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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。+ |$ F) C5 ~3 d; V1 y
netlogo自带的social science--traffic grid这一例子当中,
/ [- @7 E9 g) J  B6 `0 P- e* x( oglobals% R. z) T) I' }( l4 V( _
[
* c5 }& n2 W4 w  grid-x-inc               ;; the amount of patches in between two roads in the x direction
4 \8 x5 o7 ]$ Q( q& [  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) ^# K5 e" k& M# P0 h0 ]  @# `  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
: g' f" R# F3 h  `3 V2 w                           ;; it is to accelerate or decelerate
7 T+ _" l' P# i. U  phase                    ;; keeps track of the phase
1 @* a1 N) K. W7 @" N: e% O. n  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure5 J* R3 F' `2 C
  current-light            ;; the currently selected light" q# m1 l. Y3 \
, M" X# H; D) p% Q7 H& P$ N: X# n3 v
  ;; patch agentsets) `5 }- \' d  P" C- y3 G
  intersections ;; agentset containing the patches that are intersections( R2 O3 Q* z7 s6 u. d
  roads         ;; agentset containing the patches that are roads+ Q8 s6 ]; s* K3 g
]5 w( @+ G5 E0 U0 V! W* O/ M

( `6 K' ]* `3 k- rturtles-own
/ D0 E3 ~4 h$ ^( D8 D  k' `# Y[. B' Y' x( w6 w' \2 Q" B* N6 k
  speed     ;; the speed of the turtle
& {6 E8 K' |4 V  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 x2 ], h/ v6 N  C% z3 L
  wait-time ;; the amount of time since the last time a turtle has moved
% @# X9 Y3 ]( [" \5 G8 D" C0 z) _]! {# f4 R9 V4 I$ F4 |- G
9 M2 {: L9 k* y
patches-own$ R. G. _1 s) _
[8 e9 I: I( Y1 A0 M1 s) t  r- P
  intersection?   ;; true if the patch is at the intersection of two roads' e6 T. Z4 h/ X1 r  t
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( k, h) N" `8 l+ g1 S( ?1 `                  ;; false for a non-intersection patches.  Z. j6 Q( a& ]  L* D" B+ t' w- M9 @
  my-row          ;; the row of the intersection counting from the upper left corner of the
$ m" o  M6 z! `: w3 \1 c- E! k                  ;; world.  -1 for non-intersection patches.
# _2 f. t) C& j* B  my-column       ;; the column of the intersection counting from the upper left corner of the$ Y3 ]( d$ }' J, P
                  ;; world.  -1 for non-intersection patches.
* g, h% Z$ L  u, j+ B( `( m  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 ]  t9 t$ I" ^3 e, K0 K7 _* C
  auto?           ;; whether or not this intersection will switch automatically.! q3 Z4 t5 T3 l, d1 O3 E
                  ;; false for non-intersection patches.
7 }- t% \0 q; k7 o% \]/ c2 m' o+ n9 W! f* L8 r5 {

5 v! I6 {! U( O" f2 w# m& ]' ?6 }, W  q4 b
( i5 F2 N( j2 d! R! u% G0 q;;;;;;;;;;;;;;;;;;;;;;
: Y. ?# D4 t9 C) C;; Setup Procedures ;;
& K, G' ?) Q4 O- n- Y;;;;;;;;;;;;;;;;;;;;;;1 \' j) p) j) J$ |5 k

7 |  _; R3 ]1 t+ B6 B;; Initialize the display by giving the global and patch variables initial values.
# P8 I& i2 |4 D0 ]3 Y, {$ P;; Create num-cars of turtles if there are enough road patches for one turtle to" D+ e' v( C8 P2 D4 v9 s; F
;; be created per road patch. Set up the plots.
7 @- _& p6 F8 c, ^to setup
2 L; V/ z' h; K6 ]  ca
" q9 ~+ d" U* m. U! V; X' z  setup-globals
& x4 a8 p2 B3 j# O2 U' w  r0 q9 V* ], u' M" Y; p3 B( m( A3 t5 r
  ;; First we ask the patches to draw themselves and set up a few variables
8 v2 t7 [- W6 o5 Z  setup-patches
) {! U2 ]7 T# T, o+ S  make-current one-of intersections
. J. N$ J; f+ d) p9 W5 g  label-current8 m! v+ B1 n) K

