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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。" r# W7 B9 G* T7 j8 r
netlogo自带的social science--traffic grid这一例子当中,  M8 ~1 P$ ?. I+ a2 G3 H8 B6 A
globals
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* U5 t$ {: C2 |; d& f  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, R" ^: M. I2 O+ Q: \! y  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 w3 q' H) ~- [8 [% q6 {/ \2 H  acceleration             ;; the constant that controls how much a car speeds up or slows down by if: @5 W! e( x- {6 y$ r/ W* [* s
                           ;; it is to accelerate or decelerate6 S! `! U( f$ g' Z5 }2 b$ F+ F
  phase                    ;; keeps track of the phase
9 H8 c/ Z4 p* E# ]9 F  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure8 t& h* O* H8 \- ^
  current-light            ;; the currently selected light3 T3 d5 }# R2 N5 l$ d
# i: h$ I  N6 K; y
  ;; patch agentsets
4 T. |( ^5 P' e5 N  intersections ;; agentset containing the patches that are intersections
7 U3 ?* ^7 D1 ~& F: Z# ?% m  roads         ;; agentset containing the patches that are roads1 i2 ~% [: Y% E( _
]
, r3 d( z5 B0 A$ q
9 x' y. R* j" ^0 h' Sturtles-own5 E) m; J' [+ H; [- v0 C
[
, s; c2 @" |( j) [! g' q  speed     ;; the speed of the turtle
+ G. X5 ~% V/ {% O$ j7 w0 E  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 a9 W2 D! @* x
  wait-time ;; the amount of time since the last time a turtle has moved: _& @7 X% |. I$ l6 J
]0 n% s( |4 J1 u8 b) p( c4 y

2 g1 b) t" J  O$ i1 A8 S" ?. f& _patches-own9 l1 i( y, l% Y2 O; y
[9 j3 S8 }0 j+ @7 E  W9 M. o
  intersection?   ;; true if the patch is at the intersection of two roads
5 M8 e9 e! J* ?  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.5 l! K5 l# U4 ~3 I+ P
                  ;; false for a non-intersection patches.
; E2 h$ V6 y0 h* K# O& W6 T  my-row          ;; the row of the intersection counting from the upper left corner of the3 {! U& V3 K; n; d- U5 n4 O, [7 Y
                  ;; world.  -1 for non-intersection patches./ M/ V1 R9 Q8 N
  my-column       ;; the column of the intersection counting from the upper left corner of the
8 d' Y! [7 j/ M& Y( F                  ;; world.  -1 for non-intersection patches.
6 p' Y  w. r" ^, u& N  @; g# D/ [  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.9 ]) G  Y( {. j, ]
  auto?           ;; whether or not this intersection will switch automatically.* e/ N! @. j' O) ^$ W0 Y0 c+ m
                  ;; false for non-intersection patches.
% a7 k/ s; r" ^6 ~6 [! G! `]
9 I; Z1 x0 y" g: ?
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;;;;;;;;;;;;;;;;;;;;;;# _: C; [+ l* G5 f" ^5 S9 t" D' @
;; Setup Procedures ;;, d  ?& [. D6 Y, L/ N" W9 {
;;;;;;;;;;;;;;;;;;;;;;$ r7 H6 s7 _3 S9 Q2 [2 `' ~

: o& E$ N% f, m;; Initialize the display by giving the global and patch variables initial values.! w3 O  O4 h2 Q) S. L  ~- @: m$ y0 O
;; Create num-cars of turtles if there are enough road patches for one turtle to
2 G* P, @; W( D" ~7 K, |3 O9 x/ b1 ]" {" m;; be created per road patch. Set up the plots.. Q- p+ F# G  s% @5 ^1 ~
to setup, K) Q6 l3 a) I3 g; B5 M
  ca- w6 h. `1 ?  S/ R
  setup-globals+ x* D# n- y  s! j$ `( h1 A$ A
% A1 W; }0 g% @# a
  ;; First we ask the patches to draw themselves and set up a few variables  Q* R5 k& J' w5 {
  setup-patches
4 a: k# L/ a! s# x. |- b  make-current one-of intersections0 [3 P- O4 z1 p# B9 a. E' Y
  label-current5 \+ g; x  n3 h/ Z# H. w3 p

