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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。
* r0 b, F  l: lnetlogo自带的social science--traffic grid这一例子当中,& _% O% p& `4 a  P0 J. [
globals
3 m) H! f7 h: L9 h& {[
! }5 i6 A( x% j) L& S  grid-x-inc               ;; the amount of patches in between two roads in the x direction0 c* Q( x* a6 M
  grid-y-inc               ;; the amount of patches in between two roads in the y direction5 ^' f3 ]* N4 G" I# a% B
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if2 E; m; E" F- x/ v8 `* U$ N2 \7 ?0 m
                           ;; it is to accelerate or decelerate
) d) L( Y- D: D7 }+ ?  phase                    ;; keeps track of the phase4 n! \* r2 r1 {8 x. D. h6 c  a
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, J2 ]. A; Y) ?% V% I
  current-light            ;; the currently selected light9 N* V1 p+ @6 }! i& J& P
& o* i" d  Y: j! G' ~
  ;; patch agentsets
8 F) U" o" u5 V  intersections ;; agentset containing the patches that are intersections
, ~1 i7 v5 h: n- g9 u- T  roads         ;; agentset containing the patches that are roads
" @- {& K: h+ U. P]
5 M0 m6 N) a7 a$ |/ R- h
6 z7 p- [) u* ]5 R% Q8 nturtles-own
' I( L* u9 D4 }7 Y8 j[& ]  k& Q2 k, D" F* {
  speed     ;; the speed of the turtle
8 o/ I, d* x8 |2 Y  up-car?   ;; true if the turtle moves downwards and false if it moves to the right  Q+ o( _  q* M( p5 S
  wait-time ;; the amount of time since the last time a turtle has moved2 ^6 A: r4 q4 F% ^/ y3 Y/ m
]
  g- o, I- i3 A' O+ N9 Q! D  l
0 X! O0 q( \( i- S( n. `% `patches-own# f5 T) J' I/ d$ @
[
/ ~; G0 N1 u4 i6 x3 R  intersection?   ;; true if the patch is at the intersection of two roads
* w' H7 ~9 |( c( H2 N7 R/ F  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
- f  o" \) L: n                  ;; false for a non-intersection patches.
, K, Z* C# W+ u0 S$ T7 b2 q  my-row          ;; the row of the intersection counting from the upper left corner of the4 Q6 V" F- ]9 W$ v5 a& ^; Y* X
                  ;; world.  -1 for non-intersection patches.
% U, k, |; v& S$ ?( t7 R# a' V; }  my-column       ;; the column of the intersection counting from the upper left corner of the% d7 j' c2 i% j" x  T8 \1 V- g
                  ;; world.  -1 for non-intersection patches.
9 m# T9 x( z1 j/ V! `5 O8 P8 P% Z9 i8 G  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
1 `+ o2 D# Q  U" K4 g6 ?  auto?           ;; whether or not this intersection will switch automatically.
/ s. s  i  \7 D                  ;; false for non-intersection patches." ~+ W! ^7 \. A- t8 Q$ b& w, R
]: j4 r4 o; j8 X9 E

  v* `  ]: _4 F6 k3 [6 F8 Q5 w" G4 T. u% \
;;;;;;;;;;;;;;;;;;;;;;
* t- G. Z6 N  y7 r$ `;; Setup Procedures ;;
) M0 Q) B0 E' I: X;;;;;;;;;;;;;;;;;;;;;;
, H6 p- Y+ h$ |2 `1 ]9 b' @2 O# O2 {, N
;; Initialize the display by giving the global and patch variables initial values.
! p0 F$ u8 D( X% k2 @;; Create num-cars of turtles if there are enough road patches for one turtle to) }- H: o: P: W! o1 h, w8 S! V0 J& p6 A
;; be created per road patch. Set up the plots.; p( I8 d' I2 v! v$ C$ }' |
to setup
! t8 L/ v; @4 p! }. ]5 Z  ca' @+ M1 O4 i/ I3 L
  setup-globals, H% ?- }$ ^: E

3 ~" D. m+ z& p$ Q/ @# [. J  ;; First we ask the patches to draw themselves and set up a few variables
: ]4 t, o2 V- a! F) ?  setup-patches
6 a7 b+ t" P+ T) s  d4 u  make-current one-of intersections
) w4 e* d) O$ `  T1 B0 K  label-current  u9 V+ c; m0 X6 w' L  e5 b- `
3 D0 H4 I5 M% d
  set-default-shape turtles "car"  _) M, N8 x7 p8 {

