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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。, K% P3 e6 W) t' F5 S. y& G
netlogo自带的social science--traffic grid这一例子当中,
- P! e  Z  F" l: z7 `: x( Qglobals
; x9 G7 q( t5 V5 Z7 `' a/ k[
$ T( _0 h( e5 v- ]& f) J- c  grid-x-inc               ;; the amount of patches in between two roads in the x direction, Q; d: Y$ `3 ^5 X( X/ s; L! m
  grid-y-inc               ;; the amount of patches in between two roads in the y direction4 b  R8 c8 C) Y) H+ S
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
) n" T6 [) G1 C, a6 ~" H                           ;; it is to accelerate or decelerate6 z) h6 B, M8 z
  phase                    ;; keeps track of the phase- i& I2 P' _( X) W. }; S3 y
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure' _" O% F; V( ]
  current-light            ;; the currently selected light: b$ i6 Y* M  J

" Y5 ]! Q! I$ _4 a! y8 |  ;; patch agentsets  u' A! Q% a, a0 y; t
  intersections ;; agentset containing the patches that are intersections
. [$ v1 q  A( O& e# h# s  roads         ;; agentset containing the patches that are roads% J% L& {: s3 h8 E  E1 R
]
- ~. H& y* ]7 F
1 g7 P$ d5 \' ~turtles-own
5 \9 `3 e- w, l[
& d( Z( b. K/ I/ `) Y  speed     ;; the speed of the turtle' I* q( k+ X5 y' [
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right3 r$ z. S4 L+ A# E) C& f
  wait-time ;; the amount of time since the last time a turtle has moved
: ^) ?' m8 W- z" D2 o+ V2 P/ n]
; B/ P5 Y5 O7 y
' K3 e( D( W  Xpatches-own
6 w7 P2 l# P/ k" y! e3 E: l; ][0 k" a& F  |  ]
  intersection?   ;; true if the patch is at the intersection of two roads# T* P1 H+ ~0 ^/ _+ f7 N( @
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
5 c$ R  u' c/ A- \                  ;; false for a non-intersection patches.
) p1 E( d. i4 c$ x$ l& _$ \# y( E  my-row          ;; the row of the intersection counting from the upper left corner of the
$ F% w/ H" y* Z5 d5 w0 C                  ;; world.  -1 for non-intersection patches.& |& d* y5 l* _6 u
  my-column       ;; the column of the intersection counting from the upper left corner of the* q& p8 I5 R  K( r' Y
                  ;; world.  -1 for non-intersection patches.
) g/ G( @; B# d+ v; ], K  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
$ _" J6 ]- s. Y; ~& [  auto?           ;; whether or not this intersection will switch automatically.6 D# C( ?2 Q4 E6 N8 U
                  ;; false for non-intersection patches.
# m# U. o8 o0 N. K, f3 Y]
8 G8 Y" T5 k( \/ T( G, u6 e
1 @6 @4 I) L+ P  R
4 K" N* _+ `& V# |;;;;;;;;;;;;;;;;;;;;;;
4 z1 @8 K( F  ]. U0 R; q;; Setup Procedures ;;
% R% v. T$ O$ L0 S; p5 f7 t& `;;;;;;;;;;;;;;;;;;;;;;
" B5 p# T: ]- j5 z) o, [
; z* s$ _6 A) K, \/ q;; Initialize the display by giving the global and patch variables initial values.
2 g# }9 T  q+ ?- q;; Create num-cars of turtles if there are enough road patches for one turtle to
9 h3 q, x9 b5 B' U;; be created per road patch. Set up the plots.
3 B8 n! B6 T! t/ l  q, mto setup$ R9 M( [- h% b  F6 U9 Z
  ca+ H5 @4 y. z, j  ?$ E' y* b
  setup-globals  {. i4 K* y: y; J

' A1 |0 q* _3 V- m- Z4 }  ;; First we ask the patches to draw themselves and set up a few variables( n- C  f) ?+ Q% g1 l
  setup-patches3 f& K, q3 _: [' c
  make-current one-of intersections
+ S6 _, E3 v5 I0 j  Z# _  label-current
4 H) x( a2 g4 m, d: A/ C5 M/ `- z0 s. P, h! P. T
  set-default-shape turtles "car"
" X- ~6 _) G9 j5 y2 Q+ m4 O, j5 ?/ v# S1 ^4 c* _
  if (num-cars > count roads)
9 ]# ]0 ]8 x% ]. Z5 A  n  [9 b" V4 P5 t4 c' s7 j9 i$ `+ j1 @
    user-message (word "There are too many cars for the amount of "
+ T$ w4 _* E  u: \9 y- t- z                       "road.  Either increase the amount of roads "
  n7 I- H5 r7 a) Z* u                       "by increasing the GRID-SIZE-X or "
% l6 o) s9 `* m( V                       "GRID-SIZE-Y sliders, or decrease the "
9 }* j. ~  M) i# ^                       "number of cars by lowering the NUMBER slider.\n"% u- |. R, L5 E7 _; k* p
                       "The setup has stopped."): m( O- G4 h: |) y: P! b* m
    stop
4 p% F2 z# d4 n' j2 ?9 v! R  ]$ d# g  _/ C; p- B

