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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。. L' T1 Q  c, u' P+ R( L
netlogo自带的social science--traffic grid这一例子当中,$ K# j- m4 [$ a; V
globals
$ U8 T' X1 Z3 r3 `- l5 [[, H# T$ \  a) ?3 Y. _1 v0 K
  grid-x-inc               ;; the amount of patches in between two roads in the x direction* k) E5 Y9 H+ u. ?
  grid-y-inc               ;; the amount of patches in between two roads in the y direction1 D) a  W( {" S* n5 ?
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' r6 {' ~+ E: t; O. c                           ;; it is to accelerate or decelerate
$ H. J6 r; {6 Y8 k: b( b  phase                    ;; keeps track of the phase+ b6 G. e4 q+ U6 h! T
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure% u) d% h9 n1 m7 x) w4 T. C( S
  current-light            ;; the currently selected light
& j! k/ G; _; w( ]( ]
0 \. h6 {5 x& ?$ [$ r, O% l  ;; patch agentsets
3 M3 z9 {' q* C$ X  intersections ;; agentset containing the patches that are intersections: I! D7 r2 A; ]' ]1 `
  roads         ;; agentset containing the patches that are roads/ H8 w4 [$ G1 W0 i. L! d
]1 \; Y  Z" V2 v+ E2 c  J- Y. C/ |

+ }5 S( |0 u: u% {2 L' x1 pturtles-own/ t) J3 f# t) U1 f/ ^' M% ?2 V$ P
[* Q7 `9 `9 ?$ u1 W( n1 X* v$ j
  speed     ;; the speed of the turtle
/ H. @4 {" i9 _1 N8 F9 [  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
" w# k" {/ Q* y$ Y  u  wait-time ;; the amount of time since the last time a turtle has moved/ e( B. m; B1 T4 r( [/ e
]: W9 |# C' v, E
- ^6 H% O2 M4 g( i/ l/ ^
patches-own6 ]+ e% C" ^/ t: I8 c" S, A9 x. D4 ]
[! D, k& {( ~2 U/ J
  intersection?   ;; true if the patch is at the intersection of two roads
# m0 H; {+ J5 c; g" ?  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.0 n8 [" c+ B* s/ `) }8 \
                  ;; false for a non-intersection patches.
6 j9 q7 K% k/ w2 T. X, s, A& p  my-row          ;; the row of the intersection counting from the upper left corner of the3 M% C/ {' I" g- T: }, R
                  ;; world.  -1 for non-intersection patches.7 y4 `: S' J7 s; r
  my-column       ;; the column of the intersection counting from the upper left corner of the9 A# ?% D' u- k4 B
                  ;; world.  -1 for non-intersection patches.
7 n7 L' d- @, U- X- R  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.& q0 T" g; G+ P- X- L( n
  auto?           ;; whether or not this intersection will switch automatically.) w. ~! X  T/ h. p
                  ;; false for non-intersection patches.
2 X. u5 ?- Q( ?]
0 o2 x! z' V! W- `+ o  A4 {7 c9 K. A9 \- a7 G9 K* @
8 \! A# \' p1 v; w1 R
;;;;;;;;;;;;;;;;;;;;;;
  E1 {+ B* C% V  b6 t' g;; Setup Procedures ;;# }( k" d. q8 I; D! H
;;;;;;;;;;;;;;;;;;;;;;' X) P2 U) }/ `: T9 m% \, e. F

- Q% p$ G) S6 X9 M3 T: ~;; Initialize the display by giving the global and patch variables initial values.
. p2 `2 \7 T0 x5 c2 w5 \;; Create num-cars of turtles if there are enough road patches for one turtle to# e0 ]# }. V- j% h5 t
;; be created per road patch. Set up the plots.
: M- `9 L- B; Z: ~1 ~8 e' ?to setup- [* h5 f* g& n
  ca- |3 k* ?- r( y6 S
  setup-globals
* J  {, _2 g$ j
+ c" y; _5 u5 }  ;; First we ask the patches to draw themselves and set up a few variables
. a: q. E/ r; P) c  setup-patches2 s" D3 I2 P$ x" ?
  make-current one-of intersections: y2 K3 [1 ~% w, t
  label-current
- T7 l! _: Y6 n
% R. C$ Z$ W# C: L9 W  set-default-shape turtles "car"
6 }; V" n! W* u4 W5 n7 M; Q' j0 B( G( W6 M, q6 t; L
  if (num-cars > count roads)1 V' Q  _% n& P* ~
  [
" X7 P2 C$ x& w  _+ O    user-message (word "There are too many cars for the amount of "
4 C/ ~; _1 k1 o                       "road.  Either increase the amount of roads "# \$ p% o7 k! v- G
                       "by increasing the GRID-SIZE-X or "
2 c& X+ \6 W9 c5 b                       "GRID-SIZE-Y sliders, or decrease the "
- t0 d9 G1 O! a% Q- Y) k, L" [7 }                       "number of cars by lowering the NUMBER slider.\n"
! L4 N3 |& F: @* l! c  n                       "The setup has stopped.")3 o( U/ M, C  [  r
    stop
  {8 z9 p2 A* j4 w+ e1 X) V) i  ]
5 x& s7 A0 G, |
& H5 g2 X7 h7 `$ [  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color/ a: ~( e0 r9 h" l( N! d' o3 ]
  crt num-cars' n0 |- d$ F( w( B
  [; Q3 f4 Y9 L- d( v. P8 q
    setup-cars
3 t1 o0 T5 T8 |7 X    set-car-color
8 O+ K+ `+ ?9 Y: f. p    record-data
  M$ H$ L5 ~4 X7 A/ E3 K8 Z  ]7 }" x' @% Z0 I" f8 r$ p

