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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。- x! t0 X; p: H' c, r
netlogo自带的social science--traffic grid这一例子当中,
6 t, `6 ?! x& b: C" wglobals
& d9 n' E6 k  O$ w[
/ r6 r0 i) ?+ w  grid-x-inc               ;; the amount of patches in between two roads in the x direction2 I; f0 n2 A7 P8 @- H
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 f% G  k( o* v4 v8 N  acceleration             ;; the constant that controls how much a car speeds up or slows down by if& l# S& W0 x/ {
                           ;; it is to accelerate or decelerate
9 z' d3 G2 R" q$ x& O  phase                    ;; keeps track of the phase
- h5 V( c$ K! e6 K+ O# U/ C  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
: ]3 K0 U9 K# Q* y  current-light            ;; the currently selected light3 G0 ]: t0 t# j& s2 U6 ]
1 x! a& [* L5 k: Y$ f4 A  m
  ;; patch agentsets
2 S3 z5 s8 A9 u7 j  intersections ;; agentset containing the patches that are intersections
, b/ p. F' S  |% s. y& ~* }  E8 _  roads         ;; agentset containing the patches that are roads
2 I& P. f3 T& \) n# D]
5 g0 l5 E& t; h8 C5 j$ c4 \5 J# B; c( H- [9 V' Q9 M
turtles-own
+ N' M& g- b# L# W. G[
. f& Y; ?* |) E. ~2 u; t  speed     ;; the speed of the turtle& t# Z- m6 C- d
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
  v& Z2 f7 y3 j# S7 r. z  wait-time ;; the amount of time since the last time a turtle has moved
1 n9 u  Q% Q; m- N0 d7 J]: s$ y/ |  K3 Q6 W* y5 s0 f
* f8 o& q! g! d
patches-own1 k, @) p0 l8 V. H
[0 X6 W( t4 r  p# p
  intersection?   ;; true if the patch is at the intersection of two roads7 i$ E; s2 d4 C1 Q, ?
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.' u9 ?% e1 L9 k" c" E# j% X- s
                  ;; false for a non-intersection patches.
% y# f0 j7 S8 W, O# ~8 }5 k# Q  my-row          ;; the row of the intersection counting from the upper left corner of the
& L  g- I3 |, o* @                  ;; world.  -1 for non-intersection patches.
; b3 p/ d$ t" m  my-column       ;; the column of the intersection counting from the upper left corner of the
1 n% _/ G* n: o1 |                  ;; world.  -1 for non-intersection patches.
& d! V3 ]$ D8 h* z! s  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.: Y; y  G. @  j8 C; P% E
  auto?           ;; whether or not this intersection will switch automatically.8 V; g9 n! T9 e( C3 U; H( p
                  ;; false for non-intersection patches.
# D4 x# l- Q8 t6 n6 p8 J" l]
5 e' w3 G$ S- Q' h  l: s6 I5 x! Y, y5 u! v" E& s

' P- q) e6 E) _' E;;;;;;;;;;;;;;;;;;;;;;/ |' P5 s$ c0 Z1 z$ E3 ~: g7 R
;; Setup Procedures ;;
' {, \& ~/ p! p" a8 K- c;;;;;;;;;;;;;;;;;;;;;;- ^, ]8 ?1 o4 Z9 a" @3 y# ~  R
$ C& _. E: g0 j  s2 }
;; Initialize the display by giving the global and patch variables initial values.
9 ]3 s  W/ d) W8 _0 _: V8 a. v;; Create num-cars of turtles if there are enough road patches for one turtle to( V5 k3 J( g# G1 N8 c
;; be created per road patch. Set up the plots.2 e7 m, \- ~* V" i' @8 J" f
to setup
8 {5 U- _7 f" v! s5 I  z  ca" f9 t; t: y' m" U4 F
  setup-globals
2 ]6 I$ o7 L6 j5 K
' A( X3 k3 J2 Z9 e& G2 d  ;; First we ask the patches to draw themselves and set up a few variables1 X, O8 S" q& Q- I' t; {2 h
  setup-patches8 c* w2 Q+ Q4 s- a* b& D7 ^
  make-current one-of intersections& D, l2 t8 C! H5 Y
  label-current
* ~1 @9 O' b0 G  Z) l
! F  R- V+ r4 K) t7 _  set-default-shape turtles "car"
0 P7 t: v2 m* e% z. w6 s9 ~& L  z( D$ d; B" S; Q# Q
  if (num-cars > count roads)/ u6 Q( |4 d$ z# A, _+ e1 {
  [
& I# h' y# Z7 [& _    user-message (word "There are too many cars for the amount of "
% M; J- V' d$ \7 \% J' s                       "road.  Either increase the amount of roads "
2 E# y& T" L* y" ?% O                       "by increasing the GRID-SIZE-X or "7 c' c/ D7 R- ?; J8 G, V9 T
                       "GRID-SIZE-Y sliders, or decrease the ") ^1 m3 u& I* V8 Q  b
                       "number of cars by lowering the NUMBER slider.\n") r  R/ [' I3 G9 _; m
                       "The setup has stopped.")4 `8 ^. u7 a6 K5 s; p
    stop
; q9 @7 z- \8 q& Q* V  ]; h, Y6 Q7 D# p, s
' n8 N6 ]2 p. b/ I* X4 x
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' h$ U! M  `: |  a; c/ Y* x4 h3 k8 t/ X  crt num-cars  F% @9 @1 u9 V& A
  [9 O1 g# q2 ~5 z6 ^+ J# ^! F  Q
    setup-cars
4 ?  G1 [2 w( A: _% j    set-car-color' U# x; r. }$ t% N0 D
    record-data
+ V0 c; @+ U2 e  ]
, v" }5 i& R0 t8 V) b, [1 n# g( c  B- ^
  ;; give the turtles an initial speed1 V2 r$ Q0 Y, S! a2 O
  ask turtles [ set-car-speed ]
* @/ N3 T7 v- T0 o: r4 V6 F" A0 N5 A: D
  reset-ticks
) K2 X% p+ K( `3 y. Y  b8 \4 Dend- a( h' g% o' d6 v

