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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) ?9 ]- h" t0 \netlogo自带的social science--traffic grid这一例子当中,
0 O  o3 f1 s! z* c" a! s5 U+ \$ zglobals/ ]& s( }! b) w4 j. V0 ~5 q; q
[
/ ]5 c# m2 O& a8 S% `- r% k  grid-x-inc               ;; the amount of patches in between two roads in the x direction  w  _: \+ u( u: e
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
4 ?) E) q, z6 L$ k! w  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' V6 V1 g2 n+ y2 y                           ;; it is to accelerate or decelerate
7 `9 g1 o0 [( N% G" m' d  phase                    ;; keeps track of the phase5 m+ b5 h/ m  a8 O& w' M' [
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure6 [3 c. W% G' M2 C+ e7 U9 X3 Z
  current-light            ;; the currently selected light
2 h; S' p) @- x) \: m; y3 o2 }9 B; y. o7 ?8 \
  ;; patch agentsets3 B& P2 U  s) w7 C) J' X! t* z1 w0 y
  intersections ;; agentset containing the patches that are intersections
" q7 Y0 p4 {2 Y& C, Z4 H1 P  roads         ;; agentset containing the patches that are roads
/ Y& T' A% K3 k], N2 _- D8 u8 V2 o- m$ `) s

% l7 t& q  n& c% o. }# Cturtles-own" K& i( V7 U% S4 ^
[' c5 ^9 \0 D  N' k% c5 g
  speed     ;; the speed of the turtle
3 q: {6 f5 N( C, |3 {  up-car?   ;; true if the turtle moves downwards and false if it moves to the right2 K  a: \* j' D) q9 M
  wait-time ;; the amount of time since the last time a turtle has moved3 N  F+ w# U1 {$ }5 {$ S
]
! i, ~9 B! r, t" [- ^; t' V: i3 ]. q
patches-own
0 a3 u' N) X; W/ g' d$ V# b" H[4 e0 ^% h& Z' R( x
  intersection?   ;; true if the patch is at the intersection of two roads! S5 W2 ]* N! i7 {5 x, N7 y8 z0 [
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
. B. j+ F4 f* E# i6 ?, x7 V                  ;; false for a non-intersection patches.5 ]$ \; X: p( ~& M
  my-row          ;; the row of the intersection counting from the upper left corner of the# j1 W; }' U* Y& ^
                  ;; world.  -1 for non-intersection patches.  i' ?( a4 U8 \, c8 C
  my-column       ;; the column of the intersection counting from the upper left corner of the6 o: b. N$ o/ K/ b
                  ;; world.  -1 for non-intersection patches.! P0 p/ B* E5 a) A& @' h' {
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
3 f- c  u' f7 m; w) W  auto?           ;; whether or not this intersection will switch automatically.* }7 @# I- P& u6 h
                  ;; false for non-intersection patches.
% f- ~& E. N' }- f: y7 J* o2 T]
8 p" c9 }. P- @2 V) g" @8 }1 |+ X0 z, _' c7 e

. P' M" a1 a; G# X;;;;;;;;;;;;;;;;;;;;;;0 c  I- B/ u7 I
;; Setup Procedures ;;9 Z: A. d4 l( X  Z
;;;;;;;;;;;;;;;;;;;;;;
* }  T# i5 p, E  E7 ?
% \6 X; _3 u* Q! z, x1 S. u0 L;; Initialize the display by giving the global and patch variables initial values.
1 }- j& P3 g% V;; Create num-cars of turtles if there are enough road patches for one turtle to
' V$ c8 a' x0 S) };; be created per road patch. Set up the plots.
( b; w/ _: f0 sto setup' p. u# S& h  B; s
  ca* A  n% }# @) C6 v. k
  setup-globals) u. k3 a/ P4 V8 N" o$ r

