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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。& {/ d# u1 }7 I+ d
netlogo自带的social science--traffic grid这一例子当中,
. `% a/ N/ D! n/ \, O  S% Z/ bglobals1 R, c# B) P1 Z; x
[
0 g5 e8 E5 v  l" L% R3 V8 }+ U  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. ^( P) c% [! |2 s  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, }! Y) g) X2 Z7 O  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
. M$ ]: c7 B6 `  G) d3 X                           ;; it is to accelerate or decelerate
2 f, N. ~2 V+ ?: F) N9 V5 v  phase                    ;; keeps track of the phase
: j: D! T" L  G' Y  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure! Q; R6 h9 }5 `( W& T
  current-light            ;; the currently selected light
) b, u$ r  ?* K  l3 Q- O3 K/ d8 P- p4 ~3 `7 g) P
  ;; patch agentsets- _3 s1 B$ K1 s$ Q& w
  intersections ;; agentset containing the patches that are intersections
6 m' g0 O* t3 Z3 _8 R" \  roads         ;; agentset containing the patches that are roads: Q* `0 S, r8 s4 C8 _% u5 \
]
6 ~  e% w/ C9 a1 n
6 ]2 d, X* ?3 v4 g7 aturtles-own
+ I7 a2 v1 ^+ b% F: k# L& B[
6 ~) g% k# s! Y* U2 m; [  speed     ;; the speed of the turtle
( ?% P5 w4 u8 P' G2 N# k  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
" x! }: ~# v. a- N  wait-time ;; the amount of time since the last time a turtle has moved
* ]/ U& T# y( m' m- I- ], }  p]  y4 I* o" S8 d9 I/ Z$ v6 D* F

; n6 Q* _7 p$ m) ^" Q; Gpatches-own
! W; L/ b* W7 [  {+ e; V[* p' T  X! @) O, f! ]8 E8 z3 w8 t
  intersection?   ;; true if the patch is at the intersection of two roads- `9 l7 }" K( P( ~4 c6 N0 D
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- C! k4 e) q8 F& K
                  ;; false for a non-intersection patches.8 d% q: S+ _, k9 {0 t0 O  h
  my-row          ;; the row of the intersection counting from the upper left corner of the
) B# }- [# c5 z# s/ `8 F                  ;; world.  -1 for non-intersection patches.
4 [: s$ [6 N: }9 j  c' B  my-column       ;; the column of the intersection counting from the upper left corner of the
- e* i& q& e( j0 a5 ~: y                  ;; world.  -1 for non-intersection patches.
2 G. R0 _9 |9 B/ X  N: Q  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
1 ]% w/ q- q0 p  auto?           ;; whether or not this intersection will switch automatically.; X9 Z2 r3 }- I. f
                  ;; false for non-intersection patches.
) G. y2 G  D! P7 V1 F1 G% R5 m]
4 \2 U# [4 C" \3 A+ h, W
$ F2 A: N, j# i) a  r. ]) o
. I# x( P, q. Z7 [7 C) {;;;;;;;;;;;;;;;;;;;;;;& s, V# B" T. C% W, M3 U8 T
;; Setup Procedures ;;' f$ H( e3 e7 X# o! _
;;;;;;;;;;;;;;;;;;;;;;
1 q8 Q+ o/ o8 E# V0 I$ z8 ^$ V# Q8 g# ]3 o
;; Initialize the display by giving the global and patch variables initial values.
1 |* u6 O* U# p& x. u;; Create num-cars of turtles if there are enough road patches for one turtle to3 A/ N9 k9 r* T( \# @" e3 B
;; be created per road patch. Set up the plots.
. r9 }( S9 n2 [/ R1 L2 }8 Uto setup& ?- t0 ?; x; l, {2 y
  ca
- X% s0 _* u* D/ R; n8 |# G  setup-globals2 t, T# w( ?- V! W" C7 _

" V- v) X8 l9 Y" f4 ?  ;; First we ask the patches to draw themselves and set up a few variables7 t1 n  G! y8 G: _
  setup-patches
9 F( I; @) m6 r" O' y  make-current one-of intersections% ^4 m5 f. l: [9 g" I" s: V
  label-current
  |+ Z4 k: W  D# }& Y7 o  F; Z6 r8 V( }& E3 {) e
  set-default-shape turtles "car"" C: E! V1 M% [& B
" d) E( T0 X3 E" ^; Z4 i+ Q
  if (num-cars > count roads)
9 Z4 `* I* w2 z  [
% V& q( P: ]* d/ }. g* U9 z    user-message (word "There are too many cars for the amount of "
! P( J; \" H* n+ v  o- [" W                       "road.  Either increase the amount of roads "
5 L# w! E" p$ Q& p+ L/ ?2 y                       "by increasing the GRID-SIZE-X or "( N1 P  j4 J2 f, g5 B
                       "GRID-SIZE-Y sliders, or decrease the "$ i5 a% ?" t7 K& J, X
                       "number of cars by lowering the NUMBER slider.\n"! ?8 \9 v' ?: }, K
                       "The setup has stopped.")* b" w4 w" L* B
    stop: p- u" V; X. E3 K8 E( i  j
  ]2 L* i8 [3 g3 l1 s, t8 X2 y

