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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。
8 U" L" M, D3 `% m( Y3 }netlogo自带的social science--traffic grid这一例子当中,
0 ]2 j' o8 M' {9 x/ ~3 A. c" aglobals/ \) Y/ A9 |9 M( a
[
! y0 W" T2 ]- }, A$ F8 H/ r9 @+ A  grid-x-inc               ;; the amount of patches in between two roads in the x direction  w$ O% H+ @, u9 L' H$ l
  grid-y-inc               ;; the amount of patches in between two roads in the y direction2 B9 P3 H) O: {1 P2 o  |
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if6 V! D4 v# Z" Y8 X4 j5 i4 g
                           ;; it is to accelerate or decelerate
2 R" C3 q, C6 e  @! T4 j  phase                    ;; keeps track of the phase8 c' G$ Q3 G* t5 Y. u9 [$ E1 K
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
2 K$ Y0 `, f' n) g9 F2 Z  current-light            ;; the currently selected light
3 f5 [+ a1 O- M: ~
) T5 Z7 X% q# S) Z' `  ;; patch agentsets
( y2 P' h4 I# r+ w: b$ E5 n& S/ t  intersections ;; agentset containing the patches that are intersections9 L; K9 x# Y' N5 G* k
  roads         ;; agentset containing the patches that are roads
" a$ ], T. M+ m3 s8 r  Q]% w4 d9 w6 y- S2 K: c
! q& v$ D6 T) c& |  P+ A* p
turtles-own6 U1 c/ e9 T  x* e( H8 ^6 x
[
4 i; J0 \& A& C4 J7 M5 ^, y5 }  speed     ;; the speed of the turtle2 e+ [6 K' b( _' g: {
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
# A, H( J; _* P  wait-time ;; the amount of time since the last time a turtle has moved
* [) p* ?; r' g]2 I. @% X5 w! ^1 x
) L' K+ h3 W7 [$ g$ d- H! a
patches-own
( m7 N/ z6 R4 H) r  m8 Z[
9 }9 }: u, Z1 N0 n; U9 E7 a2 ?  intersection?   ;; true if the patch is at the intersection of two roads
0 |  j. b3 r/ R/ T0 G( d- i2 A: I, l$ t% C  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.  l" S8 {8 o' M) l! t6 {
                  ;; false for a non-intersection patches.0 n# N; \$ Z! v% [- n3 v
  my-row          ;; the row of the intersection counting from the upper left corner of the
$ ~* i( m  q; f  d3 y4 J7 R                  ;; world.  -1 for non-intersection patches.
9 c/ n2 {2 i% [/ t  my-column       ;; the column of the intersection counting from the upper left corner of the5 E* P0 H3 h7 d% `5 Z! r! f
                  ;; world.  -1 for non-intersection patches./ ?- L- Q; q) @8 B; N) [- D) D
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.- H( ]; l% O+ j0 P" w
  auto?           ;; whether or not this intersection will switch automatically.
5 D! e0 f9 _# c' }8 a9 ^                  ;; false for non-intersection patches.8 ]% U2 k( f& `( J- `
]
0 q$ _4 K# g2 s5 c( _$ e7 g, H+ m8 w: w
( J+ }4 I2 b3 j5 {
;;;;;;;;;;;;;;;;;;;;;;- k' F- E) i: b, K$ @
;; Setup Procedures ;;7 B/ q* A9 `- l; T# _* S
;;;;;;;;;;;;;;;;;;;;;;( }( }* V& q* X! w; \, y" F

& e2 B! {) }2 O# u1 W;; Initialize the display by giving the global and patch variables initial values.
0 X% {8 m/ `% M! W1 F9 V$ k# u;; Create num-cars of turtles if there are enough road patches for one turtle to$ W/ [0 M3 H7 n: W: X
;; be created per road patch. Set up the plots.# B  _/ g3 h$ c5 Q2 c/ r" s4 r
to setup
; m9 J) a* S4 p$ y9 Z' H  ca1 `% R9 K+ y, N! z4 y- X
  setup-globals
( J# @: }7 K, A1 N3 q! P" m+ E5 b, i* H
  ;; First we ask the patches to draw themselves and set up a few variables
9 ^! G* V8 h/ b5 @  |  setup-patches( b, F5 P+ ?( U" v1 k# N0 W
  make-current one-of intersections
! U- q; m4 B. ^  label-current
- `# E7 o% G* K* F# S% w+ ^1 ?0 ^
, o; a" A/ n4 ]! v& ^  set-default-shape turtles "car"9 r- N5 n- x) z: b$ C
9 v/ t  R# J1 P+ B5 d
  if (num-cars > count roads)
, C% P# j! b! b) H$ i  [2 A7 ^- }: L" d: o8 P+ n* z
    user-message (word "There are too many cars for the amount of "
$ B; b/ D3 z* M( T' K6 u) V' R) M, o                       "road.  Either increase the amount of roads ") [9 x) I8 v% k2 C/ O* v
                       "by increasing the GRID-SIZE-X or "9 F& F9 y" n. ?. C- m6 h; r
                       "GRID-SIZE-Y sliders, or decrease the "$ S( Z1 [( r% h1 W) R
                       "number of cars by lowering the NUMBER slider.\n"- V  j6 e6 u- L! g( ?3 H! W
                       "The setup has stopped.")$ q/ r+ K, p. f2 [4 Z
    stop: L. {4 G. B5 ^$ z8 |; a
  ]) y; X! G4 C5 Z& A" f3 e' _, O! l

