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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。% x4 g( ?" Y2 A' k
netlogo自带的social science--traffic grid这一例子当中,8 F0 L) e4 Y- ]
globals9 K+ K! ~, _) G5 L% ?: q/ x
[  K0 O2 G6 A; M/ O! B. H+ u* O0 J% B
  grid-x-inc               ;; the amount of patches in between two roads in the x direction# H( H6 L+ }5 O  W- o& t
  grid-y-inc               ;; the amount of patches in between two roads in the y direction* v% k9 v- v, l$ _5 r+ X
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if, b! K# v+ P& _! V
                           ;; it is to accelerate or decelerate
  Q; |: B5 D2 O& e# M. M+ C  D& Y6 m  phase                    ;; keeps track of the phase/ Y* u  R; U" |7 w0 G
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" G+ K1 G0 ]9 X+ u9 ?6 M
  current-light            ;; the currently selected light
, x$ u8 i/ d$ Q' @: a* X
3 c1 c  \, j5 [" S. l2 u3 l3 u& k  ;; patch agentsets
' V8 Q( z+ ?  U' G& Y9 G1 i  intersections ;; agentset containing the patches that are intersections
  S; U: u4 w# G# c  roads         ;; agentset containing the patches that are roads
" N! o3 V& f. o& B' c) I; n: U. `]- c+ \; G5 B% P7 D) k

$ \. ~) f7 n! @2 x4 q) U3 @5 d* Zturtles-own
( ]2 e5 g+ K) `6 j$ B+ u2 l[( Y/ Q  u0 r! x/ T8 t, o
  speed     ;; the speed of the turtle
% P/ K. W7 J0 @7 r3 `' M( a4 u  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 b, D. A$ b4 U$ m* I0 L; o; \7 U
  wait-time ;; the amount of time since the last time a turtle has moved
" G$ N& J& y8 i# R2 w$ q4 Z9 |]
9 j* J$ x+ p$ i3 `( S7 D, g" Z, L# P
patches-own
. s! ^4 i6 V0 s6 r( r[" ?/ N4 }2 d7 \
  intersection?   ;; true if the patch is at the intersection of two roads
$ _: Q) u" I( v5 ~( V  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 X; ]2 L! |& Z, J; O; {! W, g                  ;; false for a non-intersection patches.: B* t& S% f: e2 Z0 X
  my-row          ;; the row of the intersection counting from the upper left corner of the
0 a4 J: R/ U0 t+ V8 c, l2 D                  ;; world.  -1 for non-intersection patches.6 _# l8 {& }# ]! V2 U
  my-column       ;; the column of the intersection counting from the upper left corner of the
9 V: T: @( {: y9 {                  ;; world.  -1 for non-intersection patches.  f% ?# n5 O3 p1 ?/ l* B$ ]5 @
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.8 i4 t( A( q0 b' B3 p. G! U
  auto?           ;; whether or not this intersection will switch automatically., G- y5 }, q; D: D' W' j2 s
                  ;; false for non-intersection patches.  E8 {2 _+ k7 ^- @) `4 X# ~
]7 C- ^: T9 Y& |
8 F/ P# L2 u/ }) Z9 Z

) q2 ]/ @; [# C+ @" |' z& g;;;;;;;;;;;;;;;;;;;;;;3 j  L9 U  X( X
;; Setup Procedures ;;
, k7 I) V. G2 a1 i' V, X8 x;;;;;;;;;;;;;;;;;;;;;;' b2 c& J: A* J6 b, u
; b; M4 a* w2 A: n+ {  Z
;; Initialize the display by giving the global and patch variables initial values.7 A$ L: ?& K! X: k- ^4 d
;; Create num-cars of turtles if there are enough road patches for one turtle to
* @1 B, D! W" e! Y$ H;; be created per road patch. Set up the plots.
. a9 N0 f5 M! h7 ^6 }" h3 C( Dto setup
9 }/ V# \) }2 \/ O1 }  ca( O, K' o; b$ m
  setup-globals7 s& D/ K) A5 N- G3 [7 l

( s, @9 I  K, u+ @) |+ I$ a! C+ n  ;; First we ask the patches to draw themselves and set up a few variables2 r2 {0 T8 C; R- p( C5 \7 E
  setup-patches
5 Q9 ~: v8 q/ @. M1 g, D+ a! j9 B  make-current one-of intersections
' W0 c2 F2 g; q, n; ]  label-current
( l  T1 _9 J; b; h+ |" m. [! k
. h" L; G' e2 M8 a  set-default-shape turtles "car"
8 H& y( d" h3 T/ ?% b  ]2 m. g
+ p+ Y0 c1 U* ?/ P/ e5 }  if (num-cars > count roads). h' m1 k' W& [( p/ S
  [
. b( H/ }) R) h2 k    user-message (word "There are too many cars for the amount of "
, o- t& Q4 K0 k+ C                       "road.  Either increase the amount of roads "
& P. U4 m2 H! e7 w6 h# ^                       "by increasing the GRID-SIZE-X or "
& {! z7 |: b7 O7 P& N) X' E                       "GRID-SIZE-Y sliders, or decrease the "
- d9 Z6 v0 c1 }: o  \                       "number of cars by lowering the NUMBER slider.\n"
+ f8 l. J( i' g2 @2 W5 D                       "The setup has stopped.")+ Z& _8 K4 Y9 N! q
    stop
# R- X- f- d- e1 D! A7 n) d; M  ]  }/ N% D4 Y* O; N8 V) W! W

