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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。3 k1 D! n: L- D2 E) l
netlogo自带的social science--traffic grid这一例子当中,
- V/ j8 n" d! {; e8 Sglobals
; C! c1 i% c' m, X8 p& K: `$ X[
* C" ^& L( X+ r, D/ D3 s( S' t1 [, G  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 G: ~4 F$ `8 e) `4 [+ z, K
  grid-y-inc               ;; the amount of patches in between two roads in the y direction# E, {3 m7 g# H! t! q/ S! \( l+ ?
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
. l: e: g+ X% U1 f( d' O) `5 h) Q* n" _                           ;; it is to accelerate or decelerate+ G/ y( m! @( q7 Z+ @- {/ N
  phase                    ;; keeps track of the phase+ X8 v5 G( s7 }1 o6 w; q* n+ }4 s* F
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; A  K. D: g' V5 i3 E; E  current-light            ;; the currently selected light
: R' y/ ^* a+ r. @+ r( k& s, o- c- ?( k) u+ ~
  ;; patch agentsets
- T) b* I' w; _7 f4 ~  intersections ;; agentset containing the patches that are intersections
, }3 J  `  `  x  roads         ;; agentset containing the patches that are roads  C) f! d$ `; ~* {% s9 {
]
+ y, a; I" t7 \+ P) ]: l, S
6 E. L' p' I8 X7 Fturtles-own! X5 D. M9 ?2 @+ C, p+ y9 a5 ^
[
5 r9 N  a$ ~  n2 c* Z5 D3 F2 s& ]2 t  speed     ;; the speed of the turtle
! ~/ L2 a" C8 X' Y  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 |$ `: |! k8 H  A  wait-time ;; the amount of time since the last time a turtle has moved
% s1 u) g( ~% ?6 {]7 X, J( T* J8 N
; T! u* A& [! x9 Z- T. V- d
patches-own: y2 `( z+ U# @' n% t* L
[
- a7 t% Q. s# ]4 K  intersection?   ;; true if the patch is at the intersection of two roads
) ~% x, A- c3 v) h0 p  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 N. I9 m2 N* O: u  u                  ;; false for a non-intersection patches.& c* k  y* w! P& F/ R0 V& r! ?
  my-row          ;; the row of the intersection counting from the upper left corner of the4 ^( X* n- K, u' q' Y+ ]. v
                  ;; world.  -1 for non-intersection patches.- ~9 M: F: e( X
  my-column       ;; the column of the intersection counting from the upper left corner of the5 `1 y9 M+ b7 Z' \) Z9 H3 d3 r% E
                  ;; world.  -1 for non-intersection patches.3 ]9 b- Q0 }  p3 f
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( D- }( h7 Q: p  auto?           ;; whether or not this intersection will switch automatically.
( D8 A  X( @: J4 M' u                  ;; false for non-intersection patches.
- U1 r0 k, y! A' O! |]
8 j3 R% L: y3 W2 K. y; z+ p1 A4 C: C" B! P* e
. x! D% I' o# u' C) o# ]# M
;;;;;;;;;;;;;;;;;;;;;;6 r2 s5 H4 [; g  U. P# V& Z/ S
;; Setup Procedures ;;& n/ B8 I, d5 g8 M3 }
;;;;;;;;;;;;;;;;;;;;;;1 T, C- K3 a' Q* D+ H# Q  E- _
$ \( n* E8 Q$ f4 l, W  E1 f+ Q
;; Initialize the display by giving the global and patch variables initial values.
2 t  g0 O$ a, a8 j; G% X/ y;; Create num-cars of turtles if there are enough road patches for one turtle to
) }/ j! M3 K# M$ {* O;; be created per road patch. Set up the plots.- C$ a6 q" A( h0 c
to setup, k- d  N. |$ C
  ca
' p6 P* j, i2 q* o- L  setup-globals" y+ _0 @+ S( U4 g8 }: r; H6 s
& A2 R) ^7 E8 H
  ;; First we ask the patches to draw themselves and set up a few variables
0 I; J1 I- v. D  o/ j) y; v( U& R  setup-patches6 H4 P# @% x1 u2 ]! y2 X& ~
  make-current one-of intersections; [: N% b% _! G5 Z
  label-current* F0 `3 T" o2 M

' S5 K* L) w7 R# [9 `; K! T  set-default-shape turtles "car"6 u2 e5 g9 h7 m) W7 d( y

