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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。; h, }4 A1 N# w, g9 N* x
netlogo自带的social science--traffic grid这一例子当中,/ O/ t) _5 H" J% K3 b. i+ \( F
globals& Q) L% m4 f& P! z. p
[+ |, W3 S+ D: @" k% y: e( Y- Q
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
- x% O6 c* T4 s, k  grid-y-inc               ;; the amount of patches in between two roads in the y direction
( N* Q9 N8 P7 W5 `  acceleration             ;; the constant that controls how much a car speeds up or slows down by if5 g& Z# j* `* t4 s5 \' w  }1 L4 J
                           ;; it is to accelerate or decelerate1 `' }; x- b  u5 Z
  phase                    ;; keeps track of the phase& F2 x; z+ a+ p. F  h$ z) ]
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
, N- N, \3 O5 H% [2 O. ]5 u7 ~  current-light            ;; the currently selected light5 `4 Z5 c# m) S; e
9 c! i# r) J! }/ B8 H8 \; ?# S
  ;; patch agentsets
6 `& R: y2 }, ^: `8 x" c  intersections ;; agentset containing the patches that are intersections
& l- m' e5 J$ o$ @8 {: ?4 [. s! H- u  roads         ;; agentset containing the patches that are roads& _2 s1 K' D% n8 l' ~3 @: ]
]* N: j) {) \& R: `( c
' `' V( z2 b1 P+ x. ~
turtles-own7 N( D* {. h" P% i
[) S5 z& G0 K8 _" j" m
  speed     ;; the speed of the turtle% e: r, v, o6 g& F3 Y/ X. t
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right# L' z7 ?( N# }6 ]
  wait-time ;; the amount of time since the last time a turtle has moved
. F2 J1 P( E( g0 J2 Y7 M]4 K6 s* D( b- a: T
5 I6 ]/ B, B. p
patches-own
: L/ U8 y1 C4 H. s: d% L7 V[
0 `1 p. w* D/ j, T7 M! j  intersection?   ;; true if the patch is at the intersection of two roads% A9 b. A5 [0 [2 G) M( c& r* ~2 z
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false./ k/ l* m$ S. _8 b$ p
                  ;; false for a non-intersection patches.
3 p+ S! [8 u# N; ~6 e. m  my-row          ;; the row of the intersection counting from the upper left corner of the
1 P: t9 i1 [& Z7 o& h+ R                  ;; world.  -1 for non-intersection patches.
, w6 q! |( k( }1 O% A) x. C  my-column       ;; the column of the intersection counting from the upper left corner of the& e/ o, z' Y4 y% I; C- O* J% z
                  ;; world.  -1 for non-intersection patches.3 g+ p% Y' ^# h( b3 w
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
3 F1 y5 l' C8 {$ ^: _# r  auto?           ;; whether or not this intersection will switch automatically.
+ ]+ r7 m# w% @6 n$ z                  ;; false for non-intersection patches.6 _5 N4 @) P( S* W. q6 w6 v* p' Y
]
/ B  h3 A' X! V2 `4 q, B! E* K* z4 ~  m( N6 i. _: n5 W7 ~4 Z7 ~

- z/ |" C4 n! N# K- o; w: M  k# r;;;;;;;;;;;;;;;;;;;;;;
' U' W* O8 r& s; s;; Setup Procedures ;;, |9 n5 e6 H  Y  D
;;;;;;;;;;;;;;;;;;;;;;3 q! A# `. ^* y( H$ J

# j3 q  F5 l1 e! `" d. P;; Initialize the display by giving the global and patch variables initial values.
3 _5 t. e: ^6 v8 G6 |0 c% J' D$ p;; Create num-cars of turtles if there are enough road patches for one turtle to
( }$ M) T: o9 C4 v2 X6 m; o;; be created per road patch. Set up the plots.* k5 t$ r2 i+ c- a5 W
to setup  }6 _2 v7 w6 m( r+ W
  ca! _' q; S2 C$ y" L
  setup-globals3 F# ?, |6 d1 `6 S. Y
! `& h1 u+ Q' I8 M9 ~
  ;; First we ask the patches to draw themselves and set up a few variables
8 j2 K+ f: r4 Z. Q8 d1 d  setup-patches4 C% l1 x1 {. P& x# e
  make-current one-of intersections% i8 k9 c( L$ M  x0 _  R, Z
  label-current
  b, i# w# Z" F4 y; O! Y
; o' |  ?) o3 W# W0 c  set-default-shape turtles "car"/ V- j1 i6 @4 h# b' m* b

