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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。$ A3 j3 S" L9 m1 Q
netlogo自带的social science--traffic grid这一例子当中,  f& S+ h5 w& v, `8 ^) ?
globals
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; D. H9 j. f2 N  grid-x-inc               ;; the amount of patches in between two roads in the x direction
( L: N) f& c: s5 c8 |  grid-y-inc               ;; the amount of patches in between two roads in the y direction- Q; `5 M, J. O# F' S
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* s6 ^$ n+ O1 Y( n
                           ;; it is to accelerate or decelerate
" Y2 x  g5 A8 M" L  phase                    ;; keeps track of the phase
- S" e6 p/ @4 W- z" F8 I: r  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
. }4 X, o- k6 o2 v  current-light            ;; the currently selected light: \# q4 |) K# @: `. y
2 \3 v' h. c1 D* i' o! C4 A
  ;; patch agentsets% j& B4 X# y( ^* C( T# a: z; A
  intersections ;; agentset containing the patches that are intersections
2 s2 O- i8 l1 D, L: N1 u9 n  roads         ;; agentset containing the patches that are roads8 k" l% u; l; L7 O( ]3 ^
]
% R& I: d: l' e9 V" z! }3 x" j
$ h8 i. a$ R' M+ K* N/ Gturtles-own0 [& V6 h4 d3 e
[( D) i- f; X& `6 U  j- Y
  speed     ;; the speed of the turtle7 s7 X. _, k/ C! Q) d6 Z2 ]& d4 Z
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, E# p8 d' j. T( |  r) ?' r) q
  wait-time ;; the amount of time since the last time a turtle has moved2 F- a0 e0 M! }+ f0 M
]
/ _" c. p# ^) I  s8 y
) u8 q( s: s+ I; `8 @& E0 l& Wpatches-own
7 R! A: J1 a' \- M: u9 I. v[
; ]# F+ Z" m$ ^9 Y0 i% z( V, z- g  intersection?   ;; true if the patch is at the intersection of two roads
4 a3 q) Q, v! `! e  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
, L4 a. m# P  {7 _                  ;; false for a non-intersection patches.$ U) @' q" b, p( P1 G' W
  my-row          ;; the row of the intersection counting from the upper left corner of the+ Z. U2 _8 s: l
                  ;; world.  -1 for non-intersection patches.( n9 _) x7 d9 @2 A, o
  my-column       ;; the column of the intersection counting from the upper left corner of the5 J0 T- ^8 \$ c7 J
                  ;; world.  -1 for non-intersection patches.; F& J- X. B' ~% m9 w5 F
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.+ F$ N7 P/ ~5 j9 x6 t  v) @
  auto?           ;; whether or not this intersection will switch automatically." `* v) D, |! |5 I7 h3 G6 k
                  ;; false for non-intersection patches.; G7 [7 k  Q% O: i0 A+ x( o9 x  j
]
0 H5 }) F. V  `# W- L7 d
4 z+ S2 P8 |% Q
) M% h6 N- F0 i$ I5 N;;;;;;;;;;;;;;;;;;;;;;
4 @1 X- r1 ~! o! R0 y- k;; Setup Procedures ;;/ W+ s, ~! x$ X; d- t. w
;;;;;;;;;;;;;;;;;;;;;;
$ |" g* [( m: p! M* C: i4 G
3 Q, n, E* Y6 R; {% i;; Initialize the display by giving the global and patch variables initial values.
9 ~9 t; q3 j8 p! Q;; Create num-cars of turtles if there are enough road patches for one turtle to. q2 k% V9 E+ a
;; be created per road patch. Set up the plots.
) s- x/ V) J1 P4 ^2 X! f# dto setup
4 `& l( w" R3 I+ ^2 V9 }  ca
1 \# d# A, q0 s* Z9 i8 Q  setup-globals8 Q! V; ?& |( @

