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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。) _) H5 r# P' A2 z* O, _( w
netlogo自带的social science--traffic grid这一例子当中,1 f; b! g7 O$ d$ i( l
globals6 }. ~6 F* e4 L1 D+ {0 z7 `) v
[
5 |8 _* I/ I, C6 D! w  grid-x-inc               ;; the amount of patches in between two roads in the x direction4 ?" ?9 g& }( ~
  grid-y-inc               ;; the amount of patches in between two roads in the y direction: l( B! e* o; K
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
3 E5 i+ n1 m) y* W                           ;; it is to accelerate or decelerate
( \: p! c% z" }  phase                    ;; keeps track of the phase5 m: b( f& o( ?. d
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
1 v$ j" w# a/ p, z  current-light            ;; the currently selected light
  t; H* l4 R6 r) m9 k% [3 r& D: ]$ W6 I# |! a0 i
  ;; patch agentsets
. k6 M% Q+ D; ^5 p6 |  intersections ;; agentset containing the patches that are intersections$ b" g. O  [/ z6 u
  roads         ;; agentset containing the patches that are roads
8 l7 D% |2 X3 A]
" `! b! F$ F9 u' Z, Z6 ^) e, E8 d/ w/ `
turtles-own
/ y( s9 e" U6 q[; [9 E1 Q( p% W# P( I9 N
  speed     ;; the speed of the turtle, @" U- j! O3 F5 X
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
9 C8 H4 {( Y" ^; |1 p% K) z" J  wait-time ;; the amount of time since the last time a turtle has moved$ U- d# {2 [  ]! r& L% N' i
]+ [+ b) f- L( w7 e+ _* K( i

' L/ X$ q4 A7 {4 \patches-own+ p3 o' o7 j5 B# W8 X
[
  q4 k* y6 [5 ]3 c  intersection?   ;; true if the patch is at the intersection of two roads8 K4 }! S- y, X
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
# A" i4 l, A+ P. I6 E  ~+ b                  ;; false for a non-intersection patches.% t( o7 d+ K& z4 K
  my-row          ;; the row of the intersection counting from the upper left corner of the
1 X1 r. r0 t, o! u* j: J2 X! H                  ;; world.  -1 for non-intersection patches.9 n/ ]1 a! M1 `$ K. N. `
  my-column       ;; the column of the intersection counting from the upper left corner of the
0 |, n5 l$ g1 t* H4 e7 q                  ;; world.  -1 for non-intersection patches.
1 {* ^: j0 `. |( O/ C  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
0 j4 w; r4 g' D: p" v, m$ x% W  auto?           ;; whether or not this intersection will switch automatically.
6 g7 P4 R2 S. _4 s- y                  ;; false for non-intersection patches.
6 d! i! c  Y! i]5 R2 O& L) q* y5 w
& g+ j* C3 T: Z+ I7 d$ {
4 |9 u( x; K$ Y
;;;;;;;;;;;;;;;;;;;;;;
+ M* \# y; o9 l+ Q* i* z;; Setup Procedures ;;* ^# J4 ^. T. x8 e" [/ i, S5 [/ |
;;;;;;;;;;;;;;;;;;;;;;
! p3 d# o- [# G9 I. c+ B9 _3 Q3 |* I' O# ]5 _% m
;; Initialize the display by giving the global and patch variables initial values.
: V) h* a, ~! n1 ~2 C* L;; Create num-cars of turtles if there are enough road patches for one turtle to% D- X# R( @4 e. r1 w9 R& h
;; be created per road patch. Set up the plots.
5 I6 t1 S. D) f+ m% zto setup: Z; }& \8 ]0 l" T8 k
  ca* [$ w+ g( ~( }: I& Z! C1 b
  setup-globals
9 q# t/ n! I2 G0 D
  K0 W) D$ G2 D! l# Y  ;; First we ask the patches to draw themselves and set up a few variables
  _" _! f, d; N! s0 n  setup-patches
* m1 a0 U" ~! J8 K( X6 h  make-current one-of intersections! Z" t  f8 ^: Q# J8 b; z; I
  label-current
) L2 P, s7 d2 ^" t* S- F( {" f) N0 `% J; C) t
  set-default-shape turtles "car"
3 Q" A1 q! {8 o; d) g
6 V$ T, t  a( D$ b3 U2 z  if (num-cars > count roads)
+ L* F- _- _- r, W8 y  r  [) U( _' p+ W- k. w% v! ]( A$ @
    user-message (word "There are too many cars for the amount of "0 n' c2 X% y# ?$ ^  w6 N2 H9 A4 W
                       "road.  Either increase the amount of roads "/ y/ Y9 Z8 T6 M6 L  V: G
                       "by increasing the GRID-SIZE-X or "
8 j. H& j0 S. ?6 i4 d+ l& V                       "GRID-SIZE-Y sliders, or decrease the "
- I6 x  _  v8 `  A' Z, i                       "number of cars by lowering the NUMBER slider.\n"
7 i: @8 P% B- `# F                       "The setup has stopped.")
* y$ ?% _* S7 ]/ r! p    stop5 x1 {$ t8 A: J7 S' Y. V* W
  ]' z8 I3 Q  ^, h/ ]+ |& w' @  i

