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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。" @6 N) q( A: d: d" _/ Q+ G+ c
netlogo自带的social science--traffic grid这一例子当中,
, o$ @. z7 v: H. J3 K# Nglobals
8 d8 ~- n. e3 t[" O" w# [& T$ B5 M9 |1 p
  grid-x-inc               ;; the amount of patches in between two roads in the x direction3 I1 R3 g1 |: x0 s) w
  grid-y-inc               ;; the amount of patches in between two roads in the y direction4 V8 w6 j% V8 j0 G; a
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if, \$ P5 x; S: y1 j
                           ;; it is to accelerate or decelerate( t. E+ t: s3 j6 i+ @- A4 s
  phase                    ;; keeps track of the phase; J  B+ ~! r& u; B7 d
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ f1 P" d1 @0 {5 {+ \- ?  current-light            ;; the currently selected light
# i1 S- V7 l5 y. M) g) S9 n# V  \" \5 U, C9 Y7 y
  ;; patch agentsets
& m" y, y6 [, [4 G9 ^8 t% I  intersections ;; agentset containing the patches that are intersections
2 O, m' y1 \! R7 Q7 y; y  roads         ;; agentset containing the patches that are roads
9 u" z3 i5 C9 ^]7 i& Q" A* p- v' w- G( S

6 P4 [6 u0 S- \1 Q& ^turtles-own
6 N- H0 D5 z3 v$ q) s9 w- _[
" o$ v% P1 w% |7 S7 R( ?+ e  }3 N  speed     ;; the speed of the turtle
$ R/ C% _8 r: `; b  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, X9 I) s5 n+ X' C  x3 g; N2 d
  wait-time ;; the amount of time since the last time a turtle has moved
+ h$ r+ Q, X; j( S, T]3 W* \) a9 j& x& f+ o/ Q4 C# K0 P" [! \

* _3 s/ [( k5 M( Q3 d6 v$ Opatches-own) g4 `) ]9 T7 L8 L6 t
[
& x! {+ M7 o) Y/ N2 W  intersection?   ;; true if the patch is at the intersection of two roads
8 n. I5 v% D" v# R  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
* q- [# T  J5 n1 l2 V2 M                  ;; false for a non-intersection patches.) y4 |2 h% c1 M* e- g- A( [: K
  my-row          ;; the row of the intersection counting from the upper left corner of the
6 C2 v" |9 x  \, A- P- {0 x                  ;; world.  -1 for non-intersection patches.3 \, _' P' Y$ p/ f& x0 p
  my-column       ;; the column of the intersection counting from the upper left corner of the
/ K5 G2 W: e7 R3 A7 Q$ u/ Q                  ;; world.  -1 for non-intersection patches." R0 l5 M6 z1 i9 s: f5 G
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
2 w4 [: B% o. O3 s- G/ I  auto?           ;; whether or not this intersection will switch automatically.
. c/ i# w( R4 P; [( D; ?                  ;; false for non-intersection patches.
! B8 U7 g3 Q. O]1 n/ R1 S2 f8 N2 h

5 r7 z/ X( \/ Q3 [) ~
8 n7 R0 R( c: ?, R7 _% r3 X;;;;;;;;;;;;;;;;;;;;;;
5 y+ T! u5 k1 k;; Setup Procedures ;;
7 f* f3 n* W! W9 e;;;;;;;;;;;;;;;;;;;;;;$ A  t4 c- t/ F: n
6 P9 R# X" o9 I8 a& Z7 C5 [
;; Initialize the display by giving the global and patch variables initial values.
, m' J" ?8 G& J5 u1 B;; Create num-cars of turtles if there are enough road patches for one turtle to
: Z7 G! v6 B3 L* h6 G;; be created per road patch. Set up the plots.5 m4 Y& H9 o* |( A3 Q. }2 J
to setup6 d% ]2 i# d' J$ c
  ca
5 v4 U& F7 n+ }' F  Y% R# W  setup-globals
  ]6 p) ~0 F8 `. m/ o( k2 m) P! e) T& v
  ;; First we ask the patches to draw themselves and set up a few variables7 {. d% |, E' a( T  r- M
  setup-patches0 u; j1 B& q: i  z% w2 d
  make-current one-of intersections' a4 x2 y: D) ^5 k
  label-current* `% ~" \( K. L4 b6 r

