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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。& K9 d/ ?/ i! F, t( }( d* |1 J  o% J4 v
netlogo自带的social science--traffic grid这一例子当中,; B, c+ i) q1 c( A0 x
globals9 c9 D* E3 @: l' Z% n) P
[8 A- R3 J2 ~$ r5 w" w. T
  grid-x-inc               ;; the amount of patches in between two roads in the x direction* m( S/ w3 ]. C$ S
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
1 }. c( k0 l$ ^! J: _  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
% K- S' I: `  S, d! g                           ;; it is to accelerate or decelerate9 w( f7 K" l3 ~9 F0 Y, z& w
  phase                    ;; keeps track of the phase6 e1 I1 }  H+ v9 R/ J# T
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure* b4 l" }/ |9 n' m
  current-light            ;; the currently selected light, A  X! z( A% H$ Q/ R& s, ~# N0 L7 T
! }7 \8 e/ W* s+ p1 b2 t9 ]  T
  ;; patch agentsets
- B/ B) p9 j9 y  intersections ;; agentset containing the patches that are intersections
- D8 o' A+ {& A& W4 x0 m  roads         ;; agentset containing the patches that are roads
9 i/ V3 F# X( s# a) R/ q]
! S9 u; n) y  E) C1 ^
9 y0 t& M+ ?8 B# {0 |* X/ x( X  Tturtles-own# K, W$ C* r  o$ o) T
[7 y( X) W: _. p% s6 O
  speed     ;; the speed of the turtle
' c3 Y: y$ ~. ^2 v  up-car?   ;; true if the turtle moves downwards and false if it moves to the right+ N. U& p+ m- P
  wait-time ;; the amount of time since the last time a turtle has moved& L" c3 V! D( _7 [7 U
]2 O3 J! n& R7 |( k! ?9 |$ P8 B- F' S

" x- g! p, D1 ~) u' {( Wpatches-own' k: [2 R- K: s
[
/ z* E7 Q6 p) N( B  j- ?5 h  intersection?   ;; true if the patch is at the intersection of two roads
2 l$ K2 n! I! ~7 c9 G% h  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
- A7 C& H) ?; O* G2 o                  ;; false for a non-intersection patches.
& d. }( x# P/ b" C" x1 `  my-row          ;; the row of the intersection counting from the upper left corner of the* s+ b$ \4 G  M6 @# N7 Z
                  ;; world.  -1 for non-intersection patches.
1 L0 U" O3 `5 C/ w; @9 c8 H! X  my-column       ;; the column of the intersection counting from the upper left corner of the; }( V1 q8 A. A) y4 L
                  ;; world.  -1 for non-intersection patches.
* B: R$ h! H% S. V% T  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
/ e! R/ E7 n7 p- U4 r8 S* r  auto?           ;; whether or not this intersection will switch automatically.
4 w& _1 p* P1 {% s4 ^                  ;; false for non-intersection patches.
$ A# s+ F; ?8 A]
% y/ l+ N$ h; Y- u# D5 o
5 n& N& n/ z4 h4 c2 ~! v# K, e7 p8 V0 J: p- g: U7 W& k8 A
;;;;;;;;;;;;;;;;;;;;;;
6 t; q6 w3 b1 c% ^$ Z0 E% Q;; Setup Procedures ;;
+ N* l3 w$ G* J" X( `- s;;;;;;;;;;;;;;;;;;;;;;! C' J" [4 D3 k: s

1 O/ A3 _2 O2 f% t' I1 d" p: Y/ O& ^" `+ W;; Initialize the display by giving the global and patch variables initial values.
* p- X8 x- ?) _. |6 a;; Create num-cars of turtles if there are enough road patches for one turtle to
; h. u# }( R8 Z# A4 m) F' R6 Y;; be created per road patch. Set up the plots.2 M$ x( D) R# G
to setup
; @% s( w2 X: a. s, S) |  ca
  G. w8 J) H% F6 C+ z6 h# L  setup-globals
$ a% }# N/ J( B. C, c
6 p1 H! P* p. [, d0 g) P  ;; First we ask the patches to draw themselves and set up a few variables
  G# Z3 \+ f5 @( K: C( g' B  setup-patches
5 j8 A' i) W2 v) {/ g" L. V  make-current one-of intersections
$ K- l& h7 q/ M2 {' J0 J: c  label-current
! c# ]  F$ b) }- B& Y+ w) l; \+ X8 f6 l
  set-default-shape turtles "car". W. m, U7 s" R9 Z5 F
( v4 c( C6 [# B' A+ {) R* p: K
  if (num-cars > count roads)
) t, V$ J; p: {& I0 w  [* z' ~' M* h/ T$ q9 Z2 l) k# `
    user-message (word "There are too many cars for the amount of "
% c; ]0 P1 x6 \# }/ S# j                       "road.  Either increase the amount of roads "3 T) [" v1 C. O
                       "by increasing the GRID-SIZE-X or ", j2 R1 Z2 N+ ^
                       "GRID-SIZE-Y sliders, or decrease the "
) o! ]4 \, a2 g' r( m                       "number of cars by lowering the NUMBER slider.\n"
/ x4 M. ^$ K: T. C4 n                       "The setup has stopped.")
+ j. ^3 M. M) Y$ `! K; ?    stop5 H) I% K# N8 |& |0 t9 ?5 Y/ w
  ]( p  a& N9 l3 g; h) b' U% |

