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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。& D+ T0 [4 S4 p6 x8 s* ?
netlogo自带的social science--traffic grid这一例子当中,2 W, E0 j+ o, ?$ ]3 P! t
globals
- g/ n* H! I" _( T+ M8 Q" Z[
3 D& ]! z2 }1 o# J  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ [# A& n2 h& V: a
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
# j0 p& i2 j# f# t$ A  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 f9 _' l. t( ~  ~0 ?) `* j                           ;; it is to accelerate or decelerate' i6 _4 f9 I& {, I! T
  phase                    ;; keeps track of the phase
; t0 t" V0 F3 W6 ?* s' T  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ ^3 y7 F; o( }/ J
  current-light            ;; the currently selected light
  ~6 d2 P9 ^& M$ r# a, P+ p
+ n7 |; P& m) N1 l) T  ;; patch agentsets
3 u2 ?8 Q1 d- x5 p/ V5 H: a  intersections ;; agentset containing the patches that are intersections7 X( @$ O2 D6 x7 X$ P
  roads         ;; agentset containing the patches that are roads1 r: g( m* l( _& ?$ n+ P
]5 |* N% J' f- i% ~

. Z# g3 I4 X- D1 B; E* cturtles-own
1 l9 a+ G9 l3 s[
  a$ p8 n" }/ ]0 \9 E) Y$ E- J  speed     ;; the speed of the turtle
, {* b0 C7 z1 f% v3 e# V; s6 S  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
8 X7 Y* z+ h2 C, R9 c$ j  wait-time ;; the amount of time since the last time a turtle has moved9 |! ~1 H' H+ {, q
]
; R% u1 p9 L2 E% g& }9 e! k
: ?. V: K: @) L4 wpatches-own1 `- h5 N! @: P( }* M" E' ~
[! ~& y) ^! Q9 f( H3 U/ c$ r5 K7 r
  intersection?   ;; true if the patch is at the intersection of two roads% g# @$ d" e3 g4 l( ?2 ]
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false." I/ Z/ {* l: `* a6 V, o
                  ;; false for a non-intersection patches.2 Y$ t. W0 t, Z( S* s% `8 M% S, i( q( I
  my-row          ;; the row of the intersection counting from the upper left corner of the
# I6 ?2 a* }. u/ {0 ~                  ;; world.  -1 for non-intersection patches.
9 n$ I& t+ C0 X4 i% K: ~2 a  my-column       ;; the column of the intersection counting from the upper left corner of the
' B$ U8 w! n7 v                  ;; world.  -1 for non-intersection patches.
% p$ H( P  M' C% z6 S8 b5 L  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.& x0 V% t8 e, Z7 `. l
  auto?           ;; whether or not this intersection will switch automatically.
# O: L% W3 V" X6 a4 w0 A                  ;; false for non-intersection patches.
' |4 r7 R: z$ u, Z5 ^& k3 ~  @]  h7 B% |( x, J% f

$ F( |$ H1 C/ K6 `* q) M8 q+ P; o0 S  R
;;;;;;;;;;;;;;;;;;;;;;
/ m( M0 T9 D% Q;; Setup Procedures ;;
0 ^; y, G& h9 v" ~" f4 x. J5 A! U+ Z;;;;;;;;;;;;;;;;;;;;;;
8 Q: A' J2 s5 A
; z  K6 Z' a6 z. Z;; Initialize the display by giving the global and patch variables initial values.- Q' w1 G' p/ i* {# E% E7 Z0 O  s2 x
;; Create num-cars of turtles if there are enough road patches for one turtle to/ H0 _5 i: O  S; U5 S
;; be created per road patch. Set up the plots.
) V; I+ L2 n' K( ~" o9 k- O: X$ z4 jto setup
) j. l2 L# q% u9 c9 F5 y5 R" D9 Z  ca/ r+ H) z4 @% e" F; P- x% i: I
  setup-globals
& g5 s) d; h) g8 @( K0 M5 X: w  B
  ;; First we ask the patches to draw themselves and set up a few variables
/ S. W: t. r7 E0 [) L0 |3 v& O. O  setup-patches
: s% X* f8 m* L) e  make-current one-of intersections1 h$ C" G  [  ~) K
  label-current
2 z0 M2 X0 D, y. n
. r$ R2 u/ v, [  set-default-shape turtles "car"( l4 d; m5 W6 x
; Q+ ]& v4 N7 Q/ j& |
  if (num-cars > count roads)& K# x# B0 c  m5 d! v7 \) \1 b
  [' N1 C. i* x) I8 C. _8 L0 g
    user-message (word "There are too many cars for the amount of "& Z5 |( E) u6 `. C) R8 B0 g
                       "road.  Either increase the amount of roads "1 O. q3 V' r' R7 f" h* ?
