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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。& b& [# N: W6 w% a+ _+ k+ F* U
netlogo自带的social science--traffic grid这一例子当中,* x- W9 `( Z: E1 T$ f. r
globals- p; S9 G$ y1 P& D
[  @; n, w  S* Z. [9 ^/ ~: K0 ]
  grid-x-inc               ;; the amount of patches in between two roads in the x direction; a9 O4 C7 V* @/ \$ |* s
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
( O' r+ v- b: Y8 b1 ?7 O" o) @; h5 r  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
% r; X( V9 d' }# K1 U                           ;; it is to accelerate or decelerate5 _; A, \6 i! F* [+ F* e
  phase                    ;; keeps track of the phase0 i0 j- B: d# z! A8 D1 Z
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure( X5 A6 X- ?& M5 W
  current-light            ;; the currently selected light( z, M- `, H+ X# i( `+ N4 s
: w0 X+ z- W+ H0 ]* {
  ;; patch agentsets
6 W2 t' F7 P2 w4 [% s! K  intersections ;; agentset containing the patches that are intersections; G+ z- Z7 L8 W
  roads         ;; agentset containing the patches that are roads
7 k7 t) m' F" F]
' y$ u& i: h8 c  U! J  a: D8 P# \" m6 \1 a
turtles-own8 S% X. p& [9 n4 Q. P0 n
[
2 y2 h- @( F, H1 [& T6 T! [' w- R& p  speed     ;; the speed of the turtle
/ S- l" L& o5 z( |  up-car?   ;; true if the turtle moves downwards and false if it moves to the right" Z. s2 n! _% g  w: a
  wait-time ;; the amount of time since the last time a turtle has moved* O; M! e! E' K' c% }% ]& f
]7 G" `2 V$ g) @8 R
: M6 _$ A/ O  Q( a3 }
patches-own
: v- T+ b2 ^' Y5 n$ C[
; D3 O3 z0 ~+ n4 i4 P: y$ m8 `  intersection?   ;; true if the patch is at the intersection of two roads& }7 j1 i0 \: g/ ^. u
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
7 {) r) ~( M* D9 }3 s                  ;; false for a non-intersection patches.
' Q/ D8 W9 O4 A* {, ?  my-row          ;; the row of the intersection counting from the upper left corner of the
& g! q) ^) B% P5 C% K2 m) T0 Z                  ;; world.  -1 for non-intersection patches.! V0 t: h/ u# y, j2 S
  my-column       ;; the column of the intersection counting from the upper left corner of the
0 a' l- V/ p; }! Y: m                  ;; world.  -1 for non-intersection patches.
% n/ h: o; i+ B8 D6 R6 R2 c" d  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.3 F& {5 k2 m  G3 N# @+ \
  auto?           ;; whether or not this intersection will switch automatically.
3 k; U# G6 S- O$ B) V: p                  ;; false for non-intersection patches.
, H1 E6 t/ K* Q7 z2 @]
  [9 P1 j: c8 N) ?  W  G3 _, d: `
* b: S6 _( ]) W
/ U" h# f% w2 t& K7 Z8 i;;;;;;;;;;;;;;;;;;;;;;
# Z+ `" `% t. W1 G! l;; Setup Procedures ;;$ y& K3 l2 C9 |% R/ t1 V' Y
;;;;;;;;;;;;;;;;;;;;;;
  y7 G& v* v/ j& A4 c4 I) \6 g/ {# W/ Z2 H2 q; f& s
;; Initialize the display by giving the global and patch variables initial values.8 ~+ R3 ]' j% H& F. P
;; Create num-cars of turtles if there are enough road patches for one turtle to' f) l/ [& ]# g0 X9 v7 @5 H1 t7 [% Z
;; be created per road patch. Set up the plots.
