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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。
! m" `" O% W& g3 \  X/ Fnetlogo自带的social science--traffic grid这一例子当中,8 Y- D  I7 W. v/ ]
globals% P4 }3 v( ?7 W; T
[
2 L0 P# U- J5 Y  grid-x-inc               ;; the amount of patches in between two roads in the x direction
! p9 P. V4 t" p' C1 m' [  grid-y-inc               ;; the amount of patches in between two roads in the y direction( F' ^( F  ]- f  m+ n; u
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
9 `, ]8 \) v# y7 f0 U                           ;; it is to accelerate or decelerate
/ Z! O: Z; _% M4 ^, l# a. s  phase                    ;; keeps track of the phase
% @' x# X- Q% F: g: J6 _  j- n! L$ _  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# Z5 b3 Z6 x4 S7 D& P7 G
  current-light            ;; the currently selected light# K' i' \' @1 O8 Y

( k8 X2 Z. G/ m% e3 g$ b( L: G! L% k  ;; patch agentsets
4 r7 s" d0 ]/ y/ i  intersections ;; agentset containing the patches that are intersections
5 i) R1 |- j! ?1 Y" h8 U  roads         ;; agentset containing the patches that are roads1 k) [7 f5 f+ f4 Q/ V/ s
]6 r1 {- {6 W/ F/ m( w/ g

# b6 I8 F! S+ ]/ l8 D' Tturtles-own$ d/ ^* {9 H8 O( o! [( r" ?9 s, ?7 f1 S
[
9 ?' [, a5 z. v; a  speed     ;; the speed of the turtle
9 \4 o$ {" e/ G& b2 W  up-car?   ;; true if the turtle moves downwards and false if it moves to the right  ~# ^, x# C5 {8 b
  wait-time ;; the amount of time since the last time a turtle has moved9 r6 y; m9 C* V4 ]5 x8 N
]6 V( N* J  z- T! ~
) a8 _/ l. S. b8 x% P
patches-own! _$ K* ^8 X4 W" `
[  Q. c  b! _+ a7 }0 U& o  S
  intersection?   ;; true if the patch is at the intersection of two roads" r! I) S; G) c. e
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
0 x3 I/ S- z0 ?( p( p) w. Z                  ;; false for a non-intersection patches.  b  S  I7 e) _0 r* H! K
  my-row          ;; the row of the intersection counting from the upper left corner of the
5 c: \3 t% z5 g+ f                  ;; world.  -1 for non-intersection patches.
4 D- q8 I& y  N* _' O% [. f3 O7 q  my-column       ;; the column of the intersection counting from the upper left corner of the5 c, ^' U, X$ l5 L  W8 l4 x9 o
                  ;; world.  -1 for non-intersection patches.
' n; k* t4 m% b. `% p  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
- [, l' @4 u( }& F+ j# p  auto?           ;; whether or not this intersection will switch automatically.
  P+ r, B  f+ q! `1 ~/ e                  ;; false for non-intersection patches.
% m+ B; V# V5 L, r- \" \0 p" ]]
0 z6 u1 r; Q, Z
: S) x# I7 m; v" e% h
  D7 w, V6 |% @3 u9 |6 B;;;;;;;;;;;;;;;;;;;;;;
  L, L5 K1 Z4 s9 i/ y/ E7 _;; Setup Procedures ;;) Y# Y9 B8 t0 B, k6 h/ ]# M1 a8 t$ s
;;;;;;;;;;;;;;;;;;;;;;: k9 L, m$ l: U: w' L
7 ]& p* J" ^1 k4 n1 W$ {
;; Initialize the display by giving the global and patch variables initial values.
: y1 y' Z: g: i+ Y4 O;; Create num-cars of turtles if there are enough road patches for one turtle to( }- }3 @4 o+ g( B
;; be created per road patch. Set up the plots.
9 Q0 ~& |& \5 V* Nto setup8 _4 ^2 Y+ j: Z3 G: @7 [
  ca/ H% s) `7 X2 K7 O- `$ b) r# G5 c
  setup-globals
4 Z6 F  _8 [, }7 o% V) ~3 A, J& g3 }# ]1 E: I
  ;; First we ask the patches to draw themselves and set up a few variables6 ^" g. G( _8 i' p! D2 j
  setup-patches: s% O  w9 }2 G2 `
  make-current one-of intersections- J# k  A8 }" [6 a, h+ \9 p
  label-current' `8 ~; r1 A5 x) C% r2 e: A
4 \! \; O- P- G, U, r4 i% J
  set-default-shape turtles "car"
2 g5 D4 n8 Q+ u' Y+ J% B7 T% F1 v# c) ]
  if (num-cars > count roads)
0 o  g  ~' }- T# k. r  [
" E3 f% \% R" U* a6 K    user-message (word "There are too many cars for the amount of "
; w% g6 y* L: c/ n                       "road.  Either increase the amount of roads "
3 {+ i$ e: H1 ~' Z                       "by increasing the GRID-SIZE-X or "
; J4 n. B9 x6 s+ N& g1 [1 L                       "GRID-SIZE-Y sliders, or decrease the "
1 A6 n* h5 @, F: {5 k/ t                       "number of cars by lowering the NUMBER slider.\n"0 m) M# B, w/ N9 ?0 N0 d
                       "The setup has stopped.")& O  ~$ O9 N9 A
    stop' Q- }$ D+ e5 x) `  R
  ], X- W; W- Q) d* F2 g9 ]

