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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。
! i/ G  W! C& g! F3 G2 y* Nnetlogo自带的social science--traffic grid这一例子当中,; }) Q3 ~2 H0 @" }
globals
( c1 t* O, y  L! d! C: S8 c[/ r& Y2 S, n1 s
  grid-x-inc               ;; the amount of patches in between two roads in the x direction  h) w5 ^( `" m$ f
  grid-y-inc               ;; the amount of patches in between two roads in the y direction& J9 ?3 J4 `8 ^! ~+ {5 r- b% s9 H& z
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, Q+ o8 ~% F9 C& v% L1 a$ B                           ;; it is to accelerate or decelerate7 z( p3 E5 J0 ~4 v& f& _
  phase                    ;; keeps track of the phase. r( R! O1 i) T3 s1 H
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; C2 ^/ v0 w% X# T$ Z, e  current-light            ;; the currently selected light, E) E; E3 G( n, E% }* B" w

4 V% S" Z  R) s' w5 h  ;; patch agentsets2 e' M+ L# D4 W* D
  intersections ;; agentset containing the patches that are intersections7 a- r3 u# }4 d5 p% {
  roads         ;; agentset containing the patches that are roads4 p+ M, L- T% x' E! v0 h
]1 F" x# e: ?4 d9 r0 P

  X; R# C$ H' {  H9 ]turtles-own! ^1 B; Y' D( M$ H' M) X8 A* V7 ]
[
% @) x. q3 B2 v& U$ N; g7 p5 x  speed     ;; the speed of the turtle
9 Z- t) W: F6 b1 Y  up-car?   ;; true if the turtle moves downwards and false if it moves to the right$ C# `2 v/ y/ d
  wait-time ;; the amount of time since the last time a turtle has moved
* `3 M% g/ Z2 ~+ p]
5 ~% L" }( ]5 C! Q
/ x9 x( Q# I9 h9 N0 |$ Lpatches-own
$ O# p2 f3 _+ O; `[8 l/ ^; z( K; V4 Z5 U! A8 ]( P
  intersection?   ;; true if the patch is at the intersection of two roads# r1 C9 y* K  r/ |4 b  P
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.  o- s, t: p2 F& U9 m0 r$ y
                  ;; false for a non-intersection patches., r0 @& W) m- F, O* t3 i
  my-row          ;; the row of the intersection counting from the upper left corner of the9 l( @3 c" D. d1 k2 w" V
                  ;; world.  -1 for non-intersection patches.: |5 C) T! @: a( O4 ?
  my-column       ;; the column of the intersection counting from the upper left corner of the5 R" c8 u4 u! k
                  ;; world.  -1 for non-intersection patches.
# M; r4 @% V1 P  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches." u2 B1 H$ g8 T9 D3 Q
  auto?           ;; whether or not this intersection will switch automatically.
; h+ j1 L+ Q9 E$ q* p6 R. I0 r                  ;; false for non-intersection patches.
4 m2 i: Z' D* j4 @' p5 Z- J]& H2 H) e( @, P5 j- L: I
: N: T0 l4 g$ x

7 B; k( N: Q& `& z9 B$ r;;;;;;;;;;;;;;;;;;;;;;
. Y. b/ z9 l# e, V* J" \;; Setup Procedures ;;0 ~" Y* z0 w3 f+ E& [
;;;;;;;;;;;;;;;;;;;;;;
5 e: e) @, j  A, l; j; b4 l( z/ L7 f$ i! O3 W1 Y- Z! i' ]
;; Initialize the display by giving the global and patch variables initial values.
' q/ m" n$ v/ |5 E( t! D# b  l# \;; Create num-cars of turtles if there are enough road patches for one turtle to
0 V  J1 ]9 P) H  p$ ]8 \7 T# R;; be created per road patch. Set up the plots.
# y5 n% j# n$ [7 @3 h/ jto setup0 u1 Q4 y2 k  q6 l0 h# A( H. d
  ca. @0 e% Z+ B8 J& F' j8 D
  setup-globals- q2 K0 a0 ^2 n

