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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。, {  p7 F% o" k+ U
netlogo自带的social science--traffic grid这一例子当中,
' h5 F" X+ ~4 c) S3 b/ Z! i5 Aglobals, P* G4 y. Z! C
[1 r+ I. f. u) R& [
  grid-x-inc               ;; the amount of patches in between two roads in the x direction/ d8 ^$ V* H$ I- |9 \6 x
  grid-y-inc               ;; the amount of patches in between two roads in the y direction( {" i7 Q+ E& z
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
9 ?# p# B4 p- R, O+ U% U% c                           ;; it is to accelerate or decelerate
& t( ]# H& d4 m( s, D4 u3 J  phase                    ;; keeps track of the phase* F6 ]& w+ o" V
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# t+ V; {0 X5 \$ Y2 B, A' x
  current-light            ;; the currently selected light7 o3 p6 Q6 z. e* Z7 a/ [. k

6 m0 F- O" P5 t2 r: }+ W0 C  ;; patch agentsets
7 T+ y, x, U3 p, W8 C  O: U  intersections ;; agentset containing the patches that are intersections
) Q. B+ D5 z1 @  roads         ;; agentset containing the patches that are roads7 ?6 H' e# Q6 \/ u
]
. H; x$ \$ @! P7 f. H0 v+ J3 _; f' M  E6 L8 t8 R9 R
turtles-own' C1 C* V& j% ?3 k7 V( f; Q
[
/ ~8 b* v# M  n; J8 D; P1 {; K  speed     ;; the speed of the turtle" @! ?  ?% I2 r1 s
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right  e$ ]# }: y. d  e
  wait-time ;; the amount of time since the last time a turtle has moved
- \3 D$ n  _. I) U0 z]
; }0 z& Y) Y" a; ^
! l7 Q! ~& n5 k6 M* {- I) s' @0 Cpatches-own2 V, ~) b% L* P! H% r& b3 W1 ^
[, A) X# ?( d4 _/ s
  intersection?   ;; true if the patch is at the intersection of two roads
! {. N1 N& x3 g  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.$ M( g) W( z9 }2 P  q
                  ;; false for a non-intersection patches.
' c0 O) [3 h  Z/ X( V7 q. F2 G  my-row          ;; the row of the intersection counting from the upper left corner of the
+ a3 X  x( ]7 u. \' Y                  ;; world.  -1 for non-intersection patches.
9 l) T8 e9 Q& \) C  my-column       ;; the column of the intersection counting from the upper left corner of the. u1 m' [2 r% ~2 U4 m5 p
                  ;; world.  -1 for non-intersection patches.
; r* n- t, p. T  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
* `  P; E4 d' C2 Q  auto?           ;; whether or not this intersection will switch automatically.5 v. D0 m$ v1 n2 c/ A6 i
                  ;; false for non-intersection patches.: w# _5 ^3 T5 K( y
]& _" h% v! i( \* X- x
+ \/ a& H  m7 I0 f/ W  ~

% k9 b) g8 w/ a; L& F;;;;;;;;;;;;;;;;;;;;;;
3 n) R' f( u: z2 z;; Setup Procedures ;;* Q+ R3 S. @5 w" U6 Q
;;;;;;;;;;;;;;;;;;;;;;
0 O0 R1 O2 n/ f* y5 q& o$ N- Z
( @, _7 g9 m% r$ @$ `;; Initialize the display by giving the global and patch variables initial values.
5 s( }) H8 o& k' Q9 j8 |  K. ];; Create num-cars of turtles if there are enough road patches for one turtle to8 H  a7 S2 _9 Z# w' p. ]4 ?( O
;; be created per road patch. Set up the plots.9 N( F' J* s. ]" q' U) ~3 m
to setup: O6 Q9 V8 x5 a* ?
  ca
1 l0 H1 M* Q+ d/ W5 w  setup-globals
( c; ^# U. a6 c. H* n8 `$ M) ]* ]/ T1 j' `7 {) v2 t1 J
  ;; First we ask the patches to draw themselves and set up a few variables7 o) |5 J( D" D: r- M. J2 Z9 @
  setup-patches
( R. g) f+ R2 c) \  make-current one-of intersections: o1 i7 Z! w5 ^1 \, j
  label-current5 F0 T; r/ P' a6 O/ E

1 r' `2 v8 \* H9 O) A* W' Y  set-default-shape turtles "car"5 v$ |. u; h: @& c( U0 f6 K7 d

