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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 q# @) j9 u2 U% \netlogo自带的social science--traffic grid这一例子当中,
% X  O2 ^6 a4 E1 B0 ^' m. Nglobals
, x, B* A, E) L% _; p# x[, A/ l, p# F% j
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
) U0 f* b% I" _8 n2 ~9 |  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ o8 u$ `+ X' z2 h! n
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
& o/ _. {" C* W( u# b                           ;; it is to accelerate or decelerate- j8 F: Z% ^* _' j
  phase                    ;; keeps track of the phase% m& l2 ^  b$ y7 T4 n
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure2 e8 K# N* ~+ O  W; d
  current-light            ;; the currently selected light  x1 H/ N8 d" q& B2 y9 ]3 u9 L

. {4 W0 S( {$ D  ;; patch agentsets
+ D" P+ p* F, w( u2 O  intersections ;; agentset containing the patches that are intersections$ K4 Q+ O0 D& ~" Q- O) s8 }! g
  roads         ;; agentset containing the patches that are roads# n; a0 d; }7 ?% {3 D2 u0 }8 n: ]
]+ U' `+ g7 @' z: q

+ K; i+ P2 a  Uturtles-own
: E3 Z# S% i: n) l& G, q+ z) v[; {, m! f, ]; e% u  @
  speed     ;; the speed of the turtle/ `; U1 f2 w1 p4 M- Z
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
5 Q3 F; p! N/ U4 d6 |  wait-time ;; the amount of time since the last time a turtle has moved5 H5 M# S3 H7 A, }, S
]
9 i( e3 w! `& n% q8 P. x. c2 p1 y! Y* {( ]5 j: o8 M; [7 m
patches-own) R) I% A' [* b, a4 \2 i$ R7 i
[4 x3 N1 T8 x+ R! Q- M/ O) A/ a
  intersection?   ;; true if the patch is at the intersection of two roads
% \& a, f- u: Q3 d$ N  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
  Z) k, V! I' O# Y                  ;; false for a non-intersection patches.+ w  O% v0 Y9 h
  my-row          ;; the row of the intersection counting from the upper left corner of the* U$ r" L4 w" A
                  ;; world.  -1 for non-intersection patches.2 W6 u. ~$ T% F! A: b! l
  my-column       ;; the column of the intersection counting from the upper left corner of the+ y5 B; x' V/ ^8 z
                  ;; world.  -1 for non-intersection patches.( r6 P8 ?, G7 m: u9 [. ^; g* x; ?
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( n. c7 e3 T7 v$ b2 [2 g  auto?           ;; whether or not this intersection will switch automatically.
7 K: H+ E8 Q/ F! F; ^. t                  ;; false for non-intersection patches.; f3 z1 s- y( E! l9 ]- d) u
]
1 |, }* c9 k3 i! C, R% I9 H0 o, U
7 z# F2 R& R. i" D; G+ a: k. S2 A8 ^4 X: j: ~/ R0 i
;;;;;;;;;;;;;;;;;;;;;;8 N! l0 ?$ T. @5 v
;; Setup Procedures ;;3 {" t' ?( q2 h: H, [( Y* a
;;;;;;;;;;;;;;;;;;;;;;7 j, b' E6 M( m3 W7 m8 k2 @8 Y
4 u6 L2 ?# M: s; ]6 z' X' |
;; Initialize the display by giving the global and patch variables initial values.4 p& B3 x6 c; n5 d$ D
;; Create num-cars of turtles if there are enough road patches for one turtle to/ G- f( A' i1 r  E
;; be created per road patch. Set up the plots.3 Z- p# N& @2 B1 H/ ^* l
to setup$ P0 h$ d  [% s. {" c
  ca
/ o! h3 v' {0 E' o' ^$ J6 {/ C  setup-globals0 A2 Z  r2 Q% }0 Z0 ^- @2 b7 A
9 G: D+ A1 E1 t+ o+ j/ S
  ;; First we ask the patches to draw themselves and set up a few variables" J8 O' t* O( b& \! x+ u
  setup-patches! B3 f4 L$ R+ J* R9 T
  make-current one-of intersections
) m" B; o1 X% B" D, s8 q  label-current
$ D& q% o$ _- Y7 M5 K! }; [- R
1 y; V$ M; }  W, U" x, y0 }$ |$ {  set-default-shape turtles "car"* i; M1 Z3 g' {/ t" x1 f

