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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。
! `! Y1 i: B4 I% s; mnetlogo自带的social science--traffic grid这一例子当中,
! {7 G& d2 V" W+ l7 ]globals
. K' w3 [$ K# s8 W' h2 d[
* B& Q9 x9 A8 L! f; O  grid-x-inc               ;; the amount of patches in between two roads in the x direction
) h+ J; F3 i; f+ w+ H6 H/ Z  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, I8 q, J! l0 S+ u9 }! J  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
  o; N6 b' F0 l4 B/ i                           ;; it is to accelerate or decelerate
* D1 [) y" ~% H0 Y. h; a; r( g2 Y  phase                    ;; keeps track of the phase6 |4 D) b7 E+ F: r
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure2 F) n, \0 d( [0 ~( i; t
  current-light            ;; the currently selected light
- O/ q2 f/ z5 J% u7 O2 ]4 r! z) h1 |" `& S8 ]. b, }
  ;; patch agentsets$ `' L: |/ A6 A0 i8 \3 J9 R
  intersections ;; agentset containing the patches that are intersections
9 j6 ~$ T% R" r  x, ?4 Z" z+ F" \  roads         ;; agentset containing the patches that are roads* ^2 X! u" h. h% {
]
' W5 r/ `& L1 I& ~& a) {. w
, T7 F0 U) }9 vturtles-own+ r1 K3 @( _8 Z+ E1 i' q, q
[2 I- d2 z; J4 Y0 U1 u/ j8 M+ W
  speed     ;; the speed of the turtle
' D  k# g; n5 {! t# \5 l6 p0 {! P  up-car?   ;; true if the turtle moves downwards and false if it moves to the right3 X% W, [7 X/ k6 B( E/ v. T
  wait-time ;; the amount of time since the last time a turtle has moved: h1 y2 m/ @2 n7 t
]
. p2 T! F' J" Q; R- m/ T1 V* e! b2 f2 G8 ], _( A. Y
patches-own/ {. k5 L' g3 y
[2 w$ r0 ~% Q- H, o; S
  intersection?   ;; true if the patch is at the intersection of two roads
& E: S# `. E" H+ m  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
2 l0 Y, N7 {2 [8 C. v' `+ p. _! X                  ;; false for a non-intersection patches.
1 P) T% K* n: E' f3 ?  my-row          ;; the row of the intersection counting from the upper left corner of the
- v5 z& c0 [  I& O                  ;; world.  -1 for non-intersection patches.
! u7 x  j; P+ ~1 U0 E- H  k  my-column       ;; the column of the intersection counting from the upper left corner of the% z& W: n* p# h) F
                  ;; world.  -1 for non-intersection patches.+ Z- L8 s% p% G
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# a, _4 Y9 \" {2 v% \
  auto?           ;; whether or not this intersection will switch automatically.
/ T' s2 G$ M8 A6 C7 g) E$ ]/ V* F" m                  ;; false for non-intersection patches.
1 L( Z* t9 ~% Q' g]
; Y: B2 O( I( }4 c3 v1 H; k
5 x, q6 Q$ @0 R* B3 V4 w4 m, b. E/ {# J5 D' ^
;;;;;;;;;;;;;;;;;;;;;;
5 M, E: w2 T$ x5 F7 M( p. K! c;; Setup Procedures ;;9 ?% V$ \! l2 t, Q4 e
;;;;;;;;;;;;;;;;;;;;;;
% P/ k) u7 ]% `/ K5 y0 ?) J
- V5 g: Q( Z) g6 ]( |;; Initialize the display by giving the global and patch variables initial values.! ~. h* O! ~1 ?! e! i9 q- A
;; Create num-cars of turtles if there are enough road patches for one turtle to
$ i( t; A# B5 I- Y. M;; be created per road patch. Set up the plots.! v& }/ J# H. e! o
to setup& Q( n& \- O% S/ _+ E5 N& J
  ca
) Y# h7 q7 q2 W* z7 N6 {8 g  setup-globals
5 ^- z* d6 `' M3 _# ~$ I) X0 v* I$ s5 A/ A
  ;; First we ask the patches to draw themselves and set up a few variables; y0 D; D( t6 }3 ^+ S. i8 P
  setup-patches; f0 n; M# f- Y# S$ a9 X, T, O! w3 ~
  make-current one-of intersections
0 w' l: S2 J$ {( y1 v. `, p; j  label-current
! n5 m; |% M, U7 B9 D6 J4 V3 q5 X  `. E7 d; ~5 I: s' G! V9 i
  set-default-shape turtles "car"
- {$ N, o& Q- T% @- E
- w) k$ n5 i* e+ {7 J$ D7 G. z0 G  if (num-cars > count roads)
