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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。
$ I& H$ g; A7 o" T$ Y6 Xnetlogo自带的social science--traffic grid这一例子当中,
* Y4 h4 K7 f# p) S6 H# H/ R% uglobals: H4 }# \. _" N
[
* u* q6 {' |  j  d) t3 z4 T  grid-x-inc               ;; the amount of patches in between two roads in the x direction& X3 w9 j: B* S6 `  w1 S
  grid-y-inc               ;; the amount of patches in between two roads in the y direction8 s  w: d% K6 i$ B+ t& W6 c
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
) }; I0 P) X! V* u9 ^                           ;; it is to accelerate or decelerate( c2 z6 {. H5 K1 {1 p! e
  phase                    ;; keeps track of the phase% |9 u* g5 t9 s. l
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
: V/ {" p& O1 R* S1 F  current-light            ;; the currently selected light4 x; o/ M& n" z2 W, O

  P& y# h: {$ ~( y3 X# U, C- B. _  ;; patch agentsets$ z) d  B8 b; n8 m
  intersections ;; agentset containing the patches that are intersections
) a& `0 c2 c) o; K& L9 y  roads         ;; agentset containing the patches that are roads
' K7 P7 {, M9 E! _$ q$ g]5 J. B% I; |- m0 a
2 m! _: C$ o5 z8 O$ T
turtles-own7 F$ Y8 g+ N  O' a7 F
[( g, I3 O( R1 T( q
  speed     ;; the speed of the turtle. C+ ^$ i* s  f' ]
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 R+ x; w! ]- ~9 t  wait-time ;; the amount of time since the last time a turtle has moved  [3 Q: ^% ]9 M/ n, ?- f
]
( y7 O/ @+ n- h3 U9 X+ i& @  @9 D+ n- Q+ _& g
patches-own
' U# C4 M$ x; W" R[
/ l+ T  a8 g+ t( {1 w8 K2 ?2 p- |: K  intersection?   ;; true if the patch is at the intersection of two roads
# ^5 G& _) E0 S9 H! i: X0 e7 r  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
" k- D, ^) }: K1 ~! P5 C                  ;; false for a non-intersection patches.
% q" ^7 _3 a( w# W# t' @" R  my-row          ;; the row of the intersection counting from the upper left corner of the; t9 A% s! m# \- e: @
                  ;; world.  -1 for non-intersection patches.3 g3 w' w+ ?- l* Y- V1 D, n
  my-column       ;; the column of the intersection counting from the upper left corner of the! z% j$ H( w1 A
                  ;; world.  -1 for non-intersection patches.
! A$ j4 `5 s" k- Z5 f  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.6 X, p3 l2 t4 c/ \
  auto?           ;; whether or not this intersection will switch automatically.& t5 g& W" _& s
                  ;; false for non-intersection patches.
+ i+ @% _3 f6 _2 B8 h]. e' X: F; ~0 \7 C! J  r
/ R5 N, U3 |4 W2 R9 x/ C
+ T- r5 |9 w$ @% N# Q; M
;;;;;;;;;;;;;;;;;;;;;;2 _1 L* n9 ~% J4 ^
;; Setup Procedures ;;  J* R" A9 ^' b' r
;;;;;;;;;;;;;;;;;;;;;;. g: |- r$ h9 x8 O

* M9 c. X, V) p; \8 _. L6 h;; Initialize the display by giving the global and patch variables initial values./ w! F% A" X) j
;; Create num-cars of turtles if there are enough road patches for one turtle to3 {- j& h% D0 |7 ?
;; be created per road patch. Set up the plots.
0 G' [. ]" `2 H. a* C( I2 Kto setup; K' S0 x* o: H9 }$ X
  ca2 G( R4 w: q  @! J8 c) C: d4 N, T
  setup-globals: ?; j& \. o+ y! a+ F- Q, @

