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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。! p; U0 D5 W9 R& h1 h8 }
netlogo自带的social science--traffic grid这一例子当中,
, R1 r$ J& m/ yglobals; Y% c0 E5 @% F2 H* ~2 y& |. L
[
% \3 t" K9 P) |+ X3 T  grid-x-inc               ;; the amount of patches in between two roads in the x direction
0 I  Q, m# D% f' w  grid-y-inc               ;; the amount of patches in between two roads in the y direction3 X2 o/ E" N9 d5 f! _8 p/ X8 @
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if  E) S+ b1 w# m8 g+ L. c, V
                           ;; it is to accelerate or decelerate
* U1 ~+ H/ i2 D/ _( m; O  phase                    ;; keeps track of the phase
- a) k+ |3 g+ |8 s% T2 F1 P1 W  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure- D  t; o# Y; ]# G3 c  D
  current-light            ;; the currently selected light9 K7 \& o1 ]8 u. X$ f

% i, l4 p" Y9 _& k; r; G2 ~6 H( T) n  ;; patch agentsets3 a4 _* p! Q0 I. t
  intersections ;; agentset containing the patches that are intersections
8 F/ P9 T1 I+ x  roads         ;; agentset containing the patches that are roads
# c0 O  F& A6 l# D2 g]
; @) _3 B1 x! m# c( h
; I0 `; ?$ C* [; W% x1 Cturtles-own, _7 |; q. B  V0 x" Z2 m4 b
[) J& }7 P# C+ g8 ^4 M8 G
  speed     ;; the speed of the turtle
% x* T5 s# |4 F5 }  up-car?   ;; true if the turtle moves downwards and false if it moves to the right; A- s3 ]7 J: B" z4 }+ @) P
  wait-time ;; the amount of time since the last time a turtle has moved
/ _* w) K. a. C]
: E$ u3 S+ ^7 ^
" o. Z6 {. P7 c  d/ I) Q5 t% _patches-own# l$ z2 v* Y& Y$ ~7 S& \' q. I. x
[
: Z" D) L' `/ l3 y$ ~* O  intersection?   ;; true if the patch is at the intersection of two roads
6 c& y4 F4 Y' Q' X; u  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
7 o1 X7 q+ Z$ R, p: l2 l$ t                  ;; false for a non-intersection patches.; n. B  {; ?) m
  my-row          ;; the row of the intersection counting from the upper left corner of the. N6 h2 w% e2 F$ Q3 G& m& r. }
                  ;; world.  -1 for non-intersection patches./ F% a7 G  h; r8 J
  my-column       ;; the column of the intersection counting from the upper left corner of the
0 \" c: X. Z$ L8 Q% g9 K7 H, d0 G7 g                  ;; world.  -1 for non-intersection patches.' j8 _# l6 N* d
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
0 D/ T9 D7 {9 t  auto?           ;; whether or not this intersection will switch automatically.
6 ^: B5 j' o% R! ]: b* |                  ;; false for non-intersection patches.* t5 K4 Y+ u- A
]0 E9 d& d, F: Y) @8 l
$ [- ~, Y* c0 v  q0 {, Y1 X

# N* ^. i  ~/ B6 V1 `7 u;;;;;;;;;;;;;;;;;;;;;;. t+ G# z7 S4 n9 G! @& z2 m0 x* v* i
;; Setup Procedures ;;) @9 i' M0 |) |: U* ]
;;;;;;;;;;;;;;;;;;;;;;& K; j2 b; o: A
6 i, R: W9 Y' |  m
;; Initialize the display by giving the global and patch variables initial values.0 |" a8 s3 O  {/ k) o: z+ |
;; Create num-cars of turtles if there are enough road patches for one turtle to3 D) B# n7 L. |1 x
;; be created per road patch. Set up the plots.
- {& @: k. P2 q4 z9 m- tto setup
1 t& i0 F2 q# o$ Y" P  ca% x% Z: N, ~9 `  ~* E
  setup-globals2 D$ m7 s# q; d1 j

