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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。, S1 M' C( }' ~$ |8 r( S; z7 `
netlogo自带的social science--traffic grid这一例子当中,
2 m5 w& I- P8 q1 J& j1 Qglobals
; W  S) a5 Y: N+ |4 T[
9 S+ `, A4 i9 X9 K( f9 V' F  grid-x-inc               ;; the amount of patches in between two roads in the x direction
3 g+ K5 m2 r1 J4 F, Z# d- U/ F  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 j6 k8 d) r. O3 }+ ]7 M+ i0 C  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
1 G, v( G# g& |5 ]                           ;; it is to accelerate or decelerate' j: L4 n; Y$ A* s9 K5 o, {
  phase                    ;; keeps track of the phase
+ i  f# K9 o) O2 Q6 q  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; x  W' p1 V% ^; {( W4 B! y  current-light            ;; the currently selected light5 b  P8 t* j( Z: p. G

% j3 x, C+ Y- s* e  B  ;; patch agentsets
% ?1 A9 G9 {7 ]8 _# E) \2 {  intersections ;; agentset containing the patches that are intersections4 `; S( s) g8 K( ~
  roads         ;; agentset containing the patches that are roads* M6 L& d+ S: X1 r4 ]( G
]+ k2 k+ Z1 ^4 k& k) c
4 @5 m! S3 ~% Y& s4 Q" G
turtles-own* X( j, A6 F$ o3 V% u# B2 `
[
; b5 b* U% l# u/ ?2 E0 G! T+ [  speed     ;; the speed of the turtle
* a3 d5 i% l; Y' Z  up-car?   ;; true if the turtle moves downwards and false if it moves to the right  g7 d; M$ I: A' A  n+ X
  wait-time ;; the amount of time since the last time a turtle has moved1 {% l+ F2 C" D6 ]( o8 v+ M
]: d- A- H7 t8 H- K* Z. p, f+ V

( P3 |! X) ?& W$ H- Jpatches-own9 V$ r' y9 j: f$ b, a: ^
[  k& }3 }; `; M% L! s$ \, O
  intersection?   ;; true if the patch is at the intersection of two roads
/ f# S7 _8 A0 p" a5 o% L0 e7 s+ p  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
& Q3 Z& h" O, r  ^+ b                  ;; false for a non-intersection patches.3 G: Q6 \' X: Y' O7 ^
  my-row          ;; the row of the intersection counting from the upper left corner of the
, C# @3 G7 N6 w: @; ~8 j+ g                  ;; world.  -1 for non-intersection patches.! L; l3 B" v4 t
  my-column       ;; the column of the intersection counting from the upper left corner of the  y$ M+ I+ A3 Q9 s6 E
                  ;; world.  -1 for non-intersection patches.
( t' G% m( E) r$ e4 x' Q7 N  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.% u& ^7 Y/ ~# ~$ w  d0 Q
  auto?           ;; whether or not this intersection will switch automatically.
$ L6 o: g' X2 D: x  v2 y                  ;; false for non-intersection patches.
3 n/ A: Q6 ]* M  @. E2 \]
2 e4 d3 }5 }/ Q7 l7 _
2 e/ B( `5 X; b
5 r  z0 N4 Y; O) ?6 Q4 |;;;;;;;;;;;;;;;;;;;;;;
! Z  O( A. z" M6 p5 |! W7 j0 s;; Setup Procedures ;;
/ @. x, i; y2 X! {7 b- c4 Z( H4 A;;;;;;;;;;;;;;;;;;;;;;0 j6 [: _/ j) B  @( D% E
" n0 t" h! p  @+ R' g2 U8 I
;; Initialize the display by giving the global and patch variables initial values.
6 V9 L% U- t- Q; J: m;; Create num-cars of turtles if there are enough road patches for one turtle to$ C2 G2 N$ C( O$ \) s
;; be created per road patch. Set up the plots.
6 z: ?( o/ e' c* Z" Nto setup
4 G/ ~- J* @4 T5 B: g" C. D  ca3 }& V* y) w7 W$ w
  setup-globals
8 L1 w9 A, n! G5 z1 P
. z) d( Y1 j* S8 Y, H  ;; First we ask the patches to draw themselves and set up a few variables
( e6 Z  _" }) e; c/ U6 y- w  setup-patches
* e7 v% S' i6 ?; F- W! O9 O  make-current one-of intersections
% U: c8 K6 k  P  _& a. }  label-current7 P) u: A/ a, x5 s. ]

