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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。; _, o6 a  o% v6 E! @" A
netlogo自带的social science--traffic grid这一例子当中,
/ ?8 Z( W, s6 a2 J! ?* Zglobals
; u7 F, G3 R# Y+ z& R2 \[! G$ I( J/ s, t6 Q$ H. p
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
! G4 I, u9 |" a! [0 o0 i  grid-y-inc               ;; the amount of patches in between two roads in the y direction  W% N/ L0 _! w1 U$ G  A
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
. ?4 Q$ h/ d4 I8 z8 H8 {                           ;; it is to accelerate or decelerate
$ U7 Q6 L3 M( f' C4 d' E) B/ E( ^  phase                    ;; keeps track of the phase
6 |" Z3 ^6 _) u  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
& k7 g4 a8 P' L# R2 E  O9 M  current-light            ;; the currently selected light3 ~. O+ J2 X+ o1 H! e

, z( r& h( }6 q; R3 K; z  ;; patch agentsets. P5 H+ m) l9 W
  intersections ;; agentset containing the patches that are intersections
$ w+ \& ^" [4 h; y9 O. X4 L- k  roads         ;; agentset containing the patches that are roads4 i3 }* Y/ f% W' L% F
]
4 t2 F& p& W* ]# B4 [
: k9 H* @* B8 Xturtles-own' u2 b1 U  M5 P* F
[
/ h1 N0 y  d, V0 _- d  speed     ;; the speed of the turtle
" a6 G8 m6 \$ Q+ Y) E5 `6 _* E  up-car?   ;; true if the turtle moves downwards and false if it moves to the right; O4 z9 j+ n) _' p+ h* N
  wait-time ;; the amount of time since the last time a turtle has moved
/ a* x. q5 r" c! S4 d* S]
; _& ]6 h3 [" o7 u1 s: M7 ~4 j, y4 s6 {* w. T$ R$ Q
patches-own
2 t1 e. z' H# B' v% |3 c( k[
: L, V  D" [4 ~  intersection?   ;; true if the patch is at the intersection of two roads
, t  i* \4 ~/ F8 `4 U  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 ]7 F$ F+ Q" A0 B0 K7 f& `
                  ;; false for a non-intersection patches.
6 e0 M' Y. p' s$ ?0 Z; B2 L  my-row          ;; the row of the intersection counting from the upper left corner of the$ u2 \# y( x& {$ t0 W1 r
                  ;; world.  -1 for non-intersection patches.& M7 A# I+ _( C9 n/ L% C) I( p1 P
  my-column       ;; the column of the intersection counting from the upper left corner of the
; I6 N6 k/ ^0 k$ `                  ;; world.  -1 for non-intersection patches.
* f6 [+ P- Z" J( w, J( s: z, R  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
, w- W$ N" ^8 I, U  auto?           ;; whether or not this intersection will switch automatically.
& v5 b8 j2 L& B! ]3 Q                  ;; false for non-intersection patches.
4 h. ?9 M: h6 W6 ~# L8 Q( f]
3 z& U1 y# G' \0 w0 p, G+ B0 V* L$ l$ I, n4 ^
1 \* J2 X0 @9 e$ ^6 U
;;;;;;;;;;;;;;;;;;;;;;
8 G! Q5 r8 g7 c6 j  D;; Setup Procedures ;;
% {1 J/ l' P8 D;;;;;;;;;;;;;;;;;;;;;;
7 d. n! N- l' U+ i0 Q3 q. w# f8 Q
4 [7 x$ c' R* }& e! n;; Initialize the display by giving the global and patch variables initial values.+ ^3 J9 \  e7 D' P0 Z( k
;; Create num-cars of turtles if there are enough road patches for one turtle to
; ^5 F& r* U* O% n  \;; be created per road patch. Set up the plots.$ U  s7 G: ?5 T8 @; l
to setup) j/ J  E  `3 w# G# D  W4 {0 p" O/ c  {
  ca. c- a; E; ?+ H, a/ E1 c
  setup-globals$ A, ^$ {6 u% r% a4 ?2 r$ p9 E7 O! m+ ]
* C# \0 n/ J4 M  f* d; J8 M
  ;; First we ask the patches to draw themselves and set up a few variables, [% C8 v. s8 Y+ z  e
  setup-patches1 Q  r3 n  |% }
  make-current one-of intersections' _7 O& w- l" |" G" z
  label-current
4 e4 X7 [' ]6 t% Q( S, b4 w5 M- a4 i7 j) P
  set-default-shape turtles "car"7 @8 g7 [8 c2 \0 s+ p

