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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。
6 i! q- }, F/ q4 Z5 anetlogo自带的social science--traffic grid这一例子当中,
/ \* N- e% a! x9 Y3 [globals
! o/ L3 g9 I5 l: j7 U. U1 g[0 W) e9 ?$ V; b# A6 z3 z0 O
  grid-x-inc               ;; the amount of patches in between two roads in the x direction3 f" ~3 x% m0 p' r* r
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
3 G) [8 q" C9 A7 x  acceleration             ;; the constant that controls how much a car speeds up or slows down by if+ h- `4 ?2 M) \5 I0 T: L3 u0 y
                           ;; it is to accelerate or decelerate8 O9 r7 q- y5 L$ y" W, v3 X& f# T
  phase                    ;; keeps track of the phase
+ v; L' Y% g( d( Y" _: D  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure2 y: f/ ~5 N& V8 f
  current-light            ;; the currently selected light/ m4 @3 A* C+ M9 Z4 f, c

& B  L. J" a+ [' s, r  ;; patch agentsets
: @9 E+ t$ N* b( ~+ a$ ]4 n! {  intersections ;; agentset containing the patches that are intersections
- c/ @8 ]4 G# `+ Y  roads         ;; agentset containing the patches that are roads4 q5 \2 ~6 ]+ ~6 T
]6 Q2 o$ b$ P# x( u7 L+ y

0 J1 B" B  @- E4 Cturtles-own
& Q  R4 I/ Q* `  q& o7 r- @[3 S5 L3 z5 F4 Q9 B6 i
  speed     ;; the speed of the turtle0 L- Y: j$ {* w) y+ }
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right- r% Q( \  ]+ H6 |- F
  wait-time ;; the amount of time since the last time a turtle has moved8 b) |8 V5 c' k; c
]1 b$ a' K4 A7 l
; z, h; P: z; C. s8 _
patches-own
, J: w3 z$ `+ r[
( @: D" ^$ @3 l" F% H/ m: c  intersection?   ;; true if the patch is at the intersection of two roads
  x) k0 |3 d4 ?; I* C6 h% ?! _7 N  green-light-up? ;; true if the green light is above the intersection.  otherwise, false." {. z- Q; a: f8 ]* D  s9 g
                  ;; false for a non-intersection patches.# i2 L9 M8 \1 q; |$ \% T' I
  my-row          ;; the row of the intersection counting from the upper left corner of the
" m& P9 O  o, C$ T( G/ G2 j                  ;; world.  -1 for non-intersection patches., M0 m! X0 n( o
  my-column       ;; the column of the intersection counting from the upper left corner of the
+ Y2 N& d$ G$ p' O# V                  ;; world.  -1 for non-intersection patches.
6 }% s1 a( _, z  P4 e+ o: Z  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
' g. P% o" e, d1 M, z  auto?           ;; whether or not this intersection will switch automatically.. @/ g% C" R/ z7 c) o' q
                  ;; false for non-intersection patches./ r1 n" x* K* [2 O* i3 |
]
4 A' l3 N& p* I# w) h
% |( _+ f( F8 o2 u) p/ G' F
' X7 A" h( b& o3 ~9 z7 O;;;;;;;;;;;;;;;;;;;;;;% q* y% S0 p+ {: f
;; Setup Procedures ;;
2 Z) ~9 e- d" p" l( q5 C;;;;;;;;;;;;;;;;;;;;;;
( X9 X  f, h( L9 a$ t: P3 w) n
' I0 f. e9 b, k0 H# a3 G( m;; Initialize the display by giving the global and patch variables initial values.: F. S/ {& M* `0 z: u; |
;; Create num-cars of turtles if there are enough road patches for one turtle to3 X" I' a  T! h% r) R  H+ R/ u5 `
;; be created per road patch. Set up the plots.3 V/ K5 Z6 J; t- o# n- B
to setup; R; x. l, S0 W' d
  ca
7 }) }* e1 ]+ G+ k! }- y$ K/ L' U  setup-globals
* F2 l3 s! `5 r  N8 K& @3 k
" G# Z  M3 C) @' `2 y, L  ;; First we ask the patches to draw themselves and set up a few variables
' O$ A# Y8 J0 C! v$ R! [* C- F  setup-patches
% x+ c( K& F$ y6 U  make-current one-of intersections
2 y4 ^  D# I, Q* s+ s( k  label-current7 v% Z2 f7 J$ y$ I) y3 V! a

