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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。
! Z* X6 H' ?+ P9 Enetlogo自带的social science--traffic grid这一例子当中,
7 w7 r* ]6 P0 ?9 hglobals
! M. T# y0 I# n" D: K/ E9 T+ E" R[2 o; n. h0 _; ]+ G) F
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% L4 H( H& x% q; {; i  T  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 ?# D3 Z$ m% b2 B  acceleration             ;; the constant that controls how much a car speeds up or slows down by if; w" C5 t3 K5 v% v
                           ;; it is to accelerate or decelerate
' a$ ?* }. [( P* B  phase                    ;; keeps track of the phase' R5 M; t" [% x' |  L8 E1 }
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
) b% j( p2 w! ^( b1 y3 c  current-light            ;; the currently selected light/ S% t* B( D/ [7 L

% D( w* X: `* Z8 P* \  ;; patch agentsets0 F+ t7 ~: g8 Y: k/ ~! x# I0 g
  intersections ;; agentset containing the patches that are intersections5 S/ \& }2 P0 X6 a" \) Z
  roads         ;; agentset containing the patches that are roads# X( a6 r1 J0 C# G
]
9 ?! W3 _0 i  \5 b+ s7 @
0 m5 V% ]3 x+ c3 d/ Xturtles-own
5 ?4 \3 m7 I& s2 {# w$ h9 y- w- D[+ w" O  R$ Q0 c
  speed     ;; the speed of the turtle" f6 }* _3 B" @" u4 A
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
3 E( W) G; N8 w: @9 \5 h0 q6 m) M  wait-time ;; the amount of time since the last time a turtle has moved, T( f5 G+ d* o; S  V% A2 E. Y8 \
]9 O$ H' M0 ?9 W/ H* f0 ~) p

$ S9 @. r8 q1 G# A7 k- jpatches-own
) [  M$ ^$ |" D, I$ r- u- x[! d" h# D3 F1 ]) Z
  intersection?   ;; true if the patch is at the intersection of two roads3 W! M2 f+ h' C
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.6 U7 f. q6 t3 q1 E
                  ;; false for a non-intersection patches." j/ ]- [0 z% d9 g0 B/ K: U/ h3 b
  my-row          ;; the row of the intersection counting from the upper left corner of the
9 a" Z. r9 c" i* _                  ;; world.  -1 for non-intersection patches.1 _4 a4 \4 l6 z5 z6 O3 }7 T; x7 z
  my-column       ;; the column of the intersection counting from the upper left corner of the3 g" h8 n" C5 c  c
                  ;; world.  -1 for non-intersection patches.
3 |$ D- X: Q8 s! C2 M  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
$ m  Y0 Q  p" I  a5 c9 ]! `  auto?           ;; whether or not this intersection will switch automatically.
% ?2 V" N0 n  n8 e% J- d                  ;; false for non-intersection patches.9 `4 D/ C4 W/ W, z" }5 ~6 E
]' @- S" J, y7 E# b( E

8 h! J% q# I) S6 G" P, _6 _% F# q& v* C- i( X; o
;;;;;;;;;;;;;;;;;;;;;;
' x5 j0 @; W5 l4 X5 A;; Setup Procedures ;;
- u& r: L1 `" T;;;;;;;;;;;;;;;;;;;;;;7 N5 f& b2 a0 N6 L- X" l6 d1 v# L( \

) ^: O. l2 Q4 R7 b# `, ^, Z;; Initialize the display by giving the global and patch variables initial values.4 r  h9 Q6 c# h3 f1 p  S# g6 C$ v# R! O
;; Create num-cars of turtles if there are enough road patches for one turtle to
* U* b* u* y8 ~1 F. s, _% g- }' V" i;; be created per road patch. Set up the plots.* z# ?! Y" B# w2 K
to setup
" ~  B' I* `( M2 v0 R  t' P1 o  ca
' O9 @- }& Z$ G* n7 y  setup-globals
: p  @  }2 |' U2 |6 c
' }% Q/ }2 V. O5 X5 \6 Z: d6 f1 y  ;; First we ask the patches to draw themselves and set up a few variables
2 a7 a* N8 X& N# Q4 {7 z$ i7 T6 v  setup-patches4 r& _% W. ]2 [9 S; M* ]
  make-current one-of intersections8 G+ G4 u6 b5 h, ^# S2 e
  label-current
' g7 n' N3 W% t! [+ i1 v! L
5 W2 x9 z' p6 M) X4 u+ H! u  set-default-shape turtles "car"+ N4 ?0 V& d+ Y) P6 P/ D, o# J