; e6 G' P) N2 {8 I/ `  if (num-cars > count roads)
0 F- J0 m- b8 W3 p5 O8 u  [4 C" {  i# {. _" f
    user-message (word "There are too many cars for the amount of "
+ @5 Z4 [, x5 D  F5 C& n* [                       "road.  Either increase the amount of roads "
" M2 T% M9 M# `6 A                       "by increasing the GRID-SIZE-X or "
7 D3 a* R8 e. g2 P" Q                       "GRID-SIZE-Y sliders, or decrease the "
: N' ]5 q) m: ^3 j' j8 R                       "number of cars by lowering the NUMBER slider.\n"
( ]+ D& b- o/ g. q5 k                       "The setup has stopped.")! N1 \2 a% Z# P% c+ a; A' C
    stop& c% u! _( y: N1 w: c! m5 i
  ]
! x% O4 ]' R7 l0 P" `+ z$ z
* o# z  p$ w6 m2 r& u  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color9 f; H. v* R8 O, Q
  crt num-cars
* {( K1 V" P" ?$ o. o/ W% E  [
. `5 k( a, O% h# F$ C    setup-cars
5 r9 T3 L+ q, E3 ?) }% L    set-car-color
( u) p  j3 m. o4 m/ ~5 P* ?  h: k% u4 ]    record-data
3 d2 ?: n. ~4 A1 x" m( J5 o  ]
" H& T; O- l/ X) Q' D5 q0 l* v
1 Q7 r: w9 a: v. e' Q+ w( X& P  ;; give the turtles an initial speed1 M: B* x5 Y6 J, G/ g
  ask turtles [ set-car-speed ]$ Z' }& c, N. o+ ?( p; y' o" z# `) H9 q
, n' }. [& k/ R% q! |
  reset-ticks7 v; B7 i! B: i) C) W- ^  n- G/ I
end+ F8 t/ t/ c9 G) t: O

% n, Y- d  i, R' O' n8 ]8 };; Initialize the global variables to appropriate values
; p. e$ Q6 ^  Gto setup-globals9 J) L1 f( w) {, T2 `4 g, N
  set current-light nobody ;; just for now, since there are no lights yet
' M6 z% G! M$ X1 t  set phase 0
  l& {  Z/ I6 I  set num-cars-stopped 0
6 l% I. i8 t; l7 [$ l4 M  set grid-x-inc world-width / grid-size-x
+ H* Q9 B+ j1 K# Y3 i' A3 p  set grid-y-inc world-height / grid-size-y
( h& ]1 B9 ?; p* U5 j$ R: z
/ |# Y1 w6 d' W9 R, i  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary  f( n8 @9 |/ W) d! m. e2 a
  set acceleration 0.099
  ^! X0 M  y! T# N7 L' `7 ]end. ^" y) d  n- Z6 S

$ q4 d+ [5 c5 k% v5 C3 s2 I5 r;; Make the patches have appropriate colors, set up the roads and intersections agentsets,1 P& E5 f6 E* u7 d1 D& T# V. x
;; and initialize the traffic lights to one setting
7 E6 O/ j: R. v% M' _7 t8 g- Yto setup-patches: q) h" r  n3 {. ~
  ;; initialize the patch-owned variables and color the patches to a base-color1 Z3 {6 Q5 P, R9 G* @
  ask patches( q0 b" n+ G0 C2 T" v# Y7 o" Z
  [; V5 \4 I8 f2 g6 Z3 M
    set intersection? false
) N8 G8 Z. d8 D: X$ _4 N. q    set auto? false; E' }  g1 G/ V- r& l/ \
    set green-light-up? true
# G8 m: G0 E, P. `5 P    set my-row -1  O2 Q5 w3 Z' ~3 q1 F6 U+ @' E
    set my-column -1
; n7 J5 [9 A6 ^9 ~, O/ p    set my-phase -11 e: o9 N- _# m
    set pcolor brown + 3
0 |6 s& m9 \) c/ k  ]
. s9 F9 o+ i3 i4 J5 Q0 T/ ~" [, U
0 q/ ?$ j, N1 ]! P& r8 M! s  a% H  ;; initialize the global variables that hold patch agentsets
" a- b% r# s% Z# P6 i0 k. m, c- @  set roads patches with
! g; l( l  A& g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ s3 \5 ~* i/ }! X- P- u  w6 N* N0 \1 t, v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& f! r4 d7 |5 H7 ]' n  set intersections roads with
+ h4 X2 m1 `$ R, `1 z) ~( {9 ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and3 \$ j' o# h) s: ]
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, C2 p* G0 S6 ], ~8 r5 F- ^8 ^7 |& D1 K: g6 b2 s  P/ q
  ask roads [ set pcolor white ]1 z6 [+ `$ @9 S' J& x& {
    setup-intersections
. P0 l" }, [+ `& D7 T$ `/ ~end
2 ]) T# V$ t* C8 m$ R5 F其中定义道路的句子,如下所示,是什么意思啊?& q& p8 l6 _6 \1 {: }  D/ U/ H7 P
set roads patches with
! G1 v' [9 B' a/ T6 p  E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ Y7 v) E  H5 [5 U: w7 V
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. c' E- J- E6 v) [( F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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