! `. G) V! B. W1 Y5 }  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
/ l* ^( Q7 \+ ]3 G* X$ P  crt num-cars
- h+ }# R# Q" N" w3 h' J; i. }8 T  [
' \4 O* D2 f" s    setup-cars
- ^6 Q  F+ q# x/ @! q/ D1 v, A5 Y1 v5 v    set-car-color
) p1 T( R$ S4 r2 I# R( O) n    record-data3 c, c+ @4 d. L* Z+ K
  ]
( m) _2 W1 J5 ?: Z8 s- u! w! u0 v! `
  ;; give the turtles an initial speed0 T# R/ @6 y# ~. t# @" W, v
  ask turtles [ set-car-speed ]: y& }1 J% \' g3 B5 ^# N

) V% K# z2 b% D3 Z3 n% _; s  reset-ticks4 T3 N# ?2 w9 H" K! P5 o
end
* h% q5 G2 ~  n6 ~" x/ {
. T  e7 v$ L! q0 z" q;; Initialize the global variables to appropriate values5 l/ y# _1 f) R8 M0 `
to setup-globals9 B2 l7 w0 `* y. d( o) s
  set current-light nobody ;; just for now, since there are no lights yet$ P& ?* \/ t3 p+ Z- U+ ~
  set phase 04 b% ?+ D" |: b* B/ G
  set num-cars-stopped 0
4 p, d  x- S. f- l( M  set grid-x-inc world-width / grid-size-x
. a" A& L+ s. `7 j, d  set grid-y-inc world-height / grid-size-y; e1 h$ ?& m4 O

! B( N6 [6 }. X8 g1 ?7 J0 m  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary# c3 \% S  ]* S1 B- Y0 d
  set acceleration 0.099% r( |* Y( E; m% i) P" o- p! e/ ?
end7 I8 C7 x! j2 F& T3 ]
: Y  Q, {' X  {( V# O
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ l* L: [4 K* t; X; @) J3 H* Y
;; and initialize the traffic lights to one setting2 \. g- S4 I/ h, O, i
to setup-patches* J: u" ^  u( g0 _
  ;; initialize the patch-owned variables and color the patches to a base-color5 J- ]0 o& f5 P& k+ H& D
  ask patches/ F% B  {) C8 q' \
  [
. ^9 ~. C1 A6 d' n) d    set intersection? false# t- l7 S  n; z7 {
    set auto? false2 c8 [( u4 ~- ~8 s2 ?
    set green-light-up? true
1 p$ [  E% }/ B/ b4 j5 L. {    set my-row -1: l, r1 X2 ^! f6 H  d! ], O
    set my-column -1
. }9 F$ G4 C- w) X    set my-phase -1- n. M/ E, f, M# B, d. v
    set pcolor brown + 3
; l4 c4 C+ i$ X# n" R+ i  ]
+ b8 D1 c: U5 D. H+ _2 ~1 N6 b2 i  [" P1 G9 J& }4 y+ I- O" r
  ;; initialize the global variables that hold patch agentsets+ d. P) Z4 d$ Q4 j3 B
  set roads patches with, m. K6 {$ C. K& l
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, w4 S( j' v6 P    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- F' u# i2 g4 b2 p* Q' s! i  set intersections roads with# O0 G  V+ R1 H/ ?
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and. @: y/ U! G! c$ y' N: E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 j" l3 D/ Y) R1 f
- j/ |1 m4 e+ a0 l& t
  ask roads [ set pcolor white ]
3 [. ^2 c, s  f    setup-intersections* [6 z$ E% Z( \! C# \
end6 y% v" \3 b9 T
其中定义道路的句子,如下所示,是什么意思啊?
: U! f( K8 U; m) P set roads patches with: U0 \5 b  Z: @5 k' V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 _! K+ f$ D3 h0 Q- T# {/ T2 P. v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* B1 k3 A! h5 a/ ?/ `. v
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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