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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。
) x7 U  L2 W) N" V* P6 Z( x8 Wnetlogo自带的social science--traffic grid这一例子当中,
1 E: f. w) x( U" P) j) R. Iglobals. T7 w8 N) A2 i1 E6 u9 {' Q
[  l7 P+ [4 \: \& P
  grid-x-inc               ;; the amount of patches in between two roads in the x direction. U: P% Q3 T: w" b# E' f1 T9 h
  grid-y-inc               ;; the amount of patches in between two roads in the y direction* Z/ r. n3 l$ O/ I( ^) n# q- L
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
3 T7 M3 V; v% C7 [! l                           ;; it is to accelerate or decelerate
; m' i' |: w$ g0 N8 u  phase                    ;; keeps track of the phase+ @: v  S2 B# f, C7 z+ c( ]8 p
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
9 d' @3 T8 m6 ]7 ~2 u! v; c$ q  current-light            ;; the currently selected light
8 X- Q5 Z- a& K
# P+ k  D+ J# u; L  ;; patch agentsets+ ]+ V$ I1 P; M( e
  intersections ;; agentset containing the patches that are intersections3 {, \& v  g3 d8 H! _: d
  roads         ;; agentset containing the patches that are roads6 W8 Q2 c. F) A% z8 B/ A+ O
]  @% }' t) G: O$ H, `+ M7 }8 N
) ~% {) N& v6 j0 {; a
turtles-own
2 u! \$ |- V; N* h4 Q[
3 J. q8 T0 K$ a  speed     ;; the speed of the turtle* U' m0 o' _( e5 W3 P) O: _/ |
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
6 h% H6 w# J6 I& k- R  wait-time ;; the amount of time since the last time a turtle has moved& q# W* t1 V: u* w; q( L( t/ O
]( V& ^+ w" r, u1 b/ Q

( D9 L" e; [. `- Rpatches-own
# O, x; N- ]: i- z[
; a1 t4 v  j, Y  intersection?   ;; true if the patch is at the intersection of two roads: \' b% R: Q2 p: ~+ e4 E
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.$ Q$ U( t5 t& R" j$ Q. x
                  ;; false for a non-intersection patches.
; \5 H+ M0 [+ W% l. b  my-row          ;; the row of the intersection counting from the upper left corner of the
8 S% o9 S4 f. s1 ?7 j( {2 `$ u                  ;; world.  -1 for non-intersection patches.
# N& Q  Q' X: r0 R2 [7 d. W  my-column       ;; the column of the intersection counting from the upper left corner of the' B: f2 z5 K7 ?' c, C" _  [# N9 y
                  ;; world.  -1 for non-intersection patches.7 ^; k# o( R- [5 X. C6 c' F, C
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# D  u- }+ r* {( ~' R
  auto?           ;; whether or not this intersection will switch automatically.
; y( C3 r4 ^. B: _* S' a# l                  ;; false for non-intersection patches.: s# t3 F5 @- Q+ O( k9 r# }
]# e; M' D6 v9 @# D

/ p/ D; s: a5 v3 T- z/ m6 m6 h/ w3 h7 z
;;;;;;;;;;;;;;;;;;;;;;# u5 ]( P: E: \% }
;; Setup Procedures ;;
5 W" w8 r( ?* v) Z0 C/ a;;;;;;;;;;;;;;;;;;;;;;) u+ ~" f1 }2 d; M9 \8 m+ P

( k5 R  p5 @- R9 m) h;; Initialize the display by giving the global and patch variables initial values.
' w# K; I6 U+ B3 Z; W;; Create num-cars of turtles if there are enough road patches for one turtle to. G3 U# K) {: w: G
;; be created per road patch. Set up the plots.0 p  R) o  t' \- p- @
to setup7 I+ H* D2 i! J  Q+ M5 x! s
  ca6 Y0 R$ N. K$ N8 I1 b9 o
  setup-globals( B6 N& j% n* {$ w4 _6 M1 |
, L& P. Y  r1 U" S
  ;; First we ask the patches to draw themselves and set up a few variables$ X" n- |% H1 h+ q
  setup-patches8 U( ?/ A& a; S3 I' B$ G
  make-current one-of intersections! J- j. ^7 H; w- y- E* [2 c% G
  label-current/ }! m5 l/ `. v9 G% E
( h: Q+ R1 G. P
  set-default-shape turtles "car"; h8 [7 J1 N* B/ T
. p8 h0 ^; F! O# S! d7 R
  if (num-cars > count roads)
# t' |6 _7 f* z/ S. H  [) {/ o2 |; c8 K* _, a: s
    user-message (word "There are too many cars for the amount of "/ @* @9 E# u5 P/ W8 c+ K% B& n7 _
                       "road.  Either increase the amount of roads "
; l# \4 W# x/ h. ^* p  A                       "by increasing the GRID-SIZE-X or "
1 J) e- Y7 w! ]/ k2 S                       "GRID-SIZE-Y sliders, or decrease the "3 n$ \. ~, f% e* Z2 Q
                       "number of cars by lowering the NUMBER slider.\n"* x4 c/ u+ U. Y) y
                       "The setup has stopped.")  |6 d; {: l- S4 U  s* K
    stop0 A) R% ~* e6 j  Y0 ^8 @
  ]
. A& ~& }, z1 C+ _- X- \" D3 j2 Y9 J
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color& N/ q4 [. v* u& m: Q! Q
  crt num-cars
5 p" {* k1 s' G) U9 p* {  {& n: r0 D! ?  [
  b5 T* K1 S5 G1 m: R; M, ]9 v    setup-cars
) m7 R2 y& |) w6 n    set-car-color
' J" C, h/ W' n+ y0 G, D1 H, J5 ~7 x    record-data) G& G2 ?; H1 U4 z! n7 c: i
  ]- ]2 ]5 m& L; ^* Z

