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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。
* w8 X( Z# A2 ]" o2 Qnetlogo自带的social science--traffic grid这一例子当中,
" |6 F" Z& l- T' h2 w/ ]globals
4 e4 z5 M2 l) I: L2 m[' D, P, A3 l& G& D1 y; [$ T! s4 u( ?
  grid-x-inc               ;; the amount of patches in between two roads in the x direction, j1 i2 m1 i9 B( r7 B3 f
  grid-y-inc               ;; the amount of patches in between two roads in the y direction6 L% x/ x& d: g% z9 j; c. R
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if8 ^7 F0 A/ ^6 q6 V. a
                           ;; it is to accelerate or decelerate
$ q4 T/ d( Y' U4 s& R  phase                    ;; keeps track of the phase
2 A3 q7 l% D" \# f6 p7 Y  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure; s8 W& y0 B0 K5 H3 D% w
  current-light            ;; the currently selected light
. }+ ]: G/ M" ]/ _3 @$ ?# w/ ~% k" ?
  ;; patch agentsets
) z0 F1 t; ]* n& D+ v0 k: G# @- e  intersections ;; agentset containing the patches that are intersections: d: N6 x1 c8 N1 x0 t( [
  roads         ;; agentset containing the patches that are roads8 W8 Z3 `$ q5 D: |1 n
]7 d/ |9 h3 ^8 s0 p' s* w' e* z
- C# p3 ?2 x1 r& [7 d
turtles-own
  Q: @1 _; P; [* K5 @1 C7 N[
- l, B; R1 I0 p) q  speed     ;; the speed of the turtle
5 c7 l! z8 M- I. l  up-car?   ;; true if the turtle moves downwards and false if it moves to the right( n& s, m! G. G, D. A! i
  wait-time ;; the amount of time since the last time a turtle has moved- t( i9 q# v& A) f- \1 }- x
]2 p# T6 ?* R1 R& ~; R( p8 f

; s7 D. z, @4 s7 R( i4 H: e% |patches-own! C; w4 l8 h2 F9 O0 ~7 a7 ~+ q* W, u
[
' P8 F5 w4 Y/ ^  intersection?   ;; true if the patch is at the intersection of two roads' T2 A* q* u+ n5 R* g) y" V
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( j/ o/ ]1 z! Q8 i+ ^+ q  [                  ;; false for a non-intersection patches.6 i7 D& c' }1 s' A* s7 V5 z/ H, r
  my-row          ;; the row of the intersection counting from the upper left corner of the0 r, d2 v1 q) l
                  ;; world.  -1 for non-intersection patches.
" V& I# J# v) }# Z4 u  my-column       ;; the column of the intersection counting from the upper left corner of the) Z/ |9 O2 ~8 ]0 v) [
                  ;; world.  -1 for non-intersection patches.
. {4 \; M  j! M% X' Z  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
) D" J' T' c% \. r  auto?           ;; whether or not this intersection will switch automatically." P* ?- H8 r, @2 ?
                  ;; false for non-intersection patches./ O6 k9 T+ J, ?# @' A
]
: v# B9 b! L- E; T0 v5 U0 B' u# y8 I2 d5 u/ p) w# o
2 I$ C) O/ Y) L2 Y0 u
;;;;;;;;;;;;;;;;;;;;;;& x- h8 v, m, j9 V! L+ I4 z. B
;; Setup Procedures ;;
2 F. r* e! B# t# t$ W;;;;;;;;;;;;;;;;;;;;;;# p; Y( L6 D- r

