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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。0 V8 |) G4 R0 [8 N" o- D9 C5 |
netlogo自带的social science--traffic grid这一例子当中,5 @( f/ A6 s6 j7 r7 m2 z& u
globals" |7 z! H# N9 R; V1 p
[" B) @' f7 J6 M
  grid-x-inc               ;; the amount of patches in between two roads in the x direction9 L# I% v2 r/ b! V5 v6 @
  grid-y-inc               ;; the amount of patches in between two roads in the y direction( a; i" _5 e: M; A5 n' D
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
- X( b. P8 Q- L! d6 o1 A# I+ C# ~; L                           ;; it is to accelerate or decelerate5 ]- R  i; d8 H" W" W7 K
  phase                    ;; keeps track of the phase
( G( Y6 T; C" F) o" e& l4 L0 F6 _7 D  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
3 J" I0 L8 G! S& e7 d( @  current-light            ;; the currently selected light9 ~  u$ z7 V; F1 Y1 U

5 S( h9 C* I0 S  ;; patch agentsets% J9 [& C) a% ^0 L) @
  intersections ;; agentset containing the patches that are intersections
, `- X0 d! A. X  roads         ;; agentset containing the patches that are roads
% P" }1 I3 y; g) B6 H]" W7 ?0 X: u# F; T/ Q' x  B

6 |$ g% S+ w0 ?5 @6 i1 B% M) Fturtles-own
8 }* B" t8 ?. V3 Y& O; d[7 y" b: ~) D( A0 v2 t* m9 Q# W" y
  speed     ;; the speed of the turtle
9 t# ?: n9 [3 G. h5 I7 D& S. A0 F  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
9 ?; V6 m+ V) e( R5 b5 C3 ^  wait-time ;; the amount of time since the last time a turtle has moved
6 p- o$ M8 @7 a( U4 }], h3 V  F, ~4 m3 r- q2 b

