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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。" o3 F. ~+ \. N. X5 q2 I/ M$ n
netlogo自带的social science--traffic grid这一例子当中,, B, ?+ p- z( M+ Z/ H; z
globals; O8 z$ \! m" ]7 Q' ?. a$ [, ^
[
& k! c7 {3 j: E, n2 W9 k  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. I& I+ I  ?# o, G6 z  grid-y-inc               ;; the amount of patches in between two roads in the y direction
" Z4 o3 G/ ^8 E) P: m2 D  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 |, n  o" h. f* ^5 D9 \6 ~
                           ;; it is to accelerate or decelerate
# Y' Q. Z/ i% ]4 ^6 {7 [  phase                    ;; keeps track of the phase& _, `% u, I+ W9 K, W( V4 }
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; |: L4 a5 W( K/ \) U  current-light            ;; the currently selected light
  x: u8 G2 |$ R5 N- ?3 e; B, w) j/ s/ m7 S" B2 U+ G# m+ _
  ;; patch agentsets8 _6 E5 j5 C) b& P9 x: c
  intersections ;; agentset containing the patches that are intersections
4 {* |2 U" j" E* p. _, n. y  roads         ;; agentset containing the patches that are roads; `' u" O0 _% L; C* j
]
1 Q- I$ H, O+ _) D( \* |9 y4 A0 y7 r; P, i
turtles-own/ s7 q2 N% n9 |# N9 Y% s6 A1 b4 |. {
[
0 q+ s: ?+ I( U/ [$ x; o" H! n- W  speed     ;; the speed of the turtle
1 _' R  i( P5 z3 d$ N- [2 _  up-car?   ;; true if the turtle moves downwards and false if it moves to the right+ L2 [" I4 r# R2 o
  wait-time ;; the amount of time since the last time a turtle has moved
3 t  g* K0 j- i6 {4 {]3 ^$ u3 G: b# I) R5 i

& w: U2 M- N# `patches-own
4 N6 r: G6 Z  X[5 w  ]3 ]% R! P7 y/ L+ C4 U- G
  intersection?   ;; true if the patch is at the intersection of two roads% q& ~7 C! r+ A$ |
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
" y) z2 i8 B7 X% I  L7 _* I                  ;; false for a non-intersection patches.
6 L7 s2 N( e6 x+ h2 |8 }  my-row          ;; the row of the intersection counting from the upper left corner of the
4 c( k7 o. l6 U                  ;; world.  -1 for non-intersection patches.7 g$ ~" k+ O  \) K4 o+ f% ]' d& `$ a
  my-column       ;; the column of the intersection counting from the upper left corner of the
% Z. v" ^& U5 ^9 J# g! A                  ;; world.  -1 for non-intersection patches.4 x. \/ @7 [, e1 T! O: h# n2 n1 H
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
$ g+ y0 t1 a# m) a0 B  auto?           ;; whether or not this intersection will switch automatically., F  W! \( k+ i9 f( I
                  ;; false for non-intersection patches.; d5 i2 Y& `8 X1 c: n) m5 _+ l7 P
]
: m5 E! ~* s! d1 u. V. j
9 W: `2 O  ?% A% x* _
# n2 _2 ~$ L! C6 h2 O8 \;;;;;;;;;;;;;;;;;;;;;;: u) R/ b6 N9 ?8 h# v
;; Setup Procedures ;;  j2 p- A3 w0 @6 y, W1 N" t
;;;;;;;;;;;;;;;;;;;;;;) e/ k& a7 y* x+ ~, G, {0 x

1 y: n0 ~3 T7 {$ q3 U7 o% n;; Initialize the display by giving the global and patch variables initial values.
" D$ N9 r* X# W) L( {;; Create num-cars of turtles if there are enough road patches for one turtle to& L9 Y0 D. G% g  Z3 l4 h% ^
;; be created per road patch. Set up the plots.4 G, o2 E/ k. N
to setup
8 X& t& o) D# {' \) _; B  ca
/ a' J! n) J6 b  setup-globals% ]6 _2 Q6 a5 n4 J& k

$ S3 \$ `7 N+ u( M0 Z! k  ;; First we ask the patches to draw themselves and set up a few variables8 |6 z8 O# m5 z/ }, e% v
  setup-patches* c' p  J. U$ t9 z/ o, ^
  make-current one-of intersections% ^$ r& i* ]$ A6 ^0 D9 G5 \
  label-current& \3 W1 z( x: E- ~9 v

