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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。
9 {( @& [& i" R5 B7 c( gnetlogo自带的social science--traffic grid这一例子当中,
2 F  m( O/ [6 B$ @8 z$ Zglobals) O) a+ z# D" L3 S$ v( b/ t( ~- s1 [, [
[2 F- }0 Q; |5 \, p5 c
  grid-x-inc               ;; the amount of patches in between two roads in the x direction8 p' \7 }! W% _9 R+ \& i
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
$ i) U$ U7 n7 G& i; K7 m* ], j  acceleration             ;; the constant that controls how much a car speeds up or slows down by if# y" _. G; a) F/ s, U0 f- g
                           ;; it is to accelerate or decelerate
5 B5 v$ |( K# L+ ^3 _4 E  phase                    ;; keeps track of the phase
& Q) E8 ^  E. _5 C4 S  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
& ~! o5 P- T% m: B/ b2 o2 R$ H6 H  current-light            ;; the currently selected light
% g2 g: D: w; j6 V, b4 i+ |
6 I# z- B( T8 R  r0 Y  ;; patch agentsets
7 I0 v& r: {1 O. e+ v  intersections ;; agentset containing the patches that are intersections3 T0 ^  c3 J2 a( Q
  roads         ;; agentset containing the patches that are roads
" V8 J" [# U$ [+ v& N8 H]: Z- O+ d1 p0 b1 g6 I

+ k' j$ o( X* ?& I8 k1 {turtles-own3 d4 V! d6 ~9 V- Z
[
% t/ \9 v& p6 h6 i  speed     ;; the speed of the turtle
+ g% _' P! F$ z. @6 d  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
; b9 Y- y# Z6 k" y; \6 ?  wait-time ;; the amount of time since the last time a turtle has moved
* T$ r/ E) q+ K) ]3 j" l]. |; K/ a$ H! Q. Z( v9 w( z

