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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。
" h' x% X. k" @+ t1 i, o) Xnetlogo自带的social science--traffic grid这一例子当中,7 ^" y7 ]& H+ `& k$ M
globals! }& C. k7 B( K1 L. Y' k
[
) s7 E4 F, [2 r2 k- R5 d* b. d  grid-x-inc               ;; the amount of patches in between two roads in the x direction
& \. B1 c% C/ [9 H  w6 N' W; I  grid-y-inc               ;; the amount of patches in between two roads in the y direction
% q- L  v# q' {! ^; N  y! E% v4 l  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
! ~3 Z5 g! a2 c0 A6 m; A                           ;; it is to accelerate or decelerate
% k5 H! r# V# A  phase                    ;; keeps track of the phase
7 H1 G! U$ c/ n1 y% L  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure0 R  m8 m% x3 l0 E* h' M, L0 F) i
  current-light            ;; the currently selected light
! Q. R8 D; n7 k% S* c0 s$ [1 c6 B- E/ ^: |1 e0 M. ~
  ;; patch agentsets& I, H4 a( {8 N
  intersections ;; agentset containing the patches that are intersections
. V3 p7 R' ~3 g  roads         ;; agentset containing the patches that are roads( V' m7 r3 g! d0 [5 G# U' M
]
" ^3 y9 q' p/ S, z( c9 \& t& U5 Q' ^. ^2 ~1 l; F  c9 X4 A
turtles-own1 M- x3 T8 [* o5 F. W
[
: @$ f! G# I/ X4 m  speed     ;; the speed of the turtle
6 A2 m: h: |. x0 a% u  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
0 M3 A3 ]! ]" r. M. L0 G3 k1 L  wait-time ;; the amount of time since the last time a turtle has moved  D( a& {2 B' c$ k* C/ `
]
0 m9 _6 K: d% j2 k
9 m* u. E) w* Gpatches-own" T: @- J. \. [- b" L  Y
[7 M) W, A4 e; x, _' t( I7 ?! A
  intersection?   ;; true if the patch is at the intersection of two roads( G; ^. T! {6 ^( R! {' {
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% J( E: G# n# M2 w                  ;; false for a non-intersection patches.$ X1 j0 t" [3 M* h2 P% K+ ]6 A! w" s
  my-row          ;; the row of the intersection counting from the upper left corner of the
, B' ]% |9 `/ z9 R: ]                  ;; world.  -1 for non-intersection patches.
3 W; @' Y) h( K- C' W  my-column       ;; the column of the intersection counting from the upper left corner of the
' U; `" J) k* _9 r4 S' ?( x1 M) _% P                  ;; world.  -1 for non-intersection patches.7 {- _) F9 Z5 H) F/ p, \
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.7 R$ F5 t( q( [( r9 n+ J! m3 ]
  auto?           ;; whether or not this intersection will switch automatically.: Q1 [" K# P! l& H- R
                  ;; false for non-intersection patches.
7 C3 z( ]  m( y8 w/ V( a]
, G$ H  m2 Y* A. b( y: }3 z2 I
. b* ~& q( L* h! Y0 U, Z7 j2 I7 h1 B4 t. W7 c/ k- s6 |/ `( ~. l
;;;;;;;;;;;;;;;;;;;;;;
5 H8 i  ?' _, K2 I1 L2 \; d* |;; Setup Procedures ;;/ I7 W7 f; K2 a0 U& |+ `' S; F* }
;;;;;;;;;;;;;;;;;;;;;;1 T7 ~& M" e9 f- V, G) q- |+ _$ b
3 e. A7 T& @2 P" F8 Y
;; Initialize the display by giving the global and patch variables initial values.
+ `' ]8 B9 k4 @5 P& F# ^;; Create num-cars of turtles if there are enough road patches for one turtle to
. H' v' J& Z) C3 T$ n;; be created per road patch. Set up the plots.# P: J+ C% q5 f2 z% ^9 T7 f
to setup
9 T7 {  q$ f' y, L! s( |# T3 w  ca
* {; d. H  M! |: Z  _$ }  setup-globals
( e! J3 D' f# V% \% t6 s8 b+ `9 [* ]' x
  ;; First we ask the patches to draw themselves and set up a few variables: M- q: f  i8 \. I( X
  setup-patches4 U. A" u, ^/ j1 _3 @
  make-current one-of intersections0 x  g: i4 ]- F* v9 ~6 o
  label-current
0 H) }  [9 n) r. @8 x  n- n7 S* G; p1 U9 z3 C# u
  set-default-shape turtles "car"" P% E7 C; }  O2 {/ }8 O