: _& G! M, X& ?$ M  if (num-cars > count roads)
0 L' H1 e. q7 P1 }% ?; }  [" I" a, z- I/ [$ Z- W% L4 D6 t, h- j
    user-message (word "There are too many cars for the amount of "1 j8 ?# C$ B) @0 r, N
                       "road.  Either increase the amount of roads "$ U( X) p+ [1 j' R1 M3 c' }; `8 T* z
                       "by increasing the GRID-SIZE-X or "8 m3 ]* I1 z& Q" w# o2 ^' X4 p' h! v
                       "GRID-SIZE-Y sliders, or decrease the "
/ F% d8 L+ L/ Y6 P                       "number of cars by lowering the NUMBER slider.\n"
7 |" T: ]4 C* I) N! I  X                       "The setup has stopped."): x2 b" n5 o7 V$ h
    stop1 C0 k0 m/ W) N: h
  ]& Y1 l1 B$ ]. K2 Z1 _
$ R" t1 @' w$ _  V" g7 G
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
2 M  \+ A1 j8 G  crt num-cars  E# b: ?4 E, V7 `+ W/ g9 A
  [2 o3 U' K+ I& f. W  v* ~0 ^$ [
    setup-cars
: c; h( g- q$ t( h% u: L    set-car-color" i4 o0 a2 @' x, G+ m  U0 {2 I" p) o
    record-data
- m/ Q3 {3 {( G( B: T  ]$ D* I  p) L; {2 z* f
: m4 v! g  }( _
  ;; give the turtles an initial speed
% I" w( W3 O1 h$ e  ask turtles [ set-car-speed ]
3 ~0 Z7 h* `! _+ S' `* i6 V4 a/ Q" s. h' |  s! I6 s2 v
  reset-ticks1 v9 U% x2 I9 r2 A" B
end
& m1 Q6 R2 _& j$ G8 _; D* u- W; ^  G: E! |2 K' a4 F" T0 p
;; Initialize the global variables to appropriate values* r1 ~; s! B; f9 J- c
to setup-globals$ L0 R" w: a6 r. B) e% W* c; s0 q
  set current-light nobody ;; just for now, since there are no lights yet
4 ]! X* l6 E9 D  set phase 0; ?& v1 u5 k: e) o6 Y4 e. Y
  set num-cars-stopped 0
, y) k$ ?$ `- b2 P  set grid-x-inc world-width / grid-size-x8 ]) `7 q  Y  e2 x4 X: _
  set grid-y-inc world-height / grid-size-y1 l0 f+ Y$ }' D5 n+ O
9 z0 V% y* V2 }+ j" E! a/ ]
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary4 F- Y* F" h+ r+ n4 B9 n
  set acceleration 0.099
& G/ N9 f$ l+ g  F& ]end
# X; G) z2 Y, D3 X6 G* @; I2 Y; Y' @  R1 J* `, _4 a
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# d6 _" v7 k0 W& e; o" ~( y1 i;; and initialize the traffic lights to one setting
. n5 R, ^0 o' l4 eto setup-patches/ j. R) E7 M4 D0 G1 P
  ;; initialize the patch-owned variables and color the patches to a base-color
5 P: B$ k4 K9 _5 O0 {  ask patches5 s+ Y$ p6 A2 W0 ?+ s) o
  [
7 }- Q4 h2 Z; z$ L& y( ]  l    set intersection? false
7 N, C+ ^& W  M! z- E$ Y3 D    set auto? false
* H# l" f9 i: A    set green-light-up? true) L) X' m" l, P0 a) B
    set my-row -19 X, s, V8 W- X- k6 q
    set my-column -1# o( e1 _1 h) L
    set my-phase -1
  U4 t( K1 _+ s. n$ M    set pcolor brown + 3  I- r4 h% ^0 x
  ]& D6 ~$ V; h. ~0 o; F
" Y! R& ^2 k' Y+ l# f
  ;; initialize the global variables that hold patch agentsets( L3 }& {6 V# m" d  u+ X. Q# [
  set roads patches with$ F, l2 y) |8 g& ^! R: k8 `
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 c* o9 M' z2 m2 N& e3 [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- {7 \' t# x! v' T3 N  set intersections roads with
7 u2 P& W4 @3 ]$ p: A7 D* C    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
1 l& M9 \8 p# l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 L/ ?1 H3 a' r( B

) Z3 V5 Q9 \( U( e, m( W/ f  ask roads [ set pcolor white ]5 q2 x1 b+ M  i: ^( G' S' @0 ~( L
    setup-intersections( V" V& ~2 `2 l" O) l
end" R" g' S" E3 `6 @/ w6 Q$ ~5 ~; t
其中定义道路的句子,如下所示,是什么意思啊?) ]$ w5 s* d( O0 w
set roads patches with( c* s0 s0 R/ T5 v; \! X6 \0 U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. ]: b9 e+ c" ~0 R$ n; Z1 g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( Z8 g; x. E. u* m6 _; ^% Q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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