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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。% _! \  i, J7 A" k
netlogo自带的social science--traffic grid这一例子当中,
  M- a' n# x, f: [. Zglobals
5 v* ~' q# W4 @, `8 t[& d: J  e3 G& F- Q
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% Q+ ^6 W3 ?; z5 H  grid-y-inc               ;; the amount of patches in between two roads in the y direction
8 z! C7 h9 x% Q: w  acceleration             ;; the constant that controls how much a car speeds up or slows down by if! @! \, r3 t0 V7 p8 J( s0 X5 N
                           ;; it is to accelerate or decelerate
4 ^- ]5 I! y1 Y  x  phase                    ;; keeps track of the phase
8 B! D, y  l0 P6 X  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# X/ t  [3 Z: P  ^# l1 \
  current-light            ;; the currently selected light* O& w: J8 R$ V, f4 M
' ^: H( ~5 [3 z$ G8 [# @7 y9 G: Q
  ;; patch agentsets
* l! p  @+ \6 K  intersections ;; agentset containing the patches that are intersections% z4 A1 k+ U1 C& r, Q1 u$ H
  roads         ;; agentset containing the patches that are roads& o" }! n- u- o
]
4 S* L0 P8 \0 H$ i* w) T: g$ k6 N4 {; u' g) L8 Q3 |8 a5 `
turtles-own
, r/ J5 e1 i1 X% r1 t* ]5 T[
2 q# p4 t* i! _1 G2 S! O  speed     ;; the speed of the turtle+ g$ p9 p5 w. y4 S( R9 I) |5 S- A
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
$ O9 o9 Z# y* C0 E7 q  wait-time ;; the amount of time since the last time a turtle has moved
$ e5 p2 S% p! n, {) G1 v: j: B]
; H8 z! d5 ]& [% ]7 L
& |- t$ d9 ~7 S/ N, Fpatches-own
) O, V" ~% Q- x9 O) g[8 c1 h7 r- o/ I; j
  intersection?   ;; true if the patch is at the intersection of two roads
/ n& y2 P5 ^7 ?2 P  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.7 K/ ?, G8 |2 x' H
                  ;; false for a non-intersection patches.
* _& l& P: D* q' ], c! V' X  my-row          ;; the row of the intersection counting from the upper left corner of the
& {) F& H. T8 T( P$ {                  ;; world.  -1 for non-intersection patches.4 J7 U7 Q6 b' a# i& C, f# M
  my-column       ;; the column of the intersection counting from the upper left corner of the
- N+ a. z+ n. ?- g0 h+ N                  ;; world.  -1 for non-intersection patches.# g! s! \, T- {, Q0 ?
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
5 j# o7 \9 g" D  auto?           ;; whether or not this intersection will switch automatically.; n& S5 O7 U/ [0 X; W  a
                  ;; false for non-intersection patches.
  |; ~9 ?) Q' v. y* ?3 U9 H]) S4 `0 j% \8 U# _0 B2 q& F
3 z+ M4 q0 G) c$ T% N6 h

: @- U. }8 V) P6 H& ^$ b;;;;;;;;;;;;;;;;;;;;;;/ h9 S+ O  x8 B: n
;; Setup Procedures ;;/ U+ B5 ~4 m; E& Z; W+ R8 G" E
;;;;;;;;;;;;;;;;;;;;;;7 u( U$ y: F: b( G3 h6 `8 p
7 i- B3 p7 ~6 z7 C
;; Initialize the display by giving the global and patch variables initial values.+ P- f! A5 Y2 \
;; Create num-cars of turtles if there are enough road patches for one turtle to
0 n2 M+ V: u: s;; be created per road patch. Set up the plots.
3 n* U% V! x3 |# yto setup
4 Z/ x9 x/ M1 G0 w5 O4 ^  ca
; K4 r: t) T$ v* ^( n: m' k  setup-globals- e. R. I. e* k  F

8 Y' Q% L  O3 x- {  ;; First we ask the patches to draw themselves and set up a few variables6 Y; E- g5 q) v2 [3 w
  setup-patches: d: B9 I. e+ t( W
  make-current one-of intersections6 X1 n( S8 J$ N6 [1 }# o' n
  label-current
0 d. h  g5 i) t- N$ h& `1 y' D; o% G, J5 V
  set-default-shape turtles "car"' G) x& V! w5 `! s" c: }0 v4 E

