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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。
+ e: M7 ?* ~6 C( i# |4 ~( R* G* Lnetlogo自带的social science--traffic grid这一例子当中,' Q; c2 h& T" l1 s; Y
globals0 a% }& Z+ t4 ^- \6 Y' I( O
[8 H, ^& ^7 P* L0 T
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
6 P7 F% t# u8 s! W* n  grid-y-inc               ;; the amount of patches in between two roads in the y direction8 e1 M# t4 V# U  l! q  m
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if8 e/ E: \+ Y0 ~6 }9 G- f
                           ;; it is to accelerate or decelerate4 z3 v- j! f/ V. J
  phase                    ;; keeps track of the phase+ v' ^2 A6 M% Z5 P" K& x$ N) c
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure; g( A* F" \3 A2 \4 W; k
  current-light            ;; the currently selected light
$ H3 V: o! i4 \: Y# M
! ~; _2 s  I( F! q! g. j4 e6 u% ~  ;; patch agentsets( Z# P  P$ u# n/ a* L  U! j
  intersections ;; agentset containing the patches that are intersections/ s6 @- B, j  ?6 z" M
  roads         ;; agentset containing the patches that are roads) B. [" ^/ _, _) Y2 b5 P- j- ]4 `1 H
]
* K5 T( U2 e3 n8 y8 |5 X! C  O# L) b: c0 P9 `% [; I! W3 A$ e
turtles-own# w5 |  t$ b; X& u* z
[1 l5 O% u0 {) H! h( Y
  speed     ;; the speed of the turtle" W" K5 T8 W0 f0 j/ Q) B
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
* r; k! T) S- }  wait-time ;; the amount of time since the last time a turtle has moved1 h, B4 D7 L# D5 @  M) ~# Z! l: E
]4 f& K: \6 G' Q
  J7 O. o! c, H7 l8 Z
patches-own
, s$ h/ I! a& B) O[
# H" Y4 B+ U  S6 ?# l+ ]( v! ]  t  intersection?   ;; true if the patch is at the intersection of two roads1 U" ^8 \6 J6 R( w1 c
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false./ S* q) U" \8 e3 ]9 r2 ~
                  ;; false for a non-intersection patches.$ Q0 T# H* c. o% O9 u. f" l2 D
  my-row          ;; the row of the intersection counting from the upper left corner of the
5 m- _2 L3 x( R( X# w. [+ }; g7 J                  ;; world.  -1 for non-intersection patches.& v2 n' Q( B% e- y9 Q: i# G
  my-column       ;; the column of the intersection counting from the upper left corner of the
* O2 P$ n. |/ |6 U: `0 f/ A' e                  ;; world.  -1 for non-intersection patches.
3 i6 I% G) |7 J. I3 Z  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
# d& r0 K- T0 J  auto?           ;; whether or not this intersection will switch automatically.
$ \1 N: i& r* Q( n                  ;; false for non-intersection patches.
8 i; `4 P+ g$ z]
7 a( y$ j8 W3 m; D! h  d
2 i) G" j; r3 e  V) L. d9 R
* c2 m  e2 A0 q9 c4 [3 m;;;;;;;;;;;;;;;;;;;;;;8 Y* m7 I% Q1 v& S$ F0 R
;; Setup Procedures ;;
8 B$ @3 i- d& o& h;;;;;;;;;;;;;;;;;;;;;;
: r/ D' }1 Q& S
& e: n* p4 t6 d, Z3 {;; Initialize the display by giving the global and patch variables initial values.: [/ X. h" ]* [% O: G2 M
;; Create num-cars of turtles if there are enough road patches for one turtle to* Y6 _4 N0 _! U5 i
;; be created per road patch. Set up the plots.
# X: {2 |. q+ ?  Mto setup7 K6 G8 y  K$ m* A$ \& Q
  ca8 ~: i5 K" ~1 m" O+ T& p
  setup-globals7 |  s- r; N) `6 Y. ?

5 H8 T1 m% X4 y; L! c  ;; First we ask the patches to draw themselves and set up a few variables1 X5 v" p' s: L+ c4 T. a1 ]
  setup-patches; n( P8 E( k  A/ z
  make-current one-of intersections1 X$ A# ]8 V: }! j$ I
  label-current4 ^. m) P, t3 P! w8 H5 w0 F. o+ P

