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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。: H4 M0 M  v2 |" u1 |, y( {% ?
netlogo自带的social science--traffic grid这一例子当中,
8 s* _; r# Y8 ~1 e  zglobals) G8 v, _$ c; I) N5 |* H
[
, S2 r1 Y! Q9 M9 `$ D/ a5 n  grid-x-inc               ;; the amount of patches in between two roads in the x direction
) i. B4 [# l: |8 V+ M- V1 r5 h8 Y  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 _+ O( s  g+ b: @0 S# M& S  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, l) C8 @* k  ?" Q                           ;; it is to accelerate or decelerate
, R. E, J/ ?4 m: c0 Y; q  D  phase                    ;; keeps track of the phase7 t, n/ F; n+ W5 A& W. A% X$ H- B
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
7 t1 b2 C- ?9 P( v, E' m  current-light            ;; the currently selected light
1 {0 K7 d* l$ T9 h, n2 t* v# s7 z7 m9 Y
  ;; patch agentsets
+ @. \3 {  c2 A. m  c! r2 C8 t- M  intersections ;; agentset containing the patches that are intersections3 v/ m9 G( W" \* M( G. s- v4 I
  roads         ;; agentset containing the patches that are roads
; o4 j! i3 v+ k0 ?1 _# M]
7 W0 \2 I' n. Y: h+ N* G0 X% p* N- b4 M
turtles-own
+ o  v4 t2 V' x% I2 X0 S[& I" B8 [  A% Q) T: ]5 g
  speed     ;; the speed of the turtle
. p  |" G" C" d; f" Q  up-car?   ;; true if the turtle moves downwards and false if it moves to the right2 G; Y% B# g/ W$ I* U+ N6 Z
  wait-time ;; the amount of time since the last time a turtle has moved7 z7 L9 b* u+ w  {! C6 D8 j" q' _
]2 d* }; {# _6 N3 j
( ]4 l% F! f+ a) j  k/ ~# [
patches-own. O- L5 B2 g6 j
[( x1 k/ I, V" \! d8 G
  intersection?   ;; true if the patch is at the intersection of two roads
8 Y2 v% h  M% f) k  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
, [, E8 r( T+ m5 S% X* q                  ;; false for a non-intersection patches.
8 @7 {2 d1 {' }! ]! u; Z, ]  my-row          ;; the row of the intersection counting from the upper left corner of the0 i( C) L! b9 i3 |
                  ;; world.  -1 for non-intersection patches.- y2 Y# u$ M7 V1 k+ h4 o- C
  my-column       ;; the column of the intersection counting from the upper left corner of the- S+ ^) [' j; m! u
                  ;; world.  -1 for non-intersection patches.
& n: G' p0 [; D; f% U  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.+ S/ d1 c& b  |! N5 x1 C
  auto?           ;; whether or not this intersection will switch automatically.1 d  G4 {. J: T" M* O6 ~- ?& N
                  ;; false for non-intersection patches.
3 W; C( d, T3 X4 w% A( |  p]
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! E, H5 T: s9 d/ D0 r7 J3 f% a/ G  S
;;;;;;;;;;;;;;;;;;;;;;( N7 O" s  t1 l/ h( u4 M
;; Setup Procedures ;;
, a. s# D  m0 U- x+ t) V;;;;;;;;;;;;;;;;;;;;;;0 t9 r5 ?$ j; E2 p1 s' j+ z
2 l7 m) a' ?$ G. J* h
;; Initialize the display by giving the global and patch variables initial values., S6 q) e/ D3 @8 G
;; Create num-cars of turtles if there are enough road patches for one turtle to
' @: [. w* F3 ^% b* B;; be created per road patch. Set up the plots.) }, p- \" r1 L, [
to setup3 h5 K) K5 o. V" e
  ca2 ?% i. r4 q( \* L+ P
  setup-globals' w9 u0 P" i: V% O: K" H9 ]
! g9 J! q( S8 i
  ;; First we ask the patches to draw themselves and set up a few variables$ f0 Q! q9 r! _
  setup-patches8 h* ^+ A4 Y( T/ R8 Y8 s- X- |
  make-current one-of intersections
4 w: y* m2 b* w+ P$ `: a" l; l  label-current9 R! T# y- X4 g
% t  C; h) O# s+ t
  set-default-shape turtles "car"4 n1 ?% l+ k- f- {
5 d  c6 |0 N) B
  if (num-cars > count roads)
2 a' q( i: j* ?/ @  [) B0 E( O0 m& Q2 V( g( Y* p
    user-message (word "There are too many cars for the amount of "" T8 Z2 r1 [) ?
