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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。
. [! V' ]8 u0 V& s( U1 x- Lnetlogo自带的social science--traffic grid这一例子当中,
8 P# X# M! \) n/ _# C0 vglobals/ d* d4 d* u8 f0 J7 G
[  s) }- v  S- G
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
" n1 _4 p/ I8 }, B  grid-y-inc               ;; the amount of patches in between two roads in the y direction; P1 J6 S4 `* v$ k: ^* }
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
; @' E  a; X0 e                           ;; it is to accelerate or decelerate% ^6 f2 Y: `' c/ ~( W7 X
  phase                    ;; keeps track of the phase3 Q) X. b6 R1 U1 ^
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ A1 O5 g9 v7 P+ p  X4 A  current-light            ;; the currently selected light$ z4 c4 v- q* X$ l4 m% }
% Q' ^, {/ L" n7 E' V+ m
  ;; patch agentsets2 r6 s. {4 i4 j) X  C1 A
  intersections ;; agentset containing the patches that are intersections" _4 y( M& M% L' j& O. x' R
  roads         ;; agentset containing the patches that are roads
/ G" H- n6 a5 x4 S]3 D- m0 f1 N* ]  B, w3 n9 D' H* {
6 J5 Z6 ^5 X+ n- t+ Z% Y
turtles-own
1 r- N& D. W( o# c# D[
" `, h5 n/ Z5 c  speed     ;; the speed of the turtle
, k7 ]' B5 [2 S$ _$ y4 r  up-car?   ;; true if the turtle moves downwards and false if it moves to the right. J, E: t1 L- Q
  wait-time ;; the amount of time since the last time a turtle has moved2 F5 M) B* J0 U" Z0 [
]
9 X( j8 o1 v( G0 @% Q* p" H4 r5 P
patches-own
! |) u  t) v3 {- `0 R8 D( s& I2 x4 V[7 x* g  H; W* c* ^( n4 y3 M
  intersection?   ;; true if the patch is at the intersection of two roads
! E9 y/ s! P3 c& |' X( t$ U  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.5 ]5 z$ y) ^% \6 O) _" N
                  ;; false for a non-intersection patches.3 a4 t% I- G4 j9 ~, ?1 N
  my-row          ;; the row of the intersection counting from the upper left corner of the) t* ~  u: m  `& c
                  ;; world.  -1 for non-intersection patches.! F9 u* w0 S! B4 ?
  my-column       ;; the column of the intersection counting from the upper left corner of the
  ~8 S" e* G1 L                  ;; world.  -1 for non-intersection patches.
( T. Z, N1 U  K' z( }9 L  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
+ j- w1 t2 O& a6 h/ s5 G/ k( m: z  auto?           ;; whether or not this intersection will switch automatically.
) k# [- e$ }0 r2 ]) S                  ;; false for non-intersection patches.6 h5 ]- A3 {2 ]1 [) z$ O; J
]
7 P4 y9 O/ W3 w. ]- P" z9 X7 C5 U  G" p4 a8 f# m5 k
# m- T% {' r7 ^. D
;;;;;;;;;;;;;;;;;;;;;;1 J3 n0 g, i7 l3 l* r( i4 q
;; Setup Procedures ;;
% X7 C7 p6 T4 }# i. a; s;;;;;;;;;;;;;;;;;;;;;;
- T  i/ n3 K, Y6 B: }( A' j6 C0 }# ]1 |" P3 N4 t% ~, {
;; Initialize the display by giving the global and patch variables initial values./ w5 v/ z6 U4 m* r' a8 \4 I: R
;; Create num-cars of turtles if there are enough road patches for one turtle to
. Q% y+ r" s+ c/ b$ Y, q  O;; be created per road patch. Set up the plots.+ m/ v5 o+ d4 e) s- k
to setup- A+ V5 n2 |9 i
  ca
% d5 x; u; L& u; G  setup-globals
5 ]/ R. P! [6 Z0 s+ b% d: H( B/ c3 }; A0 h( x, N
  ;; First we ask the patches to draw themselves and set up a few variables0 m" }3 y" i+ X( d  B# z1 W
  setup-patches
: ^$ L9 I' r/ Y  make-current one-of intersections1 A, [2 c9 y1 V3 @; e# N( d2 K
  label-current
/ Q3 E% n9 L3 i0 O: I5 Q5 Y6 E4 {3 |
  set-default-shape turtles "car"
4 q6 |) J& w8 J; G" N
0 i# k( n$ J8 S  if (num-cars > count roads)2 P  v; H, h0 E. r+ e' w* z
  [
