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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。# {8 X" l6 C3 A; q1 Z
netlogo自带的social science--traffic grid这一例子当中,, N$ a3 k  ]6 n7 }
globals
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  grid-x-inc               ;; the amount of patches in between two roads in the x direction: u8 W0 m6 w! p# [
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
$ a- A( p8 n. v* ^6 C, g  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
0 w- ^1 d% ~: T  N  V. p9 f                           ;; it is to accelerate or decelerate
: O9 `9 r# h1 p$ y' t  phase                    ;; keeps track of the phase$ o% T1 U$ }6 e: e% z
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure. P8 S* N0 d9 ]* |
  current-light            ;; the currently selected light
, i  u6 F1 i8 K) }; a
# K3 r5 D" U8 u! ~  ;; patch agentsets6 E$ n4 t; [/ |$ ]( }1 V- ?2 H
  intersections ;; agentset containing the patches that are intersections( T- k" S  j9 Y7 ~
  roads         ;; agentset containing the patches that are roads
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, ]7 G! q/ ~0 r1 m1 N3 Q& u
1 g5 ?# p# M$ Fturtles-own
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  speed     ;; the speed of the turtle3 J5 T) l1 W9 _' E; B, ~. p
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
" [. Q' H; [2 a  {1 c2 D# b( Q  wait-time ;; the amount of time since the last time a turtle has moved
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patches-own
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  intersection?   ;; true if the patch is at the intersection of two roads: @$ E& U9 S, E/ R/ j
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
; k4 K1 v; N! g1 u                  ;; false for a non-intersection patches.0 G9 S8 a1 r+ }2 b
  my-row          ;; the row of the intersection counting from the upper left corner of the
0 w4 d5 C# H* y5 S1 n; J. p                  ;; world.  -1 for non-intersection patches.) \1 G9 i& O* W
  my-column       ;; the column of the intersection counting from the upper left corner of the
  j( g# @( D3 f  ?, ^: k, k/ E                  ;; world.  -1 for non-intersection patches.
1 o& T+ N# F5 ?) _. K  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.! `& E* t5 @1 @; |. y; F
  auto?           ;; whether or not this intersection will switch automatically.
: n1 W( E# i$ H                  ;; false for non-intersection patches.
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. D( k" o  o& q% A;;;;;;;;;;;;;;;;;;;;;;- Z; `! ], u+ |: n1 A
;; Setup Procedures ;;
: w, J+ [& P, P5 f5 j* v# l' @/ q;;;;;;;;;;;;;;;;;;;;;;! Z5 F) {" g# N4 O5 E( A& b
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;; Initialize the display by giving the global and patch variables initial values.
0 u' C- t$ Z# d. G6 B. k/ g. i;; Create num-cars of turtles if there are enough road patches for one turtle to) }* u2 c( @- J7 q5 A
;; be created per road patch. Set up the plots." v; |' C6 c2 W% V
to setup
1 {  q$ [5 D% X# r$ t  ca
* [- N) M; t# n3 v  setup-globals5 q5 i/ X# H! p1 E
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  ;; First we ask the patches to draw themselves and set up a few variables9 X. ]9 u# p, x6 {9 t
  setup-patches
. ~1 C# ~  x" Z( f1 y8 d" _  make-current one-of intersections0 x+ ~' F5 r1 n! l1 U. M: x9 M
  label-current$ V! V6 K5 b1 W) ]" u: k" ]
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  set-default-shape turtles "car"% T7 v8 S- h2 L8 Q7 A* s
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  if (num-cars > count roads)
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    user-message (word "There are too many cars for the amount of "7 ?8 m- b6 R# @& @6 A
                       "road.  Either increase the amount of roads "+ x- n" a. p% b8 A/ N5 f' P% Y
                       "by increasing the GRID-SIZE-X or "4 O; e2 F: l' T, s8 Q4 y
                       "GRID-SIZE-Y sliders, or decrease the "3 T! C7 R, \& J
                       "number of cars by lowering the NUMBER slider.\n"& a& k8 q4 `3 o1 v. T
                       "The setup has stopped.")
