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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。
- @- O- r/ o4 V  I8 O- [netlogo自带的social science--traffic grid这一例子当中,9 B9 X; V- j8 J+ _2 \* \; {! d
globals
! y" Q1 D9 ~5 D3 O[
. {+ N7 x8 s1 l  grid-x-inc               ;; the amount of patches in between two roads in the x direction
' c1 R% Z. A9 ]. s- [: {3 J  grid-y-inc               ;; the amount of patches in between two roads in the y direction
7 {8 [5 a3 R" |0 q; K+ n0 o  acceleration             ;; the constant that controls how much a car speeds up or slows down by if# x% C& {( D, T- o4 e, s$ D# ^( A
                           ;; it is to accelerate or decelerate
$ Q* R8 v3 L9 ~) ]7 [. A  phase                    ;; keeps track of the phase
* X7 ^4 I+ h: l! s  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure. P/ a; b0 m4 a- h2 a& E
  current-light            ;; the currently selected light
( b( D: U' N' \. E( L7 L: |0 Y$ m
- e1 s# W& I0 U6 V5 \& y  ;; patch agentsets
7 ~% O& @/ w( L, P2 @3 A( e  intersections ;; agentset containing the patches that are intersections
& `+ v1 {& G. I7 o* n: p$ _$ b  roads         ;; agentset containing the patches that are roads5 W6 b4 ~1 S1 o5 }* N
]
) _/ s; l& Q: s
! _3 N% i2 ?; O/ F% ^, fturtles-own
0 f9 O9 C9 Y5 M$ K* e[0 F, E+ [8 [2 Z( j1 o- `: r" C4 u
  speed     ;; the speed of the turtle
1 e; ~2 O  n  b& O) z) M0 D/ U3 o. T1 t  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
+ Q9 S9 K5 r1 o8 N# I2 c! o  wait-time ;; the amount of time since the last time a turtle has moved
* G- P7 K7 [. C, d]
% k7 T2 j' a3 t8 r9 F. u! D1 T# R1 X/ n4 ?
patches-own
, A5 X% k8 ^* V- U' B( t7 l[
% W+ Y9 S% @% Q7 g3 Q( N  intersection?   ;; true if the patch is at the intersection of two roads
! w' l0 @/ v& r8 ?( C) _  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
" W$ X0 y/ L& X+ u" v( J                  ;; false for a non-intersection patches.# L3 B+ r% ^3 o
  my-row          ;; the row of the intersection counting from the upper left corner of the2 ?8 z: w( |* `! |4 Z  p
                  ;; world.  -1 for non-intersection patches.
$ V: ?3 r$ I* H1 V+ \; h+ x  Y' ^  my-column       ;; the column of the intersection counting from the upper left corner of the
1 p( k4 z5 V" A                  ;; world.  -1 for non-intersection patches.
: X3 I) N+ ~. ?! E. z5 ]  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 X5 a' S7 u$ a$ Z
  auto?           ;; whether or not this intersection will switch automatically.3 k0 m# g% A- ~. F( ^
                  ;; false for non-intersection patches.
. E+ I' P, _5 e: V* `5 Q3 U]
  U& y: U: p: b
' _" q% _% N$ a7 n, o
) p& d3 s# D$ O1 T# m( e( ]* z;;;;;;;;;;;;;;;;;;;;;;
; c( d2 R9 H% R8 K% R;; Setup Procedures ;;) \. ?+ x+ ~! ~+ ~" ^# J
;;;;;;;;;;;;;;;;;;;;;;
% S/ @/ V( P7 V4 A  X
; v' [! z( P* B4 Y! P;; Initialize the display by giving the global and patch variables initial values.
+ ]) [# m: g& w- G0 |4 G% c;; Create num-cars of turtles if there are enough road patches for one turtle to
$ W* L2 w  ]/ F! g7 H! w;; be created per road patch. Set up the plots.: U( q/ R. }, X! j' _( G& e
to setup. ]( |0 H: p( {6 t1 e) I
  ca2 ~  d% \; E8 ?5 y' I* z* I
  setup-globals
; Q) V1 b& c( l; w! ]5 Z) l
+ K. l+ P4 N  j' a6 }, n8 M  ;; First we ask the patches to draw themselves and set up a few variables  e1 [7 O. M7 p! _* c. V  q" C
  setup-patches
) W) S3 l  J$ u, r$ E. c  make-current one-of intersections1 V6 H+ Y1 V  d0 K& T
  label-current8 X- x* a9 l* G# n% ?