) B" V, D+ K" I# L( I  set-default-shape turtles "car"
3 d. n2 Q+ [* A3 k+ x1 B
/ z# {, Z2 W% p  if (num-cars > count roads)
$ Y; A' a' Z- P) \. v  Q  [4 n) h9 @6 r6 J( N4 h4 b) k6 e
    user-message (word "There are too many cars for the amount of "
& E2 {* i4 J8 E2 T9 O$ t                       "road.  Either increase the amount of roads "* p$ R3 M, G  V9 L
                       "by increasing the GRID-SIZE-X or "
0 z4 z. D3 l  H# R                       "GRID-SIZE-Y sliders, or decrease the "2 \8 h. A( _( Y+ i
                       "number of cars by lowering the NUMBER slider.\n"
8 u3 ^, }$ `; n6 n( O0 X                       "The setup has stopped.")
# @$ {* O& |' J8 n3 ~& V+ Z    stop
7 l2 U' @% O. u  x6 q  ]
# o: l5 R' a0 b5 P" a* n9 ~6 x3 v$ Z5 L8 p
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
3 E, f! Y, i9 j/ ~  crt num-cars
0 A6 t' O  k6 x/ `5 t! B0 l  [
4 R1 e% r( B) G# \    setup-cars6 k" S  E9 s- Z4 ^
    set-car-color6 M$ ]" D9 X" `2 \) H2 r2 c6 S
    record-data+ U3 F1 a4 i0 Z4 G: S5 ?
  ]
3 a& X6 d% M1 H0 C; b8 b, C# }6 f$ S0 H7 Q& i
  ;; give the turtles an initial speed5 W. v8 U$ ^* r$ S. W
  ask turtles [ set-car-speed ]
2 [2 Y' q6 J$ ]5 x8 c0 k7 f0 s8 ]; W! A/ C( g  A) A% i" c
  reset-ticks7 T' }+ C4 Z$ p
end5 `# [$ w% H) d4 @5 |

/ p! B! H! f+ o! ?) E;; Initialize the global variables to appropriate values! w  P( K* u0 p$ K! r
to setup-globals; v* h" e' r) }3 Z  {
  set current-light nobody ;; just for now, since there are no lights yet" ]. g$ f: p- y4 }
  set phase 0
- j+ _$ ~; ]- l" l  set num-cars-stopped 06 H2 a1 j. P+ a# {
  set grid-x-inc world-width / grid-size-x, d7 Q' r, [$ H2 Z6 g- ~
  set grid-y-inc world-height / grid-size-y% @. R4 w+ ?! P" V. k8 W' H& i" E
" A7 Z0 a4 l+ A6 J1 H  a
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 z3 l& a6 V; m! {  U: ]: f/ i: |
  set acceleration 0.099. X* g: N$ |4 w, M7 r
end) H! c: Y% ?8 G; v0 w6 D: n  m

- F3 O9 J' a6 V# M5 h;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
; x+ A( A5 z: I9 W8 o;; and initialize the traffic lights to one setting% k% \/ z. S1 K  l* H
to setup-patches3 R+ Z+ [+ o/ @
  ;; initialize the patch-owned variables and color the patches to a base-color
) e3 L1 w4 o! N. `& o6 m! H  ask patches
6 x; A* L: p* H& l* M  [+ v  s' M( z, e7 U  S
    set intersection? false
8 _% `, J5 [, @    set auto? false: y5 u' ~4 \* Z8 C. E* Z6 g
    set green-light-up? true
* Z% k) n0 x+ A* F7 t    set my-row -1
! w( B. A. r; j  \    set my-column -12 D- W" W" G  c2 {" Z8 d/ @
    set my-phase -1
# {: E- X# q* C( f3 o+ o% U3 @; L    set pcolor brown + 3
4 t$ J7 K) e+ j0 S2 {  ]
$ N% U" D8 C; a
2 {, b+ e6 a& l4 K: A/ ?+ L4 H  ;; initialize the global variables that hold patch agentsets
: p* C5 S  g5 I# D4 h5 z% M  set roads patches with4 z' E& h% r& u- a, v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 D( A/ s! j4 ?6 B
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) i- {, O2 ^+ @; v& O
  set intersections roads with
( {# Z* N7 G3 i2 I$ p2 Q' _& m% c1 _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and4 w. g1 o2 D+ n, q* G0 V
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 H$ f- |/ c2 s6 ~3 e
' l- Z6 h" z" [- X3 T
  ask roads [ set pcolor white ]
3 g6 l7 H; L# i' P) L( c/ F& \; v    setup-intersections4 p; Y& k0 M2 |2 c
end
4 f# h" J8 s6 z4 ~& y8 d+ ~5 P其中定义道路的句子,如下所示,是什么意思啊?
, f2 i+ a) L- l- }3 r( v; Y set roads patches with
) O1 q, d5 R, K9 v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 g' t- H- d: C8 }9 S7 R2 h8 |
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 W* P+ x' P* o1 r0 y* T5 }
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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