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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。
" r0 n! a" F. ^. e$ a  S, Enetlogo自带的social science--traffic grid这一例子当中,3 I  G9 N& m: i7 h
globals  Z& `/ d8 F& w. T
[! x- V1 M0 k; F6 p. ?3 x
  grid-x-inc               ;; the amount of patches in between two roads in the x direction' V. m$ k/ F9 b6 w( I
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
# w$ e7 e5 m& ~/ w' o3 n! F8 T) X  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 L& y, ~; Z. s
                           ;; it is to accelerate or decelerate
1 w7 N9 a) o" F7 Y1 [) O  phase                    ;; keeps track of the phase
" q. o) H+ {* ~; ^2 c6 U  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
5 _' T8 k; W" N5 x) q  current-light            ;; the currently selected light
) S0 x! }0 _- y# W- e' I$ X' R
  g3 B: T: a+ X) A5 Z  ;; patch agentsets( a8 ~5 j, ]& x, s* x
  intersections ;; agentset containing the patches that are intersections
  i( P9 b2 B' r  roads         ;; agentset containing the patches that are roads0 e5 Q; L9 \  i9 [* B: {
]
, Q+ b& m; E2 D; u3 J
! A0 H9 W9 b' ]9 ~0 l7 w/ Tturtles-own
6 b8 s0 w6 |- z( b0 i5 F: o1 j[* n! a( U2 M- K8 M2 r
  speed     ;; the speed of the turtle7 q' ^1 v5 l1 u# z( h
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right2 \; @/ q6 C$ t# o5 @
  wait-time ;; the amount of time since the last time a turtle has moved
# ~/ R' e/ W. D" J9 c3 X]
* @9 G" J) ]" y. `. Z; ?
- P# X) q, M, R3 \' ?7 p8 ipatches-own
# a( j  o, z  J- h, m; T- p$ {( k[1 W" l! L2 g. d
  intersection?   ;; true if the patch is at the intersection of two roads
- l) G' a3 p1 r) Y. [  f, G  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 w' v7 h- g/ K) ?! e' s
                  ;; false for a non-intersection patches.
0 Z# f4 Y4 |6 c' U0 q9 q  my-row          ;; the row of the intersection counting from the upper left corner of the/ L9 x4 j! o! @5 e. y2 e
                  ;; world.  -1 for non-intersection patches.
7 o1 t- y3 h& D  W# x7 Q+ t  my-column       ;; the column of the intersection counting from the upper left corner of the
1 o% y0 Q. U% Q, _. O7 [0 F                  ;; world.  -1 for non-intersection patches.
6 ?9 G5 |6 e% _' L8 R- N0 Y  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  Q1 A3 U% \! i# u8 A
  auto?           ;; whether or not this intersection will switch automatically.
; ?! }. h, c% R2 U                  ;; false for non-intersection patches.
# h. k( H, z" \* g1 E- r: t7 L]6 K# R$ o- t! ^- |0 I" ~
4 Z, ~; o7 `, C
9 O9 @  \/ m) l5 I
;;;;;;;;;;;;;;;;;;;;;;
2 ~5 `; d/ x% k* d% {;; Setup Procedures ;;$ J1 x' R: {+ F* s: e  w
;;;;;;;;;;;;;;;;;;;;;;
& A3 `; U# H0 T3 d- b( V. ^% d9 S1 u% C: f! |, g/ `' k
;; Initialize the display by giving the global and patch variables initial values.; t& R2 F+ D( Y4 A! Y; Z
;; Create num-cars of turtles if there are enough road patches for one turtle to
1 D  \8 ?( M, J' E$ |8 g' ^;; be created per road patch. Set up the plots.7 b- R3 k5 t+ }+ ]/ k! z; K
to setup2 y* p% ~- E1 R
  ca
; h9 {7 A6 W" k  setup-globals
3 r: r, A7 _! D' m. V; W5 W/ N) x% w" s1 t; D& j. a, R
  ;; First we ask the patches to draw themselves and set up a few variables7 d) ?: b7 [2 f4 H1 P+ C
  setup-patches$ y6 n  Y% x4 k. I7 U
  make-current one-of intersections9 y& e* G/ h' z( r: P
  label-current! ^( J8 R( x) M4 |
" n1 E2 P- g4 ]  C. A$ C. k5 u
  set-default-shape turtles "car"
7 f8 v3 _( S- x! n8 d  r, Q* B* ~  ]! {0 f
  if (num-cars > count roads)
( @& I) ^) A8 e! r  e  [
7 k2 L7 N# E/ M1 T8 ?, H    user-message (word "There are too many cars for the amount of "% j5 y: h) \0 u
                       "road.  Either increase the amount of roads "9 W7 s: N) q" v  F2 l+ I$ d( Z' r
                       "by increasing the GRID-SIZE-X or "
' [* u: Z; n- T/ L4 s, V' ?                       "GRID-SIZE-Y sliders, or decrease the "% S$ u0 N7 a; F- ?. {! \/ T" @$ c: w
                       "number of cars by lowering the NUMBER slider.\n"
8 a& _+ ^' d7 o" u8 A. _4 P                       "The setup has stopped.")
