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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。( M2 z' k! f+ B) ~* m  g
netlogo自带的social science--traffic grid这一例子当中,$ ~: f0 `3 E- m1 i4 V3 v" z- G# q
globals
) j3 Z/ {3 |7 y6 o6 a: @" ~" f) W[9 K. \" m3 ?' c/ j, X4 `& w: x( w
  grid-x-inc               ;; the amount of patches in between two roads in the x direction0 y5 L) V" B8 c
  grid-y-inc               ;; the amount of patches in between two roads in the y direction, S" s1 R* [: h
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* N% F8 W6 A1 h0 C& w! l
                           ;; it is to accelerate or decelerate
! O$ P/ I8 K0 y- Y1 s0 D4 {  V- s  phase                    ;; keeps track of the phase$ {" O2 l) a" U$ h
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
4 \! H" A. B/ R, F$ _  current-light            ;; the currently selected light
- x$ Z) b3 w9 q4 d/ ~' U5 Y- m' V/ w
  ;; patch agentsets
8 d3 O' w  W2 h0 m" V% O9 H& P  intersections ;; agentset containing the patches that are intersections4 L( e. B8 t# S0 E3 d+ y% }
  roads         ;; agentset containing the patches that are roads& ?- X. \. @" A6 G+ B" G. t5 E
]* \/ U6 J) t& F( g1 N( e

( d: d6 w, j& \$ u- S% t' ^turtles-own
! i! X1 |. N4 T2 `% h5 Y[
! r+ a) D5 ]% y7 A7 h% d" _9 V  speed     ;; the speed of the turtle4 ^3 [5 |" Q2 F% ^8 s; w7 h
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: W: V, V! K2 N% W4 `  wait-time ;; the amount of time since the last time a turtle has moved# C0 s; c# n4 ^! F/ A7 b
]
5 y$ O; p  S. |. t3 `, p: S: @4 R$ C) x/ ~9 n' P# u
patches-own
) l, t+ t# B1 C5 G- ^5 s[
9 _* X7 G  E( T+ u! C, ?0 j: L  intersection?   ;; true if the patch is at the intersection of two roads
4 `# k5 S! I% [, k( d2 z( o& W: o$ E  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
' V8 Z' p* H+ m/ |) q6 J& D2 }                  ;; false for a non-intersection patches.3 z  s  E' V3 ?; s% Q
  my-row          ;; the row of the intersection counting from the upper left corner of the1 f5 w$ G1 X- l' M( j
                  ;; world.  -1 for non-intersection patches.' `- J( Q  `( y. M: G
  my-column       ;; the column of the intersection counting from the upper left corner of the9 Z3 l" g2 M9 X* @0 c
                  ;; world.  -1 for non-intersection patches.
5 F  S( L; T7 R4 U0 d; G  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.! D) j2 b* e: \1 F4 g
  auto?           ;; whether or not this intersection will switch automatically./ W- r! @7 R( N' i0 x) p6 q* V
                  ;; false for non-intersection patches.) U( e! [  s) b
]
( G) l% D) M! Q$ a7 k  a) h% Y& M
. d. G; ]- H+ P, ?) I. q
;;;;;;;;;;;;;;;;;;;;;;
. P3 B" F6 K% t( J- ?;; Setup Procedures ;;% p" U6 n: P9 ]8 \% }, _
;;;;;;;;;;;;;;;;;;;;;;
: L* B9 D4 K  F9 I$ h& Q: U* b# S
;; Initialize the display by giving the global and patch variables initial values.
& S- y" r% _: j;; Create num-cars of turtles if there are enough road patches for one turtle to) [! f! L- J% S; b
;; be created per road patch. Set up the plots.
& x- r& x7 J% g. F0 J# S+ {to setup  i1 ?3 G0 }' h6 c+ f! s' a
  ca
$ Q% M3 Y: S/ B( L2 @  setup-globals# H) u1 B3 \" |) T$ v4 j5 u