                       "by increasing the GRID-SIZE-X or "5 Z/ O8 b# Q, a* ?4 h2 N
                       "GRID-SIZE-Y sliders, or decrease the "
) P/ O+ O9 @) J3 q9 a9 c3 g1 {                       "number of cars by lowering the NUMBER slider.\n"7 I3 |: o. D( `/ U0 P# D
                       "The setup has stopped."): G) L) N+ _+ E) o; J( a
    stop
& h; `7 k5 W( K8 Q  ]
1 W1 o* d2 ?, V- b2 j7 l  B! y5 C: H* h% [' H0 j
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
) f. @/ w6 |; p3 S  crt num-cars, S5 J; Z, N5 U9 C2 w' P! d
  [
: o5 C- L3 T2 B  n    setup-cars
: m8 i. l# t# N$ `  l% U3 f" x    set-car-color) G) |, L7 s3 }
    record-data
, m: U* K! V$ U% ^( {6 F( a7 O2 o  ]
4 |+ b8 f5 t) K7 U, A5 q! v4 P* p# }& V: J1 D- o6 o
  ;; give the turtles an initial speed8 g5 G/ _! L* y6 o2 m8 q" m# \
  ask turtles [ set-car-speed ]
+ q6 [; B% x3 [* r# J0 ], j- q
! y! o) h+ e5 S8 o. o* V  reset-ticks
/ m* N6 |1 z" }- xend
5 E9 i7 Y6 L5 R& Q( y
7 l$ G$ z1 U+ M! L2 `;; Initialize the global variables to appropriate values7 B# Q5 M- N! @3 d/ U. L
to setup-globals
+ O, G  ]7 Z. ?1 [* I% t6 o- n# v  set current-light nobody ;; just for now, since there are no lights yet: N9 _0 Z' n- a! h! p+ x$ `9 k
  set phase 0
! j/ {1 W+ r9 d5 \  set num-cars-stopped 0
; K/ @* X; Q( g% o  O  set grid-x-inc world-width / grid-size-x1 y1 E, l+ ~# p" s
  set grid-y-inc world-height / grid-size-y
! ?9 ~. M2 C( O% F% @  b! l( c& Z$ |! E! [% `+ @
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary. f' ^6 g- I7 K! F
  set acceleration 0.0993 k2 c7 ?. L0 v9 V* w' I8 q
end
. s; A$ q! v  R( H. y, e
  L  C! e, [" m- W3 K& l4 x! \/ w- Q;; Make the patches have appropriate colors, set up the roads and intersections agentsets,( M0 B& |: Z8 v0 D! Z: Z& H- {" q: k
;; and initialize the traffic lights to one setting
! I% a) j/ p& bto setup-patches% }2 L* v) B: A- h* D9 t
  ;; initialize the patch-owned variables and color the patches to a base-color  E2 a( K1 ^4 w$ Y' ~
  ask patches* Q9 y5 r5 m: ~& C9 _
  [
* ?! [! m2 P, A: n* Q# \    set intersection? false6 V* d4 \( z& Q3 f2 Z3 J
    set auto? false& a0 P) T3 d& I0 O
    set green-light-up? true( H/ ]2 h* R9 Q  ?. O9 m
    set my-row -1
2 U" j7 X* Y0 L5 G0 T6 N. y% D    set my-column -1  ~+ C, Z' _: u, u( U: W3 P
    set my-phase -1
" H! v9 C$ V8 K( X0 q5 D! [5 Y. \& ~    set pcolor brown + 31 b8 ~* @! h: M, R- A. D4 y
  ]
5 j9 m4 ^2 F7 L$ {4 `, ^
8 B, t+ J' y+ V* y; x  ;; initialize the global variables that hold patch agentsets" Z6 v" R& v! Z) }! G. A: o
  set roads patches with3 y+ _: W+ C: m& B' K2 E) F# E- C8 h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 ?! [. Y' g! y6 o3 k    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: s% V1 Q" L4 ]5 G  set intersections roads with0 M) O: y0 J+ G6 {' c' |& d1 c
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
) S4 c0 u; ?/ v& ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# r" [$ H. }4 [" g6 O% Q
  J' I0 G3 }: u+ P) ]8 `2 f
  ask roads [ set pcolor white ]
3 U3 C* `6 M& g5 p    setup-intersections; c) d  s1 t8 c' |% \3 j! z
end
% Z6 G7 J0 J. E! L3 @3 u; ^其中定义道路的句子,如下所示,是什么意思啊?* x% D' x* R8 B- a* A
set roads patches with
% A- S+ L$ a7 G- F9 a$ }* t  Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 k- z4 v. |; h2 J6 u# J
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. U+ K+ r" ~1 i" M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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