$ G% o. `; ^" l5 ^9 w" O  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  I' M% b8 @! f2 `4 o& }  crt num-cars
% c& t9 w  G  x0 j" O1 \. k  [
9 \+ _1 F9 |* _+ `    setup-cars: B6 w% g" Y  }; j$ q
    set-car-color% x. G, \) }1 C. O& n& G
    record-data
  ]) H! X1 X8 z1 W  ]
" ^) r1 {: M$ A" o& z! @1 @$ z) ]5 c
  ;; give the turtles an initial speed" i  q0 ?3 f, n/ C. l2 G: ]
  ask turtles [ set-car-speed ]$ X0 z3 D/ ^+ ?% B6 p7 a# X8 D/ ]

4 }7 L/ s# ~" C$ Y; v  reset-ticks
9 h' M. h; q9 a  fend! t" e0 }! P( S  G/ Y* v

+ R7 Y2 H: K( B;; Initialize the global variables to appropriate values1 k0 {( s* a& b1 [# }" @: \; _1 i
to setup-globals
* d: J7 n" h' B! k  M8 i  set current-light nobody ;; just for now, since there are no lights yet
' s8 N# u8 i, s5 R: d  set phase 09 G% L3 B: P0 N+ |, k
  set num-cars-stopped 0
; f. C( d! j+ s6 Q  set grid-x-inc world-width / grid-size-x
, |6 v& G+ f0 C  set grid-y-inc world-height / grid-size-y" b% Y) n2 z8 z/ D$ {

, V' ^5 {" ?7 x  x0 n  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
" D1 }# A8 d' T# r  ~4 T+ ?  set acceleration 0.099* ^. _# Q8 n) V# S1 W9 X, ^! }" L1 i
end6 j! e( O- s# m8 F+ B% [& ?

- e# y9 Y* k1 `/ g8 G;; Make the patches have appropriate colors, set up the roads and intersections agentsets,* N" w0 C' h9 d/ m+ d$ `
;; and initialize the traffic lights to one setting  ~* B+ A+ S# Y3 B
to setup-patches
# F3 E/ B" A$ K- D' Q  ;; initialize the patch-owned variables and color the patches to a base-color
( R& R2 j+ U0 b0 \  ask patches
3 j! p9 k6 P2 O- Z3 k/ P/ D  [7 o! Z0 `1 @7 P9 g7 F/ l4 e1 x
    set intersection? false1 I) f4 c; q- X) D
    set auto? false9 {: ?1 A  R0 v6 E* X* z
    set green-light-up? true+ s5 s: R, F" P3 F
    set my-row -1
; I5 F- q6 B1 F( t    set my-column -1
6 T9 ]2 `1 |6 L    set my-phase -1
9 K7 [  U3 P7 L9 {8 D0 X/ \; l    set pcolor brown + 35 G' a) N/ R5 T" R
  ]
, |* S( k3 J, p" R* \* Y% R# C3 j
5 u  b- I6 N- H; ?# {( m  ;; initialize the global variables that hold patch agentsets
* N( [* W% G7 L4 H1 Y7 C  set roads patches with" S+ s# n( D# `# {+ ?% V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) B! \6 c  d- k& J
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 Q4 ?3 f2 q/ o! Y
  set intersections roads with
2 w; o" j0 W/ T3 Z7 V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and- h8 u* e6 {8 f+ i9 j. q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 j9 y; e! G, ^7 k( @9 W
0 E2 _6 m6 {# c' k1 Z# M1 B" r& k
  ask roads [ set pcolor white ]' D  Q8 b; B. k0 n( H4 n$ U- Q/ v
    setup-intersections. O. @7 @& `$ U+ y4 [1 I
end2 G% l8 V8 M. }1 n* u4 u
其中定义道路的句子,如下所示,是什么意思啊?7 z2 U2 N1 u. C' \3 H0 l  J
set roads patches with* M4 {7 X+ I  r8 s6 A) l
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 j. Z& x5 w0 }' k7 S) f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 R: V1 `6 y) V  f+ s
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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