6 z' M" }; ^8 r+ g  ;; First we ask the patches to draw themselves and set up a few variables$ ]1 y9 T$ [' p
  setup-patches7 Z" ?4 L8 B' k* v
  make-current one-of intersections
9 p+ u4 P6 ]! H7 C; ]( m* X& }0 o  label-current! ~( T" @0 s0 z0 t# o5 L' v
8 R6 @- _& i( E" `0 u( g
  set-default-shape turtles "car"
9 h/ t% r$ e( _1 h
; l: V5 V$ m$ [/ W4 n9 ]6 B2 u  if (num-cars > count roads)' D7 P* H& x8 k% K3 w) R
  [
$ c1 e, q$ @! k- q  U' W    user-message (word "There are too many cars for the amount of ". f) H2 m0 N5 b
                       "road.  Either increase the amount of roads "
) R+ [; Q% i0 Z. }: I                       "by increasing the GRID-SIZE-X or "' x8 D9 n% j8 U! i
                       "GRID-SIZE-Y sliders, or decrease the "
) Q8 q* w1 A& y  w                       "number of cars by lowering the NUMBER slider.\n"8 {$ O: ?9 {; [; q! M% o. p7 m! i
                       "The setup has stopped.")" d7 d2 Q- j( M4 Z3 Q
    stop
3 q$ G7 A$ _# E  ~( J  ]& z' a4 ]( \, B5 V- p$ K* \

! _+ b7 r$ x- P  I% j4 _" _  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: n% o5 i; U7 J7 v& |# O
  crt num-cars- y, j" }/ G: \( r2 B5 R
  [: o0 L, u7 ~1 e( O5 X  l1 G
    setup-cars
+ \9 b2 L- n! D+ }, D    set-car-color
& k" N' {8 ?- S4 t: |* j    record-data
8 g) l, D- P2 t5 S  ]
* V/ k  L/ Z+ E2 Q" N/ V3 L
8 q4 K2 i: ~5 }& j  L! `  ;; give the turtles an initial speed" Y& z/ l# n! w7 \9 y
  ask turtles [ set-car-speed ]
7 N3 u0 f& c7 e) R( w( E# Q3 A1 G% L0 R6 `4 m- X' ~* @
  reset-ticks
- ?. {8 D* W& A- H* Xend
  W0 o+ s; B( U4 G! y
' m; [# h2 F5 f2 p; Z6 K;; Initialize the global variables to appropriate values
, Z+ m- T. K* _# sto setup-globals9 h" h8 ]$ p, _  c
  set current-light nobody ;; just for now, since there are no lights yet
  m! w6 D* H" T# ]  set phase 0
$ g! \' P7 g' L+ v1 _  set num-cars-stopped 0) q! U( `+ Q5 t" B
  set grid-x-inc world-width / grid-size-x
& }  s0 e' M* M, l- k6 X6 v  set grid-y-inc world-height / grid-size-y
. L, l) [) i3 [" b; ^5 x" u; Q
, |4 ]) r& G' ^& L9 s) A  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% k) n% i' L& j1 H3 G+ B; b7 F  set acceleration 0.099
% S/ t+ ~4 N4 J0 zend9 p7 d. }6 p$ s* s

" {( `7 F- S. F  y;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
8 }& ~) K0 X' B. I4 v6 }8 F;; and initialize the traffic lights to one setting
! a& r* {6 `: y( z0 |to setup-patches) ^7 e! I2 V; m; O4 ?: H& O
  ;; initialize the patch-owned variables and color the patches to a base-color% N2 e- F0 n1 d
  ask patches
/ z0 E5 t8 o/ u2 X0 H  [
& E1 R0 w% `( \+ T3 k# Y; U7 M    set intersection? false: L& ], A' y$ g" v' b
    set auto? false$ {- q9 p' M  B) Q
    set green-light-up? true9 H7 }: B) t6 r* R
    set my-row -1
5 t% p5 x1 e( B9 d+ f/ k    set my-column -10 `" y7 V/ {$ j2 L2 _
    set my-phase -1$ c7 p6 B( u; e' t) [
    set pcolor brown + 3' ?: Q5 _4 {9 l) L! @! C5 u
  ]$ q% {! T& u  k3 s

) z' I2 Z, j/ V+ w6 _  ;; initialize the global variables that hold patch agentsets
" ]1 P" V3 P8 M  set roads patches with2 C. x9 ~/ m8 ^- k4 v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% \( P) g2 w- q; \0 I, O: i( q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( j  S2 H4 F! h! b$ n- u0 t1 I  set intersections roads with- G" c3 w* X$ t* ]' b) K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and" y4 ^8 [0 e/ \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ K! o4 x& u" b% A; _. J0 F; A
: d. D1 V' m$ d  ask roads [ set pcolor white ]9 c( T8 O/ V& z+ k8 \
    setup-intersections" g( v8 G' v* e# Z& p9 \- }0 b
end
. r) y. r' @5 v其中定义道路的句子,如下所示,是什么意思啊?
- }+ a) h/ W3 Y9 B6 c& g4 U* R set roads patches with
$ u2 n( w% C+ f; b4 Y' R  K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 N% @: P! Z$ |; C6 P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) ]( `/ c) P6 g, A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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