5 [6 V/ }8 j* o; h; p  ;; First we ask the patches to draw themselves and set up a few variables
7 P  ^  X& T: x  S8 R& ?+ U7 `! }  setup-patches# p$ ^8 H/ `& G* {# l* X
  make-current one-of intersections
9 c0 T" }% r/ L, X- ?# t2 g  label-current
  T9 [3 P, j5 y& p0 A( X' z" |/ i/ L6 [! \
  set-default-shape turtles "car"% A0 G; U, d- I9 [1 h1 j5 d+ M
/ R2 p% q- C& J2 K1 ]
  if (num-cars > count roads)
  ^6 S4 ?1 J; P) t  [
" {) C/ d6 M  F0 g5 _% b    user-message (word "There are too many cars for the amount of "3 `  y) x- B& r8 |% O5 g' d8 t
                       "road.  Either increase the amount of roads ". V0 J7 K; I/ j  W9 D# k4 O3 R; J
                       "by increasing the GRID-SIZE-X or "3 C& J$ \$ a) m4 Z. f) G7 E
                       "GRID-SIZE-Y sliders, or decrease the "
7 {( @& U0 a# ^1 W                       "number of cars by lowering the NUMBER slider.\n"
0 Q/ J% T, [/ I% E  R9 \7 }& U                       "The setup has stopped.")
, p, w% e8 x# Z. f/ N, V) x    stop
; U& O  D/ m  q* b4 ~( M  ]
; t2 S/ Q$ }. b
5 o+ l, V9 \- q  A) K$ K  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color, T' \6 Y3 a) G: h2 ]
  crt num-cars
$ i2 v/ T2 h! N0 W& [7 B4 p% ?1 Z  [
# {+ W! \- g  n) l/ W: P    setup-cars
1 S, t: p' \2 V" H    set-car-color
, M; H' K2 @- q. X7 M! j    record-data
+ y8 m% }. ~  y& t# G8 T& }% @5 ^  ]
2 _1 `7 ~- _0 c# Z, S8 e8 Q! x$ J" M1 b5 m; ^
  ;; give the turtles an initial speed
& Z8 D* z8 ]1 @9 X3 x/ X( L: w- h  ask turtles [ set-car-speed ]5 V5 |1 M; }# c, |. q4 J' \+ e
- N" T4 ~9 S: E3 J4 D8 p% t2 q
  reset-ticks
9 j( y5 V8 T, G0 {. z! j- w! d, rend
4 G# S8 N+ ~4 _0 S4 u: v1 }. j$ L  W; \+ H$ Z
;; Initialize the global variables to appropriate values+ g) h# {$ J4 B' Z( u
to setup-globals  A5 ?! |1 W0 y8 V
  set current-light nobody ;; just for now, since there are no lights yet
4 e- B% @' K% j5 w8 h; s  set phase 0
6 x! S$ W! {- J$ Y! f& e  set num-cars-stopped 0
- K. P3 n! G" m+ \/ X9 `5 w  set grid-x-inc world-width / grid-size-x  ?  {5 r0 _, b' n& `
  set grid-y-inc world-height / grid-size-y
9 v( X2 H; a  |
6 S. g6 l0 p  K+ u  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
  U( p1 |( E: i: W; H: Q  set acceleration 0.099
' |  l) c' m1 u8 O7 S: S8 wend; C3 l( k. v6 M. w+ J

# `: U7 y$ Z- L. o; ^9 y8 I& c( A;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
( f- |! r9 Y* J, I! f$ A;; and initialize the traffic lights to one setting
& P( i" j) w2 O5 Wto setup-patches
) h$ W4 l3 _# M3 ~; h( c  ;; initialize the patch-owned variables and color the patches to a base-color
  T7 x" r# W' Y: K3 V  ask patches
7 t+ U# S# p/ i1 R% o7 B; R! Z% _  [
; `4 I+ K; {' C, t6 k# s    set intersection? false
: R3 B, |& J+ _    set auto? false5 V- `0 I) g7 q) S
    set green-light-up? true
/ z: y* g7 }: c  G    set my-row -12 a1 h: s; j9 C- f2 `2 V9 g
    set my-column -1( E7 w% G( z# W; G8 N5 x- F7 V% n# }
    set my-phase -1
9 e( Z/ H- }. i( E$ u8 B9 z    set pcolor brown + 3  R$ U+ m8 ?# a0 F2 K1 R
  ]
3 c% j/ _7 b  z" D3 X# y" l3 F+ ?% x
" ~" a# |# _* J  F' R/ k  ;; initialize the global variables that hold patch agentsets$ X$ ?5 E' U" s2 i; L4 C, @
  set roads patches with' W7 T5 j/ x: h/ \  F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 c) p9 S% |+ n) H9 @, L0 u$ l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 U! z" }3 P! a# K  set intersections roads with
9 F' \3 Y) S0 ?4 l8 P8 x    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
9 h4 i! b9 z  M& p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! W2 x& O  V4 q  ?3 X- G5 P* o
! ?8 ?3 V* k6 g8 T# n3 e  ask roads [ set pcolor white ]4 d1 [) ]* o' Z. Q, |
    setup-intersections
/ m/ _! }' i  [; ]# Rend) c+ a) u% g9 |* Y, t
其中定义道路的句子,如下所示,是什么意思啊?
# U7 C: a0 Y; }! T- A; S set roads patches with
" u$ M: x8 s: o6 y" i& X3 J    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" R' j9 y1 \( B3 E/ z- c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ v' d- u" @( t- B7 W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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