; Z& l% N( V4 X  if (num-cars > count roads)6 f8 W( I7 _5 Z7 D
  [
# U% |& P; [. t, u0 S    user-message (word "There are too many cars for the amount of "+ z. m. {, b, c
                       "road.  Either increase the amount of roads "
" Q$ `- O( B% z! d3 F9 B8 J$ H5 o                       "by increasing the GRID-SIZE-X or "
/ m" s; U, Q' c. h% \                       "GRID-SIZE-Y sliders, or decrease the "0 V2 x$ V$ J7 w) l! e
                       "number of cars by lowering the NUMBER slider.\n"
+ N2 r$ Q9 e1 r. _' C/ C                       "The setup has stopped.")7 q+ P& c7 b- K" _
    stop6 g( E. n" C5 o3 ^  _7 ^! r
  ]
" b+ s* T1 ?+ b1 @+ X' \) o$ H" r2 ~; v
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color+ C* D0 u" q  c" ^* {* z
  crt num-cars' |  u/ i) h, l
  [9 l! f8 C8 d7 w9 d7 L
    setup-cars9 J- Y* V, Q/ I9 U* r  B
    set-car-color
2 D0 C- b# q9 B" K    record-data
3 p; Z" {6 o7 x( P) J4 r/ ?  }- ?  N  ]
( D4 L- Z! R8 c' g, l( R. ~+ X$ x4 A/ b3 N8 {# i' R7 ~6 D, g2 ]' b# ?
  ;; give the turtles an initial speed* h: u" h* O) g
  ask turtles [ set-car-speed ]
: c3 E, T/ z3 Y# y2 q2 p7 D" [
5 S# I7 P0 s, J2 F; q: o  [1 o  reset-ticks5 l( T0 u' _  E' W! m9 M/ i- L
end, R5 G0 @9 g8 z9 e2 j' c, z0 f; Q

  J! q+ W# r  L+ [& }1 O;; Initialize the global variables to appropriate values  t# r, ~. ?& U! n
to setup-globals: Y5 M" B/ Z% l) z( [- o
  set current-light nobody ;; just for now, since there are no lights yet3 g9 ^8 k+ ?# T) r0 P7 r1 _
  set phase 0
3 g# [3 J' M) `- x5 K6 m. p( g& d  set num-cars-stopped 07 Q- M; i8 }4 w5 |. r6 z
  set grid-x-inc world-width / grid-size-x8 a; E2 L) F1 u4 R0 F9 B
  set grid-y-inc world-height / grid-size-y
; x% O7 O; A2 m2 l7 D( ~3 e9 j! V- }& f; X, Y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
6 q  `" }; c+ w: i' Z! y  set acceleration 0.099" `+ a1 X7 H, J
end0 |- B$ f" M* G8 p
4 G, Y( ^9 Q6 C! J$ N! z) p
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
! y6 y1 g3 ?; x4 N) n2 ^: C1 |( m( [;; and initialize the traffic lights to one setting5 l+ Q9 M6 {, q3 v) |
to setup-patches
  P/ w  f( k0 M) K* `& u  ;; initialize the patch-owned variables and color the patches to a base-color4 A+ _) a+ P0 z2 [9 r3 W0 X
  ask patches
( }1 [8 E! B! k3 H4 Z' k' h  [$ V) x$ v% I  Q$ W0 d
    set intersection? false
& P3 P- ]+ Y4 X+ f$ ?    set auto? false
6 H1 w+ A6 z2 T- C* K    set green-light-up? true( j* A. I! n6 v3 B  D: n) K
    set my-row -1) n& {9 W" P* m% [9 z6 p" i* `% g
    set my-column -1
& Y& q3 J1 H& o  o1 H4 {    set my-phase -1
. Z1 |( i. A) ?: A- b: L    set pcolor brown + 3* z2 G. w# P& b2 B& `! L0 G
  ]
% |) T% H& K+ I8 H) E. [$ R
: r: B+ Y5 `: _: l' S  ;; initialize the global variables that hold patch agentsets2 B$ R+ ~: }" n
  set roads patches with
0 C& ^0 ^; s8 H3 C& W3 Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% k% B1 }- T4 _" q2 |1 v- I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 x* `5 N" C- F  set intersections roads with
6 g) F1 d7 m# ]9 z& t/ f' ~, H    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and$ Z0 G1 O+ y& L- E8 w. P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; g# _. Z8 T9 M1 y+ e

& y3 g' [& @+ K3 q3 v  ask roads [ set pcolor white ]4 b6 w- w+ \) s+ ?
    setup-intersections+ v  ~, v# L( L
end
% u6 `* A6 K7 u其中定义道路的句子,如下所示,是什么意思啊?+ \: }% U$ C! i. r, S
set roads patches with, f) ?) B& N( e3 g* ?% B9 B) @  t% Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: H, D" t, [3 O3 q6 Y9 E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: w2 y7 n9 Q6 \: j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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