/ @/ r, M+ r5 ?2 t! [9 M2 m$ ?    stop! H4 u7 C0 ]$ d0 l6 L% @
  ]
% [. _5 K3 b0 x+ w) v3 q1 ^2 u8 E2 M; p
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color) H2 w' U% o  H1 C7 i
  crt num-cars
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' n, ]6 Y9 F0 n6 ?& w    setup-cars% u8 w8 T+ l, U7 Y; m# _
    set-car-color+ z8 p' ]5 P9 W: e
    record-data
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- b2 ~6 b: a! r+ f  ;; give the turtles an initial speed; @2 d! J" ^" M) e! W. Q. U
  ask turtles [ set-car-speed ]
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( v: v0 r, a  T  reset-ticks" u3 N9 k0 e. _
end
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;; Initialize the global variables to appropriate values
* p0 q: g# R& R# G& jto setup-globals
% n4 y) A6 Z5 a$ M' W$ y! v  set current-light nobody ;; just for now, since there are no lights yet$ f! W+ p# s% ]$ e8 Q& Y% ]% {7 n
  set phase 0- i: F  D2 E! u1 w+ X
  set num-cars-stopped 0
3 H% Y! e7 v+ P2 s) Y0 B  set grid-x-inc world-width / grid-size-x2 m9 t; v) Y( H6 {. u9 A" v
  set grid-y-inc world-height / grid-size-y
* K) [, C- k  T8 m/ l( D7 E( o# N( j$ }7 S8 M# R+ u2 A
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
  V. Q9 c9 e% ~. b. o% K: Q3 m. x$ F  set acceleration 0.099, c% ^' W3 x7 {" c
end
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9 t' m5 {2 R2 i3 S0 q;; Make the patches have appropriate colors, set up the roads and intersections agentsets,1 V3 V! }: {" M; h: ^
;; and initialize the traffic lights to one setting
9 t; b$ j2 b5 h# ?/ F3 F$ [to setup-patches$ F; V: u% O( ~* w
  ;; initialize the patch-owned variables and color the patches to a base-color
1 B' k6 U9 e6 ?3 n- V2 ]1 Q' z) |  ask patches
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    set intersection? false$ q9 {) y& ^5 K4 `# @+ K+ D( Q
    set auto? false- O: B& [9 t7 l" b; J
    set green-light-up? true
0 M  O) A! n- X' D    set my-row -1
1 ], T  E, i5 U" Z. O: S6 E" n    set my-column -1
4 }. h! k8 i" c1 X) l5 d3 s" A    set my-phase -1
0 ]: M7 H9 x( i3 z5 w+ g    set pcolor brown + 38 K5 h2 e$ Z7 [+ K! x: s, n
  ]' H2 c0 r, D, D" N- p
- M" r# i, O! E9 @1 @
  ;; initialize the global variables that hold patch agentsets
, X" O7 G( ~; ~4 R5 i0 Y: r( f  set roads patches with4 i% i& o; Q9 P! _% E+ U' L. d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  h# y1 c3 x1 R: K3 ?5 g0 i- d1 h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% [: n" B# i9 g
  set intersections roads with5 ~) R& \7 ?) W  E& ]6 [1 n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and. B- C. }- p+ M( q/ B$ P$ }, C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 j. Y6 V2 Q& C" g- d4 i7 u

% i2 t/ X$ o: ?- `& `: ^" Z  ask roads [ set pcolor white ]
  L* S- m/ p/ L0 m* @& o( e    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?9 H9 z+ h: f. u) D
set roads patches with
$ t, f# O# C% {7 ^# x' s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 Y0 X! F( Q$ V7 C9 b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* H- L8 |6 h) W* V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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