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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。0 f  Q( x  P- T8 V  }9 ^
netlogo自带的social science--traffic grid这一例子当中,
8 n( x+ g7 M  z$ h% R. Dglobals# s! ^$ k) X; n+ A, u( ]
[
4 o# k7 m0 C; \7 W2 o  grid-x-inc               ;; the amount of patches in between two roads in the x direction
  Q1 H! o- \5 \& M/ _6 C5 E  grid-y-inc               ;; the amount of patches in between two roads in the y direction- d! [* @$ }: I6 I
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, G! C# e1 i/ ?) x4 q                           ;; it is to accelerate or decelerate, L, c+ m2 l5 \) _, |  B
  phase                    ;; keeps track of the phase7 I7 e, p  W: z- S# W
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
2 x* |) C& T9 Q  current-light            ;; the currently selected light/ ~, C* |. R( D

  f0 v& |0 F& d6 P0 R4 y5 j2 J" w  ;; patch agentsets5 e* W( O0 A  A! I/ @
  intersections ;; agentset containing the patches that are intersections" }. `2 U  [$ g5 b6 d2 Y& M
  roads         ;; agentset containing the patches that are roads! \% [8 ~0 U) B8 X  p4 D- a$ b( J
]0 n8 u# u2 L& ^' S( e. [

4 h1 e& H& o3 f! lturtles-own% e( F* G) B1 V' q/ S( Q
[
3 Y! |0 @1 I# @$ o- l' q$ Y  speed     ;; the speed of the turtle
% E; A7 b: A' j1 s# P3 p  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, q% Y# o1 z0 p2 g9 F& |+ ^
  wait-time ;; the amount of time since the last time a turtle has moved+ G# k+ w9 l) V. u5 I! K0 t5 H
]
+ ]8 @8 ?% B( b4 V! W$ p" E  Q* s. x& r- o6 v
patches-own3 M8 q* L( m$ `, t
[7 J+ m/ Z( b% B$ h
  intersection?   ;; true if the patch is at the intersection of two roads
1 c. z$ U; t2 U8 ]7 [  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
- y) m8 H& T# m8 G                  ;; false for a non-intersection patches.
% g/ ~0 X" S* W7 C4 b  my-row          ;; the row of the intersection counting from the upper left corner of the
# G) I- K/ q* P  b* I0 \- @                  ;; world.  -1 for non-intersection patches.
4 U* c. `0 w0 {& Q  my-column       ;; the column of the intersection counting from the upper left corner of the
% m7 ~. w* o" W/ V                  ;; world.  -1 for non-intersection patches.
- O6 n: f( K8 x% \  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches., t" q; \! C! B3 |
  auto?           ;; whether or not this intersection will switch automatically.
! k2 K7 M9 F9 g* b+ o  m  O/ ]                  ;; false for non-intersection patches.# s: Q2 i5 t; \3 i7 k) Z
]
2 A* p# l8 p, h$ f* e! [7 H& r4 x6 k$ q) u3 ^' l

/ X/ W2 k& n% v: _;;;;;;;;;;;;;;;;;;;;;;0 {& V" |( d2 n8 @
;; Setup Procedures ;;
$ u7 n# v' i, j;;;;;;;;;;;;;;;;;;;;;;
* ~# R8 h3 b7 w4 T, J; w. y2 r" S/ ], K
;; Initialize the display by giving the global and patch variables initial values.
+ g9 i3 b; s+ [2 F% ^;; Create num-cars of turtles if there are enough road patches for one turtle to; U% S) I0 M& b' v$ n/ {
;; be created per road patch. Set up the plots.2 P0 D; u9 K# _$ b' n
to setup5 P! B2 j# Y: q0 G
  ca
& y1 k; U$ ~- V4 n+ X5 _+ h* G3 H* a  setup-globals! k; p9 P3 j5 m( J; r8 |; P

