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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。& h9 O# e5 K& }. z9 @
netlogo自带的social science--traffic grid这一例子当中,
- D$ I, E* n8 ^5 p6 G( Aglobals
2 o9 `' Q- Y+ z" B" ?[
, {' Z7 e5 ?1 i/ y; s  grid-x-inc               ;; the amount of patches in between two roads in the x direction
2 g- ]$ s- a/ s% K8 n  grid-y-inc               ;; the amount of patches in between two roads in the y direction
- I4 T/ G5 f7 d  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
) g0 E  m) p0 a* H: W# o; G- D                           ;; it is to accelerate or decelerate
( w, |2 q! v1 w7 I6 t3 A  phase                    ;; keeps track of the phase
& F3 I: G, M3 W. c5 r: h% c  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
9 U. i. z9 o+ g8 Z; y7 D: m/ k* x( v% c  current-light            ;; the currently selected light7 x- E2 G# d5 d* F
0 v( w7 \  _: [1 Y) q9 n) H* V
  ;; patch agentsets
+ C  x4 I9 ?$ [6 G- ?  intersections ;; agentset containing the patches that are intersections1 H1 f2 y0 f) [# k( D0 B
  roads         ;; agentset containing the patches that are roads
& g6 ^0 J1 f: U4 g7 _5 O]
  O" L$ Z1 e! `* @4 t6 f8 ^2 L7 n! V! o1 V: m
turtles-own
5 o/ e: Y- s2 V5 C4 R[, }5 e% m0 ^" ], K! c& g
  speed     ;; the speed of the turtle( T* j$ d5 h6 W/ J* e# l  x
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right! K$ F6 R& s' N" z& ^0 [
  wait-time ;; the amount of time since the last time a turtle has moved
# R8 D9 @3 \6 N% D]
+ Y' ^. h4 l9 N+ ?+ u/ C7 d" V, m
% K0 C1 {" ^7 R! G1 xpatches-own- I& L0 v8 o1 f! U! b  u" ^
[/ r* f- w, O+ a2 `% j- U1 j
  intersection?   ;; true if the patch is at the intersection of two roads% P" B# }4 F; o# j5 ~4 x
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
; B* r8 ^, i' }- f9 Y) R+ j$ U! z5 b                  ;; false for a non-intersection patches.5 \: N' S, Y" J2 t6 x6 p/ p  R
  my-row          ;; the row of the intersection counting from the upper left corner of the. f+ H3 J2 ]0 @4 t
                  ;; world.  -1 for non-intersection patches.1 }1 w2 {0 ^8 p8 y
  my-column       ;; the column of the intersection counting from the upper left corner of the
2 x3 `" v+ }) U) t& ^9 X                  ;; world.  -1 for non-intersection patches.. d( @9 i/ _! i
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.* [% d4 o$ f+ E
  auto?           ;; whether or not this intersection will switch automatically.3 v0 S! C' {- ~7 z
                  ;; false for non-intersection patches.) Y2 _, b. P* L! J: d! C; D
]3 v3 o8 Q3 x0 D1 s1 x/ M+ }

2 ]( }- [7 x1 L9 Q$ s
7 r, A) }4 t* J+ d;;;;;;;;;;;;;;;;;;;;;;/ m4 ?5 }+ v5 |
;; Setup Procedures ;;
7 i0 Q' ]' |  K/ |5 `3 E;;;;;;;;;;;;;;;;;;;;;;
& p! h; Q7 W: Z. ?
  Z+ x2 z2 E7 S9 D# y  q;; Initialize the display by giving the global and patch variables initial values.
2 N/ b! `" t% n& @/ g% Y$ e;; Create num-cars of turtles if there are enough road patches for one turtle to( S! q' S/ U/ G- i( P1 ~7 ~3 t5 P& |
;; be created per road patch. Set up the plots.( N2 Q. \; w: F9 H' l0 [8 j, f- e/ W
to setup
1 \8 A' D6 k" A  ca8 j9 @5 k+ Q7 t' W
  setup-globals
8 w% X5 p2 p+ l0 Q! f1 t9 H# T" O3 Z4 E: @' Z6 }
  ;; First we ask the patches to draw themselves and set up a few variables
! D: t# b. e1 l9 o% C8 ]4 o* f) }0 D  setup-patches
& ]& h6 `0 Q, m0 u. F0 V" B0 I  make-current one-of intersections
1 S% X0 I2 X  q: M  label-current0 K$ F' o( F# d$ ?5 R) W  z