1 C& U4 U7 j( ~;; Initialize the display by giving the global and patch variables initial values.. \- f9 U$ t$ @2 R: C0 Z7 Z
;; Create num-cars of turtles if there are enough road patches for one turtle to
8 k& V) [* f8 Y6 ?* o;; be created per road patch. Set up the plots.2 }( f2 I- \4 P8 n
to setup% C' h4 i6 s  V- H7 O7 `
  ca
3 ]. c' Q! t( [9 \) c  setup-globals
3 X0 F) k8 t! @3 ?' _( J, ?( r
/ f  C9 R+ p9 ^$ d7 c  |* O  ;; First we ask the patches to draw themselves and set up a few variables
3 h, o% o$ a1 P% O0 e/ m  setup-patches
/ m: q! c1 w( D# p8 b2 N" r  make-current one-of intersections& ?; Z9 T- {$ Z1 g# s
  label-current
# f3 i' F6 i. K& p2 R! n$ p8 x% Z# A4 m, f3 X6 D+ u$ u2 B
  set-default-shape turtles "car"
: @' v2 ?9 T) ~7 S) s$ B# Y4 v# b! P! T( _1 D( V- N4 T/ S% G( P
  if (num-cars > count roads)
( T+ g" J& G+ L) G  [5 k2 r* x6 F/ _: y
    user-message (word "There are too many cars for the amount of "; u1 v5 K; g& s; o1 C
                       "road.  Either increase the amount of roads "
6 @% Y$ W% g+ o                       "by increasing the GRID-SIZE-X or "& v3 i6 G5 }1 r( Y; ^. p) \
                       "GRID-SIZE-Y sliders, or decrease the "$ F0 b9 l# e$ r$ U0 a7 w
                       "number of cars by lowering the NUMBER slider.\n"3 J& @! n- E1 L
                       "The setup has stopped.")
1 g- B# i1 ~% X7 d$ q6 E0 p8 G- y1 L5 ^    stop* \. }: b! n+ |( s. `- {5 ]) y) H
  ]; }# M: l6 Y/ k% F0 S5 M3 l) o) a
! w! A. D# i  [( }  w, c" U9 {- {1 L
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color) \3 ^4 E2 ~8 H
  crt num-cars
2 Q+ G( D9 W% `- x% H+ T' U  [9 b2 q1 [. u% C2 E7 o% f
    setup-cars
5 _4 K3 q, {6 n- ?4 {4 `9 ]# {8 |    set-car-color
! z: }( b; n1 l& s4 M2 }    record-data
' m- H1 J7 t, L% ?* M  U  ]2 o  D! O5 ~2 @8 _: i! a6 ]
% e- I' A& w- U/ t
  ;; give the turtles an initial speed. k: U! Z3 r" B9 J  a# D
  ask turtles [ set-car-speed ]' J1 p" b9 s8 q0 V2 g9 c7 a+ R+ d! F
* F; Z3 c! p1 k( u. K# s# r
  reset-ticks" h; U0 B8 [' i  t+ C
end- K4 ~+ H  p/ J
+ c3 K* E1 {1 K
;; Initialize the global variables to appropriate values
( i1 e* y% x. ]4 w+ _( Pto setup-globals: e4 p$ @6 @# G/ j8 X: u
  set current-light nobody ;; just for now, since there are no lights yet
2 ~0 y! ]- q' V# W$ D4 {2 V3 P' Q  set phase 0
$ q% a  U3 R1 k0 t  set num-cars-stopped 0" N- e) e, Q- q, T* h* l! S& {
  set grid-x-inc world-width / grid-size-x) c% S' b+ o; R! Z
  set grid-y-inc world-height / grid-size-y2 o  g7 L4 R& B9 E5 v

, }/ v& f4 b4 r7 {5 ]  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
' P% z5 t7 p- j  set acceleration 0.0999 t4 S/ u: k$ @5 U* r8 O
end- Y; \# I' O& s: }1 x2 l' ~# V
  z) k# h# }8 A/ c0 x* g  K, w
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,! u% n4 X& Y6 z
;; and initialize the traffic lights to one setting- k$ b" X- n: a; j$ M
to setup-patches% k5 y" {' d* s/ k; t
  ;; initialize the patch-owned variables and color the patches to a base-color
, k# I& O' u+ W4 f# O; v$ U  ask patches4 c0 [# o9 `) a* F; @
  [- r# E9 Q% r. \. H/ a
    set intersection? false5 ^: a  a2 u* O
    set auto? false
' Z" E2 n! G7 D8 J2 A. q4 w3 c8 N    set green-light-up? true
! X: a6 i8 ~/ m1 q* e    set my-row -1
/ |2 n4 t* ?3 {5 ?+ z    set my-column -1
+ I; s$ ^" ^# M! u& @; k3 c' c    set my-phase -1" X' U* I1 B& v* t: g, T% g
    set pcolor brown + 3
4 H- p- t1 f- Q9 T% z2 e  ]
' x+ O  b; @# D. K, P
- u1 O* ~1 S( s3 J8 h  ;; initialize the global variables that hold patch agentsets
: j3 }6 \/ w8 ^5 e4 t  set roads patches with
3 W& J! ~0 z. |: T# N    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- ^% |" P' I$ y/ d0 Y0 y6 h9 Z# ?    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ R  Y; a/ O9 J. D' q- J: D% [  set intersections roads with
4 V8 y$ C" H! a; ~( [    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
0 ~2 B, F, \) s/ q6 k: V    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. U- }* E0 S+ Z' |9 Y& `/ i
5 Y( u8 i6 U# k4 k4 k& t
  ask roads [ set pcolor white ]
. J' t) D" r8 m9 ]! O8 r    setup-intersections/ ^" v% J! n4 W/ _# p4 x
end' M' \2 x0 a9 d1 m
其中定义道路的句子,如下所示,是什么意思啊?- \9 F0 ]- I% }1 P; K
set roads patches with3 L& _  k8 H' c% o0 k4 Z7 H0 W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# F$ n& Q8 D' V# {, E/ S& }0 ]
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; f. H6 Y+ j1 m$ A0 P* u) 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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