, H6 J" \- c: n# ~  if (num-cars > count roads)( n+ Y. r5 r- G
  [0 ]" o1 A& K$ U" R9 i
    user-message (word "There are too many cars for the amount of "
. d8 s; O7 Z1 U! t* H/ Y                       "road.  Either increase the amount of roads "" t8 o$ z4 X& S: s
                       "by increasing the GRID-SIZE-X or "5 Y% g" z" K9 b, d
                       "GRID-SIZE-Y sliders, or decrease the "
$ x  h; Z. a4 c                       "number of cars by lowering the NUMBER slider.\n"; H6 L. \8 |) d! B" Q  j& {, V
                       "The setup has stopped.")
5 R- W& K; I3 o0 v    stop- }2 L. d4 H" u9 g( ~
  ]
7 I" q, ]6 n, g* B" X0 J, }' h1 N$ o. v# R
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color/ f# `# ]! C9 m, b
  crt num-cars# g; [2 B- H3 u
  [
) q  r$ Z. G5 N- y    setup-cars
6 I8 k7 ?- g3 T5 ]4 z' I    set-car-color
. h0 i8 W+ p! u9 W- O    record-data& C' h% s  G$ P! j& ^
  ]
( T9 [0 T! x3 }7 j: T) i4 }- R
; l) d8 c0 K3 B# v, Q  ;; give the turtles an initial speed6 v: q/ p- ~& Q3 y  z/ ]# W: h
  ask turtles [ set-car-speed ]+ w3 U( _  A, t

( q/ P; M9 Z9 @* Z6 j# M$ ~1 K  reset-ticks$ k0 d( k* W2 p6 ]; P
end; K& s& m( [* w; l( l
8 N8 [- J( E, e, y. P
;; Initialize the global variables to appropriate values0 C& i. k# Z! d/ I- |1 c
to setup-globals
) C' L( C" `% q" F: R2 A+ n1 M  set current-light nobody ;; just for now, since there are no lights yet
* ?; y2 ~% y. @  set phase 0
/ q6 a- B7 K& |5 t4 ?& r  set num-cars-stopped 05 N0 @. n' G8 |' T2 h3 q, n, H
  set grid-x-inc world-width / grid-size-x8 ~' o5 @- Y% O; ^
  set grid-y-inc world-height / grid-size-y
: F0 N9 ~, r; b! h% `; b& I/ B) g1 j, F$ r
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary# D; s7 j- e4 W! Y, I# H, j
  set acceleration 0.099
# g5 ^" ^3 j) x, _1 t3 \end
0 @& m4 K( u" r7 r3 p  M. L) E
% W* y6 G: d2 B. }! a;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
/ p! Z( F. ?! s! V% m2 x;; and initialize the traffic lights to one setting
. ]' `3 `% T4 Q5 S) T4 mto setup-patches% }) j( Z  i6 f2 U+ E) I
  ;; initialize the patch-owned variables and color the patches to a base-color+ e6 L5 g3 E9 T" K% q
  ask patches
' u# T: d2 U% n3 g  [. z) m7 p! z2 n, e. {
    set intersection? false) n; n' p! i3 E9 G4 J
    set auto? false! v/ Z  S: Y) `$ J( ]
    set green-light-up? true4 Z6 ~8 ?. G& g. z, L* `2 R
    set my-row -1
3 F$ k2 ^4 q. d' b" G    set my-column -13 v+ u: d; M5 d) y- h, X
    set my-phase -1
0 ]5 F( B5 c; T    set pcolor brown + 3+ Z! D: Z* n# u: o  y6 [8 ~- x' z
  ]
  v0 v# `$ z, m# _$ h0 x; x1 |; U  w0 H. z# V/ x
  ;; initialize the global variables that hold patch agentsets
2 \. h# O$ s$ I  T6 O/ Y  set roads patches with
, T! x; e/ u0 D2 k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 I7 W% M5 x: N6 d- [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& B: e: v7 E3 F/ ?8 X7 @  set intersections roads with1 f9 f) y- _: |7 y/ t; O0 t
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and& r) k" k  T( g' \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; t0 n3 \% W6 r5 Y6 |# v; |7 Y( h' }$ P) k; F0 H4 I0 f" R) ^9 D
  ask roads [ set pcolor white ]& I* _6 k, S+ M+ U$ u6 n) T* d" q; I
    setup-intersections: J4 p8 m* Z, P1 R1 q
end
2 `% b/ G: x$ \其中定义道路的句子,如下所示,是什么意思啊?
/ d( l& o. D# k* c# V, H. x set roads patches with
5 Z8 ^  o! J% z% M    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 a& W4 L4 h" J' N1 }& a6 M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& F# S. _7 V# x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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