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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。9 i- e. I1 N; c: e7 Z
netlogo自带的social science--traffic grid这一例子当中,
9 [' N  D) j7 Sglobals
; H$ }. f/ [7 k' `8 d/ {[4 u  V+ o0 i* m3 I  _; L
  grid-x-inc               ;; the amount of patches in between two roads in the x direction# c4 l/ s0 _  Z" {2 G* |
  grid-y-inc               ;; the amount of patches in between two roads in the y direction; v" g4 C+ ~9 `9 O4 @8 K
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if; X) D, J; q8 z3 |6 K* g8 ~3 ~& ~
                           ;; it is to accelerate or decelerate
) K! X. k( K6 Z  phase                    ;; keeps track of the phase2 g" n/ ]; |1 I
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure5 a* F- R7 o- d, V9 U
  current-light            ;; the currently selected light
/ u9 d8 ?8 z" @5 b. X! @+ g) Q9 j- ~- }9 n) Z
  ;; patch agentsets
2 V4 T; w# t3 N6 x: e/ ~) Z, f  intersections ;; agentset containing the patches that are intersections! X8 T( I- o- i6 C+ j
  roads         ;; agentset containing the patches that are roads* e- w3 w- m" P3 z
]' u% J- Q. M% |; c1 J4 }

2 x6 g% R) y9 g! V+ q, G5 vturtles-own& [2 \  z7 E: s* x
[, E0 M+ Z8 G4 W3 q: n! J
  speed     ;; the speed of the turtle
% @' P; ?& j: D" p% {' u  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
2 R; c3 ?% ]& G% U  wait-time ;; the amount of time since the last time a turtle has moved5 q, _8 r3 z# Z* X
]
5 S' Q8 [( u, Q2 ]" A4 m  _+ _$ P& _6 ?/ u8 T
patches-own
" A; ^- C, U( {+ N5 g[7 \' m' @! S% Y" {) C" L9 p6 F
  intersection?   ;; true if the patch is at the intersection of two roads
/ I  `3 F# g/ t; G' |2 I  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% n" n! b; y/ p* t- g- w/ `                  ;; false for a non-intersection patches., F! \. H! L/ o. s0 W
  my-row          ;; the row of the intersection counting from the upper left corner of the* w/ j3 o+ f! c# K& ~, B9 {  j
                  ;; world.  -1 for non-intersection patches.
; w5 a" L; g1 A" X# x  my-column       ;; the column of the intersection counting from the upper left corner of the7 Q) s- p9 }; R# }% S. H& J
                  ;; world.  -1 for non-intersection patches.
- D7 `( S: s& g5 S5 O  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
1 ]- t3 w8 k: a* [( W+ m  auto?           ;; whether or not this intersection will switch automatically.
8 I% S3 a8 _) ]- O. q                  ;; false for non-intersection patches.6 _6 ~2 t: ^6 Q4 a
]; g7 O- V" g+ y; I  W
9 K7 ?3 O5 v: k! v1 s4 v; \7 Z8 Y
9 m2 p1 d$ g2 ]* m3 C/ P  ^" N
;;;;;;;;;;;;;;;;;;;;;;
* x. k1 E# a1 C$ e& j;; Setup Procedures ;;4 Y- B+ {( [' _7 @
;;;;;;;;;;;;;;;;;;;;;;: @+ I& e* g# t9 Z8 h8 c
! u+ I8 ?1 y) d8 _8 ^+ q6 g$ k
;; Initialize the display by giving the global and patch variables initial values.
* J4 v0 Y8 |6 J2 ?7 d3 j;; Create num-cars of turtles if there are enough road patches for one turtle to
6 {/ U7 _. ^* G& R! B;; be created per road patch. Set up the plots.
! H; O: f* R6 h1 Tto setup
& Q6 I  I6 ]: M: [: ^  ca* E; r1 w* n' A# R  _2 `* m# p/ ]; }
  setup-globals
. c% k% e( c" H% M! [; Q9 |3 f$ k4 H) E; w
  ;; First we ask the patches to draw themselves and set up a few variables
( T& o6 x" ?. _+ l& v1 o% I  setup-patches$ B0 d8 B0 I* r) Y
  make-current one-of intersections
' U& m( j% s8 m6 O  label-current0 D' m' M, b; E: h3 C8 i
9 @' S% D3 [* N# i+ y* `! J" L) r
  set-default-shape turtles "car"$ m+ p% w; H4 e1 L8 }: L/ ~9 _
3 K) O* ^  ~" w$ `
  if (num-cars > count roads)# ?  u: O, P& \; d( K* _# k
  [: P/ k5 {! ~; ]( C1 Y$ E0 e
    user-message (word "There are too many cars for the amount of "2 Y% {& S. f: {
                       "road.  Either increase the amount of roads "
. D0 C3 ~/ r$ |0 G                       "by increasing the GRID-SIZE-X or "/ U$ c$ R, Y8 c! M/ Z/ J  G
                       "GRID-SIZE-Y sliders, or decrease the "& S; y0 |8 f+ [* W. a) }2 h
                       "number of cars by lowering the NUMBER slider.\n"3 p. ?) T  ]4 F% s
                       "The setup has stopped.")
2 S# F$ ~. p* j, ]) H    stop
4 s4 X. W, ]5 Y  ]
# h- T: P) i2 x5 R
- \2 u' \+ o( e% G: j$ D  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color9 h: M8 Q2 a5 J5 w+ W  K! h( v
  crt num-cars4 n1 p0 ?! {* C8 }) K
  [+ U8 H- w, r) I7 A
    setup-cars" R3 u$ _$ [0 J5 D$ v+ L: e9 a; q
    set-car-color3 }. J" |% |+ S8 O* R! V# p
    record-data- Y  _' i! `7 f
  ]# f; V4 I5 H* I% ~
! g4 Y6 ]" K2 k& Y& k  F
  ;; give the turtles an initial speed0 A) x# s4 [: s/ l+ z
  ask turtles [ set-car-speed ], c- Z1 f9 t5 J* L& {