8 j; i: u- M/ n8 R7 v0 P' v; }  if (num-cars > count roads)
, O4 Q9 F% x7 Y% R  [% n" W8 y* w2 @* v" s
    user-message (word "There are too many cars for the amount of "
8 V' H' _3 f* @# ~                       "road.  Either increase the amount of roads ": P( @  o1 q, I# k0 m
                       "by increasing the GRID-SIZE-X or "
& a6 l8 _( D7 x, b                       "GRID-SIZE-Y sliders, or decrease the "
5 ^3 D' d% d3 r' N; r* c3 U                       "number of cars by lowering the NUMBER slider.\n"
# j* [: S( y, m" }% ]/ _                       "The setup has stopped.")
3 `5 `) s3 L- l- m4 e5 Y( e) w# [    stop" v; n2 r7 C5 J' D
  ]
& Q% Y8 H  t) J* g3 N8 ^" E
4 i+ @- D" `1 N, O9 G  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color' A" g' }4 h+ W/ `, U, M+ [' I1 {
  crt num-cars
' f! H) l; z  F+ }  [  p4 A, j2 q/ x* Z# l
    setup-cars6 @9 s) W; h& F! _5 `
    set-car-color
* o$ W; j  S2 b* r' _    record-data
1 p) @  {  U* l' I1 {4 Z  ]
! t; @$ t/ j+ r* F7 }- E% z2 }0 l8 @; ^7 r9 H
  ;; give the turtles an initial speed1 F: |, J6 Y/ {( n) v# d2 M
  ask turtles [ set-car-speed ]
6 a1 h. }0 ^" [& W1 w7 w% `6 u- O1 J5 U
  reset-ticks/ t0 a2 |+ H7 R# M* \
end; ?3 P$ x: V5 c1 ~. t2 J
% [6 x/ g9 Q$ H6 c# U
;; Initialize the global variables to appropriate values/ p" y4 I$ w4 ~5 P) d# b% u
to setup-globals
$ w8 V* I* n+ P* ^  set current-light nobody ;; just for now, since there are no lights yet$ x, R( _1 Y) _, m
  set phase 02 o- n* c) G: i! \
  set num-cars-stopped 0
& @+ h' v* b" ~; e; `' W, Z  r  set grid-x-inc world-width / grid-size-x" C1 g: @7 f- \' \0 g, I" S/ z
  set grid-y-inc world-height / grid-size-y
& Q% a( N& T3 y! H
' }% s1 y! g4 U5 _( s9 V0 |; p6 C  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
: Y0 }3 N+ u$ P  set acceleration 0.099
9 x8 O0 k) W% N& u" r% Vend, {$ x& L* {0 W& }# g* B6 l' h
+ P8 R: j4 U7 r# D% f6 e
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,5 `4 b6 c3 t% k* |. r
;; and initialize the traffic lights to one setting' f; X0 F  k' {. V( W
to setup-patches
, @$ d7 Z4 D8 `: w  ;; initialize the patch-owned variables and color the patches to a base-color: _8 y+ x! [  R( b$ L% T1 u7 u
  ask patches. V9 s/ g5 v- a' j% `1 ^
  [1 ?6 C, U  i7 z! U0 b& @
    set intersection? false
) c+ B6 P1 G/ a, W; f! Y    set auto? false
2 s5 o; \1 x2 [9 N7 a; ^    set green-light-up? true
/ L4 s& G/ g6 D* [1 A6 _1 N0 _! @    set my-row -1
  n) M7 ]% n  [8 R% D    set my-column -1
1 O9 \$ X& b0 q/ H! Y. G" [4 `    set my-phase -1
: X. j5 o" K" _    set pcolor brown + 30 K" }: [# q# m4 ~) A0 k5 [1 ~
  ]  ^/ |9 X6 ^1 N) F2 t

2 P5 z: |9 k, C+ e, T+ [  ;; initialize the global variables that hold patch agentsets2 o* ], p0 e- q$ n. y
  set roads patches with  m* {% Y1 G$ X4 J6 R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  V8 w/ U2 w  z# @5 P/ w
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 e6 g' b3 X; \5 ~  Z$ ~9 ^  set intersections roads with! R; w: M, z. K* l- R  o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and% s6 I) U  k8 o  w/ t  Q6 m0 G% M$ {
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 ]5 J% r- _* a* U% \
) {7 o, G: s! A0 _- S: z, L1 {2 E8 g  ask roads [ set pcolor white ]
. t' M# q4 |, H    setup-intersections
2 h% w* u$ A. ]  Fend# m( o( ^; K. w* ^4 r+ x* @
其中定义道路的句子,如下所示,是什么意思啊?; I& n7 w% @( l, [2 [5 ]
set roads patches with+ V6 I1 L. b( h6 V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 L3 X" v& f, c. T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( y, G* S" a, e/ ], S" v+ }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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