2 M3 [. ~7 \. i6 Q. \" {2 ~# r; e  if (num-cars > count roads)! [8 z, f: A7 I
  [* D1 X. }  G, l1 U; B9 x
    user-message (word "There are too many cars for the amount of "
: o6 d) o0 z, }9 [2 y- b* a& }                       "road.  Either increase the amount of roads "
$ `$ L' K$ l, M( B  C" N& v8 x                       "by increasing the GRID-SIZE-X or "
6 |9 G! z9 ~: X* u/ y                       "GRID-SIZE-Y sliders, or decrease the "$ a$ i% n/ g8 |; @  g
                       "number of cars by lowering the NUMBER slider.\n"; Z; j; ], K  ~- [: U# y
                       "The setup has stopped.")
$ |5 X0 c; z- }+ ~. P% o" b    stop
) E/ x' _% C0 m' r1 ~' S0 N  ]# @. d' m( \/ u/ V: f! H

, ?1 v2 \$ _  [  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
! s% c6 }% }& j! ]. @7 N  crt num-cars' U$ L" J$ V7 S' R4 r
  [6 q/ L' ^2 h" X5 X2 f
    setup-cars
. Z' {: h7 Q" v7 s& R3 Q    set-car-color
* L) K$ Q4 G6 }8 a7 K0 h  a$ l1 Z( J: b    record-data
1 c$ f0 m1 S0 w6 s  ]4 A! l3 @0 }' f: k! k; Y
+ J& s) Y  I( L) n* m* a, p  ^
  ;; give the turtles an initial speed
4 W! k) k9 i& @' D( T: z; [4 K3 s  ask turtles [ set-car-speed ]" d& i3 C+ A0 k) C) Q  s

( x' w% y# K& d& a4 r% J  reset-ticks
1 X3 ]  R, l. Q" W3 y' U% ]end
8 W( p; ]$ U# j8 I' P
& Y" v; k1 `7 E1 l;; Initialize the global variables to appropriate values
# _/ f/ n7 R9 k3 o" f2 a, {to setup-globals
. Y) M: `! g& q  set current-light nobody ;; just for now, since there are no lights yet
' z; a- G7 C* Q9 S) D8 N  set phase 0
/ n+ G+ O! Y+ N3 Z0 ]+ J  set num-cars-stopped 0& L' ^4 A3 R! @
  set grid-x-inc world-width / grid-size-x# Y1 Y: g! u& ^4 B+ p& d
  set grid-y-inc world-height / grid-size-y
; W0 P6 r# g6 |+ g' u! b4 p+ [# V' R8 n4 C6 g7 x  Z2 E& A) G- H; W; U
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary  z. Z4 b  J+ M, S9 d
  set acceleration 0.099; m0 x( V" C1 E( x+ e6 B8 ?
end1 e/ K7 X. H6 M6 d5 o
" W, M% l5 D. a! t7 ], O
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
4 ?" o) ^" a% r" x;; and initialize the traffic lights to one setting- Y7 J5 G2 ^: p" @8 z
to setup-patches
* @) K1 U$ S$ ?- g$ Z  ;; initialize the patch-owned variables and color the patches to a base-color+ C3 v1 c/ O- g$ A/ o
  ask patches% @6 y: d; n; j- z# Y2 t& i( N
  [
; a  t2 O# s) F1 U& S% f. m* ^    set intersection? false
: q" d2 R) x5 q7 k, u  Z    set auto? false5 H- d1 H& N* m/ L: @0 i/ ?; o( ?
    set green-light-up? true$ k/ N' Y/ W: P5 h+ A8 D
    set my-row -1
, j& G' K0 S# M    set my-column -1+ A1 K% H$ k, u
    set my-phase -1
4 F3 q6 [5 n( w  k& N# t/ H    set pcolor brown + 3
& e$ G( J' ^8 K9 ]( m0 x; L+ v  ]
6 N, B* V; V) g" C' p! b0 }  X1 m" t# @1 m( s8 t
  ;; initialize the global variables that hold patch agentsets
! {" T, }) F2 F' c; A  set roads patches with+ V! V7 X3 p+ y6 p  C3 A
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 Z2 H$ }$ f# G$ [' B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- m- e5 z* V/ X& e& ?& Y
  set intersections roads with
: ?" |! w0 L6 q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
/ c: n. `2 K5 u, ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 e+ J+ b% G) o
3 n" Y. Y) E# z  ask roads [ set pcolor white ]. t% u8 K9 N. M& \. j- s) R
    setup-intersections+ r$ I) e2 J  F$ X9 b3 a
end$ k1 g+ G# C7 u0 G& b
其中定义道路的句子,如下所示,是什么意思啊?
) w# f3 W3 p- c0 P! q2 ~, W set roads patches with
/ Y: ^! T7 r  j5 N, n& P. {% c5 {    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 i5 S( ?9 ]4 Q+ U/ Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ q9 \: r/ o. |' l
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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