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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。" j6 u# v* M& \) `- w+ q
netlogo自带的social science--traffic grid这一例子当中,& R! S; |+ k+ e6 x
globals" W1 W* U4 Z5 q" t0 z
[
5 b% G& Q) }4 r  grid-x-inc               ;; the amount of patches in between two roads in the x direction; G' S( B: ~3 x9 A1 S9 C4 [
  grid-y-inc               ;; the amount of patches in between two roads in the y direction9 [. h. c$ B. x9 E/ d
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
; B2 |, [# E9 L! ^5 ?' ^& P                           ;; it is to accelerate or decelerate2 _" V6 c& a7 U% j! j% m
  phase                    ;; keeps track of the phase
& d1 Z( c/ g0 m' m! P+ L+ ?  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure- T: h& ?9 M% e6 x" t; Y* a
  current-light            ;; the currently selected light0 g. `. |* S. [9 M1 P% Z  n* a

! [, [3 k* D  l  ;; patch agentsets
) @/ {0 _+ s0 Z8 d# y7 [  intersections ;; agentset containing the patches that are intersections
$ Y+ p5 z) t- W% g2 `  roads         ;; agentset containing the patches that are roads
1 q5 B% R( d. Q, y( r]: G: e, |8 F/ l) X5 J* W4 n

! H( t( e! s  [- v! A5 L/ mturtles-own
- H, z9 m, r+ W5 V: }[
3 S; P5 E  H1 g- k# n  speed     ;; the speed of the turtle1 j; N; g, z; ]5 Q, q
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
6 O2 E7 D* U1 r6 _( F  wait-time ;; the amount of time since the last time a turtle has moved
7 ~% \$ m% b7 \$ N6 F; L1 |]+ }! g+ f2 y* x+ p( H- |) G9 n
- [3 o2 S: R. H) ~& K
patches-own
7 t5 o( x+ m$ ]( `/ O8 Y9 A[
" B7 A% s* [; {( ]( C8 u3 w5 N  intersection?   ;; true if the patch is at the intersection of two roads9 l! M; ]+ D7 e& j4 s! D
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.1 T; [0 j, {8 t# h4 R9 w, C
                  ;; false for a non-intersection patches.* Y, r! D0 j" L: h# o
  my-row          ;; the row of the intersection counting from the upper left corner of the) f8 B" P, O' U- M$ g0 z
                  ;; world.  -1 for non-intersection patches.
4 N# c" X2 j' I, f1 y  my-column       ;; the column of the intersection counting from the upper left corner of the
$ A& `, v+ {- ]. `1 a                  ;; world.  -1 for non-intersection patches.) G0 ~/ G8 }9 F. l
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.' |, [5 ?  v4 J2 J% v
  auto?           ;; whether or not this intersection will switch automatically.5 _' b2 P" O# w$ P5 K
                  ;; false for non-intersection patches.# E( M+ o/ ?! E* S# G* j$ H" K6 z, i
]3 i% w' `  u( q: \- ~. j% j- P, W

9 X' b' F4 _  R" k2 L9 y# b: `  i: ]. a, S
;;;;;;;;;;;;;;;;;;;;;;/ s. {# a( V/ U! l7 s4 t, i; [
;; Setup Procedures ;;1 c# t. x6 ^$ `1 x
;;;;;;;;;;;;;;;;;;;;;;
6 U; C0 B: x1 y" z1 H
: x, W3 u) @; C. S# i;; Initialize the display by giving the global and patch variables initial values.- I' c8 v* w" ^/ D  j
;; Create num-cars of turtles if there are enough road patches for one turtle to5 ?9 @3 ]3 }) A
;; be created per road patch. Set up the plots.
% m7 m5 H& i+ Rto setup8 W2 @) @# y0 I+ h/ g3 e) X
  ca
6 A% k% Z9 e1 ~. K: V# h  setup-globals
- {. d$ @8 N$ n% W, B. r+ w# G2 H9 j/ C( T/ o9 e( z/ u+ ~9 r
  ;; First we ask the patches to draw themselves and set up a few variables
8 D' I( K  z* P  C/ i; M8 B  setup-patches
+ q% f4 K( L; q$ b3 S: `  make-current one-of intersections1 k" N: q/ e1 e
  label-current! [! u& I5 ?. H

