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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。) q( @) N6 ~% Z+ m/ i" m
netlogo自带的social science--traffic grid这一例子当中,
8 a" s3 |  L; f- P6 Lglobals9 u. H6 h. m8 j6 c% u
[6 W% U4 J" n3 R0 s4 f
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
3 x) S5 i! E6 p8 L  grid-y-inc               ;; the amount of patches in between two roads in the y direction
. C% p2 w- b' x! D  acceleration             ;; the constant that controls how much a car speeds up or slows down by if6 ~5 U6 e, J  i: _) M6 c! q
                           ;; it is to accelerate or decelerate5 N% j9 e! p# W: i) q
  phase                    ;; keeps track of the phase" u. r6 ~1 `. Q" l- h
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
. }- m6 s7 p! ?  current-light            ;; the currently selected light9 N( Z0 z9 G+ }9 d$ g

- w3 y. Y+ M. x; G$ _3 T% }  ;; patch agentsets! j. s) M+ i, _
  intersections ;; agentset containing the patches that are intersections
" `  }2 O6 }9 b( b4 \; g9 m  roads         ;; agentset containing the patches that are roads
3 `. ^4 M/ i+ A: c1 i]$ T3 s) b3 g# Y+ ?, X
3 u8 x) k; o3 [5 m/ j; C/ W2 R
turtles-own) Z6 w6 e. ^" n) A/ D0 b
[
4 u+ f5 c$ ^, f1 W1 V  D' a  speed     ;; the speed of the turtle4 Z; I& k3 S, U: B, a3 m
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right* Y8 b  O8 W. y# M# L& ]/ |' B
  wait-time ;; the amount of time since the last time a turtle has moved
& l! L7 [' `. v) Y7 W' K]
% g% J  h& q0 u' n( T6 w
5 X4 G7 Y2 N; m$ _) hpatches-own
2 X% @' E0 Q7 ?[
- g" n9 B, i# P$ H4 h& V  intersection?   ;; true if the patch is at the intersection of two roads5 s7 ^7 M2 Y5 x$ a5 D
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.9 o# h9 @2 M% n0 d
                  ;; false for a non-intersection patches.% m0 R! [8 i1 h" z% S$ u' a
  my-row          ;; the row of the intersection counting from the upper left corner of the
  Q% c: U8 @; }; M+ [- _3 T                  ;; world.  -1 for non-intersection patches.! t' J8 z' ]- D3 v8 P, o& l
  my-column       ;; the column of the intersection counting from the upper left corner of the
( \( T7 v% e  d: n, V                  ;; world.  -1 for non-intersection patches.: |- ]5 c* l0 U: x# Y* ^- L% u
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches., U! g1 V" Z0 {/ x5 ~
  auto?           ;; whether or not this intersection will switch automatically.
% E7 D: g  E' q3 Z: X( o                  ;; false for non-intersection patches.2 }  o9 L2 }, v+ {) K
]
( k6 B7 y/ i* u" S/ V! f; F9 S+ d" `# a7 z) n1 Q) R/ N: u' v  f
0 Z; S+ F4 m  X' L
;;;;;;;;;;;;;;;;;;;;;;* _. o& d9 X! L! _
;; Setup Procedures ;;
- ?6 q! X0 o  P;;;;;;;;;;;;;;;;;;;;;;
( ^; o9 ]8 w; B" D, {5 R! L. F" O/ H& U1 w! [% @
;; Initialize the display by giving the global and patch variables initial values.
# f4 m; a% i( d+ V. S1 ]2 e;; Create num-cars of turtles if there are enough road patches for one turtle to# C  |9 p6 Q) I# w* s/ z' M
;; be created per road patch. Set up the plots.
, U: k9 l8 u5 g! |# o. _to setup2 [* i2 s. \2 N" N$ O2 l9 i
  ca
5 V$ ^% E$ b9 w$ l# a  N, B4 U9 h  setup-globals
5 M0 V2 k& [% Q& L6 L( e% }+ G3 P/ u* j3 q2 V" L/ j# I5 w
  ;; First we ask the patches to draw themselves and set up a few variables0 m1 a9 L9 q- P& y1 U6 T
  setup-patches; }6 h0 x& G1 X4 s& M; X: q
  make-current one-of intersections
; V& g( f& V2 V$ Y% |# {  label-current
# u' l) j2 a9 N
  W  ?! c" y9 D) m$ W  set-default-shape turtles "car"
( B# J8 ?- Z  L8 I
; Q% J1 r* d5 |2 b& L1 {  if (num-cars > count roads)
+ T2 m# m9 \& n: v- ?0 T2 T  [0 ]' A8 O5 c( C, D/ h3 l9 z
    user-message (word "There are too many cars for the amount of "
# V8 \) @( C+ r5 Y+ V. \1 ?( E                       "road.  Either increase the amount of roads "
$ j' M5 z& ?0 V) |0 C                       "by increasing the GRID-SIZE-X or "9 W, Q) }5 b0 T5 J7 q$ o* s2 p# Q3 V* P- g$ f
                       "GRID-SIZE-Y sliders, or decrease the ") @+ e4 m7 w% u- d( V
                       "number of cars by lowering the NUMBER slider.\n"
4 `8 r$ @5 R! E& G% R                       "The setup has stopped.")
