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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。1 ~3 r: W1 y# z4 C
netlogo自带的social science--traffic grid这一例子当中,
6 J3 y, I% _4 v4 Z" d' L- x! b* B( Gglobals
' q$ A9 W  ], U( _# F[
& c: O$ d0 v1 ~, C( O  o  grid-x-inc               ;; the amount of patches in between two roads in the x direction
8 I) n" [) I. \1 f! g4 r  grid-y-inc               ;; the amount of patches in between two roads in the y direction0 O9 y, {' |7 X; m
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if( B. a& K; [" X0 h& H3 H
                           ;; it is to accelerate or decelerate
8 X  |5 W8 q% O+ M- T# ]( F9 E# s  phase                    ;; keeps track of the phase
- p; e" i) S1 T$ c* ?& d  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
5 R# C7 J/ ^, |; ^7 b. q* }  current-light            ;; the currently selected light
7 u9 y' I. {7 c$ y  ^& U
) z; X/ w, ?# K; a5 V- j  ;; patch agentsets
& C! W: q4 U- X4 r" f' t  intersections ;; agentset containing the patches that are intersections
$ k1 W, }! |/ N+ v  roads         ;; agentset containing the patches that are roads
2 E& {* k5 B' P0 Z1 }4 Z]  T1 T4 N( q& v

0 s$ |& R3 U' {4 x8 V/ @0 P) z# Jturtles-own
- V- s. D8 ?9 t9 M& X  E[$ n8 g5 i- W2 D) K8 y5 J8 A4 K
  speed     ;; the speed of the turtle
' P+ B) L* m& I7 z0 F1 o  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
- l$ c# t9 U2 A5 d5 r( e  wait-time ;; the amount of time since the last time a turtle has moved6 D0 s  D3 m+ O2 i
]1 }! V; c4 u& d. f/ E$ ]9 i3 r$ X
; E/ w$ L" H8 c$ B" O8 ]7 j
patches-own7 Z' a$ m2 L8 U6 V( {* _
[
+ z8 X' ]) W, @$ C! S" S' k; r  intersection?   ;; true if the patch is at the intersection of two roads
  ]$ f( u' r- r4 b. E  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
# z$ e; X$ M; O4 `3 u! P+ w                  ;; false for a non-intersection patches.+ {3 c2 @1 e( ]& \, t( n- G+ B
  my-row          ;; the row of the intersection counting from the upper left corner of the
7 R# Z1 x! P9 I2 W. D1 o: _0 z                  ;; world.  -1 for non-intersection patches.
% I! g* m1 p( V& [5 P0 a0 s  my-column       ;; the column of the intersection counting from the upper left corner of the0 _  C5 E' c  v  o) m8 I  J, o
                  ;; world.  -1 for non-intersection patches.
4 |1 w7 S1 v( \  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.) ?; [/ D/ \2 _* F" L/ W
  auto?           ;; whether or not this intersection will switch automatically.
- p6 P. e  @* M$ a! q" P' K                  ;; false for non-intersection patches.
0 x$ N* _! H  a9 }! R4 M* n. @]
2 s4 J/ w% K( r/ B8 F8 Q% s' Y% F; x. M9 h9 @& ]9 B. l: H9 K

0 e$ o% k5 Q, `* H;;;;;;;;;;;;;;;;;;;;;;
" Z' _$ ], T3 Q;; Setup Procedures ;;$ M/ H9 v/ J3 x% U$ O8 R& ^6 A
;;;;;;;;;;;;;;;;;;;;;;
. R5 w* t( x3 {9 D8 V9 f8 z  ?3 z3 ^
;; Initialize the display by giving the global and patch variables initial values.
+ I5 Y) p9 A! e6 g;; Create num-cars of turtles if there are enough road patches for one turtle to
5 H8 v5 }0 y! ?) {" n;; be created per road patch. Set up the plots.# ~4 n, M/ L6 g+ m$ _
to setup/ h* A% c# V, j3 h+ f: q, ]3 F
  ca
9 s+ a; ~0 g# c  setup-globals4 b5 Y" _& Y: B4 d8 Y
1 A& A$ a' K) R9 ?" u" t
  ;; First we ask the patches to draw themselves and set up a few variables% F/ d9 F! f  U- h3 |
  setup-patches
7 [0 u6 h! u* {7 t  make-current one-of intersections
6 [1 m7 L% V% e6 o$ y  label-current
+ a! f) B4 h& p4 u. U- l8 g! H. Q& L; U; ]6 @2 e) Q
  set-default-shape turtles "car". P  ~" ]' j8 u( b. k4 z$ c
; Z: ?7 U. A8 L
  if (num-cars > count roads)6 a6 j, }+ L' E3 C1 o4 D' d
  [
% p; ^; c3 i* g, Z4 r7 F% m    user-message (word "There are too many cars for the amount of "/ h1 t; K: i: v8 K! p; `, O
                       "road.  Either increase the amount of roads "9 C4 W9 x& d4 k0 r
                       "by increasing the GRID-SIZE-X or "/ u/ J5 [' b6 O" [! |2 F
                       "GRID-SIZE-Y sliders, or decrease the "
, H- v" N9 A: S" D" b- Z                       "number of cars by lowering the NUMBER slider.\n"
0 Q6 q1 {. d8 u/ A+ w                       "The setup has stopped.")
. N  X: b' |$ Q) E1 ]1 E    stop
3 E/ s+ K: g3 C  ]0 {- Y& U6 D% L2 q
$ B+ R7 n" W5 H$ K
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
" F* h6 \6 C3 w: k. Q/ p  crt num-cars" M9 f0 J% `0 z1 x$ ]
  [+ I8 P/ k) U9 }' T% W* F! b
    setup-cars
1 H: N  o5 D/ y    set-car-color
; Y/ c* m' D+ P+ P+ s" C: e    record-data4 l3 f( `2 I1 W1 a
  ]2 c* H1 j; h/ K! W& r9 A4 \

