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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。
0 D. U1 x; C& znetlogo自带的social science--traffic grid这一例子当中,
+ ~) P: j* A7 {, O8 J3 m$ Z$ _globals) z9 o& i; ?& l
[9 o  r' ]5 z& W0 M) f, P) x; _7 j
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
* G% e4 x1 ?) [: X- {9 z4 Y  ]  grid-y-inc               ;; the amount of patches in between two roads in the y direction
" Z' F) g) e; z; a, R% G1 C1 N5 X  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
& H9 E+ j# R& s0 Q" |& t' c& \                           ;; it is to accelerate or decelerate
$ a& Q* j, @% H  phase                    ;; keeps track of the phase
. b4 n/ X. ]8 G( y1 O  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure  E$ e/ g, G, V3 H- t, Z
  current-light            ;; the currently selected light
* K- L1 U# T/ `' Q& a' @$ N$ z% }- l, P4 [, u
  ;; patch agentsets
8 n) w6 G7 G! i" N( Y2 ^0 ?  intersections ;; agentset containing the patches that are intersections
# o; K' j3 }# Y/ _  roads         ;; agentset containing the patches that are roads
* B. C, k* q9 L* A]+ V; W* }, |! A0 Y
6 J: x$ b. k; f% @! n; c% }
turtles-own0 K( o/ [7 i# P% Y6 E8 e9 r
[9 s& Y" M- c9 ]8 w: ^9 |" Z
  speed     ;; the speed of the turtle
) M4 w1 {0 n" I; M  }, A1 w  up-car?   ;; true if the turtle moves downwards and false if it moves to the right2 y+ |4 M# k( l( }( U' `
  wait-time ;; the amount of time since the last time a turtle has moved
8 I5 M0 S5 W  b3 n4 o( G9 C/ o]
' H, J* ^' K: C( g% q" C
  n# ~. L% {  t8 B& T* c. R/ zpatches-own' r# s1 b/ O( N# y/ @/ Z/ u  a
[) Z( a7 n- y# W
  intersection?   ;; true if the patch is at the intersection of two roads
1 y7 ^2 [( B+ {1 d! e( n# u! z3 y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.! c( x! }. \$ a1 \5 g
                  ;; false for a non-intersection patches.
" ^& y) P' ^" @, b  my-row          ;; the row of the intersection counting from the upper left corner of the: P) D5 ^# ~4 \/ e
                  ;; world.  -1 for non-intersection patches.
& |5 t2 Y9 o0 a6 v9 N+ Z: G8 e1 f% z  my-column       ;; the column of the intersection counting from the upper left corner of the
" l0 c  f% u* B; A! X( c8 }& s3 b                  ;; world.  -1 for non-intersection patches.; o$ M3 ^2 Q' ]. p7 l  `
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% Z% ?: `2 A3 ^1 @8 M  R8 `& w  auto?           ;; whether or not this intersection will switch automatically.- D/ G- ~; L/ V' }" \( f
                  ;; false for non-intersection patches.% g. @( I7 j3 |5 y8 X0 }
]
/ t* r1 m! s+ h
4 v# J$ ?3 }$ d0 w3 ]( a2 H5 I
# Z0 c$ c+ H$ h. ^;;;;;;;;;;;;;;;;;;;;;;
9 z- S9 G  Y& f" R  Y% o5 z;; Setup Procedures ;;; f* ], U; V) g9 C
;;;;;;;;;;;;;;;;;;;;;;
! R2 T, J2 X. V1 j$ @1 \
* }" o/ H: s( B9 j2 ?. F$ [# c;; Initialize the display by giving the global and patch variables initial values.
