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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。8 I; c, n( {) c
netlogo自带的social science--traffic grid这一例子当中,
7 Q( w. ]) k6 }% e! Y( yglobals
8 B9 O8 o# K& n" B[
& s6 r+ O  ?# `  u# z7 k1 G! \  grid-x-inc               ;; the amount of patches in between two roads in the x direction
5 r1 l5 n4 N2 x+ l1 r% G. L( z# S& p  grid-y-inc               ;; the amount of patches in between two roads in the y direction
" A0 ]1 ?. A' l& {  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* j( X) ^8 ~+ f' G
                           ;; it is to accelerate or decelerate
* D9 a8 P+ e, Z- P& ]1 B( v  phase                    ;; keeps track of the phase
" L: X) D- V9 S4 A' @# L  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure* `' P! s6 L+ _2 A$ K1 d
  current-light            ;; the currently selected light
0 X: G* c% W2 l  ^7 P$ [4 i6 c3 e/ `# K+ P3 _7 A/ M
  ;; patch agentsets
* f$ a8 i$ g+ a) v3 z# b1 y  intersections ;; agentset containing the patches that are intersections
! J6 |" P7 D  E/ @) X; l2 M( R  roads         ;; agentset containing the patches that are roads6 f; \4 _3 r: A. o+ t
]
# }1 U2 T+ _7 f& i3 B& f8 G& a( j) X0 \0 `
turtles-own( u- v1 m1 G' Q7 j- M
[
( ]- h  D! u: c8 e  speed     ;; the speed of the turtle
. h. M9 V# Z" X' t  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 E6 o+ G6 o9 x1 A- q1 R
  wait-time ;; the amount of time since the last time a turtle has moved
7 o: E6 h( V" M& u) D& Y- z! F! w]
/ x/ B4 E" l% K6 L7 \
8 C& C8 k5 h, O% Tpatches-own
; r# T; ^+ Y7 Z5 B" ?  B0 `[
% P0 }- w7 `" v8 t% G1 s3 r  intersection?   ;; true if the patch is at the intersection of two roads
. v% |+ f# m( d( J  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
0 Y& ^6 F8 s" i" r. G( j. L5 F; n                  ;; false for a non-intersection patches.
/ ~7 [! k( `. d1 T- b1 U1 M2 h  my-row          ;; the row of the intersection counting from the upper left corner of the
$ n* t7 T( R  o8 x+ `                  ;; world.  -1 for non-intersection patches.
, w$ Y9 _! [( {) k2 ~4 m9 U9 L  my-column       ;; the column of the intersection counting from the upper left corner of the- {$ h/ g- S( x" G
                  ;; world.  -1 for non-intersection patches.6 ^5 e% F, g9 Z: L$ R# D3 ~
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches., r9 V6 G7 {+ e$ D) d5 E  o0 B6 B
  auto?           ;; whether or not this intersection will switch automatically.' i. v% F/ I7 C0 f- n9 p! `
                  ;; false for non-intersection patches.
% u& O( ?: Q! |, [# o]
- s, e: W( S1 e4 B& c) u; q! S" y' U/ t& L4 S) w
  a# ]4 h: g7 T: N- _- I+ d
;;;;;;;;;;;;;;;;;;;;;;4 E4 v9 |% H- ^) N3 v7 j
;; Setup Procedures ;;+ H: M1 f* l2 _  f* x  R; O
;;;;;;;;;;;;;;;;;;;;;;
' f2 _( c! j: E  c$ }5 I. \3 l! s5 u' M( O+ K% n1 c4 Z
;; Initialize the display by giving the global and patch variables initial values.8 u; e! m  }1 G+ D
;; Create num-cars of turtles if there are enough road patches for one turtle to
" v" R: v6 O/ J2 [8 R;; be created per road patch. Set up the plots.- v- F- d* O# ?0 G
to setup; z* ]$ y# i, B2 b' i
  ca, n6 F/ }- F/ r8 a* v2 w; l
  setup-globals! C* }; A! C, C4 h

8 R; M9 o' T1 J0 [  ;; First we ask the patches to draw themselves and set up a few variables9 x5 e- G; |( B; L, Z. W
  setup-patches
5 M; o: W0 _# u$ C; W  make-current one-of intersections
' D& s4 B* S6 {) W2 \* q2 \  label-current
+ W9 f3 A/ H2 j/ B* [$ E: f# ?
