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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。( a2 ~' a% F7 h# w, w
netlogo自带的social science--traffic grid这一例子当中," n# `/ H$ ?6 Q: y# r  z' ?
globals6 \  A' U( ?( u9 f
[
+ p/ d! R+ f; h- \& Y1 c; v5 N  grid-x-inc               ;; the amount of patches in between two roads in the x direction
' }+ a' ^9 e: X5 E  grid-y-inc               ;; the amount of patches in between two roads in the y direction3 D6 m7 i' G# y1 U& w4 }
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
5 C8 u1 y) _3 R, q2 }                           ;; it is to accelerate or decelerate2 O# i! v! k8 ?/ [
  phase                    ;; keeps track of the phase* S; b8 V0 {/ o# Y; I' z, u
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure: r5 |4 e" i7 ]1 t3 q
  current-light            ;; the currently selected light
. h5 S' ^7 q, t8 g  g
6 _/ k5 Q9 a; U1 s" [& l3 [  ;; patch agentsets
; k( U5 W3 S# u! j9 t& k  intersections ;; agentset containing the patches that are intersections( [2 k/ w; z0 }% J( U
  roads         ;; agentset containing the patches that are roads  @( X6 }; }7 V5 @
]
. w4 K4 X& V# |3 P9 f; ?! f3 H
/ q" R: L% f6 X2 g- N7 pturtles-own
5 v0 T5 L" Z8 p( ?6 I' @" L[
8 T6 r$ z9 @7 N* o  speed     ;; the speed of the turtle
6 t1 r4 v2 Q' `  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, h$ }4 v; _! w9 G
  wait-time ;; the amount of time since the last time a turtle has moved0 @+ c' g6 t* A9 y& Y! n, Z
]+ B# |2 p( G! I" Q

' f' J( [, p3 z, J. X" r3 dpatches-own
3 J. }  s7 B3 ]- l! T5 M[. H3 s* v0 D4 N/ u4 G' W& O" d1 F- I
  intersection?   ;; true if the patch is at the intersection of two roads/ Y" q: P( d' G: L" H( j/ [9 U! E7 ]
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.4 ~: {9 m5 s8 V% a
                  ;; false for a non-intersection patches.+ D. r- S8 C+ `8 \# x/ x
  my-row          ;; the row of the intersection counting from the upper left corner of the
' ]0 L! P1 b6 d; [( H/ f8 N' G                  ;; world.  -1 for non-intersection patches.
% T, I* O* n0 }  my-column       ;; the column of the intersection counting from the upper left corner of the' j- @3 G; Y. c. |; w* K. N
                  ;; world.  -1 for non-intersection patches.7 M) o& h. A" [) W5 Y1 x1 }
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.3 ]2 p- C* f0 F) V
  auto?           ;; whether or not this intersection will switch automatically.
) @- @9 L# v' K% ?3 j                  ;; false for non-intersection patches.
9 c2 s: c( B/ o, \: X* N; o; K]
7 N0 n; R- e8 K4 f) ?# @1 N
# M& b0 x* `1 v9 A& s3 H
3 a7 A% E$ n; V* {( X+ m/ s;;;;;;;;;;;;;;;;;;;;;;% F( H7 A6 n4 w
;; Setup Procedures ;;& I$ U( t. P4 u  o& h* W* M4 Y6 K0 {. E
;;;;;;;;;;;;;;;;;;;;;;
0 s  ?" s# _4 b" g2 f* ]( w9 Y. N4 G0 @) l
;; Initialize the display by giving the global and patch variables initial values., l9 V- Q7 r" o7 M7 e$ e8 f
;; Create num-cars of turtles if there are enough road patches for one turtle to6 c: D- X6 R9 n: r6 G' z8 L/ l
;; be created per road patch. Set up the plots.5 k9 P3 m2 h6 d2 z2 C
to setup8 J* p8 G6 U6 i$ Q5 M
  ca
4 |* w/ _2 X# c  E. f5 v  setup-globals
5 M4 ^/ k9 l( ~! H0 J! K; T' Z# f' z6 J( V$ d$ Z  h4 J! Q
  ;; First we ask the patches to draw themselves and set up a few variables
2 [3 b4 A% M2 d9 ?  setup-patches/ @' w9 E( ^( v+ C- i
  make-current one-of intersections0 g$ z0 K- b/ `% c, g& k
  label-current
, w, s8 K$ O) g! l# ]+ w% g* n$ q, J) R  T8 N
  set-default-shape turtles "car"
3 z8 |6 @% J, I8 h/ |" C6 K+ {/ s. b! n- c! g' @: P; i5 [
  if (num-cars > count roads)3 E0 y- @& n. b1 b
  [0 ?- b- N8 Z0 y& p' r; ~! c
    user-message (word "There are too many cars for the amount of "; d$ F1 ]  A. D" Y
                       "road.  Either increase the amount of roads "
- L* W2 \: g0 D" h8 K3 V! y                       "by increasing the GRID-SIZE-X or "
6 L- h$ M3 D  J                       "GRID-SIZE-Y sliders, or decrease the ". n  [2 ]0 A5 T8 b9 t8 f
                       "number of cars by lowering the NUMBER slider.\n"
# h/ x/ h+ s7 T% F; V                       "The setup has stopped.")/ x  @0 p) ]9 A9 U; P. \- K
    stop$ M! d7 F- G. |* m  v
  ]
  K* H$ K3 m5 b/ O; X& g) }, G5 V
- ~; Y6 A$ T# f  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color+ q: o6 U; c( C# U. b
  crt num-cars3 S1 F5 G5 e8 O, n4 @: u+ C
  [
$ W" Q- l( ^/ E    setup-cars0 |2 Y4 ?  J* g- i/ v
    set-car-color( r2 r, g& B2 \/ I$ |
    record-data# m* u/ Q  u. n& Z4 `5 U
  ]% n) u7 d0 T* O; H, \$ g, s