1 n* K. p# L9 h$ p  ;; First we ask the patches to draw themselves and set up a few variables
& J! j9 l! B2 J7 N4 ~; B3 C% D7 v, d  setup-patches
6 ?7 s+ ~, I" y( J" a. I. K2 W  make-current one-of intersections2 b" a! h8 ?4 g
  label-current
. r( q9 L/ Q1 ~0 a8 ?. N) B
/ b# l0 R8 T1 S/ w  }  set-default-shape turtles "car"
2 h# [* N/ k* V( g3 {, [. X
* Y  J# D% T5 m. V, t; @- n: @  if (num-cars > count roads)
" q/ x$ m! Y; b/ C# F. A: S  [
6 A6 K  O! ?. Z- Z. U    user-message (word "There are too many cars for the amount of "$ J* v! j5 p6 S
                       "road.  Either increase the amount of roads "
7 q+ d- H+ q6 f' @( X- U                       "by increasing the GRID-SIZE-X or "
; X8 ~8 I, o5 h- ?4 ]6 v* r                       "GRID-SIZE-Y sliders, or decrease the "" F. x' T7 i; H3 ?% {
                       "number of cars by lowering the NUMBER slider.\n"2 [8 q- O, S6 ^5 `) R) i
                       "The setup has stopped.")
3 Y" L2 R: \6 p8 c    stop9 S- }$ _# D% g' m# D, p
  ]
4 H, J5 O1 U9 m9 ~2 T3 \/ C, E. K& H2 X
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
3 m4 N. `  y; x9 Q0 G9 }  crt num-cars8 R5 n; A6 f2 a: Z
  [
, r" C* s0 L1 p% w" N( K! R* W' g    setup-cars
) w; ^  {1 M7 Q1 y$ }: W2 l    set-car-color
6 d! ~! e  y' @    record-data+ R0 f; t0 x7 L# {2 v9 v
  ]$ d/ K$ b: B8 b, M/ M
7 M) A" ]: o6 o( W: h
  ;; give the turtles an initial speed/ N3 z5 S* a4 L5 g! q
  ask turtles [ set-car-speed ]
+ U; V* Y' p  @
* W! l* f  z6 |$ a1 S  reset-ticks
, V4 H6 b) g3 [7 E4 t. b$ Vend
, y0 J- y4 l& S2 J- u3 n- j4 F$ i3 K+ I: o1 X2 \
;; Initialize the global variables to appropriate values, k# j6 ~" m* n3 [, e6 P. o7 m; p
to setup-globals* e' e2 Z$ r, p5 y% D8 q
  set current-light nobody ;; just for now, since there are no lights yet
4 Z) L8 S" o8 E4 u6 h6 p6 }  set phase 0
; ?3 n) W' o( o$ Y0 E  set num-cars-stopped 07 @: ?. F0 `$ Q( z8 G
  set grid-x-inc world-width / grid-size-x
& A5 Z3 i$ n3 M, P+ Q* U/ R/ v  set grid-y-inc world-height / grid-size-y0 f( M" B" D8 r- C$ h
. g5 K1 h( O- G
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 c6 Q8 o! q  @- j
  set acceleration 0.0997 Q  J5 p+ f4 V+ N
end, R' ]: Y9 Z8 l8 a1 g* P
, i, b, r/ H4 \+ o  ]. _
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
- M3 f6 b# B: m8 M% o4 r9 k;; and initialize the traffic lights to one setting
- T8 e  a" K, y" X+ F" Gto setup-patches# F8 @1 w) v% |7 O# v
  ;; initialize the patch-owned variables and color the patches to a base-color
& b4 k! @# W5 ?- V  ask patches- {+ L: u: K% M& G5 @
  [7 N% t) W7 H9 T$ n' o" `; o+ }6 c
    set intersection? false% w4 S( ?+ w, z- \
    set auto? false4 z$ J3 |( ~/ H6 U
    set green-light-up? true
4 g8 E$ V0 p: q. X# i5 f    set my-row -1
. y9 ?0 a! a0 @4 {$ S6 L+ U. N    set my-column -1
6 v* I! Z+ L& Q# I* n, t& l    set my-phase -1
, \# O* `! _& I7 h) [  W    set pcolor brown + 3
( |1 O# U: u4 `2 `8 f% E  ]7 M, m. H# P- X( f/ n; E1 s. ?- Z. V+ g

. u5 ~: O4 n  H- b, P2 O7 A  ;; initialize the global variables that hold patch agentsets
7 G' R, f2 a% k# R1 s' Y+ L  set roads patches with
' u7 L! e: g* I, l8 j  G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  z, W# }- E/ l; h; x1 F1 T
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 O( `% T( N/ j0 ^7 K( \" _  f  set intersections roads with* r, O6 ~  s' W( u) `( e6 l
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
3 W3 ?$ J) I, }7 w  }+ J$ E6 Y9 R% ]    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ u) T3 ~2 B1 a" f4 n) u3 b  \2 l7 ~* l, \& I& h" g' n
  ask roads [ set pcolor white ]
: v9 G4 V* K, Z0 w* O: d1 g* y    setup-intersections6 T4 s) M2 B( k7 x3 q
end
4 a3 _. [/ A8 C其中定义道路的句子,如下所示,是什么意思啊?' t9 s' @% O- I; L0 ~; Y5 [8 n: r
set roads patches with% L7 P4 i0 I7 r# G' Y' N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# M. f) ]2 f' C& B( b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. A# ?. b, z, D, W- l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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