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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。' M3 h8 B# c1 k' Q2 B
netlogo自带的social science--traffic grid这一例子当中,
# a; z4 L/ ?, Fglobals" U( F/ s8 {# j; ?* `' M
[
2 O, M& a. M- {. y: r# _  Y  grid-x-inc               ;; the amount of patches in between two roads in the x direction
& o: t4 e) A: Z& q! ^; m3 l5 Z  grid-y-inc               ;; the amount of patches in between two roads in the y direction* j3 B0 A: T  B
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if% U( g8 s  o# }+ n* z
                           ;; it is to accelerate or decelerate6 r* a$ s: W+ P
  phase                    ;; keeps track of the phase
0 P+ m3 z( Y% ^# V- O1 v  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure) ]. r4 j* d7 C1 Y/ t
  current-light            ;; the currently selected light
$ ]' O  O, u7 N
' z+ v2 T# Y" F& M7 q+ l0 x( K  ;; patch agentsets& m! x( y7 S+ R; t: f/ }
  intersections ;; agentset containing the patches that are intersections& [9 v* A9 ?) ?! F! Z5 k* }
  roads         ;; agentset containing the patches that are roads# |7 x4 s0 O. l* y  I- J8 ~
]
6 i3 b2 ?1 y' K" p* H) h$ W, {% ^9 f# q8 a8 f0 d
turtles-own+ h1 P, ?; c0 y; x8 |
[4 x; S' e: ?7 O9 C0 i5 G1 @8 I# }- `
  speed     ;; the speed of the turtle8 d% ~/ L$ R/ z
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 ?) a  U' f# p3 K0 l* x
  wait-time ;; the amount of time since the last time a turtle has moved/ m, w8 [% t+ \) _8 c8 n
]
/ |; A5 ]5 x  }& L8 k8 _; o2 S( C- y
patches-own" ]6 ^$ x- Q  g$ Z: n* x& d7 g4 \
[
" e0 h5 Q4 H! {1 w  intersection?   ;; true if the patch is at the intersection of two roads* z5 y9 R! m+ ?  \' `$ h, U* q
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.9 W! \% P8 f( H: c' j) I$ c
                  ;; false for a non-intersection patches.
' \9 o3 G5 u8 a- t$ n  z" v  my-row          ;; the row of the intersection counting from the upper left corner of the) n1 s1 Y$ H2 {% w2 I8 G
                  ;; world.  -1 for non-intersection patches.- y! _* g5 ^; p: V
  my-column       ;; the column of the intersection counting from the upper left corner of the3 e+ H+ O9 J) g. }0 ~
                  ;; world.  -1 for non-intersection patches.
/ @: }' p% r7 K  r" p  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
& W, W4 ^. M" C/ X3 H6 D  auto?           ;; whether or not this intersection will switch automatically.1 c2 ^' r! [1 \8 k& t
                  ;; false for non-intersection patches.) m+ ~0 d3 o0 f& B$ W
]# e. L) q+ a/ T% h) U: k

4 B2 D: Y/ v5 ~& U! u! c$ f# P2 `
7 E( k+ L4 J9 d" ~5 A6 r) [$ [/ t;;;;;;;;;;;;;;;;;;;;;;( ~) }5 M4 }, T
;; Setup Procedures ;;
9 Q# h7 M* [9 ^2 M5 y# V;;;;;;;;;;;;;;;;;;;;;;
$ k8 ]' b5 Y% k* {! X5 r4 W
4 m- V+ @7 V+ K; r& w! U;; Initialize the display by giving the global and patch variables initial values.
/ X# c. y6 M0 W9 X* Q0 b;; Create num-cars of turtles if there are enough road patches for one turtle to% n# @7 l( r0 I
;; be created per road patch. Set up the plots.