1 a1 b# |7 X' j2 }* |  ;; give the turtles an initial speed
* Q  ~+ _0 W& ~& P7 x8 v' L  ask turtles [ set-car-speed ]! H8 s0 o  {& u' n  i

1 d6 E. \6 ^0 [2 ]  reset-ticks
. p4 b# @! x! P& I. b- mend
) ^5 V& Z8 [) s/ h/ E! e8 b
$ ]! O' ?7 _/ A& v" ];; Initialize the global variables to appropriate values8 x# {5 L% @- J3 I8 }5 A. l9 u
to setup-globals0 A# C2 h* w7 A* l9 D3 A
  set current-light nobody ;; just for now, since there are no lights yet
$ m; P: r6 D1 r7 T  set phase 0
- i+ m& @, y; [3 ^; s  set num-cars-stopped 0
$ ~0 l. E' |( N# J* S0 t# {  set grid-x-inc world-width / grid-size-x
9 D4 E& a* T/ G9 E  set grid-y-inc world-height / grid-size-y
4 E. \4 O8 f, Z2 L) y4 j5 F& k$ ^' }1 C' s, c1 t$ @) r3 N
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary4 z1 r  E/ s7 c$ j7 g! h0 [1 y7 e
  set acceleration 0.099
; F+ V1 E0 U5 q, V4 y3 E3 r0 Mend
+ u: D! ~1 O1 k7 ?$ b6 g7 }. u/ }& z! W3 |- [8 B" `2 h
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
7 H/ d5 k+ i1 }- ];; and initialize the traffic lights to one setting% K8 H  B+ D$ ~1 G  x4 g4 P
to setup-patches: C: @" r( `) f2 N
  ;; initialize the patch-owned variables and color the patches to a base-color
! H1 w, h. f1 F1 \5 a3 o  ask patches
, K; p" ?0 g3 [( u  [. V3 J8 }# d7 S" P# h* }
    set intersection? false6 t) \# E- D) D- j7 Z, y: p( I# B
    set auto? false: V! Y, l: [9 B  @+ B( O
    set green-light-up? true
5 X: s9 z! C6 O0 M4 U. M8 l    set my-row -1
/ N/ s  K( n! t. \/ J, w    set my-column -1
% m* X5 d4 A7 g9 I- @    set my-phase -1  u' K( S; f/ K0 Q0 a- L
    set pcolor brown + 39 Q1 i+ m: W( h' F) s
  ]
! W8 y8 O0 L& `3 k% _4 O5 w' n3 `" o' A  K7 y& C) V
  ;; initialize the global variables that hold patch agentsets* v& u* d& Z( P/ ]: u; s
  set roads patches with
4 O' n0 t# o, r( r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: Y9 q9 I* U- I6 B! w; j    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 y+ b# ^! w& w1 ^2 y
  set intersections roads with2 |2 w9 G1 e9 `/ [. x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and8 |% Y( c) w: v5 Z( v6 o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 d8 Z; e7 q: _) p1 f/ k
+ O3 Z7 n) O2 N' X" w
  ask roads [ set pcolor white ]
3 O3 l* z) N3 J- m  m    setup-intersections
2 {$ {- y7 B7 d. V2 ~, y, bend) a+ a1 z8 K, U1 j; W4 W
其中定义道路的句子,如下所示,是什么意思啊?
" [! z$ C& _* ~# t% M: m set roads patches with6 y6 P7 m& F$ e! I) Q4 y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 V9 m% H- @/ J8 o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" w; A: @/ D  ~0 d
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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