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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。
3 l5 v6 i: n& p6 wnetlogo自带的social science--traffic grid这一例子当中,( v# X/ J" g: Z4 i8 v/ E
globals1 H5 J( s2 C6 ?1 u- F/ R
[
. O+ B; I) Y7 f+ G; Q2 p" _  grid-x-inc               ;; the amount of patches in between two roads in the x direction
' M2 N/ ~' c4 \& o% P( i  grid-y-inc               ;; the amount of patches in between two roads in the y direction5 G% i- ]) N* ~7 [2 ^# P: \
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
. H* U+ f1 L8 M, B* q                           ;; it is to accelerate or decelerate
" ~! i: c. R8 H2 b$ p  phase                    ;; keeps track of the phase3 d3 h' [3 h" F. G! Y. S( c" X
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
' p1 U8 M; n" y7 r6 k# ]7 A! M: Y  current-light            ;; the currently selected light
. ?$ a4 n! j1 w1 y5 f1 d" R' q; }% X2 G+ o
  ;; patch agentsets  R1 e  G4 ]0 a% x4 ]
  intersections ;; agentset containing the patches that are intersections
3 M6 y. D  o, a( u( v* ~7 F- I3 s4 I  roads         ;; agentset containing the patches that are roads
) ]; ]! D' b5 {1 i( m) E2 f  P& }]3 l/ K: C! L0 Y) d0 F. C. ]
7 Q* b6 N; F# O! j( O9 C
turtles-own
& K; y: e6 T0 l+ U: ^8 F[
8 ?2 u5 ?2 q7 s  speed     ;; the speed of the turtle: {( ?% P) [2 B1 F7 H0 N$ Q
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right0 x6 f. R* Q- E
  wait-time ;; the amount of time since the last time a turtle has moved
& T6 Z0 [! y& I- B0 []
3 u, a! B- P& X  `- H
" B" Q0 T9 C: x0 j" V2 N! |patches-own+ S* V- S" X( R  F
[
$ t" W3 W  D; M! {  intersection?   ;; true if the patch is at the intersection of two roads
2 d+ j9 p. U6 B0 r- `- r6 u5 |" H  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 I* ^, Q/ a  Q2 r                  ;; false for a non-intersection patches.' [" r* y/ y% U: k* @9 F) s
  my-row          ;; the row of the intersection counting from the upper left corner of the4 n3 Z; Z8 l; x# p% p; Q
                  ;; world.  -1 for non-intersection patches.
0 F2 [' |- B  g  my-column       ;; the column of the intersection counting from the upper left corner of the; W8 Z' o" \  L! e  d3 i/ q
                  ;; world.  -1 for non-intersection patches.
! q5 k+ B" @7 c, o  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches." }7 }0 o( Q' U4 a" O
  auto?           ;; whether or not this intersection will switch automatically.( j* r* l- F' s. F
                  ;; false for non-intersection patches.
, t$ ?, C5 G  n" O2 g4 k]
7 M7 b2 P' G! _/ ?
1 w$ Q( G( [9 E( j' [2 Z: Q
4 F% J  {6 C. L: n;;;;;;;;;;;;;;;;;;;;;;: g) R. E- O6 K3 Z9 Y' e
;; Setup Procedures ;;7 `! |5 h$ P9 K) x# j" l
;;;;;;;;;;;;;;;;;;;;;;
" w4 V7 u8 |0 j1 p0 t. \# o1 I0 r! ^: ], R4 c5 C
;; Initialize the display by giving the global and patch variables initial values.0 U! h. t" r$ _3 Q( R) W
;; Create num-cars of turtles if there are enough road patches for one turtle to: R0 F9 a" L$ U+ ~
;; be created per road patch. Set up the plots.
