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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。* ]" m4 Y, [- ?/ m9 I
netlogo自带的social science--traffic grid这一例子当中,1 ]8 J& p& Y) I) e/ ^
globals
5 L* a9 K6 s( N) e; ]" H+ g* t[1 S2 a& V5 J% p1 b, l
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
& J4 S) e4 M5 L" o1 h/ x  grid-y-inc               ;; the amount of patches in between two roads in the y direction' j1 V& Y) \  w
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
0 r' ~: O2 ?$ ?# G; s( j                           ;; it is to accelerate or decelerate
( r( |+ e+ T( E% x+ k. k. p  phase                    ;; keeps track of the phase0 G, m. Y) ^; u
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
5 O: y" ?- E0 w; W+ @$ a9 m1 F  current-light            ;; the currently selected light
& w3 ?  O# g+ X2 {# I) p
8 m6 [" h  U4 c+ c- k: S  ;; patch agentsets5 ^; [- b% G5 y3 ^3 d& F( l- H! |
  intersections ;; agentset containing the patches that are intersections! M+ F3 H3 P9 b2 D3 r$ K" H
  roads         ;; agentset containing the patches that are roads
$ e* Y* E* a5 r/ m0 D2 M]
% A) x7 w* W8 u6 ]* f, @9 |: f
4 q7 u0 S  g2 B& Tturtles-own" S' I! f* f- B  N- w% N$ E
[6 u. Y& F: j! o( a5 I
  speed     ;; the speed of the turtle
- |+ }6 b" z) o/ h1 c  up-car?   ;; true if the turtle moves downwards and false if it moves to the right6 R6 U* h5 [# H1 u5 s$ d' |7 x
  wait-time ;; the amount of time since the last time a turtle has moved
( b- p8 `7 U1 m. M* \0 e' a' d]* u4 c! g( {$ z3 _
4 F; _7 S1 {, p9 L( K9 P/ f- G
patches-own
  i9 i( k' T# [6 r+ G( p, [[
! |* n" o  w  C' T) P  intersection?   ;; true if the patch is at the intersection of two roads) n8 y2 Z- z! L! E5 K: j, ?  i4 L9 @
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false./ E7 k  l+ k5 a- \
                  ;; false for a non-intersection patches.
. I, s: O: S) Q2 |- q+ t- E  my-row          ;; the row of the intersection counting from the upper left corner of the
7 R9 q+ X% f1 E3 s8 s$ D6 d                  ;; world.  -1 for non-intersection patches." b+ F/ F0 X9 S' Z
  my-column       ;; the column of the intersection counting from the upper left corner of the
! {$ t5 e. m/ P6 B/ ]5 A& ~4 R                  ;; world.  -1 for non-intersection patches.
$ R- L7 |2 y; ^6 H  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
9 @8 W$ F: X/ q- \9 a  auto?           ;; whether or not this intersection will switch automatically.
+ o/ N8 j$ H7 c$ n, L& |                  ;; false for non-intersection patches.
- ?: a5 `- T0 D! N]
) C5 X  e( X+ t9 V$ e
$ K; m# i! ^- ?) j# l6 Y: d$ ~2 S6 k! g- x1 a: a5 P5 h
;;;;;;;;;;;;;;;;;;;;;;4 @% H. a5 P, S5 m6 A, ~! r$ N
;; Setup Procedures ;;
) Z% R" ]- r8 D! O: e0 q;;;;;;;;;;;;;;;;;;;;;;3 `1 J& |$ O. L

) c) x$ e$ g% \- m1 x;; Initialize the display by giving the global and patch variables initial values.% _0 k* N+ o: P% L+ M+ ?  x7 R4 _
;; Create num-cars of turtles if there are enough road patches for one turtle to) C2 S% L  b* M. Y
;; be created per road patch. Set up the plots.& @: @$ o( d; h! f: ^$ ?
to setup
" @* o- m; K8 {  ca  U- q' _: t! I& c3 U* G# a
  setup-globals& u/ d8 p' R7 {' w