, [% o+ ^2 x$ ]* b' a  set-default-shape turtles "car"
) s6 A# @  s7 c
' |" M$ X% ~$ J( ]' H  if (num-cars > count roads)
6 n8 s! q$ a. R& g: ^6 a  [6 _4 i7 Y: d+ l( ]6 T. ^) `$ R
    user-message (word "There are too many cars for the amount of "
+ q+ w  x  c8 K6 `                       "road.  Either increase the amount of roads "
7 V* M9 S. p7 G6 ?5 b8 U+ [3 v                       "by increasing the GRID-SIZE-X or "7 E% d" a8 c( Z( d- e5 v, r
                       "GRID-SIZE-Y sliders, or decrease the ": D& _/ P/ d7 w) S. d3 X
                       "number of cars by lowering the NUMBER slider.\n"' w' S  [# p5 h" `: o
                       "The setup has stopped.")0 @8 P& B# m0 ?5 F8 K$ Q3 |& I
    stop
; U; @4 F7 o6 \+ q: A  ]! t! d% t$ g$ \6 s. S1 N- {9 l
3 R' J3 P3 _0 \# z- G% c! n! L% V
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
2 N0 o* `1 U2 J0 k9 f# j  i  X# Y  crt num-cars, R9 h6 W) [1 H' S* A
  [# \. ~0 z% u( i. c6 J% Y3 m
    setup-cars
9 c4 k+ c* V$ \0 m* ?" Q    set-car-color
2 _) S: {1 a; d4 y: J    record-data8 w$ S. I* W* w, X
  ], \  ~9 s' V1 {: J$ S' u1 F# |; Y4 q

# R' e5 t2 i+ |  |! C& o  ;; give the turtles an initial speed! O* W* W5 b7 B  K; I
  ask turtles [ set-car-speed ]" |. H, @4 p: s+ s

3 B3 H4 s  u9 D$ j; F) A+ L. r+ @  reset-ticks
: ?; ^1 i7 k) S, T8 ~  [/ c& ^$ |end
3 S* Q# t& W- {* b+ W9 `9 p' E9 z) ~
# b' u5 F5 x3 _/ m% U' @;; Initialize the global variables to appropriate values
+ r! p2 F+ B9 y& H, `' Y5 p# H7 ?6 k1 K4 |to setup-globals
& ^8 I  Y& A( ~  set current-light nobody ;; just for now, since there are no lights yet
1 x% h) e. j" Q7 ?( T  set phase 0
$ t$ W5 Q* ^7 [+ m: N4 e+ K9 _; ?  set num-cars-stopped 0
) k! I% m# A; x$ o" J  set grid-x-inc world-width / grid-size-x3 W# s# H* M# q2 a
  set grid-y-inc world-height / grid-size-y2 Q7 w2 S" k9 k; W% _: L3 v

8 J! P& @+ {9 b& W- q: e  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary( X8 z( _; Q) i
  set acceleration 0.099# z, I% E, @  e; b4 U( L$ ~! d" y
end
' L) ?0 d8 C3 A4 d. C% ~$ U" s+ i5 G: ~" z% p" D2 j! S6 `# V
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
* R. s# C& j5 N5 T' m- o+ q;; and initialize the traffic lights to one setting2 @  _, E+ O! p9 s1 g) q; A
to setup-patches' S; _- U0 _! n
  ;; initialize the patch-owned variables and color the patches to a base-color" t. V, w% q( t) _! s
  ask patches" `% n8 H9 l8 E" [( k
  [
7 E, Y' c1 ?& ]6 M    set intersection? false- g, N8 G' c6 O; e% ?1 j" ~; Z
    set auto? false! _: {* a7 {3 `7 ~8 N" y- a
    set green-light-up? true, n( q3 u! w% }' X% @* Y
    set my-row -1
6 W; P1 S  t, E3 B7 T    set my-column -1  Z8 z* [& H) `
    set my-phase -1- d7 K3 b' R9 ?, Z
    set pcolor brown + 3
3 N% z& J3 V7 _6 T7 n3 _: p6 E/ o  ]3 e6 m! t, H2 y# c3 D8 [4 x
% v2 S( b6 F, f- X# [- Y0 h
  ;; initialize the global variables that hold patch agentsets
! _# b, v# K/ L' h, n6 ^, r% p  set roads patches with1 b) F1 h7 F# k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 L! v! n% J4 j$ B; d6 `. ?
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% k. e0 G  ], o5 [0 P4 V  set intersections roads with  K5 b' I1 [. @* Y& T. ?
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" Q2 l% _% {. ^0 U* L$ m5 H- ?    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  M& F# `1 ~+ m( m4 W$ V+ d9 z# e3 j) T; G
  ask roads [ set pcolor white ]
8 D! [1 p0 c! t7 C  {    setup-intersections
. K, q4 g% V. o- zend; b9 j  r7 f! ^9 d
其中定义道路的句子,如下所示,是什么意思啊?
! }6 _- t- o# p set roads patches with  w0 |" e9 }' u9 u% V+ i0 m: @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' o4 _& q0 [# `! n6 B" t* B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], t" y* _8 v3 W/ F1 K
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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