. d1 q  W) l9 c- t" U2 ]( I0 j  if (num-cars > count roads). Z  V* K, z& B
  [
! u, c2 n. ^: J' A    user-message (word "There are too many cars for the amount of "5 Z: v0 ^+ q3 F
                       "road.  Either increase the amount of roads "  h$ Y; d# u8 V' s
                       "by increasing the GRID-SIZE-X or ". |4 c0 l8 Q: c1 x
                       "GRID-SIZE-Y sliders, or decrease the "* A. A4 F' J/ ^
                       "number of cars by lowering the NUMBER slider.\n"  n9 M0 Y' e0 T
                       "The setup has stopped.")0 N9 N- B) z% ]2 p7 J4 E
    stop% z! n" x; Y8 l
  ]4 w0 `+ D0 y2 J5 o$ s4 z
- i6 H. ]# i8 i0 Z/ f5 y# I! V  Z# X& t' d
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color4 K0 E; B  A: [+ t3 \
  crt num-cars
% ]5 [  |& p3 A& u( X7 Q  [
. G8 y% L$ d% U/ E6 S) B" Q( {- f  h/ V    setup-cars* h9 B% d$ f4 E/ ]9 M2 _' m+ y
    set-car-color/ I5 H7 `% E& J+ }! `2 o4 d
    record-data: |8 F, I" n: w3 N$ N
  ]# _/ g4 ^% n. L( C. f6 @  _

8 }* O& h* \+ x4 c  ;; give the turtles an initial speed) F' b; u/ N$ s; g( ~
  ask turtles [ set-car-speed ]
& Q0 l' W/ v6 |  K. ^* S- {/ m, b# C' R5 V# i" S! q. t
  reset-ticks) B* d5 A$ Z  W4 v+ _# f
end/ @" X: V% X9 s$ v" f! G* x8 ?
# f. L* y# F; b
;; Initialize the global variables to appropriate values; R. j& @7 C0 W) [0 D4 G( o
to setup-globals1 ]& E' D& i! l. r
  set current-light nobody ;; just for now, since there are no lights yet
! {( ]& `+ T& K/ b" K6 r  set phase 0" o8 i8 c2 L, J) n" I% S: a  ]
  set num-cars-stopped 0
9 ^6 g* x0 P+ v2 M  F8 B  set grid-x-inc world-width / grid-size-x
4 }& {- [6 G8 [  set grid-y-inc world-height / grid-size-y# D7 y1 a; e. ^5 r$ p  Z
" p3 g+ ~% ]5 c7 Q
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
) h0 b, F+ u' F* e& ]# k6 J  set acceleration 0.099) V# U; m+ W+ b0 l7 K9 j8 y8 H7 j
end, e8 `* I0 n8 W

7 m) V* P; A  w;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
; J" f4 d/ K/ e/ Y;; and initialize the traffic lights to one setting
4 d7 ~! ]8 q! N+ ]& _1 W# s! wto setup-patches
! w/ d9 z4 b( F4 {3 K. f  ;; initialize the patch-owned variables and color the patches to a base-color
3 I2 M! L4 C# x  X+ i" o9 C4 O  ask patches
2 b. N8 U* k7 x2 _9 n& K5 B2 C  [
! x9 K, \  o) d0 y) m    set intersection? false; {% G- }; }" G0 C- D/ i0 s
    set auto? false5 N# F8 U, Z4 C# ^; ^
    set green-light-up? true5 @/ ~5 F) |+ J* |' O% `: r
    set my-row -1# g& T/ ^- ~( _+ Z* W1 P. \4 A
    set my-column -1
7 Y+ K; `' S6 W! b5 T0 j+ q: G    set my-phase -1
  w6 a% c5 s2 S/ t/ Y- X: y. T$ l    set pcolor brown + 3# x* `& [) Q0 {* I! Q+ L2 i# i
  ]. l1 K% S7 `6 ^4 A  o5 F
+ }& s, y; j6 w8 k5 H* [
  ;; initialize the global variables that hold patch agentsets
* {; U/ K9 c2 T$ d  set roads patches with* n% y9 [, \" Z  J% z! u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 ]+ z  _7 T$ B) d+ V7 y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; x! |) \* v! x) w8 y* @2 D  set intersections roads with
% i" }- z* R) u0 v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and3 R: `0 O4 ~8 a4 ~& G: K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 X  W' q4 w9 k

; x. O) f* O5 G) r  ask roads [ set pcolor white ]
" V) n: j5 Y4 ^( J( W    setup-intersections
3 s" I# m7 s7 [) K2 Xend
0 j2 e# Y9 c( ^) e; ?5 i其中定义道路的句子,如下所示,是什么意思啊?9 A# d( q2 S1 f* k" n5 g0 F7 R
set roads patches with. O# L2 _3 `5 s
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 C& N, H$ s& ]( h9 L) b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ Y. f, n7 B$ a* N  l* t
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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