3 M; |6 K1 I. _5 f1 R( D- p) I: p  ;; First we ask the patches to draw themselves and set up a few variables
3 W* K; s0 _! Q  setup-patches
, m% g* D* r1 j9 k- I8 \" f. D2 G  make-current one-of intersections
( W8 S$ i: T6 b# N. S& u+ Y3 X  label-current
# a1 w3 k" Z, W* c# X
6 B' u: _3 y( K- ~' r$ [  set-default-shape turtles "car"
! G3 c! N' y0 F- `* \% z% Z! Q$ H1 N
  if (num-cars > count roads)
7 m' s+ R2 {* c) G/ G; S  [% _2 D5 Y, ^& q5 i0 A. p
    user-message (word "There are too many cars for the amount of "3 `/ A5 D8 j7 h0 @
                       "road.  Either increase the amount of roads "
4 ?; m/ L4 h& ^+ L. X8 D6 E                       "by increasing the GRID-SIZE-X or "
& V' L* C7 ]2 m* M$ q9 n- R0 b. Q' E                       "GRID-SIZE-Y sliders, or decrease the "
4 |' Q0 r, X; @2 e( x1 ~6 q5 Z! `                       "number of cars by lowering the NUMBER slider.\n"6 ^" r& [' d3 ]
                       "The setup has stopped.")9 Y+ @$ [1 Y5 w2 H
    stop
8 X% v9 a! J0 q% E- Y* |% G  ]/ J5 e7 k) `, L# l2 r
" y) c" ^+ P$ p9 {" C
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
) o8 ^( q/ l1 y  crt num-cars
( \) G* u4 D  l7 |  [- E* H3 s) R# j3 ]  B
    setup-cars' [, O9 _+ O  e  r$ x
    set-car-color+ @7 t! |. }8 }& I5 H. _- y
    record-data* k! i. H0 p1 K; D( H3 ~
  ]
, I0 w5 I. R9 G9 }% z
# x/ Z+ Q- y0 C  ;; give the turtles an initial speed
7 S+ t  a! S" h% V7 C1 n! F7 _! M  ask turtles [ set-car-speed ]
  c; ?0 a( l7 {( {4 d" Y* N+ I2 ]4 e+ G2 S
  reset-ticks: ~. A" a( R2 ]5 y* D
end' y7 [' t1 `+ f$ q$ v

! q% s+ l  U  t' L& d8 B;; Initialize the global variables to appropriate values1 o& ?5 s( m  f9 S) `8 t
to setup-globals
; Z* h' t, d* n- t  set current-light nobody ;; just for now, since there are no lights yet
4 t- L1 j" ]4 c* E  set phase 0
2 }; l1 l, R( F& Q3 B' s1 I  set num-cars-stopped 0) g2 S8 Y$ a9 U, E" H
  set grid-x-inc world-width / grid-size-x
3 I9 o3 `% X! D- Z  K  set grid-y-inc world-height / grid-size-y5 ^" m- N) ^4 ], f6 K; H

* ]9 ?& w/ Y6 t) g: y7 S5 R: z  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
, h# D1 _* u0 m6 ^  set acceleration 0.099- d7 a" T. S8 Z) x1 t
end
% p9 L- ^2 X- b' d8 d' b8 c$ m: K2 }, C; u& p/ ~
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,  O% v, ]9 f% e
;; and initialize the traffic lights to one setting: |0 l; x( O# Y3 _' z, V1 ?* s2 ~6 \
to setup-patches, b! G3 V5 ~% \' Q/ r6 K: W
  ;; initialize the patch-owned variables and color the patches to a base-color& C( g7 U2 k( _- n  {) J+ t
  ask patches& f  V6 P! q+ r. Z: W
  [
; L# z) @# {' i" X* I4 ]    set intersection? false9 `8 Y- i" x5 J/ k* q
    set auto? false
# S. c9 D* ?4 |    set green-light-up? true
; K3 e, x% [/ X$ v& z    set my-row -1
( M5 Y0 y  m3 D( y! X& W    set my-column -1
3 C. G9 O8 w, E  E2 q- ~& E' d5 L. {    set my-phase -1
) h( C1 h; g+ \: y0 ~& u: L    set pcolor brown + 30 X# R- B$ e7 H% {; r/ |! l  U$ P
  ]4 Q' m% @! U/ T/ ^, j" `8 `

2 V; x) \7 _8 V" M  ;; initialize the global variables that hold patch agentsets6 j0 c& d& L- C( Q  R
  set roads patches with
% d  r9 f: n) M/ T: p- S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& Z4 ?9 X) ^! H; Q* {6 r% X5 k1 \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 y1 k1 {  M" H( l' G; I- y
  set intersections roads with
% \$ R2 [% r$ V7 A5 \! V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and) {; m) M2 r: m& {& e/ h4 q# Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  h0 q. t9 K# _) I& b& F

% j4 {; A( I& M( J. g/ @" S  ask roads [ set pcolor white ]6 @. I1 \9 X/ k- `/ [
    setup-intersections3 t8 S: V, O6 A! m- a( ?& J7 h/ p
end
" E. d: Y5 H3 \; I7 W  A. L其中定义道路的句子,如下所示,是什么意思啊?
9 X( z9 C5 f0 o, J( o! c/ ^ set roads patches with+ l+ N! _6 X( z! y; J5 U+ B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" K4 D6 v8 u$ D; s- w8 K( C1 m, M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 d; b, v) e8 a# Z7 y+ {/ L6 r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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