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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。( s$ m1 D/ t0 y! w; e
netlogo自带的social science--traffic grid这一例子当中,
7 S: n4 N9 B1 t2 x) Pglobals/ s  e' i! ~5 _4 J" C! s( [' h
[
% ~( D* a$ u$ `+ e+ c5 _0 z1 e  grid-x-inc               ;; the amount of patches in between two roads in the x direction8 ?. c2 A. ^6 L( t, ]0 F+ e- l
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
3 r2 G6 `8 K  n$ n: N5 G" T0 R  acceleration             ;; the constant that controls how much a car speeds up or slows down by if, ]5 W0 u" T" n+ ~+ y- M: l# h
                           ;; it is to accelerate or decelerate
& q, c3 W+ t6 j  phase                    ;; keeps track of the phase
4 q: l* V5 N* r% e0 k  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
! S$ ^; Y2 P" P$ v7 ?* @) N  current-light            ;; the currently selected light7 ^6 [) X$ o* t9 Z$ O5 R& g
0 N9 Q+ n! J+ X& {1 w
  ;; patch agentsets" I) \, ?6 J8 J) U1 U! g1 R+ Q
  intersections ;; agentset containing the patches that are intersections
0 U! J! U; |8 W& d6 [' {  roads         ;; agentset containing the patches that are roads
: E! g$ I) X# _) Q. ^0 l]/ [6 G3 @! `# Y

, X* M1 z/ Q& c* u; tturtles-own
8 y- `" d6 I& M$ }$ I4 i[0 ~, z; r4 [+ S9 C" {' j
  speed     ;; the speed of the turtle
- C) E' j" s3 \! ~. n  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
, A4 Y1 E+ {* q8 G  wait-time ;; the amount of time since the last time a turtle has moved% d; W7 @+ R* x- t4 I/ _1 x
]
7 ^; {; D/ @* k0 W5 e) P' X/ M/ k: u9 Z. t$ K$ S: i
patches-own
# o7 c$ Y* t6 |7 G3 S6 J4 ]! Y[
' q' z* i' B, k* w% R5 O- l3 ?  intersection?   ;; true if the patch is at the intersection of two roads! x+ w' f1 X) e, ]' E/ W4 _; B2 x6 N# c5 o
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.+ U- G& e! V8 z& ?6 D# d0 x
                  ;; false for a non-intersection patches.
# N9 }* f8 B5 e5 E: r  my-row          ;; the row of the intersection counting from the upper left corner of the, t3 I1 d, f4 w  z
                  ;; world.  -1 for non-intersection patches.
& V% j  |2 L. u5 |  my-column       ;; the column of the intersection counting from the upper left corner of the: n) q, l& Y; j- B
                  ;; world.  -1 for non-intersection patches.
" Q$ b# B7 d; G5 T) i* _  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.' n# D* w3 f9 a3 h% `$ A
  auto?           ;; whether or not this intersection will switch automatically.; E  H! t( Y% _
                  ;; false for non-intersection patches.. O8 ~0 x3 j9 p: l/ W; a
]! e, y+ y2 i# H* P( t1 Z; f4 d- X