4 J5 g. s& s# A6 s. S1 p) z7 A* D  if (num-cars > count roads)
  e4 E% L3 c  r  y( v( \: j  [0 [7 n7 a- D- u( j: Y0 E  \
    user-message (word "There are too many cars for the amount of "/ c3 s. \* p/ _
                       "road.  Either increase the amount of roads "
( |+ D" w( q, z' [- A                       "by increasing the GRID-SIZE-X or "
0 u/ R1 l1 |) x- c8 B% T$ U                       "GRID-SIZE-Y sliders, or decrease the "% V% I. H/ C& G2 t* w/ P
                       "number of cars by lowering the NUMBER slider.\n", n3 w( [7 o8 d; {5 `9 r
                       "The setup has stopped.")
2 |# E5 n# X# V* f) \$ T6 m: i    stop$ \$ Q3 ]- f% s5 b
  ]3 l$ P: i! Z- U* H- E" c- ]' i
9 {/ P: x# x2 H8 D6 ]" |! _
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  B5 H& \3 _, M( `. K  crt num-cars! C. x0 `% K/ j* m2 \8 }
  [
" w, V! p7 K8 k; H4 Q; N3 U  G    setup-cars
( f; }. C6 p6 r    set-car-color& }& W6 G8 r: L+ [$ O& Q
    record-data7 G3 q& A4 j7 n1 `' L1 N# _
  ]
7 w0 Y! T) `* B3 ?5 Y5 g! I
4 D( x7 W' r: \3 O  ;; give the turtles an initial speed
/ C5 Q% |. ~* n; M) M& i  ask turtles [ set-car-speed ]; u2 `: a3 b% U- A$ ]$ }

* A& G$ u: F# t5 U  reset-ticks
. q9 D# _5 T& o; S' [. ~6 u' mend
) {: l* f( P$ r4 x( _
2 l  u3 g) F/ \2 t;; Initialize the global variables to appropriate values+ a9 b: j  D0 m
to setup-globals  o" I) q8 m' b2 G- ?4 I+ T3 H
  set current-light nobody ;; just for now, since there are no lights yet; Q9 N0 G% X1 C& b% }/ C" C' v
  set phase 08 V- l7 K0 x6 F  w+ K
  set num-cars-stopped 0
: ?! X. N) N5 I, `5 E$ N  set grid-x-inc world-width / grid-size-x
# C2 d# t$ H9 V+ u! }4 x  set grid-y-inc world-height / grid-size-y
# W$ _0 w! `6 J/ \: t' G: U
1 C3 I8 K2 }4 o4 `- E7 c  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
3 U4 Z. P) E9 h7 h7 e7 I9 p  set acceleration 0.099
/ F4 i2 y0 I1 fend! Q% J8 g8 A5 P
! i/ n  Y' z( v: [. o: l9 [3 m! J2 x. ~
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ u6 j8 \+ b9 [
;; and initialize the traffic lights to one setting- t4 P) |5 A! |% u
to setup-patches! c) {9 O; ^9 p& p5 T, T  D
  ;; initialize the patch-owned variables and color the patches to a base-color
- v$ {7 M: [. N; h/ }  ask patches
# s) h  ~$ z2 o: l1 ~9 s  [; ]! j/ {5 w0 }6 [  T
    set intersection? false
) z. h0 f1 j  h- E+ C( K    set auto? false# e, a/ l7 y. v: G/ G: x
    set green-light-up? true
. j) k& y( ?) A; Y- W- l    set my-row -1* g" M4 l9 ]' `2 g
    set my-column -1
2 X+ Q' E# S, }! W% E8 j% Y    set my-phase -1; m* x. [5 r7 M8 R0 r2 D& o7 u$ S
    set pcolor brown + 3
* D0 B5 T/ V' `  ], Z* [- B7 z( u( X% [- q
5 Y! ^; ~1 G1 N" ]
  ;; initialize the global variables that hold patch agentsets
# l1 ?- A: r! ?0 k- }! z  set roads patches with* r; R& j+ C8 z3 U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( D. w6 V/ t3 g
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 n) r" T0 M2 j
  set intersections roads with
/ ^  J2 g# j6 G4 L5 C    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and; R7 u0 p2 u8 C0 n1 J, ?0 V
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; v3 b$ J6 i& V3 [6 K- p# j
% a2 w; d4 |# M" R" V$ O3 u2 _2 e
  ask roads [ set pcolor white ]. }+ J( `! D: d( ?) j
    setup-intersections5 O6 I) g. P& P: I8 d
end
. ]1 P! r" B' u  c6 `' M其中定义道路的句子,如下所示,是什么意思啊?
" {- c9 ]. \2 t/ M set roads patches with3 x# V1 f( B3 s# t  I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& H, s' A3 a& h& m+ E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ p' q; T2 K! s: v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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