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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。; u4 v% o1 `1 w4 a2 p
netlogo自带的social science--traffic grid这一例子当中,
$ C" A( @* F- V: f. q! ]- D1 S* ~1 o$ Kglobals, F( I3 h3 J3 E7 p2 ]  K
[- ^* L; x5 D) q- e+ ]) i( |9 O( s
  grid-x-inc               ;; the amount of patches in between two roads in the x direction! ?$ ]& Y& N. x3 V1 Y8 R( g5 U
  grid-y-inc               ;; the amount of patches in between two roads in the y direction. l6 A. {' n* p
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
% k, \* k5 w. n( D4 v                           ;; it is to accelerate or decelerate
7 ?4 H; M4 c2 U' z  phase                    ;; keeps track of the phase
5 Y. q, d' g+ E: e: e8 Z: m  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; D1 [* u1 F+ N- w  current-light            ;; the currently selected light
* _! b3 _4 l- b, `
/ s8 X. p! |; m0 J  ;; patch agentsets
8 K8 x" f( G- o( \3 N- i' Y  intersections ;; agentset containing the patches that are intersections
9 Q, Z! Y( |* s& |/ @; }1 Q- m9 Y$ A  roads         ;; agentset containing the patches that are roads
  K  ]: g- O6 A  m]0 g) s6 F4 R$ o; ^8 V

* D1 |" A: T& a% `2 z, `$ ], gturtles-own& O' V6 ~1 d) s# h5 Q/ e5 W; ?: q
[
* N- Y  Y4 b! K$ _5 M  speed     ;; the speed of the turtle
7 Z" P7 |8 E- ^9 X  up-car?   ;; true if the turtle moves downwards and false if it moves to the right4 w! o3 s! _  T3 u4 y% G
  wait-time ;; the amount of time since the last time a turtle has moved
: W' ?, Z" T3 c]
- |+ p9 r& r- X& b1 l2 F
" m7 J  O$ G8 H9 g3 D1 E: j  Lpatches-own  P2 w' B& o# A- W8 d
[
" {/ X  c, [. V5 H( M, x  U  intersection?   ;; true if the patch is at the intersection of two roads+ w6 e% W! m' ~: a# P
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false./ X! ]4 Q7 d% ^! w* o7 p
                  ;; false for a non-intersection patches.
$ m* ]# O. i9 ]; X  my-row          ;; the row of the intersection counting from the upper left corner of the
. e& D" [; k9 e* N5 f                  ;; world.  -1 for non-intersection patches.
" P3 Q. B6 x9 l( q- G, Z$ T  j/ u  my-column       ;; the column of the intersection counting from the upper left corner of the% j: o1 M6 L. y6 `+ @
                  ;; world.  -1 for non-intersection patches.' @: ^. p! y& F  g
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
) T) T9 L9 k, H, [  auto?           ;; whether or not this intersection will switch automatically.: j) U  [* ~' y: V1 J. I. V7 ~
                  ;; false for non-intersection patches.
& R, }: [; l/ d) C8 q: k! U]
! }3 v6 U7 B$ K2 c& e" y; i% z  M) J" l  p4 h1 ^. I8 v
+ v) V, u: v1 c. O6 `
;;;;;;;;;;;;;;;;;;;;;;
; N4 O. x% b: n8 l* _;; Setup Procedures ;;
  o: H: ]* f7 K, n' q3 d3 X: h;;;;;;;;;;;;;;;;;;;;;;
, r8 }4 C4 L8 g$ k, z
( A0 t3 C3 L4 n+ {8 G+ D2 I;; Initialize the display by giving the global and patch variables initial values.- K: `& c: w5 H& f9 Y
;; Create num-cars of turtles if there are enough road patches for one turtle to/ b1 k4 k+ w  x" F, r. [9 W
;; be created per road patch. Set up the plots.# I8 y6 [) \" k" Z! n( J
to setup0 c- j, |& m+ @4 _" Z
  ca2 T8 r* C. R0 i8 E7 ?  a; X/ Z! P
  setup-globals
" i* o* P/ F8 T* U# I, O  y2 d/ g4 s5 u' Y: H! V  p
  ;; First we ask the patches to draw themselves and set up a few variables  `8 e1 I$ U" U% d$ U+ w
  setup-patches
* G7 _& ]# q& @, s  make-current one-of intersections
1 c, ?" ^; G( W0 i  N. a  label-current
. j: Y7 ~( \9 D% M8 q* J' @. }0 f: d# A
  set-default-shape turtles "car"
. X3 D) O% ^+ k1 T! p0 O
. _5 p' J8 Q- i% {: ^3 q. A  if (num-cars > count roads)2 x. i0 n, a3 k' l- g
  [
& g  x) ]3 n# u    user-message (word "There are too many cars for the amount of "
" F+ J- h1 q, a6 p: F' f                       "road.  Either increase the amount of roads "0 `3 E+ \( W* ]; `- v
                       "by increasing the GRID-SIZE-X or "
: K; \2 o  F9 c                       "GRID-SIZE-Y sliders, or decrease the "9 K4 I# }8 Q5 S$ w
                       "number of cars by lowering the NUMBER slider.\n"
5 c' J/ Z! u. T                       "The setup has stopped.")
3 I, W/ Q+ P4 u* w! D0 ?# U: e    stop2 i$ ]/ v- t* @. x
  ]
, M/ M3 N$ N: q# n8 J6 o* A
! ?+ s; g$ Y( K' U. a/ i  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color/ F) W$ E& U4 |3 Z
  crt num-cars! r6 w5 p6 r/ ~0 t
  [
+ o/ X' Q( C/ c' x' c    setup-cars
2 H2 \: b) U: A$ X) q! V    set-car-color
0 t" p7 D) r' M$ n8 R! O& k1 q    record-data
- ?0 B( S  R+ m/ ^  ]& l; @: a) F/ \% P3 O. Y) O