% e, c" `8 o, n- l1 a$ c  set-default-shape turtles "car"
4 J7 @& y/ h9 U9 Y' I+ V: c4 B0 m& r
  if (num-cars > count roads)
' Q0 P7 P  s( U  [
+ E( J2 ^1 a& f$ V6 n& s$ |    user-message (word "There are too many cars for the amount of "" u9 F9 E& b  d' |
                       "road.  Either increase the amount of roads "4 T2 W) v7 a) _" @- R- g  X4 _
                       "by increasing the GRID-SIZE-X or "9 @3 P6 n" P& B0 O' h! Y3 z
                       "GRID-SIZE-Y sliders, or decrease the "  o8 Q3 q- B% O' t+ ?
                       "number of cars by lowering the NUMBER slider.\n"2 c1 |" a) K; z# v" w
                       "The setup has stopped.")
5 \  O( {! X0 C, [: e. T, l    stop1 ~* Q  L2 Y6 o
  ]
7 V, j" {2 Q2 L# {
0 V# y- E; p' v1 _  }) y; E  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
4 r$ y9 e) I1 w1 f" V! ]) T9 w$ l  crt num-cars& m! z  i' V% g' y. d& b, B
  [! g$ E$ D& r/ W# l& K* Q2 S' _
    setup-cars- [( k3 v9 e& f; s: Y; Y1 Y: j
    set-car-color
6 q3 y  I0 i5 I; B: C, h( |: H1 _( g    record-data' ~4 q8 L+ _5 ~% h3 I  o
  ]
3 P. e' V/ E2 D8 q- B/ K' ^3 Q  @  H3 n. t+ W- Q, w0 s- q
  ;; give the turtles an initial speed
; N' c. M' R1 f6 R4 y  ask turtles [ set-car-speed ]2 {, a7 k0 b6 }( L+ g# W6 u
4 E8 \+ Y' U# [  k, k
  reset-ticks
( l/ Z, m0 |& C" @6 dend
  S/ n# S$ t: ~) j& o
) L$ ~  W% m4 v5 `3 z* |;; Initialize the global variables to appropriate values
' L* \( x1 y) fto setup-globals
. s* z# x* K- M: y; r9 y  set current-light nobody ;; just for now, since there are no lights yet, u9 ?, \' J. @, v, E
  set phase 0
: s9 ~: L* C7 q  set num-cars-stopped 0
; N: v) W  W5 V2 O8 V5 E. y  set grid-x-inc world-width / grid-size-x* B% N9 b( h% C! A- N$ L2 L3 p
  set grid-y-inc world-height / grid-size-y
- S* m: t3 v: q1 h
% F2 D% v. o) e/ [$ ]5 D  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
# t. b0 V& R+ @" E. d' H  set acceleration 0.0997 l) v, W% H: B$ \
end
& F' f$ M8 s5 r- G7 {2 V+ G1 S3 C4 P  ]
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,8 K7 Q" b' c; t
;; and initialize the traffic lights to one setting% A+ C# {3 r5 C1 R) C
to setup-patches* N4 p8 M( g% O7 l& J% I
  ;; initialize the patch-owned variables and color the patches to a base-color  Y9 \' K8 Q& N! b
  ask patches
! ~$ B. h5 c, r7 @5 G  [
3 q" P: k4 b% [    set intersection? false* b0 J. N7 T8 Z1 {
    set auto? false
4 j0 J: Y2 P. i  i  j    set green-light-up? true# |& T' h2 M" [3 [" r. h' J5 [" B
    set my-row -19 t' y5 T: R( d7 f& U
    set my-column -1
$ i: a0 E% x2 _( |  D    set my-phase -1
6 p2 Y7 ^* j, V8 o1 r    set pcolor brown + 3+ o& K0 y" a  O: y5 B
  ]3 |( T* ]( _( g+ b5 l; S2 H4 @
$ w+ R4 P( v- R, ~5 N
  ;; initialize the global variables that hold patch agentsets
& l& [, [$ P' D5 M% R& A% B  set roads patches with
, _! I, W$ v3 i# l, n    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- ~3 |0 ]" c2 C/ h; H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* `! D& q( p$ ?. K  set intersections roads with$ B$ t4 z1 j) v9 r
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ {# f. P3 i# N* Z0 K8 H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 \; ]* \7 ~* ?" o

" [. N7 ~2 r' Z  ask roads [ set pcolor white ]
- J/ c2 v8 `9 V    setup-intersections6 ?+ ^- u/ Q! a2 ?( ]4 i
end
( {1 u6 o$ H7 u: C5 f; e$ \其中定义道路的句子,如下所示,是什么意思啊?
; V( x& C( G% Y& t  i set roads patches with
, O# c' l, L* ~  h5 C+ g% l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ }3 P& M( ~/ r
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) ]3 c# z# l( n  {8 J2 Y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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