( S; |) p, \2 Q  set-default-shape turtles "car"( w; `; x( E9 d% O# t+ {

0 ]0 r. L/ l- M. q  if (num-cars > count roads)* |! o; x$ u. m! n4 @8 b
  [* D9 d# i4 k: b/ z/ x
    user-message (word "There are too many cars for the amount of "
) w! D- E( X9 G4 [8 B& B4 ~                       "road.  Either increase the amount of roads "" \4 x$ y+ ^! X- |7 u4 T1 x
                       "by increasing the GRID-SIZE-X or "
+ o1 H- T  O. N% `                       "GRID-SIZE-Y sliders, or decrease the "
1 i* \8 ^4 G( a; O3 o: i                       "number of cars by lowering the NUMBER slider.\n"
+ ^0 ~+ J8 U2 T                       "The setup has stopped.")+ [' ^4 U* e" x6 T2 O6 q
    stop
& V  N2 @! S# P: T9 K  ]
: U8 K3 G- A% _- M" p( x1 n! X/ S- k) @; A* C: W. W9 [' ^
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
" x1 m4 b! _! S) c! V  crt num-cars) F: S5 E! i1 |4 b9 R$ ?+ L
  [
9 N. h% g: c+ p# M) X8 }    setup-cars
1 {6 z# f# d0 i1 X5 U    set-car-color' A% G% U* O9 y, h' g2 L! A+ c6 d
    record-data4 \2 m$ G/ @; b1 K  G" S" ]! z' W
  ]7 I* V4 E, I3 |+ u% w

" X* L7 Q3 R- ]9 f8 g  ;; give the turtles an initial speed
6 m$ m/ h7 d" h4 H0 ?$ t  ask turtles [ set-car-speed ]7 Z# k* o) L; R+ q1 I6 o0 D
2 z) R7 Z+ `: |# L  d5 l
  reset-ticks9 x+ Q# d) K2 k5 J, G& \8 y7 v
end
7 @$ z! p4 U3 }7 Q; y: J: n
9 i1 m2 v4 W+ D' v9 y;; Initialize the global variables to appropriate values
3 V# v$ i0 X& ?to setup-globals
. r) q. _0 d: |9 u' ]7 t$ b  set current-light nobody ;; just for now, since there are no lights yet
) G- I' x( r$ w* ~; Y  set phase 0
( g% l& d+ K9 ?+ A" r  set num-cars-stopped 0
. R6 C6 u# I0 G1 |+ a  set grid-x-inc world-width / grid-size-x4 @; O: W' i) O5 N$ O6 ^
  set grid-y-inc world-height / grid-size-y
' }& g0 H) M, R" n: r0 ?: R; g* C% P, \. {* s* Y% H8 t: N
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
8 o2 l! C4 j  y6 m6 \* [; [! Q  set acceleration 0.099- `2 {: s4 {9 l+ d5 B
end( m5 [( Q( |+ W4 `% S+ Q, d

9 X, B; i" r! b1 O;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
* Q2 C& \( `  L$ J: S" D;; and initialize the traffic lights to one setting
8 \8 z1 h& r$ j" F# g5 l4 p. lto setup-patches
' k5 Y& z# E* i2 I  ;; initialize the patch-owned variables and color the patches to a base-color3 M: N3 }; G: e! A/ H! d) b
  ask patches
: \. U: L0 {7 p1 Z8 E2 t: v  [
$ j9 b! U' w7 W3 ?* I# {' j    set intersection? false3 Y( F8 K& X9 B4 S' O( o4 b
    set auto? false
; P7 ~* d$ I4 D( v7 V2 m    set green-light-up? true0 F3 Q; A7 L- ^9 k
    set my-row -1
* u! o7 K" n" [* L7 Q. R) ^    set my-column -1# p- ]( D) M; A
    set my-phase -1
" N9 w1 ^% c8 g9 I  l# l, S, O( d    set pcolor brown + 3
. S8 y$ d5 Y; L$ J* \3 r( F  ]! m2 @2 u) @" Y  q, E1 X' c5 y8 ]
4 z% t- S4 p- `, J% r
  ;; initialize the global variables that hold patch agentsets
! F1 s* w, j* |  k  set roads patches with
6 z0 B& z  _9 X1 M) X/ D3 d" j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' P$ y. o0 X. ~% ~- C2 l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ x  t9 S$ h; ~8 n5 X4 b" o, I  set intersections roads with" u7 K" q6 p0 p9 M. A
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and1 w' r0 V2 q' r) q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 q+ x* B- V4 `# F$ R
+ }- ?1 I- n' ^( j- `
  ask roads [ set pcolor white ]
% `" o7 x# p, }7 U4 v  h    setup-intersections
! Z8 ^* U5 l# j) j* r; `end
# W' L4 `% F8 r& ]其中定义道路的句子,如下所示,是什么意思啊?
( M& J  `& h2 n, Q9 A( v set roads patches with4 `0 Z! s  o' A5 }
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ |: m# T$ O+ i6 F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- x, ]: X6 O2 ^' {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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