: ~% R, Y0 I$ f/ W; `3 h, A  ;; First we ask the patches to draw themselves and set up a few variables
2 i/ H3 N- X9 z7 O  setup-patches4 H6 }! [( a0 ]; `' C
  make-current one-of intersections( O* t2 V6 r) b0 o" x$ E
  label-current, w; t: {. U0 m8 A1 X
; l: R* y1 O& C
  set-default-shape turtles "car"
) s$ @6 ~1 o- ^# o) w3 P* O6 ^5 [7 }6 s$ W- C
  if (num-cars > count roads)4 M" S2 H$ P; g$ i+ Q5 ~( u6 k, c
  [; I" z& O  q1 [
    user-message (word "There are too many cars for the amount of "0 ]  ^4 a: J' |- g) |1 r& Z6 }
                       "road.  Either increase the amount of roads "
0 w0 [% k6 `4 F$ n9 m" p                       "by increasing the GRID-SIZE-X or "
; I# h- S( e( U5 u. v5 F' ]                       "GRID-SIZE-Y sliders, or decrease the "
6 R7 n% v& i  ?0 G1 e( Y! z6 v                       "number of cars by lowering the NUMBER slider.\n"2 V# z, F& n* ^
                       "The setup has stopped.")
8 J  @; `9 P' C: v, ?; y    stop
1 r5 @' H& s2 R) X7 i7 J0 O7 F  ]
. C& E: Y7 V$ [8 x' }- e7 V# m: u' g( e( M, Z' A5 [
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
/ y- Y2 y3 z9 @5 \  crt num-cars, h$ J1 l. e1 _
  [
- x. [0 t/ p2 n. p- P5 a    setup-cars
7 O7 Q) `4 m$ s% m3 h    set-car-color
' J* C- \! D0 A# S    record-data
6 x# p7 [. ?: S5 Y0 n( D  ]" ^5 U* F& |/ f% ~
  y( {1 S2 M, _& m4 E: E
  ;; give the turtles an initial speed% z" \, \+ A% z$ \4 _0 q% F% C
  ask turtles [ set-car-speed ]
! l4 @2 ~; L! g% x3 V2 v- l; Y
5 h  r0 m+ V# t+ C7 O: A  reset-ticks" T% c; O( c/ I2 `& @4 d
end. V+ M* p+ J' P) v4 c1 i2 A9 E
% s0 F, \. O- y; d2 a
;; Initialize the global variables to appropriate values
) F8 z1 A- p5 xto setup-globals; `+ M( O; k5 M$ C
  set current-light nobody ;; just for now, since there are no lights yet
% y3 t- v: q" @, ?  Z) Z3 R& e+ B  set phase 0
$ [- N8 v- f" @+ ~7 H& x, Z  set num-cars-stopped 0
1 x; V; H2 V( N8 g) L- A# O0 f  set grid-x-inc world-width / grid-size-x: A/ w" o& \+ F) z3 w
  set grid-y-inc world-height / grid-size-y7 E0 ~/ Y& D8 `4 ?! S

: x" b$ A! F$ s# |  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary5 r# p- J2 b% S1 W8 x4 d7 i$ r2 w# r( _
  set acceleration 0.099
# G5 C9 J! T) L* x% S! H* N  Wend
2 Z) R. f5 r6 w* j. e0 j' {3 x& ]; C6 ]" y! q
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 s0 _2 s; N5 t* `8 G& ~;; and initialize the traffic lights to one setting
& I7 J; ~7 X4 Wto setup-patches/ H5 ~7 I2 `9 Z( |) q& t
  ;; initialize the patch-owned variables and color the patches to a base-color
. X% |: H, U$ h! F  Q$ c  ask patches0 |! J6 G7 t. w: y( r8 S; }5 T! k
  [
- b3 I# g& A2 L& ?0 R0 [8 Q    set intersection? false% r  z( }: G8 q' d# w/ _* W
    set auto? false
9 A7 m- [6 @6 U+ o8 @7 p    set green-light-up? true* P: O' r$ B4 G0 |! d
    set my-row -1
8 S/ v5 r% p% Q: t: h, {    set my-column -1
3 m$ O! M: N8 r7 W: q# s7 |    set my-phase -1; W5 ^9 `& z" G6 M* B3 \" k
    set pcolor brown + 3
# _$ V2 V; H; B9 ^  ]
+ w; ?+ ?& i. L) }5 I
1 G8 }* B* ]4 F& b$ X8 A# y2 O  ;; initialize the global variables that hold patch agentsets
2 y8 ~! h! W2 s- j: _1 A- x  set roads patches with9 U! E0 w6 P& v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: D% ?  j# x. I- G8 I: j3 L    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' X' j8 X# S6 a( H! T+ I
  set intersections roads with
: {# L: i  v; D' t6 F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and4 |  j0 c1 ~$ P- }
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 T. a1 `& z; }4 j: _, E, J& O% r4 z' D' G6 }, ?2 I9 G9 m
  ask roads [ set pcolor white ]
! g0 q6 T: F2 ?, n; R( M6 o* B% x    setup-intersections
% x; s9 G* C% w9 m+ f" ^end' r$ \  N0 D$ T2 t) y; B/ C
其中定义道路的句子,如下所示,是什么意思啊?* V% T* Q( f& n  ?0 `
set roads patches with
& d" p: p6 h! K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 _' f. s, L% ^( v' j/ G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ E* j5 V/ m, B' {+ u  k( }2 o. p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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