# t/ X& ?- l6 y2 V5 ?6 K& rpatches-own+ f+ C$ }- Z+ d, A8 C$ h
[) @( W, I( i0 r, W2 {( w
  intersection?   ;; true if the patch is at the intersection of two roads
7 y. T% m7 ]4 L1 w) \* i  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.; x* D4 R( w" T8 v2 h. F+ g
                  ;; false for a non-intersection patches.% g; F; h8 O1 T- L
  my-row          ;; the row of the intersection counting from the upper left corner of the3 o" x: Q' C; l* |, Q% ?( a
                  ;; world.  -1 for non-intersection patches.. g& y' `! j% Y( l0 R
  my-column       ;; the column of the intersection counting from the upper left corner of the
9 I; _4 R2 _( }& k                  ;; world.  -1 for non-intersection patches.
/ r( {1 l: ]- U! i& p  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.' t, R( T/ a% {8 q6 D- S
  auto?           ;; whether or not this intersection will switch automatically.
* X% b1 }3 W6 o8 l                  ;; false for non-intersection patches.$ _4 n0 p8 j' ]$ }* X
]
- M: C: L' ^7 _( o, ^
; B8 ~7 v1 A! A0 Y' `+ [% v1 e. k: `' k$ q' T
;;;;;;;;;;;;;;;;;;;;;;
: S  r5 ]$ |+ H" f2 x) g;; Setup Procedures ;;
/ b8 Q# F! A1 X/ n;;;;;;;;;;;;;;;;;;;;;;
1 g1 }: S% H2 s3 Y
1 @  ]7 s( Z: V9 d9 m;; Initialize the display by giving the global and patch variables initial values.
! t- ^1 z) v0 `; c. A;; Create num-cars of turtles if there are enough road patches for one turtle to
7 u: W! b; s. h$ i) u  B8 b; S;; be created per road patch. Set up the plots.
6 Z$ o, b4 e! c: b8 ?9 |3 cto setup
- _: n% C' X+ m$ {* A  ca
9 y' J. h9 }* M0 q+ Y0 r  setup-globals
) i( z, n- b$ v9 P0 f; `' Z) }$ b: T  Z& k  y2 N
  ;; First we ask the patches to draw themselves and set up a few variables) g, s4 s* ]0 |3 H0 g: N- \' [
  setup-patches
2 l5 q) f9 `, Y& q* l  make-current one-of intersections" s4 X* H% R& t4 b7 T/ V
  label-current
% g: O0 P7 @1 I
3 ~+ f, o0 R2 r) i. U  set-default-shape turtles "car"
+ ]- i8 a1 K# w& |' V4 k- k! C) Q: R
  if (num-cars > count roads)
* D; d- a( e  X$ V% E  [
* {+ j2 r4 a) P: e' u) ?    user-message (word "There are too many cars for the amount of "
" B' y. F5 {0 p. |                       "road.  Either increase the amount of roads "
5 r) _6 k; U& A' r3 z- d                       "by increasing the GRID-SIZE-X or "
- g0 k+ V$ \- J                       "GRID-SIZE-Y sliders, or decrease the "0 J  e; b+ Z8 R. o! p/ Y2 Q
                       "number of cars by lowering the NUMBER slider.\n"
+ y' w0 h- c. j9 N                       "The setup has stopped.")) ~9 W7 ?' H) G' u: l$ A+ l
    stop
* [2 j1 \: u- R( v( ?  ]3 J- z2 ^- X, o& E
* e1 p8 o& v* R! k1 O, j
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color- i* H4 m3 m" E7 H. B  l! j
  crt num-cars
/ v* @" @7 z% t1 G  [
+ X2 L7 G, _1 R0 ^, a    setup-cars  A4 ]& S4 }! }' g. v; H" k) ^
    set-car-color5 q+ I) X6 E  W+ U2 V5 d! j6 B
    record-data4 I3 C9 q0 I9 N7 v/ s& J- V( r  B
  ]% i' ?/ }4 B5 e8 }( h; V) t1 o
) A" h7 ?& d; ]+ ?
  ;; give the turtles an initial speed
/ O/ u% b0 A% Q  ask turtles [ set-car-speed ]- u/ \/ n  }0 J7 p. ~0 h8 O
( f6 U, k' ]' ^, V
  reset-ticks& c$ r9 ^! E; E
end
: F7 w- p6 a9 r) ?: P, c4 _
5 g  K0 e. }7 a. Y) C;; Initialize the global variables to appropriate values9 h5 V" A7 I5 @. `5 o& g
to setup-globals
; h& _% Q4 [% A7 E9 L$ x  set current-light nobody ;; just for now, since there are no lights yet( q$ u+ z& J/ |- V
  set phase 0
" g1 [" N: S; I0 P4 v! P( c1 u  set num-cars-stopped 0
0 z+ q' h+ R, t# w+ `5 d  set grid-x-inc world-width / grid-size-x
2 H- K5 t3 I# \+ j# p" l  set grid-y-inc world-height / grid-size-y
+ I  T* K1 `. @' {
9 G2 }& U+ _/ a. h9 {! g7 m  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
9 W4 [- v" A$ R1 C. ~$ x/ m  set acceleration 0.099
0 o( z5 j; E9 b$ E% }6 y. Jend8 `- r2 w! ?" c# p8 x1 J  [  A# {+ {
# T5 E* L8 J2 N+ b; s) h& S
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
- _. m9 `* u6 e* \9 q;; and initialize the traffic lights to one setting# @! \3 S, n! n( h
to setup-patches
' q  P/ l6 p  W$ W! e; g( G  ;; initialize the patch-owned variables and color the patches to a base-color/ F  O! ^: C' z9 U1 Y% a, `9 V6 E0 }
  ask patches; t+ @. \9 w2 \5 A  a6 @$ i8 t
  [$ s5 N4 A7 ]/ F7 |) ~3 `
    set intersection? false
* a* ?3 d( i  G" D    set auto? false  Q; R7 \; {7 y! d
    set green-light-up? true
" m* }3 t* Q: G) o$ `% G) R' ~. r    set my-row -1
, U  C, d! S* @, e: r2 o! v' ?# [    set my-column -19 v: l3 x/ Y; p  n& V
    set my-phase -1
! z9 ^8 Z4 ?7 r' l, z  _4 i( v    set pcolor brown + 3
7 q: g0 O/ d& B3 \  h! k. }  ]. X; j; o$ F. Z8 T; T3 l6 W

: A& v4 x& p. e- g- N' L  ;; initialize the global variables that hold patch agentsets& F8 x8 M; v4 n* q
  set roads patches with' w% w7 }4 ?  k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& X2 s3 ?: U- h  ?; ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ p% V2 O- Z" {' N/ P5 c
  set intersections roads with. c" O5 S9 Y/ s+ r1 j. ?; x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and2 V  ]3 y9 o* A- i. z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ N" d0 C5 W' R/ T! a- D  l1 z3 v7 O9 m3 N
  ask roads [ set pcolor white ]
) y4 O0 L+ ~5 S8 K% X3 I( u    setup-intersections, b9 E6 v, [4 P+ \9 z! V
end
2 T, D1 F1 ^- L3 N- x0 ~2 t其中定义道路的句子,如下所示,是什么意思啊?
$ X+ H* @* _* Q5 k9 v set roads patches with
& K' g5 ]1 m' u0 k3 w" F1 s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) P* z. `7 O' c( g) Y1 Z4 F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 ~" A* o& D! [7 F7 k9 i1 K& E
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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