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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。
$ Y. F. W% o1 V4 }4 t/ ]  x4 Inetlogo自带的social science--traffic grid这一例子当中,3 N0 N' s6 U0 F: S* B( E
globals2 o- l9 e) S% p4 V
[8 w+ o$ D0 E  }" F6 S9 }9 Z( h
  grid-x-inc               ;; the amount of patches in between two roads in the x direction/ x% A' o# m( s6 _! \* m
  grid-y-inc               ;; the amount of patches in between two roads in the y direction6 S5 P. u8 C% a
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
5 k6 Z5 l, l" y' O- c/ |& B                           ;; it is to accelerate or decelerate2 |2 M2 v4 a  r/ E& ]' ^( i: A
  phase                    ;; keeps track of the phase! R3 P+ H- X8 t5 f
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
: R* u# n  X$ [+ J$ X  current-light            ;; the currently selected light3 F7 T! t5 i2 k5 Q. H1 T1 s
9 B5 g' X$ m7 S' N6 H6 d/ v
  ;; patch agentsets
6 ]8 j9 K3 h' [  intersections ;; agentset containing the patches that are intersections1 ]. u  e# w# B1 S0 D5 ?
  roads         ;; agentset containing the patches that are roads
, n6 O  ]7 ?& N1 T]' d: I0 c$ f! u
' H& q. R; Z. D5 s. C  q& U, ^; J) h
turtles-own: W$ U( @5 B  c2 ~
[& P: C4 ~+ K$ [% W. v: i2 ^
  speed     ;; the speed of the turtle
( Z+ X# Y5 C5 `% H9 Z# q; N; m  up-car?   ;; true if the turtle moves downwards and false if it moves to the right# c+ `/ i8 w: }+ R' }
  wait-time ;; the amount of time since the last time a turtle has moved7 A6 F( E1 Q9 N; D8 T. C5 R
]: J4 d1 n) J& d

* k/ u! `& q2 o2 h+ c: {patches-own
/ J. V- u6 H* F1 {[# \; y" c- O0 \+ i8 |6 S0 H/ j
  intersection?   ;; true if the patch is at the intersection of two roads* ~" n9 _/ ~( p" b
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.6 s* [7 b. X; T; a$ O1 z* g
                  ;; false for a non-intersection patches.
3 Q8 n. |- @3 i4 S( w  my-row          ;; the row of the intersection counting from the upper left corner of the
: j& g. G  f( j6 o                  ;; world.  -1 for non-intersection patches.
! x1 k  ~' W9 U( u  my-column       ;; the column of the intersection counting from the upper left corner of the1 ]1 A. I4 m: p' R1 D1 m# Q
                  ;; world.  -1 for non-intersection patches.
& i0 O6 z* P2 k( V, n  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.! N  `+ U  H% [
  auto?           ;; whether or not this intersection will switch automatically.$ }: Z+ l9 ^& D; X8 J3 N
                  ;; false for non-intersection patches.
% L: u' G0 H& c) s# G2 q) U7 \]- M' x% ^: @! k6 f( K0 i. S* A1 g9 n
; V* a7 X; o0 H6 B" S

2 m6 M6 o( @  t0 N. [- _;;;;;;;;;;;;;;;;;;;;;;
9 K$ _0 }- _, ~! |, c% v" ?;; Setup Procedures ;;% {- g3 N, a5 Q
;;;;;;;;;;;;;;;;;;;;;;
: L6 ~! ?! B( t* U6 ]! W7 F1 S/ R6 ~1 P' {2 ~$ F0 ~
;; Initialize the display by giving the global and patch variables initial values.3 S/ Q5 @& V/ O" U. |  T
;; Create num-cars of turtles if there are enough road patches for one turtle to
( Y1 N/ D! x$ _5 V# ]' j( };; be created per road patch. Set up the plots.
; m8 e! e) p+ b0 D( [; y/ ~to setup# l, O: d- ~, r0 [! n: ~: k" [
  ca- c' c6 k6 I# W- j0 M
  setup-globals
% u9 Q) R, n5 I5 V) x7 C" ], x, O$ [' [: e2 m% [, O
  ;; First we ask the patches to draw themselves and set up a few variables
( f+ Q0 a( K( Z/ P6 q  setup-patches9 F! q( x6 X2 `$ Q5 {
  make-current one-of intersections; R: M! V: B9 Q0 W& m* p
  label-current& G' D# u: M, t6 D

