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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。. D  |% a- `0 J8 g6 R$ O# I
netlogo自带的social science--traffic grid这一例子当中,
" V8 T# a! K" T; S3 e% o* Bglobals
. M2 W/ V# e: [+ Y[+ y9 e+ R; w& j
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
+ T6 z; G/ A' R2 S& w  grid-y-inc               ;; the amount of patches in between two roads in the y direction
# N8 k; ^/ h' `1 @% f  Y4 K  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
. u( c2 s( D/ o                           ;; it is to accelerate or decelerate' B6 w! {2 |( {( _
  phase                    ;; keeps track of the phase3 r- `; M& [* C; H- Y
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
# E3 a# Q* r8 C2 a6 a2 ^; a  current-light            ;; the currently selected light  m# R& A: g' c) }; K; N
8 o' ~5 D5 g2 Y! b
  ;; patch agentsets- Z# s7 ^: E/ C' S/ K8 H" k
  intersections ;; agentset containing the patches that are intersections
) S8 ]& B7 K* b- h+ }7 }% b5 s  roads         ;; agentset containing the patches that are roads
' Q* ~+ Q0 D1 N, b: {  s]
% s3 F6 C. o% H3 O! X
5 z; ~3 L* U' u) u  V- ~4 f+ u9 }turtles-own
) J0 w5 _, V% |1 ], Y! N[
% z0 s& N/ k, G7 f" r, S  speed     ;; the speed of the turtle; J' C. E7 v7 G  m
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
; f' S$ ?4 ~7 z* ^" Z* P  wait-time ;; the amount of time since the last time a turtle has moved
5 E7 A5 M2 F0 N! ^7 b" ~8 s]+ l! C% s; O; ~+ b% ^
( T% g- I$ |% @$ n! ~( J! a) }
patches-own- d3 I# L8 |1 o1 V# u1 d
[
9 j5 {/ Y6 [, H4 g1 L  intersection?   ;; true if the patch is at the intersection of two roads1 |; K  d$ w, n- S. {
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 w5 T. w5 g- [* F2 F# x1 e                  ;; false for a non-intersection patches.
# y; @0 u& u" {1 u; O  my-row          ;; the row of the intersection counting from the upper left corner of the7 o8 k- i  b& L6 @: i9 M
                  ;; world.  -1 for non-intersection patches.% z+ d( K' c$ ^3 n
  my-column       ;; the column of the intersection counting from the upper left corner of the" U4 n+ x/ V4 K6 L4 @' K
                  ;; world.  -1 for non-intersection patches.
# g/ z2 Q/ o# C7 _4 P0 y9 ~. {/ p- u  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.6 j+ Z0 B+ S# x; e* C; W* G& h6 F, }
  auto?           ;; whether or not this intersection will switch automatically.; _8 ~  b* h6 B* u3 K2 ]. ~  ~
                  ;; false for non-intersection patches.# f$ ]+ W3 C+ H  ?
]
) p* M1 S' G* S  V7 E3 B( ]" J5 ]: X! A  a+ n) u6 x) ?3 C

! m/ d1 h6 s; o;;;;;;;;;;;;;;;;;;;;;;
: C/ [4 I1 ?7 d/ |* k0 N;; Setup Procedures ;;
4 u$ y, ?" C& N- m;;;;;;;;;;;;;;;;;;;;;;
; M$ C5 F+ Q1 i
4 M/ t0 z% E6 d7 c- ^% F;; Initialize the display by giving the global and patch variables initial values.2 u# u. g! H1 G1 }; I' y+ o" a# X
;; Create num-cars of turtles if there are enough road patches for one turtle to
5 P3 N/ q1 V" w8 u0 P;; be created per road patch. Set up the plots.
/ k8 S' m2 \6 F, |, cto setup" {' J2 M, c4 J/ t8 Q
  ca
; _0 M7 o9 N+ K. k' v8 S# T  setup-globals
$ u$ J6 I3 v  e/ S/ L0 m, Z9 h, q1 [- o1 o
  ;; First we ask the patches to draw themselves and set up a few variables9 m* S2 |9 d9 D& n' w$ P; r& w
  setup-patches
4 o9 Z$ J1 w& ~: P  make-current one-of intersections( K& T; y, n7 `" j
  label-current: ~$ ?: r, r& z! C1 ]2 w3 g6 O9 c! P

' F5 L# ?. m% Z8 _$ e% S- {2 ~$ {  set-default-shape turtles "car"  R$ c: z6 g$ W  b7 F7 D* h6 B: t