+ s- g$ u7 ^% \
  set-default-shape turtles "car"2 K' S3 u+ T* t3 R
& ?: z2 H" G; J8 _* C' f
  if (num-cars > count roads)
# O3 ~8 P! `' K, b6 k7 o  [/ I- S( z4 L( `7 I, l, `
    user-message (word "There are too many cars for the amount of "
' o. Z# U$ s: i                       "road.  Either increase the amount of roads "% ~' l% ?/ h1 A" Y" q- z
                       "by increasing the GRID-SIZE-X or "
  W, S: u( _7 Z  |) x+ e: |                       "GRID-SIZE-Y sliders, or decrease the "3 v3 ^4 I0 P7 ~& `7 E2 F: t+ e- L9 q9 I
                       "number of cars by lowering the NUMBER slider.\n"
& x( ~; h4 C3 J1 g" H; g                       "The setup has stopped.")
3 r7 d: U: k0 }1 ~; n. ~    stop7 H, w. w* ?+ f( m" E
  ]
3 ?6 u) k4 D( j# `& C: b: Q: p, H9 p4 i3 D2 K: J
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
( k& F( z9 n' m0 T* @  crt num-cars- g/ H7 }" {9 o8 ~- l" s) g  n. Y; K
  [
2 O; Y" B9 K) b( n1 L+ s    setup-cars* V* t% }9 f/ U- M* O" O
    set-car-color- Q! T& U/ _4 n- i4 q7 u
    record-data# {- ?5 Q" r* y0 T" I* I
  ]' s) ]0 Y; d( m1 x
1 h5 `" q& f. D
  ;; give the turtles an initial speed, `6 r& E" H6 e- X& E" V( Z
  ask turtles [ set-car-speed ]
7 F; z2 _" D% i5 K$ h+ w. @; H* [% Y8 v/ y- L* ]
  reset-ticks0 y/ |9 A7 s  _5 K1 ]$ ]
end
" ]9 I  ]  k$ M6 t7 Z( v) f. B" M. X  ]5 P- M
;; Initialize the global variables to appropriate values$ m- Z* ?' k7 O; t( J
to setup-globals6 g; ~) _; z, N* ]
  set current-light nobody ;; just for now, since there are no lights yet) b8 `; j7 [# g- q+ W9 |2 P
  set phase 0" I" Z& P7 x( n. A
  set num-cars-stopped 0/ }& t+ y: ]# }. z# x9 ]- \
  set grid-x-inc world-width / grid-size-x
5 J# z% H& K! }# W! p" K- m/ d1 Q0 M( w  set grid-y-inc world-height / grid-size-y
) a' B# J& b4 I6 g" E  n  }" w! t8 `5 D
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
9 o+ J6 K$ ~  n% p; Q  set acceleration 0.0994 e7 c2 ?) \4 Y) u# H- v9 D: }
end/ Y3 {8 Z1 F$ b  u. B7 p8 y: n

" Y; e, o: [- r3 r: N;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ d, q5 k. k+ j5 @% e$ C% e; k
;; and initialize the traffic lights to one setting
) S  H, i2 s' T, h2 s) Y9 o, yto setup-patches9 K1 ]! ^' T; j# u0 M' D
  ;; initialize the patch-owned variables and color the patches to a base-color
# Y% f1 {+ C/ I$ @- |  ask patches
& _2 L& c0 ]9 Y, Z7 V- ?/ N  [
5 m6 G2 o. Q" {3 T& I9 f/ K    set intersection? false9 m7 ~4 d0 [  p
    set auto? false% d. Z; C- A" t$ |& D
    set green-light-up? true, b# D* c, X% J+ K, d7 f
    set my-row -1
4 N: s  u! r7 v: p8 A    set my-column -1# ]1 S9 D4 c( d. M" Q1 w
    set my-phase -14 n9 w- P$ T" Z" q
    set pcolor brown + 3
7 u9 G$ u, X3 }: E' v  ]: E# D/ [# C5 _, {& @) d
$ q1 Y' q; `: {9 W# D
  ;; initialize the global variables that hold patch agentsets
* v+ g) g) x' }5 x; d4 N# E  set roads patches with
5 r$ ?2 S2 l! w1 l# l, c, R! T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 n; m2 h, H1 [% M; j! K/ `
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: b6 W5 h" |5 }' _/ R
  set intersections roads with( r- t' a0 B. G4 M6 L5 i) J- L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
; V# I/ ?6 s2 t# ?    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 [" R; w7 R6 g( r9 W6 S6 e9 u* a8 ?
  ask roads [ set pcolor white ]8 @# q$ `4 X  P0 @; f% d
    setup-intersections* b4 T  o2 i# \) y9 L& D6 I
end
/ M: b% U  j2 I2 Y" {8 ?, W/ I其中定义道路的句子,如下所示,是什么意思啊?4 w4 M* o) ?$ \7 O/ ?
set roads patches with$ K, t" ~+ ~- Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; c+ z: K, n% a8 W6 ^4 ]  J
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ J6 _: d1 ~3 t+ n- {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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