( d0 _* l9 J- i9 s; u! e2 G  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color# J' e& q# w4 P  A' T
  crt num-cars
- @( R% n/ o/ l1 S: _  [& D3 @6 y' A. z  o# ]+ p
    setup-cars. K: \  I, L7 O, S
    set-car-color  [( `% x6 Y% ?' ]
    record-data
4 H% x& `/ a, x8 u% F" e; ~: v6 R  ]" u( q' q' o( @& s
/ m. h: C8 q& e/ j
  ;; give the turtles an initial speed
# f* Y) k) L7 Z) |, Y) x+ V  ask turtles [ set-car-speed ]
7 r# b( V$ U" D1 x$ p2 U
. r: Z2 A- A( `5 }  reset-ticks
  e9 N8 N/ d( n9 K0 |- w' \end
2 O! i7 r$ W- d9 Z$ Y8 w' o5 j5 ]4 k
: q9 Y2 g/ z+ {8 m  s;; Initialize the global variables to appropriate values
6 r# t3 e$ U, y) o6 V- Hto setup-globals
  P! I: e9 }$ `  set current-light nobody ;; just for now, since there are no lights yet7 ]5 U! c) V+ y! n3 Y; q7 B& U
  set phase 0
! U+ @* `' ]/ @4 p. r9 K  set num-cars-stopped 0( B- E. F( I0 `, x9 x. j
  set grid-x-inc world-width / grid-size-x
7 _! [% I, K. i  ?  set grid-y-inc world-height / grid-size-y2 V9 `* J& ^& B; R% {! v

2 ?" |0 f: h; _1 {- R8 E8 f  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
# {1 i8 k4 ?4 Y1 j1 x8 ]9 i4 p/ d+ t  set acceleration 0.099
$ Y. E' l& i0 ~5 l' c' S# lend
$ _* E5 h0 i. {. y' N0 m/ W7 a0 i. b3 y+ y- I1 ]: s% p- B
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,% K& I. Q: a+ O: k+ G1 x3 f5 x$ W
;; and initialize the traffic lights to one setting
. _. ]1 `+ n4 N4 t5 E) b: C9 rto setup-patches
- y$ ]) ?' @8 ?5 b  ;; initialize the patch-owned variables and color the patches to a base-color; K9 o9 L4 f9 H/ F) @, O7 U; P3 q
  ask patches% Q% O: h7 f, i0 `
  [
0 B4 f  V; F3 v5 i1 G    set intersection? false9 @; W7 L! |5 i& t2 O
    set auto? false
- z7 S6 L( S, ^: Y& p$ T* ^2 ~    set green-light-up? true
. x  D! D# d7 P9 J    set my-row -18 X6 q: ?6 K1 ^% x( P
    set my-column -1
$ P, G) W2 E: `0 R$ p    set my-phase -1
) S; h* l. h( A    set pcolor brown + 3: H" ]) c+ _' h* H3 N
  ]
7 z& h/ @) b8 ~: |( i) T, {
1 }/ H% ]0 r4 [0 x: _  ;; initialize the global variables that hold patch agentsets# ?' ^1 T! z7 r% r- j. R: m9 O' T
  set roads patches with# M% t* A& A& v6 a: g" G, o3 I9 V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  A- H8 Y$ E5 v% D% ]7 `1 Y: M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 _% S$ H3 u" t# Y" ~  set intersections roads with
' Z0 d( m* K3 F2 S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and6 Z. j' L, g+ l5 A  m' G5 i
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- G* ?! I; N6 h$ ~0 C; s4 y
; j- j5 T1 D- W7 L/ }  ask roads [ set pcolor white ]: F- d2 B# Y& D* r9 c5 {! A
    setup-intersections) K7 h1 n) H* X) w, ^
end+ U6 G& r0 D  J' Y8 t) t4 T
其中定义道路的句子,如下所示,是什么意思啊?
9 L( A( l( F: M; w! I9 d set roads patches with$ N8 D- I% C8 B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ e6 c1 Q0 @; w" M4 V) \$ G. w) h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% J8 y2 L, E) H0 p4 W2 U/ \* o* p( 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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