, F: i7 c2 |6 S3 h3 {  ;; First we ask the patches to draw themselves and set up a few variables' m2 m( Y/ h& n: S9 p0 a" C; ~
  setup-patches
& V* E. s% q- W0 X) M: {0 e  make-current one-of intersections
; o9 F, ]7 F- x  label-current
9 r- m. o: ^& o9 O6 E8 @" b1 q" M; X7 `  R6 u$ l- }5 Q$ q
  set-default-shape turtles "car"
# |) d; E& R3 W& B8 z2 F8 ]. Z
- T" R# ]( `' ~$ L5 g6 y  l% ]  if (num-cars > count roads)
/ A$ j5 F- J2 @! E. Y* }: o8 z  [4 J1 S& L  ^& ~. i: F
    user-message (word "There are too many cars for the amount of "
4 C  b+ g* @! V" o. Q                       "road.  Either increase the amount of roads "5 w( k) J3 j5 u1 K* A
                       "by increasing the GRID-SIZE-X or "' ~; e  ^9 S$ F- e2 E7 N
                       "GRID-SIZE-Y sliders, or decrease the "6 r3 d& J  w3 Z7 X
                       "number of cars by lowering the NUMBER slider.\n"
# I. Q: ?' e0 b+ @& t                       "The setup has stopped.")
; B4 t6 w2 w% X8 ~. a' P    stop0 T0 V0 Q9 c/ _/ K( n  C
  ]
4 l: A1 `1 v* Y* h! j& x  K5 J3 j0 a$ d5 e
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  T) `* g( d/ ]( V) c+ z1 g% [& u# ?' C  crt num-cars* w' A$ G/ i( n; J) M7 T( V0 n- O
  [$ U* ?3 Y! Z/ I( f
    setup-cars
& R$ s; W( T0 e; j; U1 T+ g    set-car-color4 c* z, Q$ y8 d- n7 [3 P% i+ h
    record-data
2 f0 s, ]1 z$ T9 u  ]# ^: m, q. ~  t

9 R8 `, h. c! U, b% j  ;; give the turtles an initial speed
% l3 _$ X9 B7 Q4 H  ask turtles [ set-car-speed ]
2 |9 @! }: g7 Y) q* D" s6 ?4 g5 t7 Q) l: v0 T5 P6 W0 e
  reset-ticks
* z- ^; j* w* U1 qend( m7 i6 f# I6 a9 r

( z6 k9 a9 n  _8 f3 D;; Initialize the global variables to appropriate values+ P3 `, o/ s( x  F  W5 v
to setup-globals2 T9 o2 C* I' }8 _0 q
  set current-light nobody ;; just for now, since there are no lights yet
' c- Z+ V! Y: c- ?  set phase 0. \0 y. Q: j) D  `
  set num-cars-stopped 0
, k( ?7 O* R* D# k  E4 N  set grid-x-inc world-width / grid-size-x! M6 d: q+ w2 {, h
  set grid-y-inc world-height / grid-size-y
9 {, f; k; t* g! H- S' m' L  l/ m5 [4 c* o0 u
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 r  r# D3 L' a  set acceleration 0.099
2 u. L2 s8 R' Q: ^. tend
* Y: T7 u7 [. M+ W% {- U7 i7 O% C% i* _3 j
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,( j* _- f- E! B% K: q- B
;; and initialize the traffic lights to one setting
2 @. |3 [) V! u8 ]to setup-patches9 {: V% G/ {8 j* a$ i" Z! d- y- B
  ;; initialize the patch-owned variables and color the patches to a base-color
" x" B/ o9 X! z* J$ R+ G  ask patches
# L4 ~( g1 @% L# I3 U% A  [1 R  ?3 d( q" O5 x( s0 q
    set intersection? false; X# t+ y# I- A, g! e
    set auto? false1 d( J% _8 E( G* ^* @
    set green-light-up? true4 C2 {' t' q; ?, N# a
    set my-row -1
+ O. P3 Z* B2 @- }4 I- {" c8 o0 j- L7 M. w    set my-column -14 C- y1 o' G+ k: \3 x/ H* Z6 ^7 J
    set my-phase -1: ?0 K0 c) d* \2 r' h* [
    set pcolor brown + 3! t7 _% ?  s) S8 a  `1 L
  ]0 \5 I( x1 h* r' X! {4 V' e

+ v% v3 l: h1 h3 A, D  ;; initialize the global variables that hold patch agentsets
/ G% p0 t' V: M  set roads patches with
% c$ r: L; D+ G. P% ]$ Q% F# j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& I* {. \0 k4 B- g$ K3 C    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 I- ~9 p5 @4 p  set intersections roads with+ E  l# q1 J5 x' @* z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and! ?  }9 f: C% R
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ F2 @' }6 Z: ^5 z) }) U* z

7 V, [* |3 u: a% w9 S  ask roads [ set pcolor white ]
( O) ]" P' e4 }" H: ?5 h6 y    setup-intersections
. T8 A' ^+ g' q7 T$ send& G8 [4 U  R) d7 A
其中定义道路的句子,如下所示,是什么意思啊?
4 `4 Q! N5 W1 `) ~) I) @ set roads patches with8 [+ t( b; U8 U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 ]; I% h4 z& |" \/ ^( z) c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: z8 z) g8 ^, g- s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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