  {0 H6 k, [! @# d6 D  reset-ticks
" N5 w9 d$ b2 z6 q4 Y6 xend( D9 a: k! L! K# B5 ?

0 Q& U: Q. T$ K, [: {, h;; Initialize the global variables to appropriate values
" G- q) Z8 z, }to setup-globals
- a; L9 ~' y3 w' X7 [  set current-light nobody ;; just for now, since there are no lights yet
% M, d. R; i9 R  set phase 07 O' V& L1 d9 d% O1 P7 s' u
  set num-cars-stopped 0
( i8 d2 c7 y1 K, Q  set grid-x-inc world-width / grid-size-x* [7 b2 H# c8 x" i/ C
  set grid-y-inc world-height / grid-size-y* ^' i9 A: |8 C! K

3 `6 O0 D" ]* a6 V  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary1 w  E9 X# _, T+ ]: D9 A
  set acceleration 0.099: y# ^4 V- e4 B9 Z
end
/ [: z2 Z+ F) D4 l- a. c) E2 @4 a5 y7 u, v/ K+ R  V( n4 M
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# R+ J( P+ y( r( T9 h;; and initialize the traffic lights to one setting  l4 f& w% k7 f/ `* N
to setup-patches2 N6 a3 w& r* c6 M/ G# x0 S  p8 \  e
  ;; initialize the patch-owned variables and color the patches to a base-color. X% ?; t1 I( U" n# g1 h6 U- O
  ask patches
# J0 F. q/ [! h1 I) L+ X, s2 b0 ]  [" p4 V0 g; e6 {7 S  R; x2 `
    set intersection? false
; W0 H' H; h6 \2 _! F    set auto? false: {, |; |& H  v
    set green-light-up? true
3 o: l* ?+ N8 f    set my-row -1
. ]6 l( N8 r9 h/ }4 _    set my-column -1
+ m3 a& Q" M6 A5 |    set my-phase -1
5 y1 g/ B) L! B* R, U    set pcolor brown + 3
2 L/ {; q) z8 J, ?9 \: t2 Q; Z  ]9 I. m$ G- F* B' c9 a  K. C
1 [2 R' U9 O: M6 X1 t0 s% E
  ;; initialize the global variables that hold patch agentsets
+ m7 K) Q4 r0 w, m: w  set roads patches with' \" D8 s: W# Y! t3 X$ r6 r
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 i2 Z! I1 n2 A" n9 [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ h( ?+ e. S( o& W
  set intersections roads with$ Y- u9 j& w# e1 z% n" q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and- @- u- U" u! k8 w4 J4 G; ]
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 L; ~% d8 X& j! V
/ H; L9 `9 q( w  {1 d- ?  w  ask roads [ set pcolor white ]2 y) @: ?4 }$ [7 z: u
    setup-intersections! _1 V2 z$ l! z9 u9 j; B
end; c3 G. N+ D* Q+ X  F) S
其中定义道路的句子,如下所示,是什么意思啊?
5 V; I: |, C5 M( ^+ w) d set roads patches with# Q$ D5 A/ o  w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 t, Y" T' a  }* M# ]    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( c. W# X' Q/ e
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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