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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。9 g2 W: W; o* A3 w6 {
netlogo自带的social science--traffic grid这一例子当中,2 c. F+ g" U% w4 b& o3 O) g
globals; G% Q/ n9 ^& L$ B% R" S( f# w
[8 H7 O) Z5 T0 u4 o4 d* a9 |. ^! c
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
& p* C5 R4 M' P0 H5 i5 w  grid-y-inc               ;; the amount of patches in between two roads in the y direction5 s: ]; \) d0 c+ H! E: p( f
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if! p1 x# a# I9 v3 S8 N# N6 G
                           ;; it is to accelerate or decelerate: M0 O1 ]- v; f- n2 C
  phase                    ;; keeps track of the phase
& {7 V/ I# d2 C3 {, |  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
8 p; ]( p9 ~& Y+ ^! z# T  current-light            ;; the currently selected light- R! q3 d6 ~/ F; Z9 l

. T: m' ^$ h' i  ;; patch agentsets
# a# s' c1 R$ b- c% n) Z  intersections ;; agentset containing the patches that are intersections' @4 L% I" v' P7 c8 e7 n, E
  roads         ;; agentset containing the patches that are roads
9 G' E& F+ t5 X! f7 H8 U) h]7 Z& `! W# A: t
+ `* S7 `1 ?5 J9 m6 c: G
turtles-own
# Z' C! V1 S- F3 m- Q4 x4 o[) ^% g% G( I6 Y* M  d3 T
  speed     ;; the speed of the turtle) A# h1 p5 A9 N1 P: c/ [: r, |
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
" `9 ]1 E+ u8 `  }8 }  wait-time ;; the amount of time since the last time a turtle has moved0 Q2 q1 h4 W( B* C# ^
]/ N" b( _6 L+ g7 |, S: @

) Q" n- I9 H6 C  E% e  Vpatches-own
  N! B7 a) M  `" {[
  i2 `( y8 H3 T) R% n4 \% r  intersection?   ;; true if the patch is at the intersection of two roads
! R1 }! _! s1 ?9 }0 c  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.) k9 ?4 b+ m/ C0 c
                  ;; false for a non-intersection patches.
1 R! R# R3 h4 W- S' \  my-row          ;; the row of the intersection counting from the upper left corner of the
# s9 z- Z& B& m                  ;; world.  -1 for non-intersection patches.+ U8 e, G. F5 n: n1 x
  my-column       ;; the column of the intersection counting from the upper left corner of the
9 \' B9 \* }! x: p3 q                  ;; world.  -1 for non-intersection patches.- J( Q5 l+ i9 E3 A& G- e& }( e
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
) D6 `* Q& \5 f+ ]' Q# E  auto?           ;; whether or not this intersection will switch automatically.8 ^" u/ a# y4 N4 x
                  ;; false for non-intersection patches., {# S$ ^& z3 q; S  o0 A
]8 t6 c$ ?6 Y4 d) r! G

1 k! e& ~4 Z/ C8 _# d% j- H
- |5 ~3 O& v0 X; E) u$ p4 x* H;;;;;;;;;;;;;;;;;;;;;;0 t! ~6 p' \, M1 E; n
;; Setup Procedures ;;* S- g4 t7 z: I, X& V8 g3 h3 D
;;;;;;;;;;;;;;;;;;;;;;
2 r* m) v7 P. @# @' I% ?  G, a2 n. e: s2 o; b2 Y" L2 a
;; Initialize the display by giving the global and patch variables initial values.
0 a( V+ G! T; ^2 L" o;; Create num-cars of turtles if there are enough road patches for one turtle to) T' M( p; m! C
;; be created per road patch. Set up the plots., @7 [1 s8 k* N
to setup
" N$ N) d6 E& z& ]5 [9 h  ca
$ B1 x# S0 a. Z8 y$ P  setup-globals
5 q/ \+ A, a/ U8 p$ U8 |( w) D, I$ c" y0 y) N8 r
  ;; First we ask the patches to draw themselves and set up a few variables
4 m9 P- N" Q+ r3 M* b% Q& Z' W  setup-patches
; F" _- B1 h$ U; T  make-current one-of intersections
/ h/ J2 r6 [, G: L  label-current4 ~3 b: V2 W0 ~8 E' @: r5 F
$ \$ R. p  R$ C; T
  set-default-shape turtles "car"
4 \5 F0 D. \4 r  ?5 }+ w: [1 J) k  H. H% r2 x
  if (num-cars > count roads)3 w# d. N' ?$ R8 o
  [$ v$ Z* D1 ^# c7 _
    user-message (word "There are too many cars for the amount of "$ I& ?5 z' C+ R% S- I
                       "road.  Either increase the amount of roads "
$ Q$ L2 {) F' ^7 U7 n! i                       "by increasing the GRID-SIZE-X or "" p' s3 M9 P! |" b, x2 w! i3 M
                       "GRID-SIZE-Y sliders, or decrease the ", |" R$ v, P6 M1 k* Q0 p- c
                       "number of cars by lowering the NUMBER slider.\n"
, }% ?) J( l. n* r# Z                       "The setup has stopped.")5 s+ o3 h& A& \
    stop8 Z  P) s0 B! f+ N" K: t3 U: t1 V
  ]
" n6 m4 b& Q; B6 e9 }9 s" n) x, Y% p# j/ T" H, p8 ]8 i0 P; G
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color4 _- O. L1 x( Q) H6 ?# e: N2 m
  crt num-cars
0 }4 V# t# F2 O! }  [  r, j9 f! p# q; o
    setup-cars
3 f! I3 @: h% \# W4 ?    set-car-color* j+ Z8 V9 q- S5 }$ P
    record-data2 p+ Z' r5 s5 G* |' t" I
  ]- F, {8 Z& Y$ N0 J
! L* T: e) d8 ]+ R& l
  ;; give the turtles an initial speed) i2 ^) J/ e( k3 m
  ask turtles [ set-car-speed ], n. p: D$ a( p; V( a# U1 i