' m% H4 l/ e) p) w, Z0 t    stop2 `% C! }  n( L  t) v
  ]
8 `# Z" X$ q- S; e8 j& d; ?6 T$ H  k7 U( X( b' f
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color$ I2 {  J0 e+ e" m9 ~7 F+ Z
  crt num-cars" L$ k" e! Q% D" p* _
  [4 ]; u2 w$ I% v
    setup-cars9 m4 Y! k% X5 Y1 D9 u- |
    set-car-color6 h5 `5 J; S1 `6 e& n+ c7 j1 q  K* r6 l/ f
    record-data! K4 i! V4 |% ^! M! S$ n
  ]
; _1 }" J. o4 g2 r" ^6 P" a! I( z8 Q: E3 }- A; z+ E/ Y
  ;; give the turtles an initial speed% K- s6 Y) ~0 [, W0 D: ^: @+ R4 r, w3 S
  ask turtles [ set-car-speed ]  O' B5 e/ |8 Q

! g9 W# ]. _+ s! W+ ?, {, S) J  reset-ticks* v+ H+ u! v$ [8 N: n
end
) k# K& `+ G, x$ L2 J
. h: B! V* C$ n+ _4 l. @+ U$ S;; Initialize the global variables to appropriate values
) n; D  x0 Z. W  s. Cto setup-globals  i: h, M, b; v8 C
  set current-light nobody ;; just for now, since there are no lights yet
1 _' R; V) G! r/ F  set phase 0
$ E2 P: {% z8 [  set num-cars-stopped 0' [# i/ u1 s/ L6 Q! k, `
  set grid-x-inc world-width / grid-size-x* D* T* z3 z! C" u) F5 j3 K$ z" Z- Z
  set grid-y-inc world-height / grid-size-y' L9 G5 a- X' P% n
$ s; M& T( i: j/ q5 W4 j
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary6 _+ B6 J  m) \6 v
  set acceleration 0.099' y$ V: H9 s& Q, N
end- _) e5 ?& `; {0 r+ c2 S
+ ^1 W1 M: \$ \2 u9 @& S
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
" I* \- K& Q2 K( n. `- e;; and initialize the traffic lights to one setting
" i' z% Y5 @( E9 Y/ Zto setup-patches- p; I$ N/ y6 G
  ;; initialize the patch-owned variables and color the patches to a base-color1 j  F5 m. h; [7 q6 t
  ask patches2 x4 a: n) B+ c% m9 c8 `
  [9 A0 ~8 z& U4 U: H, h  i4 X  a; J
    set intersection? false8 X$ `9 ]3 K# s$ C- L" R
    set auto? false; y2 b  l  {, X$ X1 G
    set green-light-up? true' W. G+ k& I; A0 w
    set my-row -1% _* C, v/ u9 q: f
    set my-column -1
5 q. w% a, R  \& H    set my-phase -15 w5 k5 e! A) K, ]$ |
    set pcolor brown + 3
5 y9 s- h  ]' L9 T/ T4 P  ]
1 p' L8 j& v/ q" j4 L, H$ m- y4 w, H( n( @
  ;; initialize the global variables that hold patch agentsets* b1 m1 G7 t6 s7 N+ o2 J& K
  set roads patches with
# B4 K1 G. d6 Y( B/ A5 ?; b8 ~5 H+ x    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 h. @- L; |/ z7 e
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' h3 O0 I! E2 K' ^
  set intersections roads with
# {; I9 p' ~4 ?! u, B6 S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and9 w; \! p5 s' X/ b3 X  A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 Q- t# D8 y& p7 s" \' U( {2 U0 A! e& M

) o  A9 r3 d6 b' }2 H* y: x- K  ask roads [ set pcolor white ]1 f$ I7 ?+ j' w4 C+ y" R8 U- j1 ]
    setup-intersections1 P' y4 B# V; y+ J: d
end
# o1 V9 v3 y- `: Q其中定义道路的句子,如下所示,是什么意思啊?
1 P% x) A0 J& E+ n set roads patches with8 f& S: b( Y6 L, T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 E1 s8 O+ l) V, F& O; C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 c; H1 V" s$ n& B# u% i
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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