$ J- s7 P/ p, L: Q& w. M. Q- G  ;; give the turtles an initial speed4 Q, p" Z1 A2 M- Y. y
  ask turtles [ set-car-speed ]
& S2 ~# p) o1 S: ^
& z; g# ?* V, d' u. x+ _  reset-ticks  r7 ~0 _* o( h- Z1 }6 m
end, l) b& Y6 m& [. R# C4 u
8 t% }9 H" T! O( S9 ^7 W0 k3 Z0 ?3 S
;; Initialize the global variables to appropriate values
4 K" [" J! p6 Lto setup-globals
& N$ g4 k( }$ V" `$ u  z  set current-light nobody ;; just for now, since there are no lights yet
0 l2 S! k# }9 M- q: o7 Z$ s  set phase 06 ~0 H2 P2 p6 u0 B! ~- l7 e; J- E  d
  set num-cars-stopped 0
" n  Y. }0 y: n1 ^  set grid-x-inc world-width / grid-size-x" T. `+ a% C* ?3 n
  set grid-y-inc world-height / grid-size-y- ]1 Q2 L3 Y- N! R2 B; b* ~
" Z3 q1 v  B, a/ h5 u; d; w' y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary" h( q$ H. a" P4 `  e7 z
  set acceleration 0.0990 |; S# p6 r$ ^
end, ?: P8 t4 p/ n+ c  D$ l

, Q! E5 y. g9 D4 S, }1 a, U;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
( p2 F# @; u# x4 H4 G;; and initialize the traffic lights to one setting% ]% t: {8 [$ e, L. u
to setup-patches
4 B8 F' G# m2 n2 U5 q4 j  ;; initialize the patch-owned variables and color the patches to a base-color  W$ e/ v/ l1 v
  ask patches
4 F3 ?. X! ^/ C' w- ~3 x  [
, j' q# ]& U# W9 X, J    set intersection? false
/ L" t  U0 B' ^3 [6 p+ F    set auto? false
9 g0 K- q& }/ K4 K7 G  i) n    set green-light-up? true
/ A. Q+ n' j4 f2 z# Y" |* Z3 i    set my-row -1
+ ]* o9 q' ]8 A" @$ I4 L3 M+ P    set my-column -18 e4 `9 u. j( u( N
    set my-phase -15 r5 O4 ]7 g, O. b' o
    set pcolor brown + 3
5 j9 [! b6 `9 x4 n5 M2 i8 r  ]& A) B' O/ s- W& j1 N

4 Z& ^1 ~* G9 R# L: S  ;; initialize the global variables that hold patch agentsets
6 `* H" T2 d8 n7 s& b  set roads patches with
6 I4 m, x2 g& v4 q, I# ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 l7 N6 a- r3 G    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! k0 z+ E. e  }
  set intersections roads with
4 Y/ M+ R2 b4 }    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and3 s& _: J8 d) o- _; S! d+ l2 ]. C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) z$ R- @) O$ s( a9 Z' ^4 z
% c- Y9 a7 Q4 ?  O
  ask roads [ set pcolor white ]
1 Q8 i% P8 h+ G$ ]; g. J- e    setup-intersections
1 f4 ?3 w" w0 K  s7 r5 B! x3 d2 `end
- Y1 A6 q. ?4 W$ M其中定义道路的句子,如下所示,是什么意思啊?" }8 _0 A! C& O
set roads patches with
9 Q# G/ f0 ~  V* ]- J    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( @- k4 q- M/ o& l* b0 q5 I. z; P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  O7 U9 E  Q  G. f% B
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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