  y7 W. H; P* D, B5 A, I# U6 T) k" t5 X% v
;;;;;;;;;;;;;;;;;;;;;;" k3 L1 j' U9 B! j
;; Setup Procedures ;;% O- Y* G0 Q# A5 Y# T) m" F. p
;;;;;;;;;;;;;;;;;;;;;;5 E% X- L$ b. L6 }/ n. Y
/ n/ ^4 j  w, C$ n" e
;; Initialize the display by giving the global and patch variables initial values.1 E! ~' {8 I6 s
;; Create num-cars of turtles if there are enough road patches for one turtle to
9 D$ ?' v; g4 i; _+ @;; be created per road patch. Set up the plots.
5 J5 o" M" F& B  |to setup+ O! T4 B. R. F, y' f8 ?8 A
  ca2 @" e$ r0 ]7 v. M) R+ D  D' F
  setup-globals
9 H" q. a7 K& b7 Z3 j" N2 m; g" S* _3 r7 u7 W! U
  ;; First we ask the patches to draw themselves and set up a few variables
0 b8 ^" c1 x* p7 o  c" `  setup-patches
  N+ j4 x, T* x7 W* L1 R* N" F% Z# R  make-current one-of intersections4 M! z2 P% H) _
  label-current
9 `# i  T# _* i2 ~
  J% @8 m0 J* \3 @4 [5 U  set-default-shape turtles "car"
3 a  Q9 x& x( u# z; s( N2 r, _; c; j4 L8 F" M! L3 ^) H8 W; |! b1 _
  if (num-cars > count roads)' z7 W9 t: ^) E. G
  [0 n' H: X' f* E0 p. [
    user-message (word "There are too many cars for the amount of "; V$ C3 D& z$ k. V' o+ X
                       "road.  Either increase the amount of roads ". U$ b5 n% v3 C* F
                       "by increasing the GRID-SIZE-X or ": Z( ]. ~, ?( K3 x% [$ C, `
                       "GRID-SIZE-Y sliders, or decrease the "
8 F% y5 A0 k  s' h8 ]' _                       "number of cars by lowering the NUMBER slider.\n"
9 \0 G, r; _$ m3 J                       "The setup has stopped.")4 W8 F$ }/ r, L3 D* {
    stop( [6 ~7 o$ Y% z" l: p
  ]& O! [5 P) Q# P" |$ ~
6 I- S' D% \6 s$ v& V& }1 M
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color* u+ h# H. W& n+ J1 Y
  crt num-cars' ]0 j. l3 F. F
  [( m3 \3 N  P" W1 }& l7 D
    setup-cars, A8 v* I  {# Y8 c0 |- h% m
    set-car-color' Q6 t( x3 ]2 N0 h7 D! n
    record-data* v, w/ K* _, O1 y
  ]
) {+ K  D. g2 X$ Q9 h( [8 O
1 H' ]$ v1 ]) t6 a  ;; give the turtles an initial speed
: m/ R9 c- p$ A% e8 V; F3 D; @- f7 Z  ask turtles [ set-car-speed ]
0 D& ~, O: D. A, f' @) @' c& K4 i# z  }" J: {
  reset-ticks
  e1 y2 p; Y9 H" \end
; v* J  [: s$ \% `
+ a( e) l' {( H;; Initialize the global variables to appropriate values
: v9 B, h; Y0 ^, qto setup-globals
) G6 m% c8 s2 u$ J4 d3 F+ @  set current-light nobody ;; just for now, since there are no lights yet9 q% M# R5 V% }" ]; k
  set phase 0
  {" L6 Q# {) Y1 h2 G; w  set num-cars-stopped 0
7 `& D% _. s) Y# i  set grid-x-inc world-width / grid-size-x+ ?% e" K. I! R& ]" B3 P
  set grid-y-inc world-height / grid-size-y9 x0 Y: C$ k1 o

  y4 B$ r0 K" x; ~0 @  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 G% `4 @: _2 B6 I# j& U6 f
  set acceleration 0.099+ f+ n% i+ [6 T) z
end
! o) j3 t0 R  B, @- r( ?. x( `+ x+ Y
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
7 R. G. U2 r6 e9 J& c/ @;; and initialize the traffic lights to one setting- H" n- E. C7 y3 g9 v: p3 ]% H+ @* `
to setup-patches  [3 ^' G  Z: c3 o( k
  ;; initialize the patch-owned variables and color the patches to a base-color
0 @" T9 \2 v. r+ b5 a# }% ?: }% o! g  ask patches
  O+ Z5 t6 V7 f1 `2 n* E  [8 E$ M; t( `/ |1 y
    set intersection? false
" y4 r: s" w. w" j# V, {1 o0 M    set auto? false
" D2 a- _# ~1 S, T6 d    set green-light-up? true
3 u; C' o" X7 q8 d  Q    set my-row -1
, p  N) C' [: v. [8 O  @    set my-column -1, P3 [8 |+ V* Q* W3 ]: s
    set my-phase -1
+ h! ^0 g! I' A8 k. c- j9 {2 r0 F- X    set pcolor brown + 37 c& U6 w2 Z6 x* M* |3 ~
  ]
1 R) I' ~0 F( v( }3 x
# Y: t# s. n; K! L# [" X3 q  ;; initialize the global variables that hold patch agentsets
1 d, Y6 s1 g$ x8 \  set roads patches with
# w  m0 y- K' e. Z: z% G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& g. q. t6 |* [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 g/ n( y5 j" W- i# e. U  set intersections roads with8 r, p8 l" c" V. P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
0 H$ m! d* W. i1 P    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ d- F+ y- @6 m8 l& T7 ], F- m
0 K0 d$ c/ \, O1 j8 a  ask roads [ set pcolor white ]: n5 |2 S5 |" d/ u" F. A! w
    setup-intersections% J( S! J& g5 K
end
* z6 p* g( `4 ^  J0 W* s; d其中定义道路的句子,如下所示,是什么意思啊?
# R& G: a( u7 h# y set roads patches with
; _' C  E& B% @9 K  D' }7 r5 N    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 e  u5 g3 E  g
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; C" ?" f* _7 F! r7 e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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