& Q6 W/ M/ R0 P/ y, `  reset-ticks2 a+ v" n  @; Y$ t7 q- j! S, c
end
) F! B9 k/ y" x! Y4 r
* x. w& K  e" w$ W; j' H;; Initialize the global variables to appropriate values2 \8 E% C0 A6 w' X. p
to setup-globals
0 S! t% |3 }: R2 [  set current-light nobody ;; just for now, since there are no lights yet
6 c& n+ b, p6 T" P) p, v( z/ `, F  set phase 0) v# C) Y$ Z+ _% a
  set num-cars-stopped 0
' E( H3 J$ S! b/ t3 f: {6 Q4 m  set grid-x-inc world-width / grid-size-x
4 s; U( \& Z3 b  set grid-y-inc world-height / grid-size-y
/ P* E" E; ~  n  Z' f# U% f: t
. |* ]8 a; U! k  U# x) f" z7 @  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary0 |3 A* r+ A& W* K! S0 ~- a
  set acceleration 0.099, M: q& s; N7 P% d) J4 p
end
; q. u0 C& H: L0 u' C
: o) J' C) \2 }5 q* a;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 i. G$ n3 I8 s2 H  P;; and initialize the traffic lights to one setting
2 P3 D& d/ H( c4 w$ T7 Ato setup-patches
( c6 ?& h1 l8 X  ;; initialize the patch-owned variables and color the patches to a base-color
. }) i& \% ?' J9 I4 C! M$ ^4 @  ask patches$ T4 h4 E, s1 `3 E9 s
  [3 [3 }8 \) a' Z) w
    set intersection? false) m% ?  A7 T; f7 R& B
    set auto? false
) B' }+ F- x9 V& R, H3 [- c* K    set green-light-up? true
' w0 E1 b/ S3 n" v    set my-row -1+ M2 ~' o% k7 `# o0 y# C
    set my-column -1. z9 x! Y0 C) z8 a! Y
    set my-phase -1* Q& u) {; {5 R/ p
    set pcolor brown + 3# E9 ]8 {, l; x: K
  ]
5 F( e1 m' u( [# H4 ?0 [# ^; t8 a, t" P6 D2 i! [6 J4 K% A
  ;; initialize the global variables that hold patch agentsets
1 {0 h7 z4 ^3 j0 r+ ~; P9 v; P  set roads patches with2 J9 X2 P! T  D( H) Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 i8 P9 H; r5 D  S, F8 l. B
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( b$ g# c% \* r% g: z3 ^
  set intersections roads with
9 w% G  m8 K0 f, S- N: ]- R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 k& \3 ]+ G# Y1 J( a% c* B2 ]
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 E6 P2 y9 r1 s

- o* Q6 [1 ~( O7 ]" B# T9 q; g  ask roads [ set pcolor white ]2 g  }& G( ?- o
    setup-intersections
! t! T% u; N7 n" s+ K4 h2 m) A* cend% S- a5 R% j$ t* m0 c5 J2 F: g2 S
其中定义道路的句子,如下所示,是什么意思啊?+ ~1 u9 X) Y, K
set roads patches with0 v) ~. j4 f  ~6 I( p; r" k0 Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' b& _  g' Y2 k& R, j
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  R8 {: k4 S  Y( u) F# a6 r4 k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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