/ z: z: ^" T1 d% `9 z  ;; First we ask the patches to draw themselves and set up a few variables+ T  V! e/ f4 y0 j  z, X
  setup-patches
) k2 h+ Y, {1 c  make-current one-of intersections
: \! T% Y. v# F2 f  label-current
8 C% i# y$ |/ m6 J* T9 t: B, S" \. O! D  O7 f9 @- @
  set-default-shape turtles "car"
; r  y! J6 A2 _& L. q& I1 z, n2 s
9 H* x# f+ \- \. g  if (num-cars > count roads)" j, [% x; n4 f8 w% g/ z0 {3 ?
  [3 p* F* H' x+ L0 e+ v7 v5 l4 X- O6 S
    user-message (word "There are too many cars for the amount of "7 [8 K6 n7 v5 p+ O: V* a* P9 {: L4 I
                       "road.  Either increase the amount of roads "
7 O) c3 p4 w+ ~9 q0 U                       "by increasing the GRID-SIZE-X or "
9 O- p8 e. M/ X* O5 U% L( L- k1 J                       "GRID-SIZE-Y sliders, or decrease the ". R" @5 {! }% D; z  L
                       "number of cars by lowering the NUMBER slider.\n"
1 |' w* m9 O% D$ e8 n& N! F                       "The setup has stopped.")
3 i( P" g; ~6 n6 y% J' W( F0 G7 t$ t    stop
0 [6 q7 n. Z! F$ O7 z  s  ]
+ y6 V; L7 L# _" o& `; _
) U( c* o2 A% h6 @8 \+ D) f  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color# E$ ^7 Z$ q0 x; x
  crt num-cars
, T) w; G$ v4 d( k+ ~8 E9 B6 Y  [1 I* C1 s1 T& N6 D1 S
    setup-cars
% S* }- X; k" [( _    set-car-color9 H7 P; M( u1 o7 [" @/ l
    record-data
* E7 ~' l0 W# b: I* u' U  E  ]
5 {+ Y% @5 D8 `0 Z& j1 X9 `+ w3 b
; F; s* ~8 c1 w" y' j% k9 ?  ;; give the turtles an initial speed
, a  u' D5 ?/ u. S  ask turtles [ set-car-speed ]: S- W% F% \. `% t' h* {' j
# C% O. H$ Z. ^4 Z6 \+ l! j
  reset-ticks
/ I! b4 Q- T1 N5 O/ jend
/ E' j  r" k5 {0 |* X+ H
5 o6 y3 c5 u5 L# [1 a;; Initialize the global variables to appropriate values
- B) }( V: g8 E/ m7 |' xto setup-globals
  {3 k' n/ ]( A& F  set current-light nobody ;; just for now, since there are no lights yet; v* w# I) Z; g) v: r' E, G/ f
  set phase 0
% \* T7 A: O" I# T) D, U  [  set num-cars-stopped 09 P  L+ q3 d# {8 U
  set grid-x-inc world-width / grid-size-x
6 E2 w2 @' n1 t3 Q9 m4 e  set grid-y-inc world-height / grid-size-y
) B! R7 o; N2 T$ _' o1 j- _" J1 Q
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary. z# |3 S. T; A& s7 F3 @8 F( k
  set acceleration 0.099# h, h$ G/ ?% U5 I/ T2 k! ?/ N6 G
end
2 W+ k, [9 l% ?1 [8 w2 _7 x
2 n, J* J9 H1 I3 c& ]& K8 E! E;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# t# [3 h/ R. b# X;; and initialize the traffic lights to one setting+ c: |+ M# s3 h9 m
to setup-patches) k* @) y# U8 e7 Z' y# P  L" q  |  g& r7 N
  ;; initialize the patch-owned variables and color the patches to a base-color4 S# [" F$ _, [3 S# r1 }# y
  ask patches
  [& R* Z8 W' {, D6 X  [. F7 @' n4 I' L6 e+ h* W
    set intersection? false5 C' x3 E0 s, H5 V% f5 D, _, V
    set auto? false7 S6 n7 c9 n% a0 g
    set green-light-up? true/ \% s) u' x5 h) r; l- M
    set my-row -19 r1 a  I0 D- Q" r) N+ G3 G
    set my-column -1
  ^# p/ f; a: U: e    set my-phase -11 n4 n5 N0 x+ v- ~; \$ e! b- e3 ]
    set pcolor brown + 3
2 o1 x8 V8 X/ F& Y% l5 ^  ]
# Y" a/ v3 G8 x; Y9 }! ?! S9 r3 h7 u6 V6 `2 w+ m# {
  ;; initialize the global variables that hold patch agentsets& V3 }. G' Z) m) u2 k
  set roads patches with1 l+ B# l4 ^7 w+ k9 P  M6 N0 Y7 U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- |/ B2 M& V" H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 z7 A5 a# w0 ~" }) ]" ]/ n
  set intersections roads with
0 f5 n  E7 v7 x* Z6 O    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
/ @/ P8 @/ }% g$ n. a7 z5 ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* I0 U0 I; r& c* s
9 @9 `% u  H4 S& n
  ask roads [ set pcolor white ]
; f% T% q* e" \    setup-intersections
  L# }3 X/ Z6 Q& d4 [end/ L4 w5 R0 ?$ n# X8 E3 J* i' V
其中定义道路的句子,如下所示,是什么意思啊?# `$ U4 `7 [$ _% @5 Z% E, S
set roads patches with4 c' {1 z* ?3 G) o7 P0 Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 Y( z- K% [. G# e3 ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 h7 M  s! q: x
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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