8 X  g7 T: o/ E5 \2 a5 P  set-default-shape turtles "car"/ k, V. _- V' x0 f/ o% E
  K  g+ s  m5 P1 _2 F7 j/ I1 D* v
  if (num-cars > count roads)
' ^) \/ u% p2 U! }/ ~  [
# b4 R8 ^' D' k% U    user-message (word "There are too many cars for the amount of "
( J0 `7 i9 w, ]4 ^! j                       "road.  Either increase the amount of roads "! }2 x: c) |: h% G
                       "by increasing the GRID-SIZE-X or "# n; z' P5 p* H
                       "GRID-SIZE-Y sliders, or decrease the "
- x0 l' e9 r% b) l( C# n                       "number of cars by lowering the NUMBER slider.\n"
$ A4 [' |8 f1 `( Z0 J  n$ K                       "The setup has stopped.")" j. H/ A. N0 k, _
    stop
7 D' I. k, `, S8 ?- X; n3 e  ]% x6 k2 ]: X: }& H0 Y# C

5 l* Y, Y/ A) Z* f' R  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color9 t1 `- z! {7 j% W6 E
  crt num-cars2 @+ r- S- @: O9 q4 T
  [7 v" c2 _- g5 I7 u6 Y* W$ _
    setup-cars
, X) g% _  o0 P' S- g( L    set-car-color1 y7 R" Y' [1 C  M
    record-data5 A- @# o1 M! P  A
  ]
5 Z% r) A4 V/ E4 w1 }# ]+ q
4 r  L* T9 z8 }# x8 J  ;; give the turtles an initial speed
) p% }  ~$ I) l; |: Y% U  ask turtles [ set-car-speed ]1 I; }) E' Q( V/ z3 ]
! p2 Z+ E) K/ }5 x7 ?4 D
  reset-ticks
$ n0 e1 w5 s! M0 \end
3 N6 A6 l* M# s; V0 M+ P4 {* Z5 G1 L7 u- u; }
;; Initialize the global variables to appropriate values, K( m$ i/ \7 y& {) ~& _1 x
to setup-globals% e/ B8 O: r; p  @
  set current-light nobody ;; just for now, since there are no lights yet
* Q5 C* g  u) e4 }  set phase 0
0 H/ S* A/ B( Y  set num-cars-stopped 0
4 q, W* L& F: L' {( A/ Q6 l$ c  set grid-x-inc world-width / grid-size-x
2 V- P. |; |# \3 u$ E, ^; k) g- S  set grid-y-inc world-height / grid-size-y* u7 ~" g! H$ u4 J% I

8 I8 _6 G% `; p$ t  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
, [! A: g& k8 K5 d  set acceleration 0.0995 L+ E( F3 K( N5 `8 N8 R
end
5 t; k: h- S( s
! S/ p' D- r) _;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ s% F3 W+ l9 F2 k$ b/ z
;; and initialize the traffic lights to one setting3 d# R0 P$ Y8 a2 z
to setup-patches
1 i5 {$ C3 H) ]) f; u  ;; initialize the patch-owned variables and color the patches to a base-color
, q/ j4 A6 y/ J/ B0 A# w, j  ask patches
$ T4 {! |! h! W5 y, L" H  [1 |/ I# ?& a9 y9 T, H" S' `
    set intersection? false
; E7 F/ H5 S7 b' m; k    set auto? false( p- U4 p/ O$ C! X: f9 o# T
    set green-light-up? true$ J' B( O+ @) w7 L9 M0 f
    set my-row -1- S9 r. g  r0 q9 G: \
    set my-column -1
: a' Z# |" G7 ~4 K/ p6 n    set my-phase -10 y1 i) c/ B- m# W
    set pcolor brown + 3' W; t' }0 ~4 |8 Y
  ]
+ g6 P+ N, w* ^% ?( E. [( h; L) `" g1 D; Q2 P( p5 }
  ;; initialize the global variables that hold patch agentsets9 B; [+ i4 _1 {5 t% j' O
  set roads patches with
' \9 k% A. f$ @5 Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! H# [; r9 \- W/ `# p- m- q2 \. f    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ h2 ^, ~' i! j. w' `  set intersections roads with$ L' f; i& e  ^! [5 T$ `
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
  V, Z* Q$ K8 U2 L$ E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  z0 }& K1 D3 ~1 s: ]( k9 j6 u0 S0 S: U: m4 ?* k, ~
  ask roads [ set pcolor white ]+ F3 J! p' n3 F& ^2 C7 t: |1 c9 Z
    setup-intersections% @1 V6 O, h$ A+ y3 M- W& T
end
/ h* w& H: s6 t其中定义道路的句子,如下所示,是什么意思啊?
; b- d8 v% c' W, a set roads patches with
. q# I+ A( |/ Q7 c    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 Q4 m) B- s5 D$ h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! u) C, L' F' Q2 u" n3 \) `1 l: e
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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