. i0 q3 R. t6 y1 ~+ x7 o% T9 d  set-default-shape turtles "car": H& e! @- y; ?+ ?. }4 t
# c4 x: q8 e- K2 Z1 |' _
  if (num-cars > count roads)! h, g7 c9 N: B. R: r- M
  [  g/ N* y! }& y3 T0 i! m% h
    user-message (word "There are too many cars for the amount of "
5 h! ?' p. n& a7 }9 G                       "road.  Either increase the amount of roads "
# F2 q0 K( s0 X: I$ ?, s: d8 i                       "by increasing the GRID-SIZE-X or "
' H+ u* f; q8 i# h& i! I4 H' P4 E                       "GRID-SIZE-Y sliders, or decrease the "" t) V, c! x4 B1 {& o
                       "number of cars by lowering the NUMBER slider.\n"
0 s5 ]7 U4 j; h- u9 |: k                       "The setup has stopped.")
+ T& y  E$ ^$ z2 s5 Q9 Z    stop
; e, G( p1 _1 r  a! p5 l  ]
; K: c/ e" `/ x' V) U9 r  I5 G# q5 f" B9 J, H
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
" J* u4 g- u$ O: M; x0 j  crt num-cars
) A& b# G* Q! {1 T7 ^3 ^% x  [' T  D& x, k1 \0 u# y( k
    setup-cars
7 V& @% ?0 U0 ~    set-car-color: {0 e- b6 M# }
    record-data! L, C9 v" R5 c
  ]
& C- b0 s. x1 x! A" S2 o+ l5 g
- m$ f, g1 I: q. f) |7 n0 _, F" }$ y  ;; give the turtles an initial speed2 A( I) W1 P2 V4 @) q" }6 {1 T
  ask turtles [ set-car-speed ]) |" o! `" j: J

5 N! P# o! m/ ^% z% H9 p  reset-ticks
; L) i- ?% J& x: R3 y: }+ Tend0 S+ [- j! g/ p. {( J2 `4 }0 @

! n2 }/ J) M1 j1 X& ^;; Initialize the global variables to appropriate values  d- m* N% v2 c& D  S) B
to setup-globals+ u' h/ n2 ]" X! D/ J" n: O. a
  set current-light nobody ;; just for now, since there are no lights yet
7 I: H* [. j' o$ f- V0 `- {/ \  set phase 0
4 L  Q9 I) L) h  set num-cars-stopped 0
8 T4 g- F" l1 `1 a* p5 B5 G  set grid-x-inc world-width / grid-size-x
/ P+ a, u0 o6 w. W5 D  set grid-y-inc world-height / grid-size-y
! t3 }  O0 B+ w& S/ h& Y$ ?. u# o" v8 g4 a' I/ D
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary6 [  Z8 w. X6 C3 t
  set acceleration 0.099
7 m. ~. @0 J3 e) m6 ?( B( k3 Gend7 ?9 O# Z" |# N# D  Y' d
2 I# ?! [( @3 R
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
% F& n& m" T" H4 {! e! Y7 _;; and initialize the traffic lights to one setting0 U% \2 Q4 |+ I& z4 `# L9 f/ ?: z
to setup-patches+ @0 v' d3 q$ u7 ]5 C0 r( L) B+ N
  ;; initialize the patch-owned variables and color the patches to a base-color! k$ [* d1 m# ^  Y' R8 y9 D5 ~6 S
  ask patches
# y1 Q* S8 ]6 c$ ?3 I/ L5 o) W% _  [% a) @- r/ c8 o# W! w6 c; e1 \
    set intersection? false
8 Q0 |& z3 j" P. w6 f$ i4 a    set auto? false8 a8 g0 f* K9 S; r: c- L1 C3 G
    set green-light-up? true5 C7 x! e0 J- u: `# ?
    set my-row -1
5 O: m6 A- C$ u6 _3 [1 h    set my-column -1
6 e% s* u2 |0 F. G8 c    set my-phase -1; t, ]+ U" i6 e" f; j
    set pcolor brown + 3
8 t9 J$ V  L4 L' G; ^0 W  ]
* ?/ Y: {1 ~& w  a: Q% B  x$ O' ?7 x$ F2 o
  ;; initialize the global variables that hold patch agentsets4 [* i# F5 S6 _+ ], w/ l! i
  set roads patches with
7 _. @6 f- \3 G7 N    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" X) e+ y% g9 o: u: C. @. M  }& \# R
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- v! L/ j) i' E# A
  set intersections roads with
$ c8 j% I0 B) ]3 L8 w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" u. H" G9 F# M8 R    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 {$ t' [- _. d! p# `
' C4 ~7 n, Y( z# n1 `- N
  ask roads [ set pcolor white ]
9 [# H3 s7 M: O  V2 z* E- f! h9 @4 G* L    setup-intersections0 ?4 X% ^/ c: Y( r% o/ Q
end
1 ~( p% }) ]: |; h% p其中定义道路的句子,如下所示,是什么意思啊?
8 {( z0 i$ [1 |2 ^ set roads patches with
+ b" Y* E& _# O8 {* K: Z0 [    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: g( d) o' n1 @2 k2 r' b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ E! j& ?+ D/ o3 y5 P! {) v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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