4 i. Z) X/ w$ u, Q: u) @  s" F  set-default-shape turtles "car"8 }2 r0 F. d5 \. \

9 ]$ e% P4 i; E. ^+ ?2 {  if (num-cars > count roads)! D( B; T0 D! B) Q
  [
7 a* _% {2 _7 t7 W, @    user-message (word "There are too many cars for the amount of "
: I+ I% q# {, ~8 ?" n6 g4 U+ {                       "road.  Either increase the amount of roads "
: p) p* M, v; N% w( L9 }2 t                       "by increasing the GRID-SIZE-X or "
. D4 ?  y+ \" q6 L                       "GRID-SIZE-Y sliders, or decrease the "7 d4 Q/ w5 [# i4 e# O1 v: Y
                       "number of cars by lowering the NUMBER slider.\n"( r5 E4 l! M0 C5 F. i' U' B
                       "The setup has stopped.")
0 ]! ?% _! o8 k/ P7 I    stop
/ K! s. z; c+ o  ]
$ q' x/ P& ~1 _% u, |4 Z5 |6 j
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color" _1 z) V6 Z6 T9 Q6 c
  crt num-cars
' s0 D/ @$ ]" _' f' m4 e7 I, E  [) K5 f  V7 m0 ?3 l
    setup-cars
: {3 w/ R4 e' O% c    set-car-color
" M' X: @, }0 Q4 {; M    record-data9 ^& `" _, |  q
  ]/ J- O( m, F3 ?5 E) y& t3 }
3 r$ j$ d9 [- [. |4 @) _+ U$ {* @
  ;; give the turtles an initial speed
! T- G( k/ D/ L: k8 G. J- H( J: a  ask turtles [ set-car-speed ], ~& K5 y3 s  E5 q7 B' ^3 y; h
" ^; X) @+ E2 k" J
  reset-ticks
" H8 O% H  T% m8 p0 P% r' [" Gend
' ~  _: Z! E1 D/ v/ ?5 z4 E# k2 D5 a6 t0 P5 Y9 N7 ?
;; Initialize the global variables to appropriate values
1 J& F2 g. v. x& Pto setup-globals
, J. t( f. H: ~0 _  set current-light nobody ;; just for now, since there are no lights yet, `, g) p/ G+ a& m/ i3 V5 T* J
  set phase 0+ y- p; b- y9 ]9 F  e3 Z
  set num-cars-stopped 0
* l: ^& W2 T/ f  A3 O& R3 G1 x# A  set grid-x-inc world-width / grid-size-x" X! m7 M2 q$ s8 s& |6 M3 U9 E# c
  set grid-y-inc world-height / grid-size-y4 W9 U6 {& Q/ M& ]+ o" p
: c& L2 `+ E7 d! B/ T& C/ t
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary+ x3 X, H/ P0 ^6 G! Z7 q
  set acceleration 0.099
( G( Q4 ]3 E! Kend8 P+ l& O' P9 `* ?
  v3 A" Q2 H! P0 x
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
2 D2 @3 W( R; Q" o! V- Q;; and initialize the traffic lights to one setting
& _# n& R  {1 |to setup-patches( C( \- U2 ?1 _6 |
  ;; initialize the patch-owned variables and color the patches to a base-color$ U2 t9 i2 t7 v: E
  ask patches
  Q; z% r" @) d; ?6 T  [
, m' i2 p4 B4 U. g    set intersection? false
9 o9 s. P+ X+ V# ?2 q    set auto? false; u5 S8 ^* }6 P
    set green-light-up? true0 N2 i) \& [6 P4 ^' L6 J
    set my-row -1. f& ]2 b' W+ n: W
    set my-column -1' P7 ]; d4 E' C: F
    set my-phase -1% t5 P4 n# L2 }4 i2 r& k
    set pcolor brown + 3
, O' ]2 j; F* @* O3 H8 Y* y  ]
( e# Z2 i( W* V
' |7 h/ w$ h8 x, }+ j  G3 z  ;; initialize the global variables that hold patch agentsets
4 u; P* X. k" F0 z! M- z7 c  set roads patches with
; R* u  F6 ?$ P$ E8 D* N! q6 a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ A& L: ]- k4 S' l9 ]3 \4 L  W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 |4 u" L& u  P, g, Z" ~& h* y3 ]  K  set intersections roads with
, z% S; y) O+ C7 |# ~( l- r9 M/ S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
+ a4 M9 D* |6 R- Y* w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, y, y- S4 H$ w* ~
4 p( a- U6 W% h" ~2 }  ask roads [ set pcolor white ]9 U0 }" n8 P; t3 {' a0 W( |2 I- g
    setup-intersections2 k0 y: C$ X" F+ F1 ^
end0 @' N  M. c2 i  b, [) E
其中定义道路的句子,如下所示,是什么意思啊?
; G7 z1 p$ J7 G5 w. g4 K+ ^. O set roads patches with0 i$ G5 ]2 u; p1 A. `( Q* J
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: l2 v4 u; T* }
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 x7 w5 I8 L; P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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