$ H$ @3 H3 ?# Yto setup) k( b/ t% Q' }
  ca  V8 u: S0 [- x2 @! k) U
  setup-globals
2 O' w  |' o, q1 ?
* }$ a# o& B  {1 Y- ?4 K: ~  ;; First we ask the patches to draw themselves and set up a few variables3 [1 B+ G5 _8 t3 I# k) W
  setup-patches  s+ T7 ^% u4 S" s  d
  make-current one-of intersections6 Y" t: z  s% E2 F. l" Q* _
  label-current: d7 Q1 e5 q; V2 f% y) `) p7 S% m

& e7 Z, A# f7 A4 A: e; T  set-default-shape turtles "car"
/ H0 d3 W( k" B& }  S7 Z% ~6 {( R1 c: C6 l0 J& `
  if (num-cars > count roads)
/ l; \& T1 c) H1 e0 {1 k  [
, ^# e; I( H0 ^/ @% z    user-message (word "There are too many cars for the amount of "# ~+ h+ Y5 ]$ \
                       "road.  Either increase the amount of roads ". [* V8 [. U2 l6 V8 x1 h: _5 E
                       "by increasing the GRID-SIZE-X or "
0 I/ Q8 l* \0 p                       "GRID-SIZE-Y sliders, or decrease the "
( z" V- t: d2 r  }, |# P                       "number of cars by lowering the NUMBER slider.\n"
# o6 J$ C. l( I% K9 W                       "The setup has stopped.")9 c- m6 B1 @0 c3 [# M. ]( C
    stop& q% X; v* |: x: H6 q5 z, f
  ]
+ o! ]* O! [/ }# F0 o' a+ F  c
- j3 p: b" F& G& D- U3 M  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 M( n' n7 j! D. a4 ?! G9 N; {
  crt num-cars
& D. h& Z# }# A8 a  [
  D3 |6 e9 h" u7 E! q    setup-cars
0 @" [! ^1 }5 j6 A6 D2 q0 w    set-car-color
( f: ~% v9 Y- k& }  X/ @    record-data( b! }7 ?) Z- B5 I7 n, h
  ]' e% o  r& w8 `+ t/ M

& X/ w7 }& B/ o) Q0 x- S  ;; give the turtles an initial speed
% T3 {  O! H7 ~' p" m& }4 Y& s  ask turtles [ set-car-speed ]
3 i: }, H. j! F  E2 C
) A5 h& i& |& U; p$ z1 p  reset-ticks6 U- Y# A' }) d6 P
end
/ v# {; V. d; J) v& B* e& W) t
1 q2 Q8 k( B/ a5 {& l: a;; Initialize the global variables to appropriate values  i- F: Y9 f; m1 L7 q5 V4 N
to setup-globals1 j, I, f. T8 {
  set current-light nobody ;; just for now, since there are no lights yet
8 U) M- u& F- f  set phase 0* c- z# Q) b7 N6 n& X
  set num-cars-stopped 0
/ r; Y" O% g. m! O  set grid-x-inc world-width / grid-size-x
4 E, H* l" r% k- \& ^/ u  set grid-y-inc world-height / grid-size-y
$ l$ z+ P% l7 E' S$ v% O" v
! @4 Q& w& m1 y- H  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary: ], x% l& j% K" B
  set acceleration 0.099
  Y2 _: h# s* vend
( B- |. q' M& ]1 S
2 A9 h" |: e9 A* G% P2 C;; Make the patches have appropriate colors, set up the roads and intersections agentsets,5 V& e1 y! t; a( x5 f: O7 ~
;; and initialize the traffic lights to one setting# P) o# l6 j2 ~$ q+ s* `1 p
to setup-patches$ p9 U( A; u2 r* \4 c  _* L
  ;; initialize the patch-owned variables and color the patches to a base-color
  k4 `( _- @2 @8 D: ?* S6 F$ X  ask patches! P1 J% v! w2 L
  [
2 U+ A5 j* @0 Y3 C: C    set intersection? false
; K; s  j1 L2 u, e    set auto? false, a$ E# J" a: r% E9 j' e
    set green-light-up? true  c; B9 h; k7 y' }% q
    set my-row -1
, w6 Q* w# ?6 p: m, g0 `) G    set my-column -1
+ E3 f' ~2 \: w' ?    set my-phase -1
+ L  R$ l1 p4 X( t. h0 ~: t) z' c    set pcolor brown + 36 x' J4 i% k7 w  e
  ]
4 a- E5 s* _1 h7 V5 n( i$ y$ w1 s
% r) ~1 H$ U2 M/ q3 i. k  ;; initialize the global variables that hold patch agentsets
+ u6 t8 A) A1 p7 d/ Q" G  C  set roads patches with
) F/ ~# [1 k" r, I" U8 K  ^2 \    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 s2 z  {$ U) i6 w8 T( r4 L) K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 n* D2 |6 B8 Q8 X
  set intersections roads with7 F( ?* q2 t9 V" S7 Q9 U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and6 J4 i% e( {! [6 y: H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 N+ J  }5 H5 [+ c8 c4 j8 {  [! R) X: _' T' W
  ask roads [ set pcolor white ]
! j& n  M3 d  n" u    setup-intersections
: l9 L. T& a# i1 A# I8 oend$ G& s4 \) i0 ?* n% G3 R
其中定义道路的句子,如下所示,是什么意思啊?
0 U& r" R+ i5 L4 ? set roads patches with
4 A4 m& U& x. n+ g) V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ q0 c6 v2 o7 V: D0 y' K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ h' T  ?! e+ ?* Q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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