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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。
' q- r" _' h# c5 M' h' cnetlogo自带的social science--traffic grid这一例子当中,1 V: `$ m; p; C- @5 a$ G
globals
% {! d+ S  X. {: r[1 g2 }( g. T5 k& }8 V) R  U
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
4 a: L9 Y1 f! h, p9 ?- c  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, L! y* Y% X1 q% n! I6 V2 d  acceleration             ;; the constant that controls how much a car speeds up or slows down by if# C$ E1 s# }+ e3 ?8 _; v
                           ;; it is to accelerate or decelerate* A% r, ?; x: F  e: {; G
  phase                    ;; keeps track of the phase. y# M1 l, D& R& P
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
  ]( s& m* h. r' w8 @. G  current-light            ;; the currently selected light
! U( b( ~1 [4 A* d$ Z! E1 N! J. v. g' d* C/ `2 C* N
  ;; patch agentsets
. t/ i4 u& I) s$ W1 {& o3 l7 t  intersections ;; agentset containing the patches that are intersections2 d% e* i9 _  k6 T4 F' Z) s
  roads         ;; agentset containing the patches that are roads' x( V7 X, I* b
]
. N5 u/ Z3 X. Z8 r* s$ s- `: U2 |/ V. j- c/ p1 v' U
turtles-own  s0 ?; J% W) a+ H5 P  p" |- L: ~5 m
[
  w. J" S% g" W1 c4 t  speed     ;; the speed of the turtle
/ H/ f" Z; }/ U  up-car?   ;; true if the turtle moves downwards and false if it moves to the right3 H* [+ a' M& h4 I( p
  wait-time ;; the amount of time since the last time a turtle has moved
" J" g2 ]  N9 q$ f0 {1 Y; E]1 r  [( z7 S- R" v; \- e

6 M3 t2 e3 k8 f4 |patches-own1 J& |! d# Q+ M% A
[2 B! i1 r, ^% a5 o$ r6 e
  intersection?   ;; true if the patch is at the intersection of two roads
$ D6 h% n% |7 s7 I  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 s3 l% G) ]: f; D( N7 g5 F5 W                  ;; false for a non-intersection patches.
1 N9 F' e* Z0 a& P5 B  my-row          ;; the row of the intersection counting from the upper left corner of the
; e  V$ f) o, w8 C' `& B                  ;; world.  -1 for non-intersection patches.5 d: F# `1 T: }. o- ?# u" B* P
  my-column       ;; the column of the intersection counting from the upper left corner of the( _4 m# X. S: B
                  ;; world.  -1 for non-intersection patches.
" _# z/ F9 H) }) z& f0 Y, ?- T+ [  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
- B0 s! ~0 N2 ]) X2 c: ^  auto?           ;; whether or not this intersection will switch automatically.
: O* E$ W$ u( k' r9 f                  ;; false for non-intersection patches.- Z8 h6 a- D2 X% i5 Q0 C$ J
]
6 w) N: E" X4 t0 P" U  _
6 w4 c. w& p# j; M2 B/ S; w& Y
2 ?: g* _# N1 v5 N5 Q;;;;;;;;;;;;;;;;;;;;;;
9 ~+ C% q, ]8 k& E;; Setup Procedures ;;' w4 v8 i3 `) k5 s  a
;;;;;;;;;;;;;;;;;;;;;;
' \1 n, \' V& M: d3 t2 i5 {+ i1 ~
' K: w& w. T6 b;; Initialize the display by giving the global and patch variables initial values.
% R5 Q" r  l8 R. L+ y;; Create num-cars of turtles if there are enough road patches for one turtle to
+ y" h8 e/ d9 O;; be created per road patch. Set up the plots.
- j% {* h9 S% g; Qto setup  U2 `, p8 F0 i) z
  ca  P3 D, K) x$ a0 C3 [5 f- _1 E' m
  setup-globals
' {, F$ J, R0 B* K7 b2 V1 g; P6 S  s
  ;; First we ask the patches to draw themselves and set up a few variables. x! }* L+ i: s; J$ k( P# \0 T1 ]
  setup-patches: i( S: y% n+ L5 x, |# ?3 P
  make-current one-of intersections* M- K! A) d5 K2 H" j
  label-current
. \8 _; I2 R, n/ M1 y- |0 ^* t6 H  N& n4 I- h% f
  set-default-shape turtles "car"1 J! V9 o  R& b0 H( z5 R+ c