* d8 Y5 J+ ~( v" s6 D1 _! E: I  if (num-cars > count roads)# C: ]$ _, G; w4 m* C0 w% q
  [( ~* h1 c& R! u3 R/ C0 T! X4 O
    user-message (word "There are too many cars for the amount of "2 g: F" z# D8 b
                       "road.  Either increase the amount of roads "6 |& I# H' E  u5 O5 }+ Z* K
                       "by increasing the GRID-SIZE-X or "2 M! {$ _- f6 g6 d
                       "GRID-SIZE-Y sliders, or decrease the "
) m0 ]+ d. t1 t% b* }' L                       "number of cars by lowering the NUMBER slider.\n"/ X$ i# x+ I4 i6 A6 o5 ]
                       "The setup has stopped.")4 G) i* }4 y1 X4 w8 s/ c
    stop
1 {* s" A* T+ `2 z$ R& Q# l  ]
$ V0 R: t8 U7 _9 W1 K/ S9 x8 Z
) q5 E( W0 T8 R$ `/ Y. \- w0 ~  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
* r( n2 I: W& a  crt num-cars
9 J% O2 @% @1 N& f2 f  [
+ X0 }7 m# h, R    setup-cars+ c) m: D" F6 j2 r+ a
    set-car-color! U) h9 p! v4 I; I
    record-data
1 E% l+ A9 e; N. Y  ]
9 G! V- U4 S" j9 W( t% B
; w8 B; E2 \" J9 z% S0 V# V1 P  ;; give the turtles an initial speed6 f# A9 q. P# \
  ask turtles [ set-car-speed ]
$ M, z, Y' g( G% y. P
3 `0 g; h$ I4 Y2 l. q) g  reset-ticks( i) v9 x# Q# l& U7 @& Q3 }
end# E6 _& H" `1 R( b) d

# C" G9 _6 _. @  s# ]; t;; Initialize the global variables to appropriate values7 g3 o6 w1 \" I' _9 a
to setup-globals1 N9 I; D( Y; p- F
  set current-light nobody ;; just for now, since there are no lights yet& A* u2 `) D  j9 @$ |9 `: b# q
  set phase 0
( y. `' Q" \; L# Z# o- u; o  set num-cars-stopped 0
4 q1 t# r; X9 t; ?  set grid-x-inc world-width / grid-size-x
7 L8 d, k3 S* [, W6 a  set grid-y-inc world-height / grid-size-y5 @! ]$ D  @' d# z, M
( \% O& M* e; N- @3 `6 ?
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary8 w( K5 g7 u1 D- M
  set acceleration 0.099
- l' W2 @3 w7 x% h3 eend. J2 S' w. w7 ?2 Q* _% {& ^4 q
9 V* o. z% H% N# F3 ~
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
' Q- i& Z8 J6 Q* N6 z( `' Q# _# V( X;; and initialize the traffic lights to one setting
4 i/ R/ Y  M$ G+ A! zto setup-patches
( s: i5 L& @) `  ;; initialize the patch-owned variables and color the patches to a base-color
. P) A. F7 _7 F+ h  ask patches
4 s/ n( \4 r3 J2 k2 [# e" x- w  [
5 W; j1 d, Q- A9 |" u% }    set intersection? false
4 ~9 {0 L% W" a8 k' C) h    set auto? false
# f- `; ?" r. d( q6 _    set green-light-up? true
: ?: O+ }" s5 D- y    set my-row -1
( N2 Y" e! `2 k: [% j: k' w    set my-column -14 Y- ^* A$ f/ V4 |! f3 B- `" B- h
    set my-phase -1
" ?0 B2 [: V% D9 ~: l' X$ l    set pcolor brown + 3" M3 j/ y, ~, X
  ]
+ o+ O" l6 ]1 {" Y) x' \
/ E4 o- F: ^. u6 L  ;; initialize the global variables that hold patch agentsets& |+ G# {, ?/ q' U$ F6 E
  set roads patches with
; o( a; e3 L; I. c- a& ^8 f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 B2 _( J3 J% k' i0 I, q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 S/ z- M$ @! L3 M6 z1 Z  D- @: [
  set intersections roads with
# u( l- W& d5 z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% O2 E5 _  j$ a+ _# h" l! p; G    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 {0 F8 `; }) X. E  f' R0 i3 |2 r$ _2 j( A5 b1 U0 K
  ask roads [ set pcolor white ]. {" v$ ^" f9 i2 b! ]  q$ b
    setup-intersections3 C# s- ?2 [- \/ B8 l, k
end
$ Z5 j5 N" I0 f) R8 L; U其中定义道路的句子,如下所示,是什么意思啊?& J! Y" g2 M, O, W
set roads patches with
# L( |7 s' @0 }# ^2 ?' _! i/ D    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  |  m5 }/ S3 \) F    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( u$ ~; l$ T8 B, C% f
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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