# E* U9 U" i) D9 g4 o# ~! f  ;; First we ask the patches to draw themselves and set up a few variables
' l5 v, @  D; {  setup-patches
  ?, `+ _% Z1 `5 a" L  make-current one-of intersections
. i# n4 d  ?: {. }0 I" k- t8 b  label-current
* ~9 t3 Q# u4 C5 R* j. g- s
; O" k, ?4 |4 \1 G- r) J, ~2 ?, h% }  set-default-shape turtles "car"' C; a4 g8 V' J# T6 ]$ H) c1 l# Z* \2 l
) _$ |1 L" M8 t/ e- ^* l) i
  if (num-cars > count roads)
& S. c0 o: z# q8 ]4 j0 C  J  [
6 K9 X9 V/ u" R; a/ ]    user-message (word "There are too many cars for the amount of "
# T: b, d6 [: f/ B% x# `' Z# z8 j4 K                       "road.  Either increase the amount of roads "
1 b9 e  G5 ^1 _$ y                       "by increasing the GRID-SIZE-X or "1 k5 M6 ^. @$ E9 n9 |
                       "GRID-SIZE-Y sliders, or decrease the "5 w1 w8 S0 d7 m: ?8 L
                       "number of cars by lowering the NUMBER slider.\n"0 R/ l. h; A( h& v* Y
                       "The setup has stopped.")
2 ]3 e! |  T6 t; W" T: y1 T    stop3 s' s. ?3 W6 F6 M  `5 j1 t
  ]
3 b7 E. [. H* d
9 W: ^4 ]& Q3 `  [  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color  y% d2 D6 n% E# Z# t
  crt num-cars: a: M( q4 D4 S5 x9 E% t
  [  u% Q- p" M; V1 X
    setup-cars
5 P$ V, r9 S! _* Z  H    set-car-color; Z9 I5 r) Z; U. _+ A8 ]4 K
    record-data2 R' V7 l) M, k
  ]
5 p% n8 U1 G1 K" f; B0 X: B* ~5 B5 @  g
  ;; give the turtles an initial speed3 X6 `: k3 ?, r7 P, N6 g; n* u
  ask turtles [ set-car-speed ]9 f; Y; D2 N0 y+ q5 f& h
' G, g% ?8 G0 s. @
  reset-ticks
0 Y' o$ y8 i# `: U! _1 kend2 O3 M6 f+ R- F5 X1 n3 p* d
) B1 Y& g- P- i$ R) K8 i# w
;; Initialize the global variables to appropriate values! z) |3 S6 Q) _. P2 `
to setup-globals
' h% ~5 x9 H4 M& W# z! M4 K  set current-light nobody ;; just for now, since there are no lights yet7 z  r& ?/ Q# H6 {0 X/ G; ~- d
  set phase 03 B6 @" j( @1 j
  set num-cars-stopped 0' x7 `' V. q  r* ^% _) i+ d. r  H& Q
  set grid-x-inc world-width / grid-size-x
. q( V  Z4 C  g( F  set grid-y-inc world-height / grid-size-y& X& D5 P/ [, Q! L; c, ~
  T4 e/ a( v8 K3 Z) O. p+ @
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary9 E3 {  J1 Y% i! k2 n# ]5 O9 k0 ~# J, X
  set acceleration 0.099
) K/ _3 I# X5 G0 j5 Q% Zend
( v0 h5 |! w! p8 }4 k; ^* a6 w  N4 u# N1 X
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,3 E" ~) w- v; X
;; and initialize the traffic lights to one setting
; {% ]$ B0 O% ~- z( kto setup-patches' s9 k% F# a2 E- d9 D; ?3 O: H! }
  ;; initialize the patch-owned variables and color the patches to a base-color. w3 a* @5 G3 q* D, a4 D* [4 S9 y
  ask patches
/ H* E0 U' u" d! V9 ^8 L" B  [
  b+ i" ~, s& M( v1 K% D1 P' t    set intersection? false
# F4 W& h6 Q( b1 @# R! A    set auto? false
$ W- g* v7 N5 w, J    set green-light-up? true" x) `9 b+ \6 {. ?  f$ |8 p
    set my-row -1
" `2 V8 ]/ l6 k4 w6 K    set my-column -1
  N1 e, _5 }! E; U  e( y9 z    set my-phase -17 M2 ~5 k9 _. W
    set pcolor brown + 33 q" Z$ j. R/ x2 \: Q0 V* z! x
  ]/ X( R# @4 k/ D/ T0 m. g

! i7 t- M! x9 ~  ;; initialize the global variables that hold patch agentsets& M2 M) ~: R# _& Q
  set roads patches with
( u$ o6 L: i7 h- l" i/ z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& i, [! J3 h7 S0 i5 l/ o* r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 u' K# w, X1 z$ a: |  set intersections roads with7 b# R4 K$ e& h$ ~
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and2 m6 W/ [- f9 R1 i
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% ~% b( v7 c  o

  m5 @( }  m- }5 z  ask roads [ set pcolor white ]
" y6 l9 P1 {5 A- R* V9 p    setup-intersections
- Y7 A5 j# a0 A, \* B: eend7 B8 C8 F! g0 t3 h# L2 m
其中定义道路的句子,如下所示,是什么意思啊?: l: M9 z0 O/ z1 y+ h5 h9 [+ Y
set roads patches with# w0 ~5 J. U# A; {9 y( D& z6 }3 |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# E! X' s( D5 ?3 R# j4 R! \% r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; ]5 N) f4 a2 N8 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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