; q  A% o; d6 n; \9 o! k# K( m) `  set-default-shape turtles "car"
) |; C4 j% F1 s, x; C3 k: M8 W  b+ r3 l( t
  if (num-cars > count roads)$ ]' g0 Y5 {# l6 c# b! }5 L% o0 \+ J3 `
  [
; n& {* P$ H- ^, n/ X: k; }    user-message (word "There are too many cars for the amount of "
" A' J* }4 n* d                       "road.  Either increase the amount of roads "/ a4 x8 g% L+ i3 W1 ?
                       "by increasing the GRID-SIZE-X or "0 U1 A) g! y" _) v* q+ T
                       "GRID-SIZE-Y sliders, or decrease the "
$ G2 a1 r  A9 k4 [) E0 w& k                       "number of cars by lowering the NUMBER slider.\n"4 b5 ?! }1 g0 f! w8 j# H. _
                       "The setup has stopped.")
# b3 z: p. a, W    stop
, B$ p( c- ?. s3 s$ X  ]. G3 j& z4 f5 ~6 K

1 @  s. E/ _, g$ V" }- a5 C6 ?  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
" n( Q; ]" M9 o4 Z+ i& j& ?* @  crt num-cars* V7 P- c4 N2 N% F9 S3 q
  [9 g  n% s9 \) i" Q
    setup-cars
; F6 P* x& A9 n9 Y    set-car-color
: I6 `  g! O2 V    record-data, O8 ~0 [* S% w) E
  ]
+ K" g% i& e$ k( r9 t- d" z. Y2 I2 w5 p
  ;; give the turtles an initial speed* }- j0 N, m+ N, t1 H0 z
  ask turtles [ set-car-speed ]
; |5 I  t" v& f6 `1 s" W7 {: Q& j% s3 a/ Y& l6 p! x; S" Q. Y
  reset-ticks
2 ?2 T: `5 |0 {end4 t( k& \8 ]+ H& |/ C2 F- Y
4 b; @& t/ ?/ ~7 f
;; Initialize the global variables to appropriate values
  n+ |4 n+ \" d8 Pto setup-globals! @, y3 w7 l! O3 T
  set current-light nobody ;; just for now, since there are no lights yet% [- L& ~3 Q* W) v& A- y& T
  set phase 00 p. m  R+ h9 z/ m) p: r& M
  set num-cars-stopped 09 |$ T! e9 H) Z" c7 F. s, d
  set grid-x-inc world-width / grid-size-x
7 P3 Q0 V# `" |2 t' P+ l  e  set grid-y-inc world-height / grid-size-y
% n; n$ ^$ m9 t' T$ _/ O) z% b3 D( V
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
: H4 }, D8 U+ t0 l' z* q6 `  set acceleration 0.099# h8 o- v) ~/ p4 m2 }1 N! w8 |
end
% M8 e# P4 H, g1 m0 z% o/ W0 j2 ~8 H' g: D" I' W
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
7 Q$ i9 i6 `( j2 n;; and initialize the traffic lights to one setting
$ C1 B$ Z+ g0 n% j* Pto setup-patches: K, g7 n6 t& [; S( c) y
  ;; initialize the patch-owned variables and color the patches to a base-color
2 R5 [, b3 @- e0 A  G2 b) J' i  ask patches
  ?1 H7 F* K" x  [# S+ z9 l" z7 Y9 W% F: `+ u7 ^
    set intersection? false
& z! ]4 @6 H7 \& D2 H- F: u3 ^, S1 V    set auto? false& O" `) B/ q% W( _4 s1 I, u
    set green-light-up? true: L! r! C$ j# n
    set my-row -1
' P1 x5 t5 z' b& f' i/ N2 q    set my-column -1* L5 @& t# {7 p9 k* k' H8 ]! B
    set my-phase -12 @0 }0 G* T9 a7 x
    set pcolor brown + 3
% ]9 o& ?% f# ?( a, E0 U8 r" Y  ]
* |9 y* m0 U5 m. q: M
4 ^2 Y' G. q9 x' p$ H  ;; initialize the global variables that hold patch agentsets. B+ ~0 V* u& W
  set roads patches with
: \- @% S$ P4 N5 }+ b' Q9 R2 c    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 Z7 Q- r! L1 T/ g7 C, k! Q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# F5 @5 V/ O! [( o! e- g
  set intersections roads with% ]% d6 w$ {' @; {) c1 h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and' G% o1 R& q6 B# f$ p; U1 G  N
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ Y9 e4 L+ l$ h' O5 ^
8 `# m2 `) R, s. ^3 ?# s% I; z  q: \/ [* c  ask roads [ set pcolor white ]
! V3 ]3 q& w9 ?8 T    setup-intersections
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其中定义道路的句子,如下所示,是什么意思啊?; c1 Z* y  q. R  ]8 r0 Q! O5 L
set roads patches with$ R6 g; D/ d: t1 k0 ^3 M' f" D
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 |# F0 I' [( _2 y* T; |
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# @& X! ]. z" A0 v: T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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