?0 K( m% P4 @6 }; `2 }
; @" z. M2 E2 E$ ^7 f- {. J. L
  reset-ticks! {% i% p. A+ D
end
- O# h5 w) h+ k* V  J: r# B# R/ k+ D! o. K- v* y3 ^2 K; i# Q
;; Initialize the global variables to appropriate values! O) E: ]; r/ o% N: x/ R
to setup-globals7 ?' _" r0 V2 `6 \' H1 ~
  set current-light nobody ;; just for now, since there are no lights yet! _. P6 O9 l2 [- l
  set phase 0! P* u0 R: G+ {( _! J% \
  set num-cars-stopped 0
- P5 U8 U5 [! S  set grid-x-inc world-width / grid-size-x
! U3 }6 o# s6 v& I) J  set grid-y-inc world-height / grid-size-y
5 ?: @3 s) \: T  Q( k) i4 N  ~9 G# ~" J+ S$ F; u8 N2 G2 I  l  H0 v
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
; @; u2 c2 S9 j: ^6 T  set acceleration 0.099- F0 a3 n( |1 X! o' M
end
+ @5 S  M$ ?: P5 A  l& E
1 A& R/ n: b) `. W# v; H;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
" N# A* L# ?  |4 ?* l9 I/ r# j8 p9 W;; and initialize the traffic lights to one setting6 c& F- d+ x$ Q+ ?- R
to setup-patches
. \; I) a: ~) T5 t5 s# N4 `" C  ;; initialize the patch-owned variables and color the patches to a base-color
& _, b3 ?4 ?. K" u9 @: ?& D  ask patches$ {2 E& A3 R1 J0 c5 d+ `5 Q
  [
, g; G+ f9 P; R( R    set intersection? false
  H9 K7 n! ^& _! \* a3 W    set auto? false4 n0 j+ D1 D" E& i
    set green-light-up? true& F* _, a- W6 s+ r5 g. t! J" B
    set my-row -1
4 x/ `& T5 D- f% j    set my-column -15 ^4 M5 K  Q8 O3 Q5 U5 n
    set my-phase -1  T; r2 }4 C* S/ b; X1 b6 ?: |
    set pcolor brown + 3
  r4 s  B8 L! [# s0 N! n, u  ]7 i7 z$ W* B9 J+ A

( U" I8 }6 }& y3 T# ?; `  ;; initialize the global variables that hold patch agentsets# u. l) C  X; b4 l, v* E
  set roads patches with
! M0 |( H8 ]6 Y2 B# ^, P) L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 N# h% _, A, l+ t3 ?9 p
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. A: B0 {# C* Z0 b
  set intersections roads with" I$ o: Y1 z0 L* G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ }  N% }6 c' J
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; @. f5 T7 Y( @) \  [% K6 e& b4 i- Y
, R7 A7 s7 [& `/ ]
  ask roads [ set pcolor white ], k5 L, ~% l& ~1 o8 }- Y+ @
    setup-intersections
% T6 u7 W6 R% V6 C: O& Nend
% p* P# d# B% ]* o$ m/ k# f+ T其中定义道路的句子,如下所示,是什么意思啊?/ H& K) P( E: \+ V* B
set roads patches with7 w8 m3 K& V2 H! j# l& h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ g8 X) e# K! N6 I1 F+ e  M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" j+ Y4 V# {5 p( W% a9 z7 K
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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