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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。2 I9 H0 {% r- B0 y: T8 p+ D8 G
netlogo自带的social science--traffic grid这一例子当中,, K/ L) F' q1 a. d
globals
7 j6 P9 Y9 I0 t[
) t$ y& w1 r) W) ?/ G9 r  grid-x-inc               ;; the amount of patches in between two roads in the x direction* {) f$ f; g2 p8 Z, }
  grid-y-inc               ;; the amount of patches in between two roads in the y direction  q2 x. q9 P/ G. Y. @" G+ G
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if6 ~& H3 c3 g) e2 N
                           ;; it is to accelerate or decelerate
) G- u7 J+ o  f  D! n& H& T& ]5 ~  phase                    ;; keeps track of the phase) r4 ^- i' o2 D8 Z  L
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
  J: F2 Y5 }" W2 T; J9 T3 R& @* b  current-light            ;; the currently selected light
! C$ N5 Z# R; C: e
  k; y" J' H  l, [7 Y' K6 s- \  ;; patch agentsets
' S* C2 Q9 ?5 Y  k  intersections ;; agentset containing the patches that are intersections$ |# e& D8 f- D" H5 N: z  m
  roads         ;; agentset containing the patches that are roads7 v0 ^' |. }+ [' n7 l- _6 k3 @  s
]% x- s2 f; b+ h* G1 U, t: ?
' n8 Q8 X- |* S% W
turtles-own
: u/ X% y! N3 L: K& a# w% f[
- v" a& Z" v2 w" g7 q8 m7 i  speed     ;; the speed of the turtle
% [" {1 U  y  ^& `5 A# N: P  up-car?   ;; true if the turtle moves downwards and false if it moves to the right% j/ P4 u3 d2 D  K5 z) U, C4 g
  wait-time ;; the amount of time since the last time a turtle has moved) @6 L7 H: `4 q' Z+ R/ i( ~
]8 T0 l9 d; i$ x" T! W! p4 x
( v- ~+ c! J. t2 ]
patches-own
9 ~; ~0 w7 P. h( Z) ?" t% |[
: ^2 |: t1 V+ ]6 Z; I9 x' C  intersection?   ;; true if the patch is at the intersection of two roads
( o8 x3 m1 W: z  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.7 [6 L5 e3 q, y4 S% e
                  ;; false for a non-intersection patches.1 i) z% G1 }; }2 q5 f" Z0 L. A
  my-row          ;; the row of the intersection counting from the upper left corner of the
6 }, P* Q7 o4 x6 t/ w& v3 ^                  ;; world.  -1 for non-intersection patches.
$ l8 v2 k0 o/ q/ `4 P& ?5 T  my-column       ;; the column of the intersection counting from the upper left corner of the( w4 Y, A# s) u1 u% o% }
                  ;; world.  -1 for non-intersection patches.
% F+ u& z% V5 X6 W7 x0 K  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.+ x+ k( c' Z( r1 v- f, Z$ @* _
  auto?           ;; whether or not this intersection will switch automatically.
1 |& p0 Z9 B# C                  ;; false for non-intersection patches.
: H1 j' }: }, @  h7 z]7 Y8 o: w8 w/ p4 v. H
7 D8 y1 Q" f8 p6 v5 N

; f) X; M1 ?' i8 ^;;;;;;;;;;;;;;;;;;;;;;) s( P7 V' E+ f- @3 a; q
;; Setup Procedures ;;
5 {7 \$ ^, i7 O& m7 v;;;;;;;;;;;;;;;;;;;;;;# [* s: a8 D1 l" s: U
. o& m8 O' a, A% I/ n! b
;; Initialize the display by giving the global and patch variables initial values.
0 F+ i4 `+ t" h- ?' I;; Create num-cars of turtles if there are enough road patches for one turtle to
9 e, Y* J) n* C0 o;; be created per road patch. Set up the plots.: |3 s0 ^1 [8 \
to setup
+ X8 I: I/ v, M  v  ca3 R$ d% P5 I+ c6 x5 y. U' z$ q. i* @
  setup-globals# o  j1 k% ^/ Q3 k, }9 w