! B' s6 D1 ]) w9 [, f( q    user-message (word "There are too many cars for the amount of "; \1 U: F3 H5 N9 E
                       "road.  Either increase the amount of roads "8 D  n+ U& x1 D8 D6 s) R
                       "by increasing the GRID-SIZE-X or "
; p% n3 z  v& }# q1 ]0 f                       "GRID-SIZE-Y sliders, or decrease the "- X( D  F# _& a- y: z
                       "number of cars by lowering the NUMBER slider.\n"
; j3 K" [9 |& i+ Y, {5 u1 x                       "The setup has stopped.")3 e) j. o2 i1 B9 M/ B5 W% d
    stop# U8 J; @2 t3 B& u  c
  ]
/ c0 Q/ X% u" a3 ]* Z  A! Z: V; Y: _7 f/ w/ r; _+ R
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  h1 c% l3 R. l5 b- N  crt num-cars' D) S2 a: l% w/ T4 X* u. x& Q
  [! ]( p, A% @5 S
    setup-cars# p& x& J9 r+ h5 t
    set-car-color( |5 w" \( t  H; O) Z
    record-data+ E8 k  \! ]% u% m& N( w2 L! {) j: e
  ]: J' y0 \' G9 Z, t" m' N

( K1 g: t# [$ X( B' m9 h4 v+ A" G  ;; give the turtles an initial speed' ?, z, n7 x" S
  ask turtles [ set-car-speed ]
5 k4 O- a0 {; j) {1 X6 y# ~/ k
5 z# U, m( G4 U3 o  reset-ticks
! f2 G" v( c% Y% Z5 }- zend
6 L0 d) b2 W! i- t5 i; h% W( m$ ?+ t0 H4 m# ^0 v
;; Initialize the global variables to appropriate values
( [/ }) Q1 |2 S, i% [2 oto setup-globals0 {9 m) c5 @. x/ Y
  set current-light nobody ;; just for now, since there are no lights yet
0 t3 a. y1 k# D2 z8 R  set phase 0
2 G/ X. Z, \/ X7 u  set num-cars-stopped 0' |" ?: ?- a6 Z4 s1 D" U" t
  set grid-x-inc world-width / grid-size-x
; s6 `% Z2 x7 C; @) S: a  set grid-y-inc world-height / grid-size-y& x5 _. c2 M; Z1 u- E/ m, U% m; m
! P. t- [4 C. ~1 Y2 T
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary# R! E6 W1 K1 t
  set acceleration 0.099
7 l* I% ?6 j8 uend
8 C2 d* ^! y0 E3 n) H4 q2 y5 t: G. l2 H7 e+ R
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
" ?$ L& ]- T5 ^3 A;; and initialize the traffic lights to one setting6 X  o/ _- k+ d
to setup-patches
& j4 @: g$ e3 H* J- |5 j, _4 v  ;; initialize the patch-owned variables and color the patches to a base-color* c: `' H5 {9 Y4 L  ~0 m9 U
  ask patches2 U* N+ [; I0 J" X& Y# S
  [$ i, @, [& S8 p2 p2 [
    set intersection? false
) f* s3 M- r; V3 M# @    set auto? false& N% E! u3 c, }0 G! t$ C
    set green-light-up? true8 s/ [) t' F3 i% D& {$ ^* A
    set my-row -1  J3 a- S$ x5 P
    set my-column -1
6 [0 B& B& y) y' G( m/ R    set my-phase -1% N- n# K1 i4 I4 p7 q0 t( }; D1 u
    set pcolor brown + 3; C; s0 c' @: P4 u3 Q
  ]
, U" O/ v+ W: L( F
  R, F3 o; k  u) b. H  ;; initialize the global variables that hold patch agentsets
- S, W4 H9 b! L' d& e  set roads patches with
% M$ i# Y# L- Y- I. W& f+ @" P* K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% X4 |) h, Q- Q0 S. x
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 F# v/ a+ v6 ?: A: O- ^  set intersections roads with5 I; E4 L4 T& ^, m. y; V6 y& o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and! C* |. s% v2 M4 u8 I6 W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) |" Z2 {% h/ R2 O, D" d9 K7 A9 o2 z& V3 N9 s" @3 c7 x
  ask roads [ set pcolor white ]
  `; O: D( n# x6 t    setup-intersections
( C) f2 v! G* J+ X- [' R$ rend
" ~. I' c- R  N其中定义道路的句子,如下所示,是什么意思啊?, V# p: V) a0 A8 A5 Y# ^
set roads patches with
9 \' j, O0 a. [2 _1 y8 E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  w; H( q+ x: w/ z8 _. h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' I& W+ q3 x) A# K+ U
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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