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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。
% E1 B7 t: \% Qnetlogo自带的social science--traffic grid这一例子当中,; K, b) v  X$ e8 Y5 ?
globals
1 z$ w9 @& Y2 B8 O5 Z2 B, ~[
, e; w# Q0 v' U+ u- V! V, g8 `4 `: H  grid-x-inc               ;; the amount of patches in between two roads in the x direction! U% X6 w! b3 U2 F  G
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 X) q2 m% n: [  acceleration             ;; the constant that controls how much a car speeds up or slows down by if! j2 Z& j7 M/ w5 J
                           ;; it is to accelerate or decelerate6 L6 X% Z8 ?! p3 Q6 j
  phase                    ;; keeps track of the phase3 R' l9 f- X& S
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
, [0 j6 p4 {( E8 A, \  current-light            ;; the currently selected light  w  [5 E/ p8 [& o+ g, G

5 _9 e  v& s) Z) Q5 G( ^  ;; patch agentsets
$ D) }0 G8 a4 O2 g6 \, E  intersections ;; agentset containing the patches that are intersections9 }1 @" ^+ j2 c6 o" |
  roads         ;; agentset containing the patches that are roads$ r- ~" q) [% ~, l& G2 N8 }
]6 m, ^+ _0 M, h% }+ `' B

9 w* b) B7 m& f8 V& y) Bturtles-own
; f/ e" ]5 o' w& b6 ^, l; C' D[
$ c) u% J. m; F$ j% U5 q1 M+ u  speed     ;; the speed of the turtle9 S! k' _" v1 G, |. ^& g* D
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right; H# o; y* q* z$ y# B' F% p0 I
  wait-time ;; the amount of time since the last time a turtle has moved
8 O: r: w0 G/ `6 S! v% {]
5 E- m. Q" P8 x) o2 k
2 s" C  X+ j! m% k7 f" ppatches-own
3 |( }, Z& w' @  `/ I. Q[& i1 g- K9 E3 {/ R; }0 c( |8 _
  intersection?   ;; true if the patch is at the intersection of two roads& g" p  J/ Z! n" w* X0 s
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
+ u2 l9 p+ w0 W2 D                  ;; false for a non-intersection patches.
, `$ X$ h* U, t. \% T! S  my-row          ;; the row of the intersection counting from the upper left corner of the* K* W9 _, k/ y* C
                  ;; world.  -1 for non-intersection patches.
1 |& f3 a' I9 O" I; r" e5 g3 l  my-column       ;; the column of the intersection counting from the upper left corner of the
8 L# u5 C! s8 H: g& P# M- E                  ;; world.  -1 for non-intersection patches.
1 C% Q: v  q0 c, C  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.* f$ V# m; c$ ^
  auto?           ;; whether or not this intersection will switch automatically.
0 V8 b6 j3 A* C  |: c7 G! J                  ;; false for non-intersection patches.5 o# v# j. k, y7 f$ A$ p
]- p; f/ z, [0 q+ Y2 p5 g" i
( H5 W& \4 I/ \& m0 _! y
2 p. F  r4 m6 t5 M7 ^& G
;;;;;;;;;;;;;;;;;;;;;;  B6 ]' A3 o# `" T# v$ M* }( {
;; Setup Procedures ;;0 g  o2 L" g  ~8 E5 w
;;;;;;;;;;;;;;;;;;;;;;
& f" s( @$ y7 \
& ]0 ~: q- q& d' q9 m2 h;; Initialize the display by giving the global and patch variables initial values.
5 j. ?$ @% d2 S+ H;; Create num-cars of turtles if there are enough road patches for one turtle to9 k. w. `9 Q  ?0 [5 q
;; be created per road patch. Set up the plots.
8 j9 j( E  Q! ?! t( n% kto setup
3 t& J0 X  a' [- s3 t! W! |% Z) c  ca
9 x+ s5 X4 v( `( H6 ?3 k  setup-globals
2 m: k+ n3 o/ K6 I5 D: S/ J- E$ ?1 y2 t
  ;; First we ask the patches to draw themselves and set up a few variables4 D- l6 D- H$ K* N( [, I
  setup-patches
' z! i7 G: _3 @7 v" t  make-current one-of intersections
1 ?& H1 T; z) z9 ]& X7 W3 D2 R5 c  label-current
4 }1 ~: g& o- f/ V' w. T) q
- E  {, P" Z' h% @3 }' e* D  set-default-shape turtles "car"# Q/ Q; j) [1 {% Z' C' j  n, r
7 A, `& A( H( k8 z
  if (num-cars > count roads)* s; H$ J0 S' ]$ ?3 u
  [
- x% t% a* q) [+ L) U! f    user-message (word "There are too many cars for the amount of "
& J7 w3 j. o$ R) K; d                       "road.  Either increase the amount of roads ". J' Y8 k( l8 ~9 y9 {, W3 M
                       "by increasing the GRID-SIZE-X or "
  ^7 t  w& j, A8 c! C/ z                       "GRID-SIZE-Y sliders, or decrease the "
0 C* c- c" _; t7 z8 {6 Q0 a$ [                       "number of cars by lowering the NUMBER slider.\n". H6 @4 \+ ^8 k, a3 R; Q+ e
                       "The setup has stopped.")
: v9 N7 J& E- Y2 l/ @7 o4 \+ y    stop/ S! g3 _3 D, p5 D) u# c4 E
  ]
' H  M4 b/ U9 |! f' G' ?
% ?( Z# M% }' a# _4 g4 c  a+ O  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
" t& X9 F$ ~3 j  crt num-cars
. }  A+ w6 _2 O2 o3 y1 i  [& n! X& B) G1 Z  H
    setup-cars
) z1 n* `. R' p: A  B: h    set-car-color1 M2 K$ ]7 v0 _4 Q) K4 d# s
    record-data4 [% A; L: I: |- F5 _6 h
  ]6 o8 M5 G1 z1 J9 K0 \+ ^