' ]& G0 i+ l. l  ;; give the turtles an initial speed3 h) H4 ]+ l9 b/ C9 Y
  ask turtles [ set-car-speed ]8 Y/ I# S" N# }" b

! S  M, t. [* K& x# Y5 g  reset-ticks2 @( [% Q9 Z5 @: A+ L! d
end) B+ k! O1 ]6 h- u! ^: q

# j1 o" U7 \4 e" E;; Initialize the global variables to appropriate values1 Q9 W8 ~1 j" G7 M! r$ k, t& e
to setup-globals
9 i9 u3 D" I* s& s! P  set current-light nobody ;; just for now, since there are no lights yet
# W9 `# D! S  {  set phase 0
9 c* m! [  M! W: a3 |9 o  set num-cars-stopped 0
' p9 C; j% {0 k  set grid-x-inc world-width / grid-size-x0 b* U1 c& l' [. m4 J0 H# G9 S: f
  set grid-y-inc world-height / grid-size-y* V  e8 M9 K( Z  G5 v

2 y; o4 A" k) U; B3 e" h) S+ C/ I  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary; O  ?# F+ @3 m: `2 l' H
  set acceleration 0.0997 @. O/ u3 f! E) m! d' l
end
7 @( ?+ S3 Y, s- X) I) z
6 }0 K8 |6 U  Z7 J;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
% d) h0 d0 H3 D+ P0 D, j  ];; and initialize the traffic lights to one setting' w3 B$ @8 E  }5 p  i. b
to setup-patches# @9 x* X' j. P, h2 u
  ;; initialize the patch-owned variables and color the patches to a base-color$ q+ \' N9 I$ U* l# h
  ask patches$ f% K6 ^9 @7 u7 t0 x  b* U- g+ X
  [  r/ l+ @$ T! j! |! D. j7 D( E
    set intersection? false4 ^6 f9 Q+ `/ R, [
    set auto? false
( p' ]6 P+ R8 P' W( [    set green-light-up? true
6 `" [. e: p* F. C    set my-row -1
8 r. @% D# f3 a! Z$ j! v( r    set my-column -17 l1 U3 T4 ]2 P3 \$ }# u9 i7 |, d8 o
    set my-phase -19 K* M8 L" n; u
    set pcolor brown + 35 X! l3 U' Q7 v; p. y" ^' b
  ]
* Z; l% W" ?, t# w4 N! A) K4 t, _8 n  X8 X  B3 ~7 e6 p
  ;; initialize the global variables that hold patch agentsets( K$ ^0 L4 `+ |) _3 a* M9 c
  set roads patches with# r/ H6 O0 @) n" I! C) V: J  i
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ h  V9 H: i7 h" b) s$ z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- o& ^7 {* h5 _- U* W, f- J
  set intersections roads with/ A% \3 p, e, j1 b& x* N. s- F1 M' F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and; j% n$ d' R0 \( W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: I6 Q9 {' W' y6 X; b
% X, e/ K0 N9 u7 x" g  ask roads [ set pcolor white ]
$ A/ ?$ Z) }# P2 V. W3 D    setup-intersections
4 _; ?" M7 v! Q8 T6 j  fend, h. V1 v, W3 w# E
其中定义道路的句子,如下所示,是什么意思啊?3 Z' u( m$ @6 A& t2 [8 ?
set roads patches with1 c. r" z2 K" _( _: ^7 M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 l0 J9 g  S7 \4 I4 {" X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# z2 t0 I+ _  x% {+ y
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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