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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。
3 L8 M- Y; m( o4 C: ^5 `netlogo自带的social science--traffic grid这一例子当中,
0 z- c& ?9 l# V8 }+ ?; c; gglobals
0 b. R% Y. r0 h- ~% a8 S[
4 C- Z) Y( J5 Z# t  grid-x-inc               ;; the amount of patches in between two roads in the x direction
9 w& @" o4 ^" t2 t& v: @  grid-y-inc               ;; the amount of patches in between two roads in the y direction& N  R' Q! p: m! f# m
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
1 T( q) W( i  i7 j$ b                           ;; it is to accelerate or decelerate
' J& A6 |" F# m  H8 }; a: q  phase                    ;; keeps track of the phase
' J$ S1 A4 a! \1 ?# q: C  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
, J0 M% ]6 h5 Y9 D  current-light            ;; the currently selected light( }) P! s# z7 w; I
) q% L1 F: U- j9 X' e" @9 J# {
  ;; patch agentsets
$ _6 S  {: u. F. C+ L  intersections ;; agentset containing the patches that are intersections+ c5 k: _* X! z3 e
  roads         ;; agentset containing the patches that are roads: L# o( [  F) v' U: X! s% O+ W
]
8 U- r" R2 N4 b% M) z- j% x9 ]# \) b2 x) w. b8 p: L1 B
turtles-own9 T% I7 i, \# D, q' b& j
[
6 P; o( t0 k2 e+ t( T* ~  speed     ;; the speed of the turtle
% W5 y% X  H6 \  up-car?   ;; true if the turtle moves downwards and false if it moves to the right" @3 W7 n! n; l- p' H1 H! e
  wait-time ;; the amount of time since the last time a turtle has moved1 t, p- b% [6 G7 p
]! v1 i- {. x1 m0 g7 d4 L  x9 ~+ ~( t
! C0 k* e0 Q% o& Y- \
patches-own: @0 E8 N1 M0 L8 N
[
( \2 r& I8 h; D6 Y7 v  ?  intersection?   ;; true if the patch is at the intersection of two roads
5 r3 K* y4 N1 |$ M% y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.6 ~/ Z% n/ |7 O5 T
                  ;; false for a non-intersection patches.' k( v6 R" E. Z2 E! }
  my-row          ;; the row of the intersection counting from the upper left corner of the
" D6 H; W/ v9 T1 c! n                  ;; world.  -1 for non-intersection patches.
5 A) w! O0 C$ s/ C4 O5 Q+ u+ b  my-column       ;; the column of the intersection counting from the upper left corner of the
% d  X9 y- x9 K& t% ~                  ;; world.  -1 for non-intersection patches.6 ^( z' o) O9 \
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
+ A7 u2 j- O3 U  auto?           ;; whether or not this intersection will switch automatically.4 c" W0 d" j8 V9 @
                  ;; false for non-intersection patches.
8 ^# N/ g" k% r  Z/ Q- h; o]
- D  \+ J- m. d! H- Y4 X5 P+ `% z1 u. H$ k7 b! E! V6 ~
' e8 K) r/ A. z2 B: U4 Q
;;;;;;;;;;;;;;;;;;;;;;
: q/ m0 h( M. h0 M2 d# k;; Setup Procedures ;;
, i8 x0 L  S* F5 e; };;;;;;;;;;;;;;;;;;;;;;
' X) [3 f' h/ [, f
& y) F: r3 X9 t) @) l7 K;; Initialize the display by giving the global and patch variables initial values.. h5 Q5 t  d# s- G+ [; {; K+ h2 a
;; Create num-cars of turtles if there are enough road patches for one turtle to
1 q; ]0 M0 |8 E' U# n+ {7 I: l* k;; be created per road patch. Set up the plots.
7 y% o& r; Y& C+ |! s, r/ Vto setup
8 k& z% M: o, F( Z# n7 ~# M! X  ca) p% G* p& s' s; k4 z# k5 @
  setup-globals2 }& F& \8 i7 R% Q7 a, y

; Z, c2 J- Z: C0 I- L/ ~; c  ;; First we ask the patches to draw themselves and set up a few variables$ e9 j+ L6 C  q+ q
  setup-patches7 Q0 v# P: _+ J# X  G
  make-current one-of intersections  _: O$ @' q" q0 u0 C+ l, O
  label-current( ]& S. ^# K1 T1 b8 R% M, T