2 C. v" B8 o1 X* }  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color! E  c; L6 S% v, i, h6 q- t
  crt num-cars4 d7 |- v, M+ H, G7 g
  [
4 N  T9 v0 N* N# @: e7 [; `) @    setup-cars1 U  j/ R6 z, L# N
    set-car-color9 \8 o) g( C  O! g' ?$ `: L* ?
    record-data
8 i* Q$ m+ {* I$ A, K; G  ]
! D# P- f: k+ W, B$ g
  v3 G) j; E7 }3 X3 T/ N( q. I  ;; give the turtles an initial speed4 p  o! M. [. `7 g& @* C1 e* m1 u
  ask turtles [ set-car-speed ]
6 G* [1 A) Y1 Y& p- L4 b  T# X! h% w  h/ J+ |1 y2 t; [/ _# g
  reset-ticks* C& Z* B7 V8 U
end
; ?; {. E0 n0 t0 r7 _4 ~* w' ]
. F2 C% K3 c2 p6 j6 X" S;; Initialize the global variables to appropriate values9 R' w1 W6 |+ i! t. Z
to setup-globals0 J* g* U8 _8 E: \* n
  set current-light nobody ;; just for now, since there are no lights yet
+ l8 I+ V$ C/ d# ?  set phase 0
8 M& U4 u0 Y: P- X) U6 k5 ?# a7 \  set num-cars-stopped 0
( k/ [+ Y- q3 ?7 b+ T, A% O' B9 E* h  set grid-x-inc world-width / grid-size-x
- U: w8 a; e2 I2 ~+ T5 p  set grid-y-inc world-height / grid-size-y
2 v) ^, s% A3 S. z/ ?: ]5 X
* o$ h5 j9 z* j' E+ ~  ^  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary9 A. d7 R' }, m% f. K% `" R
  set acceleration 0.099
3 K( [" V$ Y6 [2 ?5 Y6 d2 i3 Kend6 a% h' E4 S- Q2 s: z$ A

* p, @- S) M, p, k;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# C4 ^' J9 D5 O* \6 {3 M7 N  }/ d;; and initialize the traffic lights to one setting
% R/ C) a. |8 u! @9 D. E) ]to setup-patches
2 e. S" x1 T& ?% d0 z+ Y- ^  ;; initialize the patch-owned variables and color the patches to a base-color  K6 ^2 @% _2 p0 B6 y$ h7 g- M
  ask patches
+ m$ \! I  f! X, B0 T6 q# h  [! H" R8 ?2 a7 E9 x3 U( a
    set intersection? false
$ F2 _1 O5 x) a9 x4 |    set auto? false
% n: z6 c7 u6 P8 A    set green-light-up? true
7 R/ ^# y, i9 S3 r    set my-row -1! g+ W4 ~! ~( U% `2 Q" p
    set my-column -1
8 v4 ^4 K' R, y; ]7 B    set my-phase -1
2 S/ A8 A& d6 V7 \' s( l    set pcolor brown + 3
, b8 `! `) i" A$ r/ \- A4 D  ]: ^# P! ?* G2 M% y1 V

% T/ r% l0 k! z4 k  ;; initialize the global variables that hold patch agentsets" R& W) O( P  [2 T; r! l
  set roads patches with- T+ o) a$ e# m* U! D+ v! }
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: r' K: \: k- E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& r" I: u& U: e; {( e+ E9 A$ Z  set intersections roads with/ W. H. W3 w* J$ M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and2 a' Y( h0 r% b; s2 W% i5 o* _
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 ~& f, x) J' Y. |, }

! U- k0 t7 V- p- N  ask roads [ set pcolor white ]
2 q* g  k; I# j9 k* [9 y' o    setup-intersections
& R- V/ V% `) lend- G3 @, D, m# k' I" ^: y
其中定义道路的句子,如下所示,是什么意思啊?
$ S5 k- u/ ^; o$ p1 ~ set roads patches with& T: M; j, W" W1 D1 y& B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 ~6 o5 j) N- E" J& a! l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 v. |2 S' i+ V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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