; c( f: P+ t# }0 X; s; q6 _  set-default-shape turtles "car") o# ^  x" P1 }: q9 U
$ F$ ?9 O, X& S! L0 v$ y$ M- Z. ~
  if (num-cars > count roads)! w( s2 K1 E% ]
  [: G0 L1 w! A, _. W; W, I
    user-message (word "There are too many cars for the amount of "0 q5 Y0 D  `: Q) R1 ~, m* j! E
                       "road.  Either increase the amount of roads "
' N" u* P7 r3 E$ H1 _& A0 y                       "by increasing the GRID-SIZE-X or "0 Z2 T7 p2 q% s
                       "GRID-SIZE-Y sliders, or decrease the "5 y- o7 H+ P9 z& P% e
                       "number of cars by lowering the NUMBER slider.\n"" h) u/ e" Z- X$ Z
                       "The setup has stopped.")7 r. F( c, k2 @  j$ Q6 _- S
    stop1 s; @6 p4 o/ t' I- c) q9 c
  ]; I& B3 B# ]$ p1 }! _  |6 C

: T" w9 _; c% [9 P  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
$ X1 d. X! P; d5 \3 X  crt num-cars
  s) j8 r4 ]0 i( r5 ~3 m/ Y  [/ U$ q! A6 Q& t
    setup-cars0 e& k" ~8 x1 g: G* S
    set-car-color
; H, r5 O7 m* G    record-data
0 [2 ~6 f+ N: I) ~" d  ]+ w( p; C3 S2 g# p& n/ U$ j+ R

( j( ~2 _; W& |  q& q, C: C( _3 _  ;; give the turtles an initial speed
  G8 P% Q; t' J6 R. H  ask turtles [ set-car-speed ]
4 c3 B8 q6 _3 [) Y! g3 E& z' g2 `( B- O( y, n# Z) l4 ^
  reset-ticks
' f$ c+ I! B2 j* p9 T( w5 ^end
+ e8 G: t* B/ H. H
/ Y' i: b  k# o3 \% T. z;; Initialize the global variables to appropriate values
3 t, S4 i5 x: x7 k7 K( rto setup-globals- I7 I; a8 D) U+ y. A$ F
  set current-light nobody ;; just for now, since there are no lights yet
  h: [4 v4 u: P; _  i7 B  set phase 0+ H9 g4 n  K# ?, x! U5 M. m' B" Z
  set num-cars-stopped 06 c2 C9 I0 ^6 V: g( A6 K7 x. \  T; h# d
  set grid-x-inc world-width / grid-size-x
7 w* ?) I4 {* j; d: \! [  set grid-y-inc world-height / grid-size-y
  `) K& U8 V6 B
  N9 V. f1 ~8 c1 Q7 }, A) m" O  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
* F0 i6 o: F% W1 ~' s( a  k" f  set acceleration 0.0995 P$ ~: o$ i; q
end0 I7 I+ c1 k: V1 r7 e) S7 Y+ @
- Q. N& j; B7 w$ A
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,! w. {* n6 _9 o6 t7 `
;; and initialize the traffic lights to one setting
+ _* G0 d; ]1 l# m' a) P; ]to setup-patches: A( K+ O6 J* a8 D! v1 l
  ;; initialize the patch-owned variables and color the patches to a base-color- c4 C$ w: [4 @, f
  ask patches. }# J9 d- l9 k8 p
  [! |  R* I2 G; J
    set intersection? false
& T8 q4 z4 c- |4 L' r* A    set auto? false& d$ f8 s7 F% b9 O; M! b" b
    set green-light-up? true
; p5 Q# @$ n/ v: d5 r6 T    set my-row -1
* S% P4 E, W& ]& S( A    set my-column -1$ T, D) O! o0 J& V! i
    set my-phase -1
! V  b* x! y: }4 ]& U$ ^    set pcolor brown + 3
1 `0 C8 |7 }4 J2 c  N) f  ]% P- h6 X: H$ U+ B  \3 E

! x" f: ?) R! g& w/ g* H4 y  ;; initialize the global variables that hold patch agentsets& ^9 w5 q- p  v! O
  set roads patches with7 T4 C2 f" ]9 m3 F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ N$ x; V. b2 T# N% Z  Z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* W( v2 {5 h* M5 ^! K' s- T
  set intersections roads with" s0 g) P' v, \6 {) q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
8 E' F+ _2 ~" e% @& F) a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  S/ F6 }3 J7 ~$ P5 U% J, J

  B8 y7 s0 F, {6 m6 N' W  ask roads [ set pcolor white ]
+ j) Q9 T+ e7 d( ]5 P    setup-intersections
) f" V6 o9 N) ?end
! d- N/ p4 M. C1 s, d. s其中定义道路的句子,如下所示,是什么意思啊?
6 ?  G; V# I1 n2 R; S set roads patches with
6 e7 X- ~8 t! \+ J  U0 Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: e# h& \7 i7 X! B7 A$ C    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' P& f! P) C- _: t/ q
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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