: Y/ @- R( X; f! B" d  ;; give the turtles an initial speed6 }2 K% U" w& u& V- B
  ask turtles [ set-car-speed ]& q$ ]3 i. V/ s
7 ], B. d6 ~' u3 T# y9 s
  reset-ticks
! x3 N# [# ]+ g9 T2 R$ e0 Oend
+ w8 u8 ~, U9 ?
1 L& p1 [6 R: @+ n8 x( t" e& J;; Initialize the global variables to appropriate values0 B+ g9 w9 ]  b' n$ \+ R
to setup-globals
' v: l3 d% S8 b  set current-light nobody ;; just for now, since there are no lights yet
9 N* @1 H8 ?9 s4 @" F! A; o) k  set phase 07 N" q* ~+ L. R
  set num-cars-stopped 0& X" f0 p0 A+ f
  set grid-x-inc world-width / grid-size-x
; Z1 P8 b4 A$ [+ s  set grid-y-inc world-height / grid-size-y( _" u- O, o# V7 s% ]

/ O$ c* H2 b9 i# M# m9 C4 n* ^  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
1 F8 B9 m. ?6 V( z9 l% T  set acceleration 0.0991 I' C  ~% B% M7 B# @
end/ B: z+ Q  U# a, F8 z0 C
* I, c! l' W6 f! F: S4 \8 b& R  K
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,3 ?4 c6 r& S( i2 h$ _( B
;; and initialize the traffic lights to one setting( K7 F4 a( g% }; d* b5 |
to setup-patches
5 G5 Z( f; V# Z* w7 T! ?# p  ;; initialize the patch-owned variables and color the patches to a base-color
( e/ s! L; ^( ~  Y2 V1 s- D6 V  ask patches
' @% M8 B7 T6 M9 i0 [  [
* ?- k0 C+ S0 P  l    set intersection? false
# U5 X# L( J" ^5 x+ E* L7 L. Y    set auto? false, {& r7 m; ?$ q& n7 D4 }
    set green-light-up? true
: b, ?) _3 C: p8 Z    set my-row -1: u( ?' m# V! I' Z9 l; w
    set my-column -1
5 X$ U' n$ U$ N    set my-phase -14 U" u* S' D' {: P5 v
    set pcolor brown + 3
  X) S( k+ G' \  ]
+ f9 i- W$ o* ~( Y% i, v
9 Q  O7 N( f& h( f  ;; initialize the global variables that hold patch agentsets
* M6 z1 X7 ]( c4 v  set roads patches with
7 s5 g  k  `5 r: u+ U- U    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, J6 K& Y2 G; K+ K* q$ ]4 e  n- p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* G( O5 I0 ~7 k$ P& W1 a- A  set intersections roads with! E% ^+ M7 s. v8 U; p1 V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
* F* ?+ m4 j) U: I. e+ ^1 G  Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 w8 J0 R# a3 _
; k# Z( ~0 }5 o7 H4 {+ O  ask roads [ set pcolor white ]# {2 ^% E/ k/ g
    setup-intersections
3 f" m$ e* G$ E1 j' A6 Tend' N9 D$ z+ d: l# B6 B
其中定义道路的句子,如下所示,是什么意思啊?
% N7 k1 L. u- X, x set roads patches with+ Y/ B0 E! o9 }* ]$ L8 o# }1 x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ C! x3 F+ M8 d# T8 ~2 N. N& g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ [# N6 p. J5 l; q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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