8 D; {7 ]7 ]9 m3 i  ;; First we ask the patches to draw themselves and set up a few variables
+ W7 W! a4 t6 [" I( I  setup-patches
. a! q, Y# p8 f6 ?& Z3 G4 p5 S  make-current one-of intersections
1 O8 z( l9 h* X% m6 w+ y# Y  label-current
$ F6 J. J% D% M+ h# t- @. e0 k5 c5 N5 }) r! Y
  set-default-shape turtles "car"
) F' j$ }4 C  k# N8 ~9 Z- P' l- }' r, i! @/ \
  if (num-cars > count roads)
& S: @% E, }4 f. b  [
5 X  V. i9 v' N    user-message (word "There are too many cars for the amount of "  E! D! [7 d3 X( ~& b
                       "road.  Either increase the amount of roads "
5 ^  n' o' ?) c+ o0 ?( K                       "by increasing the GRID-SIZE-X or "; u* x, S: p1 b' E- n7 ]
                       "GRID-SIZE-Y sliders, or decrease the "3 [- d2 ~" b& ^/ O. j% F
                       "number of cars by lowering the NUMBER slider.\n"5 A- E! K2 M- V0 s  L& o2 y
                       "The setup has stopped.")
8 R; [4 ~" v& r# V    stop! V6 I$ p  [- ]9 o' {! M
  ]
/ s) z9 m7 S# v! k
1 u. H: q& c  d8 \- S  J2 E# Y  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color4 L3 m+ o& y' \( g& Q
  crt num-cars0 i5 Y( j/ [4 P: `5 R
  [- a0 S7 v4 a$ A/ I6 J# U9 I
    setup-cars  f* s" x; P! M/ G# o2 e0 b
    set-car-color
8 T' J7 ~' Y3 l" P2 R3 G    record-data
$ j2 q: j  Z4 T& X3 D) ^3 H  ]
; G) V- Y+ ~7 z4 J+ p8 j) u8 b% O: v( H
  ;; give the turtles an initial speed
4 _$ x% [% A( x/ P  ask turtles [ set-car-speed ]) C- U, ^" v( J2 i$ C# J

% w$ ^0 r! Y" D0 r  reset-ticks$ }& U/ \# S3 ~, o# H4 k9 Q
end2 A; l* b( G3 x

- L& C, ]) A* E5 b% J/ |! X' l9 };; Initialize the global variables to appropriate values% w/ q2 a1 s: c4 U; h. N
to setup-globals/ I+ I# ]# c- _- o/ h! Y; H
  set current-light nobody ;; just for now, since there are no lights yet2 ]6 K" j) ?- r
  set phase 0: k, ^9 D/ W& g" j' {# g) ]  s
  set num-cars-stopped 0
( r! O7 D8 x3 B' m9 J& u4 a5 o  set grid-x-inc world-width / grid-size-x
9 e- q) ^  `* |( \  H  set grid-y-inc world-height / grid-size-y
! e& W0 h  l; Y# v( U( d9 k: Z- W) c0 Y& _, L0 _
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary. A" t8 j8 @( r& [
  set acceleration 0.099
" I0 H* d) s' z8 r4 i  Oend
5 J0 Q+ j9 d* K0 U+ M* t) ~* F. \9 h0 r+ _& K4 v
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,9 g8 x# O" N3 y, [0 b" z
;; and initialize the traffic lights to one setting
0 O/ X$ q2 A7 r2 u) ^6 a5 Uto setup-patches
% K/ N& z5 {2 }. S  ;; initialize the patch-owned variables and color the patches to a base-color/ M- i2 g  B3 l$ r+ k4 u4 }: K/ @
  ask patches
7 `$ ]! w% _" }  [
9 F3 {  o9 H" J% n9 @& C5 t    set intersection? false5 O  v, k: {+ g5 x: w) C4 v) t
    set auto? false0 `" {0 D1 x2 b7 Y
    set green-light-up? true, ~- J, w2 i' y* \4 m; n
    set my-row -1
4 A" t; w0 w6 M5 p7 m3 U3 j    set my-column -1
5 w9 _! B% k7 R* C* G. b8 R    set my-phase -1- N, L' a# {+ w+ @' q6 v( z
    set pcolor brown + 3
: a: q; I& B, e+ T  ]
8 c7 G7 m* h* I. P( T; _: e8 O; v+ m4 d8 C6 e; {9 ]
  ;; initialize the global variables that hold patch agentsets
& h+ E0 }" i! m' O# R  set roads patches with/ A( {/ f+ h9 G1 E6 c' L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. u0 w/ x  k2 l# V4 V( m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 E, Y' R& t! p/ `* l8 o
  set intersections roads with- ?! O! k$ P& ^7 w# l
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and) \% D% l( _% u  E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- u! y' _; r+ p6 }5 @
+ w5 A/ {& q# [5 p3 B$ x. Q( K
  ask roads [ set pcolor white ]1 k* x5 u# _% b  |$ C) G! P# Z6 |
    setup-intersections
3 S$ ]2 U% w: B/ J& k+ t1 N" |end" T% E7 y# {/ d3 i
其中定义道路的句子,如下所示,是什么意思啊?
3 p+ a3 ?1 i. Q$ { set roads patches with
# v: t! X+ b- @, Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 ^" A! A6 _. q' i3 V8 g1 A( p) v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* a3 D2 E; K( d6 |7 @# t& s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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