                       "road.  Either increase the amount of roads "
# l0 C- N7 ~9 V0 v                       "by increasing the GRID-SIZE-X or "2 E& Y1 S( _( C0 J& }
                       "GRID-SIZE-Y sliders, or decrease the "5 F4 b' L7 K; u) g
                       "number of cars by lowering the NUMBER slider.\n"
/ _; D  t% |) v0 W' z                       "The setup has stopped.")3 ?+ f" z) H: j) [- r' {( m- Q
    stop
( ]( M' p9 ?8 Q8 Q% M/ W" V  ]+ a: l, z7 r0 h3 ^$ t
; N) S2 @( Q, H3 W
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color" B+ r# u5 k! l1 a" F) W* W- Z  K9 j
  crt num-cars
, l+ [2 r2 k1 g2 n. r1 ~+ _  [  c9 v! Z( C+ S' D& @
    setup-cars) n% S! |. r+ I
    set-car-color% B% z* G4 c0 a/ d  d
    record-data
% d8 P" v1 J# W' P  ]$ f6 s) I$ h# z& F: V' e9 P0 N( L
: B" {# O. a! ?& V" e
  ;; give the turtles an initial speed
3 w8 P5 {7 I6 p% f; z6 v9 P: @  ask turtles [ set-car-speed ]
4 }# J* ~7 \# J% I
& N8 o) J5 g( N* u, ^  reset-ticks
% G6 V$ a4 Z1 F, }+ s% H9 rend1 _  S: m9 y0 z

6 T( k- V/ n, o; c7 @& k4 M" r;; Initialize the global variables to appropriate values
8 X! q% ^7 x* n" {% \& F* jto setup-globals
0 L: s  T: x" Z' g( a0 `& X: w1 j  set current-light nobody ;; just for now, since there are no lights yet
3 y' |+ A  _0 s  set phase 0' Q& k/ P5 r, e& P$ H2 g7 \7 N9 Y
  set num-cars-stopped 0
1 r! V1 F) T3 ?  H  set grid-x-inc world-width / grid-size-x8 M( ]! t& X# h* b+ d! k4 R7 i
  set grid-y-inc world-height / grid-size-y
6 b) P  Z, \8 A2 Y: @
- |9 J1 l/ i7 ]: Z% y' B1 y6 I  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
6 b' l' d# k4 v* _- I* m. R' J& U  set acceleration 0.099
+ X& z+ a9 Z# }# ?  Lend
: @) p) F- t" G# u/ B0 T( U2 o
+ U% W- [4 x* ]  j$ H;; Make the patches have appropriate colors, set up the roads and intersections agentsets,8 l8 {& B. S* d9 V( ?
;; and initialize the traffic lights to one setting9 }4 g/ y/ {) n- A" V4 @2 {
to setup-patches
" @/ o0 {. Q* c$ W1 H3 F) [  ;; initialize the patch-owned variables and color the patches to a base-color
3 [1 \) |0 u& L4 {/ ]. Q  ask patches" n8 d  n& \/ Y
  [
9 K2 e- W& V7 l; V3 p5 ^- u6 M    set intersection? false( W# x2 i1 p; c2 O; {$ x2 c
    set auto? false) {+ G3 T  \8 R& X6 j
    set green-light-up? true
2 D  s9 W* s1 x* a4 F9 Z& q    set my-row -1$ h# }! @+ z$ h
    set my-column -1% v* n: |0 Z. g4 m  o; ?
    set my-phase -1
, f* ]+ o0 u2 E    set pcolor brown + 3
1 H9 V. f9 |; O# v+ n! P: X$ p6 n  ]8 [2 U/ x! E' G6 P! i+ X
  P7 [- K1 m2 r" A/ i" x
  ;; initialize the global variables that hold patch agentsets
8 e0 I6 v; d% I) \! L7 L; e  set roads patches with  N) q- Q; [; R, X& w! n3 z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, V( a; Z2 H2 i/ m9 M' D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# @& ?8 ?) T& a
  set intersections roads with7 r) ~7 ~' c% \3 s$ |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
6 e! F3 e4 o2 V: }8 @/ E2 g3 H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  {6 z5 O: G4 U, x0 r3 B* `1 ^* w( v6 E# Y# P) m
  ask roads [ set pcolor white ], s  j7 ~/ c  o6 x; t  q3 r1 C
    setup-intersections
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其中定义道路的句子,如下所示,是什么意思啊?
' X3 g% \2 f8 f- t' v set roads patches with
) @- b# ]# D" G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 A1 l  B! t/ v1 b5 J0 a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 l  l2 H$ u0 i0 a% E7 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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