' l0 @9 b1 D2 zpatches-own
& ?5 ~( ~0 J! s2 K, {[* E. I% g1 I. }. t3 c8 z
  intersection?   ;; true if the patch is at the intersection of two roads
8 _6 m7 t" A, J( o, |, b; R  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.% b$ d5 O4 @4 ?9 H# s+ R' J
                  ;; false for a non-intersection patches.# ~( S0 w% j. x2 t5 x
  my-row          ;; the row of the intersection counting from the upper left corner of the. {; |8 b( p$ _" k+ N( ]
                  ;; world.  -1 for non-intersection patches.$ z, i  v* N' z$ Z2 u* y! R
  my-column       ;; the column of the intersection counting from the upper left corner of the5 H4 p2 z6 M- J& p& G; r$ s3 Y
                  ;; world.  -1 for non-intersection patches.6 _+ H' W9 p& W+ C' y: f3 I
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches." q2 ]' F+ W! H1 j7 ?1 o5 B
  auto?           ;; whether or not this intersection will switch automatically.
1 v5 ]  P( I3 i. W# j                  ;; false for non-intersection patches.8 U3 z+ I9 M' s/ g
]
0 c$ A. ^; l1 l9 I# N7 G+ O0 M9 C7 i5 n, {5 C
- E: _# N! P0 l* k" v4 e- i7 k
;;;;;;;;;;;;;;;;;;;;;;
* I7 z5 ^8 }) x+ K8 _1 j9 A;; Setup Procedures ;;0 [& y* t) `) k4 G/ ~% i
;;;;;;;;;;;;;;;;;;;;;;3 s" w. A, ]; V9 ^: X. A2 T5 V
0 I2 v0 U+ a( g% @) U
;; Initialize the display by giving the global and patch variables initial values.
, H. u: a: n, |% H6 R9 O* D+ }; V9 Q;; Create num-cars of turtles if there are enough road patches for one turtle to
+ n+ e: {- M% m6 s8 U6 p;; be created per road patch. Set up the plots.
/ C' B( |4 @& c2 h& ~+ B9 K7 |! lto setup% l$ L* E. E* |: V
  ca
* ?% d9 j- W* p7 \) k  setup-globals
6 c/ \+ G1 P: n) k  Q) |9 H* ^4 B/ S0 ?
  ;; First we ask the patches to draw themselves and set up a few variables8 ?& I3 E3 Z, d4 D
  setup-patches
2 _- D0 J! H% b8 n( D  make-current one-of intersections: }( Z6 r" L6 Z5 J& f) O
  label-current
+ B/ g" Y" m) V0 d+ x# T; d2 ~, H: `2 z$ A$ c: o. u& g. z* D0 k
  set-default-shape turtles "car"
. c$ I' N7 @2 t' g. x2 ?- W4 C$ l: Y4 l
  if (num-cars > count roads)
& t5 _% [7 z7 T" P0 B  [
, R) p' o% V+ d7 m% e! z    user-message (word "There are too many cars for the amount of "5 R5 o) z& {# }3 p
                       "road.  Either increase the amount of roads "
7 d  l% w) {* U" x8 {! a                       "by increasing the GRID-SIZE-X or ". z& E+ L. a" p' o8 _7 ]
                       "GRID-SIZE-Y sliders, or decrease the "; Q2 k  ]. r/ [
                       "number of cars by lowering the NUMBER slider.\n"- P) h6 u4 R5 K) e- ]
                       "The setup has stopped.")# D8 S- K' a! `6 L& d3 f: y
    stop
/ o4 g5 X7 J) }  ]
' E& P# X. s! f2 p7 k
1 X3 k; t% n$ ~. R& J  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' x( z+ x) W0 H4 I: }9 n% }! k, v- J- v  crt num-cars5 p2 N8 x; t0 j" s
  [# P- e* t4 G" s- {% e* |
    setup-cars
7 c0 z! \0 m- `/ G( m/ `! |    set-car-color
# `5 I2 A1 u' }* l% E! N2 T3 Z    record-data( K/ U  A  |, p$ x3 @- P+ G! Z4 t" z3 _
  ]
& R5 B; J$ p- ?& L' g: y; b
9 Q5 p: q1 a! d, u  ;; give the turtles an initial speed
! ~: K) [' ^  D# O, @: n* O) [  ask turtles [ set-car-speed ]% ]3 \- p# B( ~
* @6 n' `- S  B5 K4 W' Z) l+ t
  reset-ticks; [: e) t7 G+ ^6 I3 Z9 L
end
3 q! F/ g; |8 e* ~, L1 F8 }9 E. Y& M
; ]. p  N' G: r' ]0 G2 s% Q% S;; Initialize the global variables to appropriate values2 i8 }5 @* v4 l( y
to setup-globals' S" D& l6 d7 t" k5 t8 f
  set current-light nobody ;; just for now, since there are no lights yet
9 y' K5 ^: N7 P1 v; ~  set phase 0
+ Q4 i% G2 {( R' m6 K2 g  set num-cars-stopped 0& U3 U9 ~8 ?/ M5 V; p) {
  set grid-x-inc world-width / grid-size-x
9 N  x" o4 `& `# E* l( \! T  set grid-y-inc world-height / grid-size-y0 |" x3 }! G2 O8 Y1 b5 g
+ _1 _/ ^9 R8 ?
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
( L# D/ Y  p4 v$ _1 s$ j5 o% s  set acceleration 0.099$ g! b' X+ }0 m, \; {
end
  [% S- a9 E0 h' _' {  t9 H9 h* ~- j0 X0 d+ Y1 q
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,2 B- L" O. v. \& u0 x& H  ]1 ^# P  [
;; and initialize the traffic lights to one setting
9 R& M9 ?% A* z, z8 f9 Nto setup-patches- @- Z0 V" u+ N! }7 \/ s
  ;; initialize the patch-owned variables and color the patches to a base-color
8 Q6 ?% g% D4 x0 X  ask patches
+ m) `' ]$ D( u2 a  r2 M% W/ x  [
; {5 n. u( {  I  P    set intersection? false  h* m4 W% m! f/ {: [
    set auto? false
$ p) p& Z, X- V+ V5 J/ y    set green-light-up? true
7 o# I6 _) V4 z7 h+ \. z7 n    set my-row -1
0 x  n& a7 m& |: M- Z( D    set my-column -1
) x! t. J9 i) u% a    set my-phase -1+ _1 t* C- C, G, ?7 f
    set pcolor brown + 3
/ H( l( M. g$ c: W+ `: B, q' {; e$ ^  ]. D! L3 C& z. E! j. ]* T$ z

8 w8 I7 D+ \. Q. C0 f% x; S  ;; initialize the global variables that hold patch agentsets$ `( d2 I! u  k1 ]4 X1 G1 N
  set roads patches with0 m, R! ~" H9 D9 m6 h5 P$ d6 _
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* O7 W: V6 y+ |: \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 M, d( P9 m6 B& u* W3 l  set intersections roads with) U# v. b. {# e
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and; D& ?: X2 n9 e
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 Q) }) l  A6 H4 E8 x! K
! ^- F, R8 V+ V8 R9 n% K. Y
  ask roads [ set pcolor white ]4 O# S; y& Q' k. B. d
    setup-intersections3 x* ~$ ^# Q  @( X3 Q0 p
end4 t% h  ]! j, x! j1 g1 g
其中定义道路的句子,如下所示,是什么意思啊?
4 E2 l7 I* `9 Q& [9 a/ S+ X set roads patches with
* J  O4 y" i( f% K2 B    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 W) M4 I; ?, t+ f1 d- k" m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 Z$ @( H' p8 j. l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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