* A- G* p7 G1 H- q& _* V1 S  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
/ m; s/ j( U; i" i  crt num-cars
. l3 \5 t# o8 T5 j7 e  ^  [# q. j) B/ |# _& \) L
    setup-cars: V; q9 D. c# F' u1 W" P( D
    set-car-color
+ T8 k' @1 x+ Z! _! V0 k! Q/ X    record-data
2 Q6 r/ [$ r: [( n: J7 \, V5 [  ]
  _1 k( \2 `7 s" Y9 g2 |0 v' r5 y% z& ]+ S% B9 \8 B2 _8 v( i( V
  ;; give the turtles an initial speed7 P! l, m- \7 M6 c( o6 P; J+ ~
  ask turtles [ set-car-speed ]
0 n$ `% W% Z: B7 r4 f, D# W: K& ~" S5 X# I
  reset-ticks; i. i6 {) q7 s9 x5 u6 i
end
* Y% n! f& D% q' F2 j2 {' K5 ]
/ Q/ S. R6 N* J  K& b. E;; Initialize the global variables to appropriate values' Q) H& \7 o" F
to setup-globals+ `' h7 I0 m2 N3 q& m; s* e+ Z9 I3 j
  set current-light nobody ;; just for now, since there are no lights yet- r7 a6 c' m* a, Q5 K& U4 G9 j( k+ \
  set phase 0. O  X5 s) k" ~% K: w2 B
  set num-cars-stopped 0  m2 [, R( U$ ^9 l# O. x4 ^( H) V
  set grid-x-inc world-width / grid-size-x9 {/ ^; {6 |% i
  set grid-y-inc world-height / grid-size-y
2 j7 E7 O& C# }( ]; B# @! j, E2 s: [& }& G, A6 K% u. h
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary6 B, q2 V& [+ ^9 l' z1 Q
  set acceleration 0.0993 ^8 b4 |/ F/ Q
end
$ k8 H% G, J" O4 M9 i$ m3 o, v3 _4 ?2 L0 ?7 |
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
: ]+ a3 d" t" t% s1 D- K;; and initialize the traffic lights to one setting
. v+ N8 x6 E( j1 e( E. Zto setup-patches- f; o6 _/ _( k& U  |
  ;; initialize the patch-owned variables and color the patches to a base-color
/ {+ B' k" F, _6 Y  ask patches, @# B% e" M& ]
  [
! a/ \! W  Z9 O! W/ g    set intersection? false
/ f2 u' @1 B( ?3 C5 l# P! s    set auto? false
2 C7 o& q# c& ~. s( O    set green-light-up? true
: K" h9 a% J5 y" ?& l" `( Q    set my-row -1# y& r9 J8 t3 }/ y( I. n
    set my-column -1- O& m  W/ N! X$ t/ y/ I
    set my-phase -1
8 I2 v/ r! j' j7 A! m% `    set pcolor brown + 3
5 q% n- \! q9 B3 d$ I  ]7 [; u/ D' O( t& a' P  w% `

+ A  w% A! G& T8 K' _* \  ;; initialize the global variables that hold patch agentsets1 `& Z* N0 x% E) X  E. q
  set roads patches with
  ~9 {6 d& q8 Q+ L! D- S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) N( e- [$ V6 P5 N* ]. w; k: S5 A    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ K" I$ g6 k# O1 i7 F# T2 ]/ P2 \
  set intersections roads with. n7 {% V  f! [! ?2 q' K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
) _; n* e/ H4 w: z) a3 g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* ^1 T! m% ~2 r  Q
4 F& e5 K9 m- P; e* N$ W  ask roads [ set pcolor white ]$ O, ]) Z& j( b4 t# h
    setup-intersections0 f' V  \6 }' T3 C- a7 {6 U. U( |
end
0 |$ y( |' ]" [4 }! _# P其中定义道路的句子,如下所示,是什么意思啊?: X2 a5 }# G2 h6 \7 T$ z# v/ |
set roads patches with& f1 T! n. P9 `* M2 p5 ~: u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) C) b% q; Y& F/ q0 S2 j+ a+ i/ r, g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- X/ Z! c  \9 s  J; B3 L' 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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