, h. d1 b" f) Z/ W' [1 c  [" E, V7 G( C2 W6 a) \8 U
    user-message (word "There are too many cars for the amount of "
% J+ \9 p" L# k- i# c5 J                       "road.  Either increase the amount of roads "
0 {2 ]7 J' q2 m& B+ F- J                       "by increasing the GRID-SIZE-X or "# E: d" x1 E1 E, V2 V
                       "GRID-SIZE-Y sliders, or decrease the "6 P+ x  Q: d2 G+ ?6 m4 u
                       "number of cars by lowering the NUMBER slider.\n"8 |1 A4 L- ]- q3 b- ?* |! s
                       "The setup has stopped.")  d* N4 p4 M* w3 |5 t
    stop4 {2 U) B( ~# c
  ]
5 `( o6 P! I9 G  _4 {0 S( k% ~4 n2 Q2 q3 k, y* ]9 \& |# f
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  `" N! {. @* p5 E( a2 r, ?  crt num-cars9 \: K0 Q7 {$ ]: ]4 W, I) r
  [
, Z" C3 k6 a  i. P    setup-cars  x) r4 `4 o1 _) p5 l
    set-car-color0 G. \" w; D9 a1 r. N$ @
    record-data; W9 K* B6 L9 a4 a& Z
  ]
8 o: x; q' b5 n, c- P& l$ O5 _' v+ Z& _2 \, i0 Z
  ;; give the turtles an initial speed
1 X' k* R8 A; e9 \  ask turtles [ set-car-speed ]$ ^8 A4 [. b& x6 [8 U

  |; D8 M$ o* _9 r7 n+ [( x  reset-ticks0 k: T1 B; n' u" s. E4 u
end
9 N* M# a* R( M  W6 R. y. Y
* V6 Y" `7 `: t1 M;; Initialize the global variables to appropriate values% d+ M& N$ _( m+ Q. ^* w
to setup-globals
# t9 e+ ]7 D$ ~1 i$ Z# Y  set current-light nobody ;; just for now, since there are no lights yet. d5 E$ @- r/ n- y( r
  set phase 0: M% g8 o. N' i# D3 ]: q
  set num-cars-stopped 0
, [$ V5 k' n9 h  G7 z. B7 k  set grid-x-inc world-width / grid-size-x, G  X- ?- |" G3 W# n- ^+ }1 N
  set grid-y-inc world-height / grid-size-y
8 w. v# U3 k) Z/ H
7 x/ O4 r, {* \7 k: c3 E, [7 t  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
- }. W5 `: b$ ]- D+ f  set acceleration 0.099
6 v' K5 N* y$ w/ G2 mend
5 ^" U: _1 F. F4 N% H) m. o) G- o% S- M2 K) o! i3 c" X: h
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 V. o# \4 [, y. b& g8 z;; and initialize the traffic lights to one setting8 Q5 t- ^9 g5 r2 G/ A1 f- o; e
to setup-patches
' k0 L) o  i, |) N# j  Y) l9 o  ;; initialize the patch-owned variables and color the patches to a base-color* d) {7 V9 m, {$ c0 r
  ask patches+ N( C! T" C# z+ P4 f
  [9 S7 ]5 y1 p' E& U
    set intersection? false$ w* `- s$ H* C' R9 i* o) j, W
    set auto? false
! o. d# s6 }1 A2 l4 q7 u& |    set green-light-up? true* k: B# I! V' D& D% B' Y
    set my-row -1, X' p- \8 t# c/ r" z
    set my-column -1
8 R" u" h4 A3 n    set my-phase -16 b0 O% L5 J' B9 G$ I
    set pcolor brown + 3
0 M0 ~. \) _& A5 w  ]
. V& a* ?- x, t, g; P! @
0 V: W0 v6 M* A9 ~, ]  ;; initialize the global variables that hold patch agentsets
) w" W3 j* J7 F. s$ |2 ^  set roads patches with, K0 ?5 F& f# q  k, T4 f
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% u6 M& ^  Y" U
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# f; m* S% J$ S/ o( M8 E  set intersections roads with
) x) P" C! n; H. `: v2 p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
0 q! W2 G' e$ n% z* V6 [9 I: `5 y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 y1 q/ g+ @: `* \/ o1 i

) f6 ~8 t" i6 @  ask roads [ set pcolor white ]
% S5 h, M9 X8 \/ ~- n    setup-intersections) ?) ~* U# E, {
end# e$ e" b) W' A. [7 L
其中定义道路的句子,如下所示,是什么意思啊?
1 k1 ~; U0 d' E! s: I set roads patches with. Y) t4 }% M. Q( m
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 n# L- A9 d- _$ `1 \7 N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" M- h1 [5 t3 k$ _! e+ [1 q( c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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