: x7 _; }$ q% r0 ]) @3 o+ W  ;; give the turtles an initial speed& n1 t% a; V" P
  ask turtles [ set-car-speed ]
8 ?' s# Y: E( g. D
( \8 x( A& u- c7 r& P# q  reset-ticks& H/ L; C* M1 g/ K
end
$ \; _# f& K5 e- ?0 b" s2 p* p9 w$ A& N; O$ q
;; Initialize the global variables to appropriate values1 Y' j9 F* w; f! B( o
to setup-globals! Z9 L* d1 N/ n* U+ D* U
  set current-light nobody ;; just for now, since there are no lights yet
0 y" x* }3 r3 v4 x5 O4 A7 A( V  set phase 0, \. y3 h5 v) g3 M' X
  set num-cars-stopped 0
- C# c/ o' O3 b) s( D2 N  set grid-x-inc world-width / grid-size-x
  j) J3 @! W0 q) @7 o  u8 X2 w: g  set grid-y-inc world-height / grid-size-y. Q+ T+ |0 ~) C! r) H/ \0 P

6 Z" j; r! F& P4 x  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary9 Y. P& X9 V# Q8 v8 a9 W" O
  set acceleration 0.099
: y" K* P0 ^' ^end. e& k+ f2 [' D

" C& c; ?8 b, o: B5 S;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
5 K0 y3 Q/ g  j3 v. n7 l;; and initialize the traffic lights to one setting
3 I8 V8 l) p0 X' tto setup-patches
+ t7 s- Q- \* `& b4 B  ;; initialize the patch-owned variables and color the patches to a base-color9 q( ?, M$ [7 |
  ask patches" E+ {2 A$ p( P1 u
  [: {$ S  p) u8 a: v4 p
    set intersection? false
1 ?( L: ?. I* u2 L    set auto? false
) O; A3 V: Y% I% n6 I; Y7 {    set green-light-up? true
+ Y$ {* H# B' d# p) I/ K    set my-row -1* e, u4 e$ m) `) M1 U
    set my-column -1( w# b- \: f* q) u; E! {
    set my-phase -1
! J% {+ Z. Z, z) R4 ^4 y5 h2 U8 p7 _    set pcolor brown + 3
2 t0 F$ w! f' D5 c- b1 G  ]
% z, z- z) P" P* x! O# x9 q3 M- b- x% s8 v. u! V' a
  ;; initialize the global variables that hold patch agentsets& l$ R* \2 m  }1 W8 X7 t7 A
  set roads patches with) X9 a5 z# s. ^. B- l; O3 M; X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) l8 H  y+ ^9 y! p( N" K1 r5 x' a6 ]
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( K2 u* S0 {' o
  set intersections roads with
  u# h: H* n' a! g( q! l* T7 Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
0 _9 V4 c4 j  X0 Y4 Q% G: G3 ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- |0 I0 N3 R+ H7 {  f: l$ R) r
; q+ `$ {# @5 T1 \4 P
  ask roads [ set pcolor white ]
6 I& I0 f' b. T    setup-intersections6 _1 [5 I* M( g' l) A6 N; G
end
# {) m$ C' C& Q( K" X其中定义道路的句子,如下所示,是什么意思啊?3 E  I4 A, v8 ^$ X: L
set roads patches with
1 F1 J" I( p  r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ [' M& x5 b+ l: O    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( G! A) t' i- A  g' _
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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