; L2 w" S) d- M5 \to setup
) z6 b3 b9 @; v( |  ca
! ^9 ^0 B! c3 p8 z- P; ~( [0 I% M& g; W  setup-globals8 A4 }3 M+ i+ Y3 @! P6 A* r

7 Q' j+ d  d6 T! u1 C( D" Q9 l  ;; First we ask the patches to draw themselves and set up a few variables
/ d4 t8 U( w5 |; d% @  setup-patches8 n6 I( g, w3 [6 Y% \- o  t7 ^
  make-current one-of intersections$ Z3 ]2 k0 p& ^$ ~8 R% u
  label-current: u8 R0 l0 O+ M! {. ~
4 A4 ^2 `4 q% B# ^0 q) i( o
  set-default-shape turtles "car"
0 [; x" e: ^* G  I5 @
/ {; x. J) a+ L6 h6 j6 X" V  w  if (num-cars > count roads)7 |$ d. S  R  U- T
  [' J4 T- Z7 A, U
    user-message (word "There are too many cars for the amount of "5 Z2 a. R  a# P/ M% g6 r) \- r
                       "road.  Either increase the amount of roads "
8 n7 v1 A$ b1 p. ~: C5 u! {                       "by increasing the GRID-SIZE-X or "" s. P5 ?4 Y& e2 h. L
                       "GRID-SIZE-Y sliders, or decrease the ". d- G( H3 O' K9 c' p7 M. N+ ^; d
                       "number of cars by lowering the NUMBER slider.\n"
, H5 ~$ ^" W) X* o; D& W                       "The setup has stopped.")& V3 A, ]$ f3 ^) M9 I6 g
    stop
+ F8 A. z; X* X+ U7 h, m+ G2 C  ]
/ N2 o& d2 D& T; U& j
) Q! h% P, y% l% U* K& w/ X  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color( U- s. {) i0 j3 o* w
  crt num-cars& [- _7 i2 ]; P5 a7 M* d1 o
  [* _( A% T& k6 c- C( a7 x
    setup-cars4 |% D5 K! P% w, R% q7 S
    set-car-color5 l2 p3 p& [& L8 R
    record-data/ e8 N! k, z, q& {+ J* ~) G
  ]0 p9 L* Y; c, M6 u* G$ ]' e  q
' ]) B- q1 D) K6 r( p6 ~0 J
  ;; give the turtles an initial speed& \  {: O) q2 ]
  ask turtles [ set-car-speed ]
+ h2 d0 X7 t; @5 h9 s* O( Q9 k) J8 I  `9 f# J' Z' S
  reset-ticks5 G; s5 \( }, J- ?
end
5 s: W3 m0 m2 l  e: i/ y% |
. P: I6 X! u- y, i* f;; Initialize the global variables to appropriate values
1 k+ |7 Y$ K$ r( w9 Tto setup-globals. {/ E' x! r, m4 S" g7 @
  set current-light nobody ;; just for now, since there are no lights yet
/ ~/ t7 z3 f7 F2 ~( L% g9 R( a5 ?  set phase 0
" ?. }9 v9 }+ U! P( b2 `  set num-cars-stopped 00 M+ j' i- }/ V" v% k! s/ r9 p; F
  set grid-x-inc world-width / grid-size-x
& t3 i' O9 ^$ X0 E- G$ @5 ~; j/ d  set grid-y-inc world-height / grid-size-y
4 z: n3 ^$ f7 c- \3 p" Y
9 y7 w5 D$ j$ i4 W# O; ~  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary5 y) m& J( t  W8 \" \: V" S- i
  set acceleration 0.099" D8 |% W2 Y! E: n9 q
end' \" @$ V& r5 T1 C) S" x5 r
% I4 u8 O" A- l$ ^: }
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,) K$ M4 j7 S5 ?8 \& g" e0 T
;; and initialize the traffic lights to one setting
; z  r# c' ^+ `' M7 U1 o8 fto setup-patches
% K5 Z. a4 q! t8 r  ;; initialize the patch-owned variables and color the patches to a base-color+ }0 j' }$ g8 N+ i1 o; g
  ask patches; U- p, i; L6 V4 a
  [" G' W" I( r) S7 G" P) o
    set intersection? false' D7 f6 W# ^2 A; A' s
    set auto? false
1 f3 Y7 Q: C; N5 _/ Y: F    set green-light-up? true
: s9 H4 M, w: Y0 v1 @5 Q    set my-row -1# _, j2 @6 P! N$ U( O  x
    set my-column -1
/ a4 l4 F6 ^. `    set my-phase -13 U' a# o& u6 b2 {. k! z
    set pcolor brown + 30 Q5 ~+ I2 v- D
  ]
7 x+ ~' H' d. C- O3 T- E* i( t, [$ y2 m$ B# p  B# Z9 P' q9 o
  ;; initialize the global variables that hold patch agentsets. x9 ^: @! }+ d9 z1 ~8 t+ g0 |; h
  set roads patches with- w6 Q6 o/ s2 s4 b* U( z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 G; M/ G9 ~* t' u. `
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) ?1 m7 W# D- B0 S4 D3 D  set intersections roads with4 k5 R- s4 w2 t
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
, B8 l; z* L# L/ F* p$ s9 w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 d( ~. {* m2 ]2 m5 r" ~+ P; ]
* [8 g2 L4 }4 U; F: G
  ask roads [ set pcolor white ]" C. p  z2 _: u/ a1 Z7 k) p
    setup-intersections
% S4 x7 O# h$ s  w# }end
/ }) _! Y8 F- h' L) G- ~其中定义道路的句子,如下所示,是什么意思啊?
" \3 q" }4 \; r set roads patches with
& E; C7 k. _" n% Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 `. Z8 h* h2 R, j$ s$ o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 C: u6 E2 N+ e2 {, J4 k3 \" [" F3 d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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