6 @. b* O) ?# H7 l" L+ Q  p: L  set-default-shape turtles "car"
( N: y! A6 L. W$ f" S9 {: ~, a6 o+ [, g; n
  if (num-cars > count roads)
( l! r9 C: L' c7 @2 l, H  [
! \; w5 T$ v8 {+ c    user-message (word "There are too many cars for the amount of "# A( v* V) a1 e6 P$ {) u! Z
                       "road.  Either increase the amount of roads "* n$ h  p- Y- _7 b. ^
                       "by increasing the GRID-SIZE-X or "! O$ {( K# T! C2 s/ j+ o
                       "GRID-SIZE-Y sliders, or decrease the "
" e2 R% G" H5 s                       "number of cars by lowering the NUMBER slider.\n"
. A  Z% Z' X* B/ |& A4 q6 d6 ]( a                       "The setup has stopped.")% c  s. T2 P' S( U2 x3 w3 A. C
    stop
9 K+ {7 W( Y! F. w7 x6 p5 R# H, C  ], Q$ S5 ?$ n5 v; H$ H
; ~+ u: p9 G1 U% G
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
/ _" U2 L* y- E% c0 ~/ x- g6 _  crt num-cars' l' H" S* V1 I& i" }; l# j% D: u/ G
  [* w/ C& h9 H# {4 k& m
    setup-cars9 x- F" t2 E- M" J
    set-car-color
" Q9 z4 \  q  y2 v. g    record-data
8 c& c* Z8 u) V  q  w* f9 B  ]4 v9 E; W- ?/ {6 r# S- b' X

" c- g3 }- Q" a  ;; give the turtles an initial speed$ d8 O; H6 z$ i/ `9 {. Z
  ask turtles [ set-car-speed ]1 Y' C; r0 i- ?/ t% r
4 ]! ~- q0 b8 p  Z6 u
  reset-ticks- @% M; G. Y; v
end
- F7 Z" i9 t: o# @+ X; g3 s3 _3 I4 I
;; Initialize the global variables to appropriate values
8 K6 I% Y2 h% G% Yto setup-globals
5 S* l/ I0 S' ~8 ]  P$ Q' L  set current-light nobody ;; just for now, since there are no lights yet
) m# w" W# z! b( O& G  set phase 0
& |0 C- \& ^7 h' I  set num-cars-stopped 0( G. [: b- d8 A
  set grid-x-inc world-width / grid-size-x
% o) H' H9 p$ V% W  set grid-y-inc world-height / grid-size-y. Z! _8 U/ N2 Z6 S
3 k# p+ t6 `' C) Z5 y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
4 i9 p" z# T6 x8 Z  set acceleration 0.099  ?' C, u0 K4 U  M2 b, p5 x1 C; _
end
- D6 b; c' B! ?+ K8 D5 [
" T; ~" L& _% u% n: w;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
, [) @7 Z* q0 W: h) ~4 @' T- ?0 v- E;; and initialize the traffic lights to one setting
) {( j6 ^3 ~- D8 _to setup-patches% F# |5 C2 X  d' O! |" b6 k
  ;; initialize the patch-owned variables and color the patches to a base-color
$ c( u4 T9 P1 V/ x* G1 m5 b% I  ask patches
" K: ]5 o/ v4 t6 E: Y$ B' r  [
8 T5 N+ [# y7 k2 R! H# _    set intersection? false7 [$ R) A; R4 @( B( p
    set auto? false
! N# @3 A  w6 d& Y) \1 Q+ D    set green-light-up? true
5 E/ w, I. _+ g0 t& ]1 n    set my-row -1& B; g/ v0 m# F& ~  z0 c4 f
    set my-column -1
, N0 i; h) H* ?7 S0 x5 s* E    set my-phase -1
. @+ _, V4 a) d. H, N    set pcolor brown + 3" O* J" h, w+ c- T4 I  v( \2 L
  ]: r- O( f6 p! A: I
' a: S- a8 B; u$ p7 _7 K) o8 x
  ;; initialize the global variables that hold patch agentsets9 \, D) _0 |% t7 ~
  set roads patches with
% {/ E+ J, ^( Q5 Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* N! j  w  t" h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; r  Q" c) U" J: [/ Y) Z, C
  set intersections roads with
2 n: S+ V* T+ `6 V2 a, L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 V! {& q" g& @) N6 t1 f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* U) y# ?. ]# v8 e: J! D3 |+ b
0 ^; |2 q, s+ y& S0 k
  ask roads [ set pcolor white ]
* R- R# J! \! @, t# V. Q( S    setup-intersections6 l$ f, H( t! x* Y& w
end5 K$ U3 O2 {/ B: t7 ~3 v7 _" ]
其中定义道路的句子,如下所示,是什么意思啊?. {2 R6 a. S" y' m0 Z
set roads patches with
0 x8 g9 r& \5 l, w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 [  a; a! R4 i; ?( K* A* l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& E, \3 Q& G. x6 ?; V/ @# B! _0 Q: T' j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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