5 [" E6 G; I) j" N* C' }  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color' U5 G- q3 M8 Q: j! S* b( X& Z
  crt num-cars
+ Z& f# S% w$ c& ?3 v; I  [5 a- \0 \0 j8 d; p$ C* ^
    setup-cars' G( y$ s4 i% L' w6 g8 T& L. k0 P
    set-car-color
, [# B/ L5 R9 j" }9 r! L& |    record-data) t" u3 d. ?8 h4 r- g
  ]. M7 k2 K9 _" f& r

4 D) n- ~/ m" f% d0 R  ;; give the turtles an initial speed  G* y& W3 g, k/ O: ]) L6 B. N. {
  ask turtles [ set-car-speed ]
2 r+ z4 K, K( |$ V: w( M5 l/ [/ Y0 L
  reset-ticks9 t6 i/ C* l& ~9 K; f2 o2 I
end' E8 x5 o2 E" A

3 V" ~% K" e* c  j' K;; Initialize the global variables to appropriate values9 A! A, o1 \8 Y$ d* o  F+ ^% H. h
to setup-globals6 J3 @1 J: \; A! i; y
  set current-light nobody ;; just for now, since there are no lights yet
6 d+ X! o2 d. r! K9 x2 j9 ^4 @  set phase 0
+ h5 c; P5 O2 b/ C" o2 n) C  set num-cars-stopped 0
* S6 K9 T' r- u" r/ \" l/ X  set grid-x-inc world-width / grid-size-x! e* q9 F: `$ J- ^8 a
  set grid-y-inc world-height / grid-size-y! U' L. O. Q  H+ Z- K

. f+ g6 Q* f* B6 Q' W  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary# }. G: W" l0 r* G" M
  set acceleration 0.099/ ]5 ^* z/ V' r
end; D* ]! ?$ z# N# e' Y

' p6 T# V$ L2 [0 B;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
% o1 C% b# \3 [;; and initialize the traffic lights to one setting
& V# M9 E5 t6 C8 _6 V% Yto setup-patches
5 {# \1 l( b8 p  ;; initialize the patch-owned variables and color the patches to a base-color
' S2 j2 [- y& r2 X. ~+ K/ `  ask patches' _" \! I: k2 A, t; M1 I$ j$ W! K
  [5 s  l# A' o% H! e, u0 q
    set intersection? false* {& z; k. e" A; h) x6 M& ~
    set auto? false) o6 Z' a3 B- a) V. `- B
    set green-light-up? true# e. J9 t8 a: P/ l0 j' L
    set my-row -1' u3 r) P& e& z6 R
    set my-column -1
% S" l8 L% v7 M    set my-phase -1# @' O) z3 Z+ T' o+ Y7 v- w
    set pcolor brown + 3) L4 J# t3 q' c: Z
  ]
$ n* G+ F. u; X$ n$ \  y, F" D- Y* A+ }( C; e! K9 S$ _7 ~7 V
  ;; initialize the global variables that hold patch agentsets' \$ s; |& J7 _" X, b, q' u6 _' p
  set roads patches with
5 L/ a) \# I% g  |( d    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- R# W9 V4 L9 H: Z" T  ~" K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 r$ F' l1 z+ G; J  set intersections roads with: G9 j4 A& K$ P# p* h( z& L4 q2 h) l- M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and& Q* K6 @" i. `# `7 e; h/ y* `
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 S  Z0 v5 U% U5 j
) }: Y) t) G$ ^2 B+ H5 V  ask roads [ set pcolor white ]
! _7 A/ ~: i" C' p$ A1 L    setup-intersections2 ]4 C/ K+ S5 H8 y! S* }' ]
end# H+ d2 ?  O6 k
其中定义道路的句子,如下所示,是什么意思啊?
' e1 e# ]' S  {3 a5 g( o# C! K1 w set roads patches with
0 `# i" {% p4 r1 h    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ E" O8 j  y5 m8 p# X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ b5 _5 a, \* ~1 N. l$ Y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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