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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。9 F+ S7 e2 O. j3 I! ]% R
netlogo自带的social science--traffic grid这一例子当中,( v5 ^. x+ i8 I. P$ c6 A0 c
globals
: h7 |5 J$ _0 q1 I[5 {7 B" j' k+ l: G; Y8 |8 N) L$ \
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
- H# G8 V, O, W" k  grid-y-inc               ;; the amount of patches in between two roads in the y direction
+ o9 P/ v0 r: `; l8 S  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
! x1 y& |9 N( h4 Z                           ;; it is to accelerate or decelerate
) U$ \6 t0 F8 m7 X* B  phase                    ;; keeps track of the phase! h& s6 ~$ ]! ^' _
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure+ T4 y; R3 a! @$ a
  current-light            ;; the currently selected light
3 X( ^2 \, C; _# F7 K" E2 C
) m2 t* \, H, D9 F2 U  ;; patch agentsets8 B4 u9 o# K% ~. F
  intersections ;; agentset containing the patches that are intersections1 b+ o1 h/ N6 L9 I; n2 Q: j# V
  roads         ;; agentset containing the patches that are roads
. p  S- a! p7 M/ i% b- G' N]) I4 x! Y) H9 b# g2 J* ^/ L! N( `

! B! ?# k9 M" a, i. C9 @turtles-own
8 z$ Q! c) h- V2 s3 D% b# `; g[" C" H7 M; ~8 Z( w
  speed     ;; the speed of the turtle
% L! r# i% u& N; @( I0 i! {  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
4 V& x& O3 q3 P) B7 q  wait-time ;; the amount of time since the last time a turtle has moved* E% ]3 [) t# s6 x( \
]  P! g" g0 r8 P! [- Q

- j) g) y$ D' d4 Upatches-own
) a* d8 j$ J0 f[- v& c' n( c5 D+ ~. c
  intersection?   ;; true if the patch is at the intersection of two roads: o% m# V" g( v- Z* x) D) u, t
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false." g. ~. x/ W5 _: {7 p1 u& m
                  ;; false for a non-intersection patches.
  Q5 X* j) r2 z  my-row          ;; the row of the intersection counting from the upper left corner of the# ^$ v' ^" i3 f
                  ;; world.  -1 for non-intersection patches.% |! q8 k) \& s6 R0 K  X  f
  my-column       ;; the column of the intersection counting from the upper left corner of the
: P8 _! ]3 B$ ^                  ;; world.  -1 for non-intersection patches.
1 c7 Q1 H' [* |% X/ i4 p  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  S9 W( _& d( U; t  auto?           ;; whether or not this intersection will switch automatically.
3 Q6 ~8 Y, Y- X7 a2 {                  ;; false for non-intersection patches.
3 d9 R0 c2 A5 x$ H6 n  h5 m; y8 n]
9 U( l( _! Y& i, j# n- q
! G  n+ w& D$ H6 M+ ~3 p3 u0 J' h$ B1 W* ^
;;;;;;;;;;;;;;;;;;;;;;& O$ g# A: p+ D4 c+ p  h0 \$ q
;; Setup Procedures ;;: K( E! y; f0 `% ~
;;;;;;;;;;;;;;;;;;;;;;  A. W7 E, I: b' {9 E# c

- S* W. d7 [8 ?( Q7 S;; Initialize the display by giving the global and patch variables initial values.
% E& b! D! T2 B3 C& O;; Create num-cars of turtles if there are enough road patches for one turtle to
' X' V. w* j5 l- X;; be created per road patch. Set up the plots.1 a1 ]: N8 m% g% r
to setup
1 N$ C, S; f9 [6 U5 s  ca
' l& F0 U+ t+ w/ h* l+ [3 d% R, I  setup-globals1 _1 U# K- V1 ]0 S' m8 B
1 ^+ e6 y* F1 h+ _* Z! c5 e
  ;; First we ask the patches to draw themselves and set up a few variables6 L7 c9 Y6 q. u# [
  setup-patches  D+ I" q0 D$ x9 z1 z7 E
  make-current one-of intersections
4 [% E- {8 g4 g, f1 A1 g  label-current$ z& X% f' q, k) B