0 Y2 w% u! ?6 F5 y( z( ]9 ];; Create num-cars of turtles if there are enough road patches for one turtle to6 D- H2 e, t7 Y! V
;; be created per road patch. Set up the plots.6 U/ }, e2 S, q8 u
to setup
2 v' O$ {2 \0 m; L  ca' y: g5 l( R: z( `( R
  setup-globals
6 @/ V: g2 i5 x* e# ^$ |) e6 X: m! P2 }
  ;; First we ask the patches to draw themselves and set up a few variables
$ t% f  x; Y$ m9 L  setup-patches% `8 U% n" u$ @5 Y% H* Q
  make-current one-of intersections
  y3 A: w, C! t  label-current; ~9 O! y, p7 L. S% E
  d! {% b0 L: K7 x' C# G7 E
  set-default-shape turtles "car"
% R( y, l- k. k3 F  F, _: U- T* A2 |
; k+ k# i) U! R+ t' [4 H$ s  if (num-cars > count roads)
$ f/ N+ M8 e6 T- F, @4 m  [3 D: k3 z* y& p
    user-message (word "There are too many cars for the amount of "
! w2 t$ u% q) q8 r' }                       "road.  Either increase the amount of roads ": E  z1 f4 B7 K9 |2 L& d
                       "by increasing the GRID-SIZE-X or "  t$ P- Y* i* v, Q4 J, \6 P- k
                       "GRID-SIZE-Y sliders, or decrease the ") R4 c0 N# p% T. C2 E, w& W
                       "number of cars by lowering the NUMBER slider.\n"7 j- a, _4 z" p9 i& n2 S& X
                       "The setup has stopped.")1 t# X& x/ X8 j: C$ k6 Q+ ~
    stop
" v- [7 N7 {9 O! P8 Z8 @  ]
1 o. B, I# Z2 E' j/ p; f  n# Y5 T: w
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color( [+ x& o, ~: c. b' o; A
  crt num-cars5 c3 B2 K, b+ o  A* c* A  P
  [
8 ^4 J) S+ ]; @9 W+ Z7 [    setup-cars
9 R; W. o) v5 S8 v9 y0 a    set-car-color$ |: a, c* a. R+ D6 |; \% {2 B# z
    record-data
- p! w" }8 c# {3 B% S  ]9 d2 {% w: Z2 _3 v- P

. O- a8 m$ q0 J% Y+ I  ;; give the turtles an initial speed
9 S: p1 g- F& V# k' s( i  ask turtles [ set-car-speed ]
+ d8 g( P$ `" c9 s
' N3 [! B3 J* Z2 w. ]7 C: {9 g  reset-ticks
9 e! J: I/ }% a* r* d' iend
" E8 E1 l* ?2 A( v) v1 i, \
3 {- p: J) @9 b( e! Z;; Initialize the global variables to appropriate values' P8 l/ a. y1 K' ~, n! {1 F; x# M
to setup-globals
5 W  R8 l: d2 Q: `  m; d7 j$ J/ ?  set current-light nobody ;; just for now, since there are no lights yet
0 r' M' c/ G0 q* v  set phase 0; G1 J, f. c9 ~+ h8 \* }" ?, O
  set num-cars-stopped 0
4 m5 e; ]$ y) V" k4 m7 }% o/ [  set grid-x-inc world-width / grid-size-x
( A1 O4 k0 k3 L  set grid-y-inc world-height / grid-size-y" {/ c# R8 X5 ]* y3 _7 X. B6 D

+ v$ X3 r) _  l- B. E# B+ _  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
& T2 c% y( E8 h7 L( S- ~& U  set acceleration 0.099
. l/ e  J  h0 j2 s. Z' @end  J" F  c2 q. @0 ~" e; w) }
1 [% c' b# V/ H7 [, f% I9 g6 P7 |
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
8 l: Q: E2 t6 {; e9 @;; and initialize the traffic lights to one setting
- [& m6 @, I7 X/ e$ Tto setup-patches" |) m$ p9 L  w+ }
  ;; initialize the patch-owned variables and color the patches to a base-color% T0 Z% y' H6 L/ Y. r; s2 \
  ask patches
6 l; m( [. R% a  J  [
1 C1 a+ `& p: D4 f    set intersection? false
1 j7 M* T' v9 U. h. i0 ~2 |2 d+ ~. E    set auto? false$ J0 [2 z  O. _  e' Z% i& z
    set green-light-up? true3 M0 s. v% M: N$ R( H; d5 @9 i: \
    set my-row -1* X$ A- W+ s3 a  L2 H
    set my-column -1
& P' L: k) \% |5 s$ r' k/ t* a' J& z    set my-phase -1! o) m" v, r2 L3 V9 H' m; c6 \
    set pcolor brown + 3. _% Y! c& o  t
  ]
8 P( f+ o1 i- T5 Q+ S- r( [" L# w, ~4 \  h3 C/ ^2 j
  ;; initialize the global variables that hold patch agentsets
( r, ?$ P( y# Q6 m! ?2 ^. K  set roads patches with
5 G( ?0 i6 r" B% R  n! A6 C; ?    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ F9 v( }- X/ l  w8 x6 f0 V) o9 {    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& E! ?) K) u1 P) y' ~4 c
  set intersections roads with
2 I6 x& |5 o# q1 P5 u# z# t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
* F- W' m, a2 V( W. ?    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 I3 u9 @* H  L) n
7 u! |/ w$ D: N; }9 v) M  ask roads [ set pcolor white ]
! N& A; k* R" a. K7 J" b, C    setup-intersections
% n. t' @2 w: C! aend6 Z6 ?6 Y: R; t1 N3 o. v4 R
其中定义道路的句子,如下所示,是什么意思啊?( u5 ]. h& K( _4 i& s# z" D
set roads patches with
! [4 `% K6 F+ h. M  v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- C9 @5 r) O3 \6 h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ ?& N& N/ B- Z# t8 T- ?# `0 q
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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