4 v0 N% y# M" j  if (num-cars > count roads)
9 a3 o5 p- l' }, C  [) U6 F* ^/ t5 ^& d/ Z
    user-message (word "There are too many cars for the amount of "" C) k' ~  f  Z2 y% _* T
                       "road.  Either increase the amount of roads "! s# s! u9 a7 I. Q" I
                       "by increasing the GRID-SIZE-X or "
0 `. [& ^9 [; c- I/ D. g" B& E                       "GRID-SIZE-Y sliders, or decrease the "; h) W( |/ d: f/ v$ E1 S2 ]. H
                       "number of cars by lowering the NUMBER slider.\n"
# C/ w% D5 t" u! \; [                       "The setup has stopped.")6 i8 {7 H2 u6 \& P
    stop
% ?' n% J# A3 n& E6 {  ]
# C+ L% H( _5 C* \  D6 V1 A
& z; L, \- z$ w  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
# j. H6 y( X. s% Z  crt num-cars* G+ D; v. m, S  x( t
  [3 n( ~+ i" q, @! O+ x
    setup-cars
" ]9 M, A# X- j  ^% j    set-car-color: q+ j5 _9 h! y8 }0 {3 X" b- l, a
    record-data
. S) N' Y& f( W* S) o  i  ]
# j/ u9 z2 \; L
* \# @3 B9 ^6 [  ;; give the turtles an initial speed
: w7 I; M4 `% ~1 I  ask turtles [ set-car-speed ]0 l5 D9 ?0 B0 q% C

9 d; g- ^6 v% e# U' R. H# R  reset-ticks
3 R% j7 v5 K/ t+ a+ Rend
) M6 H! H0 ?7 C1 c* e# h, G) q* ?
;; Initialize the global variables to appropriate values) R  T6 x2 b3 y& E$ T4 y
to setup-globals
& L0 n8 x  H# c1 i/ L! ~6 t, Z; L  set current-light nobody ;; just for now, since there are no lights yet
1 r  q7 J  M0 N: R  set phase 0; V& Y. h9 u0 t
  set num-cars-stopped 02 b3 t* N: `$ r9 T5 l" q$ h
  set grid-x-inc world-width / grid-size-x
' {  \8 p' _: [  set grid-y-inc world-height / grid-size-y9 o9 @+ I* a: ~# r7 l0 Y  j3 W* P

  I$ o. H4 O) v$ `( s  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary. }2 E4 ]2 u. R. c
  set acceleration 0.099
5 C5 R9 {9 r/ p/ h( \3 \end: X6 l+ W( C% `9 a

5 \0 W4 a4 A! y+ y3 P: ?9 d' r0 v;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
$ l! @1 E# K! x/ b0 f;; and initialize the traffic lights to one setting( O' B/ N- e; g3 `; q1 x/ C& C
to setup-patches
& T' H& m# `( n% c  ;; initialize the patch-owned variables and color the patches to a base-color
% H; ^9 W: y3 h( h  ask patches
' D& C( Z# U. Y- s9 J: k: Q  [2 w& s3 L6 ]; P, G
    set intersection? false
. u; H+ E& E# ]: O8 P7 q    set auto? false
: L' w- l& ?$ t9 t$ A+ D6 \    set green-light-up? true5 e2 H4 I& ~. U! G3 i* F) o  C
    set my-row -1
! |" o% V+ {8 Q+ i1 W3 v  k    set my-column -1% C8 g5 v% @% R2 w! O; t& t) \
    set my-phase -1
+ M& Q$ g; a; v% S! k" S! B    set pcolor brown + 31 B& Z, `, V5 e6 \% u/ ~2 _9 {& h
  ]; N6 m% V) Q! g$ z8 n- ?

- T" W  J7 i( P; q* e( m& z  ]9 L  ;; initialize the global variables that hold patch agentsets1 M# r* v, Y& S& M( M' q
  set roads patches with& M8 P; b; f) H& ~6 m* U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' i5 R  H  y0 I8 g- F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ l/ x3 I; |7 m5 N8 J5 z  set intersections roads with4 w. x3 a1 D. e# f0 d" o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
1 z$ f) P: S" w* K  b4 _$ F" r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* G7 ~9 }4 o/ Z: g9 t& |" O3 j

( s3 ^$ h- i, |8 ]7 h0 `  ask roads [ set pcolor white ]
- E# B( h) N- A  F6 k+ q7 x& G    setup-intersections4 y! e; W2 R) ]9 q# \6 h* }
end
6 D3 e# W; p" C' a  P+ l, M其中定义道路的句子,如下所示,是什么意思啊?3 z6 Q7 ]# ^: ]; N6 O
set roads patches with
& P, H( r6 k; d( T. A7 ^9 x- `3 S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ E4 T  J8 N4 H; f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. P. Q% X8 \0 `% h/ Y3 M
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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