; c8 e% l$ @0 z* X' k- n- N  set-default-shape turtles "car"4 g6 V- l9 @: S
; M; t5 j+ n) }4 ~. _3 ~
  if (num-cars > count roads)' W, S6 ]7 L9 T! F& |5 L% P
  [! \" E0 a5 V2 ?$ P! h! X, |
    user-message (word "There are too many cars for the amount of "
' i) H' j. @+ m                       "road.  Either increase the amount of roads ", J1 F2 k# o' X/ Q2 ?2 S. s
                       "by increasing the GRID-SIZE-X or "( ^0 ^8 n7 R7 z* E. }- D
                       "GRID-SIZE-Y sliders, or decrease the "
- k* u# B' X/ a0 U: c. T- Y: U) k- A                       "number of cars by lowering the NUMBER slider.\n"
& {! X; t2 J; [# W; U                       "The setup has stopped.")3 U1 j4 K7 E4 z1 L+ |& V! r
    stop  K" a: C4 o% q$ N7 p' j: _" G
  ]
1 y  o$ _" x. h. _# g. D
9 o* B4 m0 v- z0 ~' H  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color& t  U6 R$ i: ]& l
  crt num-cars: I& k, r; M7 |% F9 O+ J" ^/ d
  [- D) {  y& j, e: [' a
    setup-cars
; N5 k. x0 M2 Q) j8 H8 }    set-car-color
! c) b0 ]' m, U$ ^7 N( L    record-data# e& X4 Q( j8 S
  ]
( i, ~; Q7 ^+ l6 ?# @$ A
$ V1 Z9 l% Z7 s- t' Q) T0 m  ;; give the turtles an initial speed
/ x' h3 j1 e  H  ask turtles [ set-car-speed ]0 }$ z; i' B" N- A
. j, G9 [% a/ h% ~& g* `
  reset-ticks! U- x' h1 G7 N8 R0 K# V  \
end8 f# i" @6 t, d9 F
# q/ u; G& A  x4 ^, U
;; Initialize the global variables to appropriate values
( C; d& S7 q) Y8 q7 lto setup-globals
1 s8 [9 ]6 z4 }/ ^4 e6 `. g& ?  set current-light nobody ;; just for now, since there are no lights yet
; y. D, B1 S% E8 z+ U$ |  set phase 0
( R3 y  E$ ~3 J# g. ]2 x  set num-cars-stopped 0
+ z& X- ^/ ]( i8 {  E" s, d; ~  set grid-x-inc world-width / grid-size-x
" ]. L2 u0 I% I8 T  set grid-y-inc world-height / grid-size-y! p' d  O/ H6 U/ u

# f2 R( w0 U! T  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary* w' w7 j: q! l8 h7 |! }
  set acceleration 0.0993 G: o( M! ?: e4 P6 Q, w
end0 c  b* D' q* A# Z" r

& X1 Q( z3 E9 R5 Y  h! O( j;; Make the patches have appropriate colors, set up the roads and intersections agentsets,( m- x+ ]  |9 |3 O7 }1 a; e  K' E: d) ?
;; and initialize the traffic lights to one setting
  @; s' @, q3 ~0 c$ z+ Pto setup-patches
* K% V1 B- P- s2 V' z" y* M  ;; initialize the patch-owned variables and color the patches to a base-color/ L5 f& Y. i% c- U' O
  ask patches) ~& F+ W2 g! C" ?
  [7 E7 E2 i( [; Y
    set intersection? false% ^* l+ p9 A% R7 w9 W' w) L
    set auto? false
' H$ w" _' ]- ~7 V* _# C& f    set green-light-up? true4 o  l8 R+ A& s
    set my-row -1( F) f. S: n+ X& e! Y
    set my-column -1+ o2 e8 ]  v' i. z  S
    set my-phase -1
& l$ s% Y/ U" V) h    set pcolor brown + 3
, n8 `+ b2 K6 S' I- z  ]
) P, A( Y" K# c/ D. \
, C  N  L& x& [% @6 y% b) S" B  ;; initialize the global variables that hold patch agentsets5 i; u' ^. I* g( e
  set roads patches with
: T, b# c" m& J( D4 g  W* Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ x' n7 [( @/ Y. s/ A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% B* ~( b( `' b1 y  Q  set intersections roads with
2 N7 d0 m' C% [& X" f6 o- v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
4 x5 l& B, K! j7 t% _$ g/ h) `' j    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 g! A  E" k/ t% N
' P' v+ |" U/ k1 U  ask roads [ set pcolor white ]( Y- @2 O! Y) Z1 a4 o
    setup-intersections
! d2 _, k- W: J- Dend
& f# k+ g: W! M8 \& M其中定义道路的句子,如下所示,是什么意思啊?
- }% H; t) h: {# q' q9 {: g set roads patches with
3 e" Q: h/ A% j5 V; x    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 h6 n% i: H9 m. ?
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 [+ z) ^  k* B* n0 ^( 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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