5 _# n' A5 J% i/ W  ;; give the turtles an initial speed. W( s- {8 F7 [. O$ H( X, S6 a
  ask turtles [ set-car-speed ]! T& ?9 Y8 t6 O) V/ U) ?

8 d" @; |" T  T% A/ _% y* S6 Y  reset-ticks; i9 U: U. ?9 M4 o7 \  o0 Q
end, |2 L' l! t6 Y

' v. P" i9 q4 k% L9 U; J; S;; Initialize the global variables to appropriate values
- X! j# X: j1 R# Q7 ]: @to setup-globals
4 O9 N- c# x* u8 P1 Y/ R  set current-light nobody ;; just for now, since there are no lights yet
( \4 |1 [1 R! t0 e# U0 G' e  set phase 0
. r: E1 h* h; L1 d$ W) j( `  set num-cars-stopped 0
) |1 W1 ?8 [: u& D  set grid-x-inc world-width / grid-size-x
  z5 O" l2 u8 g% T1 X3 ~, R9 j5 d0 N  set grid-y-inc world-height / grid-size-y
& G  W2 k' T- x  n& C1 p" V' c% P2 ^% v6 n: {( d
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
: ?% I! ^, N$ t  H2 P* p  set acceleration 0.0992 }. f2 \. {8 @+ N2 M
end4 V9 _1 D! Q% [  l: S- ^& b0 v

2 s+ @7 h0 R0 o6 f# l9 B5 c;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 c6 O: R9 c5 J
;; and initialize the traffic lights to one setting) e- V( Y) S# z! T5 i
to setup-patches  \- O! c" _8 I1 b" p
  ;; initialize the patch-owned variables and color the patches to a base-color
1 h/ \. e+ z/ g. I& k( u  ask patches
# A( q) r9 g. F  [2 y. k% t! y# Q+ E- D, X- A
    set intersection? false
4 d& z  I+ t. L1 g" c8 l. S    set auto? false% y9 W) b9 L: q) A3 I
    set green-light-up? true+ z6 u) i* f- |) Z" f9 v" G
    set my-row -1+ `. I% p" x! ^% ]4 t/ m
    set my-column -1
+ s& q( o4 @% c6 s" D8 c    set my-phase -1
6 D& v1 Z6 N6 s' O5 C' C    set pcolor brown + 3
% H$ c. ~% D! i' P6 f  ]
! t: d1 T: L, R, W+ ]' |7 u. z6 O- l( b$ n
  ;; initialize the global variables that hold patch agentsets3 J5 E* N, Z5 i( r" u- m
  set roads patches with
8 E, d. _& u7 Z6 K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 R9 c2 G! e, E3 Z0 Z! q, c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 }0 q0 w9 o( [& c
  set intersections roads with7 Q- r- ^7 t$ y# v$ Q6 T/ }0 l
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
$ ?8 d% v  L* u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  K, j, r- w) R$ D" A& G1 c4 e: e: k* c1 w
  ask roads [ set pcolor white ]4 ~' _# f- H9 U- Y) V" r
    setup-intersections/ ]) B* @/ w9 `6 J3 H9 _  c
end; s9 A  {! T) f4 e
其中定义道路的句子,如下所示,是什么意思啊?- T# \. }1 `$ W  K
set roads patches with; L8 B0 C8 _  I3 |# q  ^( z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 a* x; s4 K' O8 Z! g: ?+ Y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 d( t/ X8 x0 _+ B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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