) N) T4 u! A% V: n: b+ W2 e1 z& d  set-default-shape turtles "car"
: g8 i6 Z( v: @
" U: `5 L! w8 U& \# m9 J  if (num-cars > count roads)
8 w1 C4 D  `, k/ m. E  [' M1 w) x0 U/ B9 G# ^2 H
    user-message (word "There are too many cars for the amount of "
# K1 t/ P: M8 }$ }% q                       "road.  Either increase the amount of roads "
2 b9 M, p' L1 R( ^# h" ?% r                       "by increasing the GRID-SIZE-X or "
) j6 {' v& \. T# l( G! Y* V                       "GRID-SIZE-Y sliders, or decrease the "! O& ^# q9 v0 b
                       "number of cars by lowering the NUMBER slider.\n") n, w3 P2 Y4 x8 _7 O
                       "The setup has stopped.")* v. W, U; t( a% p0 \' V
    stop
: t) k0 A9 o& P/ P' A- s  ]" S' y3 n" S% P5 o- [7 _. g
8 `" ~* L9 n- A
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
( o' q* W8 J8 X1 F6 D& B" u  crt num-cars
+ ~: d) Q2 T5 ]9 s. E/ i  [
" s& r: Y* T$ a) R    setup-cars1 e+ E6 Y- L) E
    set-car-color/ |# N3 L, Q: R2 G8 W
    record-data
2 e% h$ `- E& @6 e6 h% H0 j  ]
9 ?2 x, _2 ~' N$ a* V9 N
/ }  ~3 n( ?$ \1 w* {$ L  ;; give the turtles an initial speed) M: Z% K+ r0 l; k( J
  ask turtles [ set-car-speed ]( s8 S# [' m6 M/ `1 t  i
! E. |, }; }: M+ d" J) v' M
  reset-ticks$ e3 j# C2 o8 L1 M
end' V: `  {# q. e4 r
) f6 ~7 l, _3 X
;; Initialize the global variables to appropriate values. x6 T, S0 P) B. u2 H7 x, J. z, Z
to setup-globals
3 e; I" ~1 h- z8 t. L0 q. S% q  set current-light nobody ;; just for now, since there are no lights yet
$ C8 O: t5 h* m  set phase 0
+ d9 B, x. z: D4 |/ f7 H% h1 t  set num-cars-stopped 07 [0 x, A) J: ^- q
  set grid-x-inc world-width / grid-size-x) G5 ~) Z! k* Z+ G/ p$ k9 M+ z+ o
  set grid-y-inc world-height / grid-size-y
# r& x0 H5 T, O
* [! k9 ?; r6 r  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
/ h/ v3 s5 L& O( [( t/ m. h. O  C  set acceleration 0.099" e- h& H0 i: G7 p  l
end
% r: D( j9 @& a  m8 c  |: U
$ O$ t$ m0 S! [' S# };; Make the patches have appropriate colors, set up the roads and intersections agentsets,: A. ]2 I; p- {0 }8 `: g
;; and initialize the traffic lights to one setting0 k8 K! I' Y8 `8 ]9 I
to setup-patches, Z9 S1 \, G7 {
  ;; initialize the patch-owned variables and color the patches to a base-color
) ~& x* K( X! T  D4 r; G. q  ask patches
( d, q* b5 q# T$ _2 K6 I  [% X7 n- R# F2 R; A5 H1 W
    set intersection? false
6 Z' c+ D; G% \6 X    set auto? false
, x0 g* f0 h' r/ m    set green-light-up? true8 E: K2 V! T/ w8 s1 D' p
    set my-row -13 h  A6 ~) z( f3 T# |2 t: J
    set my-column -1
# T5 z2 z3 ?. J# V. U    set my-phase -1( `1 y( B+ @1 }1 B1 T- S3 x
    set pcolor brown + 3
3 m) G2 H, j, R$ ]8 A  ]# ]8 p7 C. u, i. w" t
% D/ i' |9 M# }4 H& {2 c2 \8 S5 F$ _
  ;; initialize the global variables that hold patch agentsets6 O: x7 a. h- @! ?  L' N3 o
  set roads patches with' S) f; c$ ?4 h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: B. Z" B- B3 ]1 C5 ~- {2 d" [" T8 {
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 k  x' ?! }  b  y: ]/ z3 V
  set intersections roads with
) h7 ^  J4 W9 a6 w8 D: F4 m* k7 H    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" b4 t- o$ L- d% O4 C9 {, }- x! C; R    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ J4 F& ]0 O8 _
$ F  c$ p7 J( G2 C$ E7 N
  ask roads [ set pcolor white ]
0 h! b6 b5 ~7 ^# [7 g; K- p  Y2 G( y    setup-intersections! a" c' n$ W, |: q9 L
end
4 Z/ m3 s8 t9 Z/ e3 e) A其中定义道路的句子,如下所示,是什么意思啊?
- }  k3 w- p- M  B# x5 l set roads patches with0 b! f3 s& c1 p% p( b$ L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 A4 l  L( c5 x6 ?# l% e$ N2 o0 c, v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], H3 p/ h& n- ^( \3 s
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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