: Y) t. V: O  F, g# f; D  set-default-shape turtles "car"5 L  ]+ t7 v8 ]
9 T8 ~/ u. g! X0 W# y6 h, U
  if (num-cars > count roads)
! c9 U0 q1 |3 w$ _$ I4 q  [
3 d6 U6 A& J) T# f5 s    user-message (word "There are too many cars for the amount of "' ~: z2 y$ V7 q
                       "road.  Either increase the amount of roads "
; m1 `( m* r' J                       "by increasing the GRID-SIZE-X or "
; C) \0 i6 A! n# q* M* C                       "GRID-SIZE-Y sliders, or decrease the "3 }. {. D+ s0 B# u
                       "number of cars by lowering the NUMBER slider.\n": G$ I4 ^2 d' G; q8 s) t# Z; k0 G
                       "The setup has stopped.")
' ^6 Y, l( I" |& R  k5 s    stop
* M" U/ t  l, u/ X; _) L  ]7 q7 v& `3 ^8 Z( _+ I0 ^
! B& v* c! L' A4 I8 U
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
, ?+ E! |6 G1 G6 ^  crt num-cars
! \, M- @, c$ b  [; U" c: O; B  O4 ^7 K0 X* P
    setup-cars
1 m& x4 I; Y1 `. [    set-car-color2 K+ @' W0 w6 K, F5 @6 c9 m
    record-data
9 N* b1 v; B. \. `  ]- b  o$ T& w7 i5 w, K5 f9 H9 N% I7 V
1 f' f2 z1 m0 ~" b& ]4 f2 \
  ;; give the turtles an initial speed1 [2 A5 A- G3 D; N  L
  ask turtles [ set-car-speed ]
4 R0 ]) g, ^3 t3 q9 j# A( J+ R; _* V2 t; w0 d
  reset-ticks
- [/ F/ A3 L4 ?# i6 Q" p& Eend3 m6 e, O7 k4 ~0 e6 R; y+ b
9 h9 u6 `1 p5 |
;; Initialize the global variables to appropriate values
7 q) J/ ?2 u* j& c. \/ bto setup-globals# J! B! A# G, f. c
  set current-light nobody ;; just for now, since there are no lights yet5 F. e; p/ |# d( w5 j
  set phase 0
$ B  V* B) S8 |  set num-cars-stopped 0
8 X  U1 A  i% m  set grid-x-inc world-width / grid-size-x0 X1 S$ J, t5 b
  set grid-y-inc world-height / grid-size-y0 F$ A1 p; @' l4 ^

% N6 ]: |' G- O8 I% R- X  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
. z1 S! r/ h: N! r: S  ]+ @) ^5 B  set acceleration 0.0995 o8 V; A. _/ h, C
end6 \0 z+ Z& D9 A# s; k" w, a* ~

; y* x) Y  b0 D( @# M;; Make the patches have appropriate colors, set up the roads and intersections agentsets,3 z  L; i& c/ q6 E, m: A) F6 f
;; and initialize the traffic lights to one setting
0 n8 w7 b3 j  n, y8 q: Pto setup-patches8 C# I# J6 Q8 a( M' X- F6 ^( p5 a
  ;; initialize the patch-owned variables and color the patches to a base-color" w& b3 S! _3 r- {( J
  ask patches
% S7 g% h  Y% d( T" b0 Q: h  [  N6 s" f8 n0 k& t2 d
    set intersection? false2 b& @' r& X3 H: u. F) U4 u
    set auto? false0 B) L$ k% k5 n9 b0 s% I8 k! U
    set green-light-up? true
+ B3 t2 {) Q5 k8 U$ k    set my-row -1# }- t' z0 h0 Q  C4 P! e
    set my-column -1$ _$ i/ w8 y! ^6 X2 D
    set my-phase -14 A2 R2 P9 h& K
    set pcolor brown + 3
* f2 z9 Q2 [- C% U/ I  ]
0 Q" W6 ^  I/ p; T- O0 T
% F3 s+ ]9 S+ ]  ;; initialize the global variables that hold patch agentsets- f- {; G8 x5 m& N( G7 @* O
  set roads patches with
$ k" m  [9 H1 E; w# ]9 P! x0 p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 N6 g* [6 ]: |5 u/ {    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 z! c5 v% b/ ]- G1 O
  set intersections roads with
7 W% J4 |0 q5 o5 f$ T: A. _5 U    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and* [5 v- Q6 y+ X( }' ^( l, P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! E+ s# y# u- ]- `$ ?" k
. t# |, [9 D! Z% y0 p2 O  ask roads [ set pcolor white ]
' H  ?+ Z( `6 }2 Q/ ~/ ?9 o    setup-intersections. n# n, G( x: J+ F. s; B. @
end
# I- w1 H! V: N) Y; z7 n7 x, C# c其中定义道路的句子,如下所示,是什么意思啊?
: [% L  U5 u' Y8 y5 o$ i7 C set roads patches with
4 [, u; `) D2 |: \: g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' a! s& n  N! }( ~2 p& I# Z( r: f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* N3 P9 U: p+ V& ^# E$ Z! [0 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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