3 _) k2 L; s4 P2 n; I5 \7 O+ a* U" b;; Initialize the global variables to appropriate values
4 V9 a* g& k/ f" c3 Yto setup-globals
8 n( L) o" J2 M. ^& X# i  set current-light nobody ;; just for now, since there are no lights yet9 k) g4 z5 `! A1 o8 D9 H6 ?+ g
  set phase 0
& K2 i% t* f* o# ?4 `) W1 p  set num-cars-stopped 01 x5 `; F2 J- B7 {$ a) }8 j5 }
  set grid-x-inc world-width / grid-size-x
: Z9 b& c4 D% x  m7 f  set grid-y-inc world-height / grid-size-y' i2 ]& a) c3 }: L( _

( g3 x: u8 W$ U# s; \; d* w0 H; Q  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
# T( \4 x: \/ C. b, {4 ]  set acceleration 0.099
. C4 ]' F7 F; Q8 P9 |* H" N, |end; m) C6 X4 K3 a/ D1 `( t/ t; }+ N) m
9 o* }7 W* V" B. B$ X, b* Z
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
3 h2 z# B" [$ t# e' ?( _;; and initialize the traffic lights to one setting
5 b* H, v1 X' M! O( ]* ?/ Z- y4 y$ S& uto setup-patches- X7 D) P6 D9 q2 }
  ;; initialize the patch-owned variables and color the patches to a base-color* b1 K1 G) ^  b* f6 E
  ask patches6 D/ ]5 |1 Y! M6 i
  [
7 f& _, H, j8 y- }    set intersection? false7 G( @" |' W0 y- o4 S$ X
    set auto? false+ T% J" s+ K& ]. @0 x( q) s
    set green-light-up? true7 O% A7 s& Y2 e0 @  F" {
    set my-row -1& |0 F. {8 b! K+ g/ n5 Y
    set my-column -13 z) k9 Q( {8 e  t- \
    set my-phase -1
. b: k& m+ X# C0 G) A    set pcolor brown + 3/ t) I6 e. D. T+ d6 `# Y( @5 E; [9 ?
  ]
1 [/ R* d2 L6 V2 x0 z- \& F
0 Y2 D  O& c  P1 C8 a7 Y7 {  ;; initialize the global variables that hold patch agentsets
5 x5 T5 X7 M. \  set roads patches with" W3 D; ]% V, x. Q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) Z/ H6 g% u& ^7 H6 ~* b
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! s8 P' s/ Y" P% ?. D
  set intersections roads with
" z- V# j! @6 e6 p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and' B6 ^' N1 \3 s$ E3 ?  }
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& i1 Z; D- o, M( i8 ~5 ~1 }# O7 M
2 |# R0 U9 E, f
  ask roads [ set pcolor white ]: w4 P& r5 c9 p: c% \6 C
    setup-intersections
# `. P: d9 M. H5 t- Nend7 P+ f( c4 T. N8 W1 F. Y
其中定义道路的句子,如下所示,是什么意思啊?
! R7 `" ~( n. Y# p  A; ? set roads patches with
0 H2 A5 z0 Y# Z, o* ~2 V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) J% r+ s# c" Q8 L
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, t$ q9 M- z8 [% J2 ?" ?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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