# `4 L& L' t# \  if (num-cars > count roads)
! J: q# ?1 l& J' {/ ^  [: L* @7 z3 ?9 C
    user-message (word "There are too many cars for the amount of "
, G0 X# O$ F0 H3 l! A9 F4 N0 T                       "road.  Either increase the amount of roads "
! X* M2 c' J- Y( R                       "by increasing the GRID-SIZE-X or "9 y& l& h& A& n, }) n
                       "GRID-SIZE-Y sliders, or decrease the "
  v) x# V3 I8 L/ {, t                       "number of cars by lowering the NUMBER slider.\n"
; ~) u1 k# v* ]) @: s  j                       "The setup has stopped.")& l2 x+ Y/ @( H" g% R$ f# q  q
    stop
' a5 E3 a# {" v( c  ]
' L4 Q3 o7 ~* v/ Z5 j
; b; _9 p: k9 o1 ~, B  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  J5 W% {3 o; L+ c  crt num-cars
6 s- l( b+ x5 C  [' o$ c& u3 K! _5 m: \0 A
    setup-cars: h2 Q6 f7 v9 B! }% }+ ?
    set-car-color8 `  `$ D; \# Y4 x/ R$ s# ?
    record-data8 ]( j, k/ o1 P9 C1 K( u, w. d5 u
  ]
. \. n) S. q4 ?% D3 P3 y. u. b: Z, W2 b. I  C( }: d) P
  ;; give the turtles an initial speed
' j$ L4 `* ^/ h1 u" _" e  ask turtles [ set-car-speed ]
# H9 k1 m6 I6 Z4 R' l
$ c4 O. z0 ]7 u' {  reset-ticks
0 v) t# z9 ?) J9 q( @" T  d, C8 Zend" w5 h8 e, K# F9 M0 p+ r# `3 W

6 c0 I* f0 x7 W7 R# Z;; Initialize the global variables to appropriate values# h/ @4 c! s6 y4 ^& o1 D0 O
to setup-globals
8 [& N. Y7 P& H+ j9 F  set current-light nobody ;; just for now, since there are no lights yet
- h9 i* e) f; [. |6 m, u; p2 m, ]6 F  set phase 0! X& W/ i' z* V' e- @& u
  set num-cars-stopped 0. q  N! W4 @- ?  K8 h7 J" q
  set grid-x-inc world-width / grid-size-x
: `% n% w: L2 p' J/ R5 h  set grid-y-inc world-height / grid-size-y
" A4 @! [: c0 O/ D
) V, Q6 q0 Y$ ]- y+ c& o  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary' K2 k' \$ G, d, F9 G
  set acceleration 0.099
9 `2 m( w+ k0 ]2 c) K1 s% k% iend; P& }' ^! D! B% d8 C+ h4 t, |

+ l% J) |) `; O;; Make the patches have appropriate colors, set up the roads and intersections agentsets,: z7 q( N8 f& D. m$ m
;; and initialize the traffic lights to one setting, H. O: I/ I7 B8 k
to setup-patches* ]& K; j; O9 v' D' d7 ~
  ;; initialize the patch-owned variables and color the patches to a base-color9 i7 [- Z" m) U% K( s8 z
  ask patches
& G! d$ M7 ^1 C0 z- e  [+ z# v; r/ D: z( L; N) \
    set intersection? false
+ T  f% N$ \( ]8 Y/ o    set auto? false7 w) ?/ g+ K% I: [! c! P. c! M& T
    set green-light-up? true
1 Y& D! J: C2 I1 k& E  c    set my-row -1
2 V7 E$ K1 l" b& a: n" O# `    set my-column -1
0 ^6 e! `9 u! @3 ]. f    set my-phase -10 S& i  k2 U( _
    set pcolor brown + 3
% j" t* \) D, o- H, @9 N* c  ]
! S- `& G" t$ C6 D1 ~& s5 W" o$ f5 g& H- q
  ;; initialize the global variables that hold patch agentsets+ T' A) h( F, |9 B1 F
  set roads patches with
) c" ?$ M6 V/ t5 h    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 ?; F! N- d1 W2 H" l) x2 ~: ?
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" h* B5 o& R( R& d
  set intersections roads with: a5 Q( E9 G+ y/ J2 f
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. g$ n) \6 O" X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% R# }2 ^; F, ^+ X* u! e- n6 k
' {! V# `* A7 G& A  ask roads [ set pcolor white ]
9 X3 y. ]- }: X% Y7 |- g$ n    setup-intersections
, i* @" J, E# j5 Send) p* q5 Q; W% x* e" j8 p
其中定义道路的句子,如下所示,是什么意思啊?
* P/ f7 e/ x6 P* W9 R  f: w: w set roads patches with3 _* I! w: c- ?# p' p$ l9 N" F6 |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 c4 F) m$ W4 ~' I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 Q; w* Y2 ~, y+ Q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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