4 ^: m" B) a4 e: p  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
4 {8 i$ |7 P6 R' d0 ?8 L# t$ J  crt num-cars
+ V" F  P  L; S, ^$ \9 y  [" U& E2 T4 F0 `3 e2 \
    setup-cars
4 E7 X7 c, l! g+ t3 Y9 i/ {    set-car-color7 l: j. G% e! z6 G5 I6 m( R: D
    record-data1 _3 a+ _& O- _: I+ X
  ]
2 l  ^7 m: l+ t0 c; C' b
  C7 g3 @, ?2 t* c* W( O* b6 K; w+ }  ;; give the turtles an initial speed9 p) v' {) ~0 ^  a4 z5 }
  ask turtles [ set-car-speed ]! C# S6 q! P" s/ B% n

! h" k- q2 `- j) W6 }  reset-ticks* ]9 Z* t+ Z7 f; B
end
5 t+ w7 N) D0 _. ~) h" A$ E8 f! X& l
;; Initialize the global variables to appropriate values
* ^4 a8 V4 G, n8 o  t1 y+ @9 cto setup-globals
8 {3 O" g0 N1 n. c; Y! b  set current-light nobody ;; just for now, since there are no lights yet) M+ z' I8 z( n2 B& G7 v
  set phase 02 ]& i; ]* }, K* p
  set num-cars-stopped 0/ S0 B0 K) u* C; P9 b0 s, R
  set grid-x-inc world-width / grid-size-x
  G- z# z6 m, _. i$ I7 o0 o  i  set grid-y-inc world-height / grid-size-y. k- ?6 `' [; W& A, m5 T2 C+ [
: C; a7 J; T% U% r
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary( \8 y$ I) [7 b! e, q. Y7 k
  set acceleration 0.099
  ]3 l1 Q7 }- g+ l2 \9 O1 Eend
: O" q% ]  c  ~3 j7 [% |& q
% J! p* d$ p& x3 b5 J6 o;; Make the patches have appropriate colors, set up the roads and intersections agentsets,1 ~$ u. ^. n( z0 f
;; and initialize the traffic lights to one setting
3 g4 ?$ }) ~8 N: o. G5 ~to setup-patches4 N" i) z) G' I6 s
  ;; initialize the patch-owned variables and color the patches to a base-color
& M7 Z  w. B$ }  ask patches7 F1 x% ?! Y- Y+ X& t* N
  [
* e# h& s8 }5 [" j6 i. D" x    set intersection? false
- Y5 t. l% J" W' J, f( R    set auto? false
$ R) A2 L% |7 }, l    set green-light-up? true7 L5 ^8 y" {3 d' m* k
    set my-row -16 p7 F% \( e% G$ O, q
    set my-column -1
' `( d5 V, v1 F# Q7 B7 ?    set my-phase -19 o. M$ ~$ ]- V$ t0 C2 m
    set pcolor brown + 3
! W" Q: g6 h  G, u3 d9 D  ]0 j6 F( Z/ b2 a5 v% R% X
* R7 G- F0 \$ n# l
  ;; initialize the global variables that hold patch agentsets+ V2 ^6 K: I6 V
  set roads patches with
2 V" h5 h9 E8 N! X/ a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* u) {. R$ S/ d) |2 G2 j" f% |" S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( S3 m9 d/ V- Z$ {5 {5 ]) j8 u
  set intersections roads with
" {4 y6 D: h! E% X9 h! @! g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and& O$ Z) y" Q9 v: {6 h7 H0 Z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ s# Z' S, d% z, |# K& |$ z; Y
& w  V! r9 b  \
  ask roads [ set pcolor white ]
( _' n$ }* j4 [4 h" q    setup-intersections$ V5 r. [" u( t8 s  M4 Y
end: ~4 E. x* T, D' M; b8 X5 m, A5 b) T8 O
其中定义道路的句子,如下所示,是什么意思啊?
- ?1 l) A, w0 |: T set roads patches with: y8 M( n+ G" R+ Y6 R" A5 W9 k$ P# g: C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- r0 |# C% K1 L( i9 s+ ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' S8 X0 {) ]) Y* v7 G
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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