. [( N% O$ b  K3 Y9 `    stop* n: d! x8 ~1 J' g) a
  ]
4 X( Z+ a# e9 g9 z( d4 X9 a8 E
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
: D' i. g; x4 \' q. Y  crt num-cars& y- w) g( r; \" x  s/ `
  [
; h! Q% w+ A4 A3 `1 x1 O$ a: ?    setup-cars$ t# a7 Z" M+ w; M+ H! p* V9 \
    set-car-color7 R  \) N+ H7 F; s2 U" T. {4 f& _
    record-data! V. n8 T5 B6 {$ a: r
  ]
8 T# Y9 f) k9 ?2 C+ t4 s6 H5 t: K1 i# H) s% l! w
  ;; give the turtles an initial speed
/ A/ m3 ]/ g, n, [  ask turtles [ set-car-speed ]
* e3 B( i! y5 c9 ?$ b5 s/ J4 i2 G% q! \8 f, H% {. O; \
  reset-ticks
7 q$ T  H, Y& D  bend
' j, j3 K  o$ X7 x) @+ Z- i8 a5 ~2 Z' k% ]4 H4 G$ r' t" V/ J
;; Initialize the global variables to appropriate values
9 s6 {; l8 K$ \to setup-globals
+ _% _4 \4 Z. C5 R* L  Q  set current-light nobody ;; just for now, since there are no lights yet) H: Z$ X8 ^8 }4 M6 B% ^$ H7 C
  set phase 0* {8 D7 M: s  j: Y2 L+ A0 {
  set num-cars-stopped 0. X  k* M  `/ z1 l! M7 h* \- `
  set grid-x-inc world-width / grid-size-x9 y# ^! O: `; K" b5 _
  set grid-y-inc world-height / grid-size-y: a8 Q0 t$ V( \  o/ Q8 F$ ?) A
' ?( q, J) l; F! ~7 G
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, q' T, H; \2 l1 K( \" O
  set acceleration 0.099
, U7 ?0 l  _& r. G) U$ ]' |end" |1 [2 o/ A' s4 L# @# `/ @% Y
/ p3 z: g- `% }$ f5 K( S9 X
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,3 V# X& c& O& {& M, w: B
;; and initialize the traffic lights to one setting
' l% A4 t" Q2 w" u; e) V' ato setup-patches  M# K5 ^& d; f' |4 H6 A
  ;; initialize the patch-owned variables and color the patches to a base-color; `" |& ~6 _. i, ~9 o3 d: j
  ask patches
" E) x& s% b8 |! u) d7 ~+ V( d) b  [
& P( }1 Z' n0 s$ ^3 t    set intersection? false
# @# T+ E" F% x( `7 ~4 L0 ]    set auto? false% [9 F% E% P8 n  ^1 `, p- B
    set green-light-up? true8 [' x' f  w1 w$ r" x
    set my-row -1$ x# M, c# Y" A( E
    set my-column -1" K, f* ^. e, I, b1 b
    set my-phase -16 [# M& q5 \' G+ I. w7 ]8 u( d
    set pcolor brown + 3
; E4 I% q. U  h( ~( W2 }  ]. S2 H2 B9 i% J6 t; p- |" V
$ X4 ^/ x$ ^% N
  ;; initialize the global variables that hold patch agentsets2 T% Y2 U  C! M5 k$ B1 {  B
  set roads patches with
% r  |+ q$ s4 ?    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 y1 F# L/ X9 T
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: w: K3 e/ e0 u# B7 z. P' w
  set intersections roads with
0 L% G4 p# k" y' X+ G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
- O- R& J7 ]6 _; T( v+ e    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* q; T% A: v9 J- K4 i
/ i9 ^" T* m' p6 ]6 K0 E
  ask roads [ set pcolor white ]' h6 z2 k0 K0 Y( m( }1 j
    setup-intersections
& w6 h) P' A" J4 `& _( i( Q$ Vend8 Y. U2 q9 A: y* M0 \
其中定义道路的句子,如下所示,是什么意思啊?8 P# |' V& x4 N# @" T% I( K
set roads patches with
! ~# z; |  G3 t7 ]0 F3 M! f; t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 b- E, F" |/ [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- N! f9 F, j: S9 i* t/ N- d5 X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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