# H3 W) j6 }& ]5 b9 eto setup
2 {: y& h% q. {/ f" T2 j1 O  ca( [6 _3 Q- y+ H; l9 {' O
  setup-globals- B$ D; O0 P8 B. B
- F0 y7 N% }3 \7 R2 B
  ;; First we ask the patches to draw themselves and set up a few variables: o0 b3 O) H8 C. Q' V) b: H1 X$ I
  setup-patches
6 ?2 e, p# J9 d# R9 N# n  make-current one-of intersections
+ b) A) A- R  e! \, t: l$ D9 A  label-current
. a; M' [+ M! F( @6 U& ^( W8 C. Q/ E; v5 Q- k/ i# J
  set-default-shape turtles "car"7 J; L" }: P: L! I3 j7 J
! \; c0 [! C- P2 E' _
  if (num-cars > count roads)$ h# d  \( Q' Z$ g
  [
4 ~, S4 ^* k. b$ H9 k& x7 m% D    user-message (word "There are too many cars for the amount of "2 }( s& f( |  y$ ~
                       "road.  Either increase the amount of roads "
2 V/ v# w, l7 b' t8 A: T# @                       "by increasing the GRID-SIZE-X or "
- q3 _1 j- Q' S9 M                       "GRID-SIZE-Y sliders, or decrease the "/ m0 x/ y# d6 \# U/ P3 C6 O
                       "number of cars by lowering the NUMBER slider.\n"
7 Q/ [/ c" k6 [7 B! [$ ]                       "The setup has stopped.")# i, T. o9 W+ t; ^! Z, X, p6 }
    stop
4 X- c/ S! Y; ]& _. f0 t# Z  ]4 n: ^8 o4 O  A9 W7 n
8 y& u  x& ~" t. V1 e* ^
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color) H. @" }* C% F
  crt num-cars
# [/ v1 ~! a* j$ ~$ [8 P9 _  [0 T+ q  P7 p3 y7 D! K
    setup-cars) z7 o3 G2 K+ J+ @! _( J) G) r
    set-car-color- B; M4 Z& \+ K$ v1 |& M% A3 d
    record-data6 {% e# Z2 L( X4 t" r: V  b9 u7 B; P
  ]
! v) n. K5 c' V
. F: x. Y) j) D1 F( {  r  ;; give the turtles an initial speed
* g9 T$ L3 q8 j( i5 l8 V" U: y  ask turtles [ set-car-speed ]/ ^- o! c& Q( J6 Q- X
' k3 m- P% w) h# P: o% [5 t
  reset-ticks
1 H; u, L; [2 ?- H3 s$ i0 @/ E6 Gend
0 v+ `  b' @" O" d: z/ T8 \- l9 t, v& d% P4 z
;; Initialize the global variables to appropriate values) C: F4 \' e! t; n# q; w- }
to setup-globals7 r0 E  m7 C8 ]0 N
  set current-light nobody ;; just for now, since there are no lights yet) b- d& N  I' H" v" H# n4 T) U
  set phase 0
% ]# e6 c" E! b4 k* |8 F  set num-cars-stopped 0
9 Z6 d; G; `5 G1 ^$ Q: j6 b  set grid-x-inc world-width / grid-size-x
7 a) @% _" H- @5 q; O1 ?  set grid-y-inc world-height / grid-size-y
& n: U' F& X1 J' N# {: t
. C7 ?% I# c8 E* u  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, v: f) W  g9 R6 p! v( Y, F" Y
  set acceleration 0.099
% R9 B" a+ E- x+ Tend9 D! C, x& U( p7 N, Z

: q" i5 J' J2 s;; Make the patches have appropriate colors, set up the roads and intersections agentsets,, K8 r) A# y" G4 i
;; and initialize the traffic lights to one setting
5 S& d& X4 i9 h6 Fto setup-patches
  h) Y8 a8 f" |  ;; initialize the patch-owned variables and color the patches to a base-color! p+ \# Z2 X8 K7 s4 a+ ?1 Z/ K" @
  ask patches+ ]5 |" F3 p- R
  [
& I' `( f# L% v  z& Q8 a0 N+ w    set intersection? false5 O- `) N: ?  l9 N/ s1 z( H, h
    set auto? false
8 n, u- d* ~- {+ T8 A    set green-light-up? true
: }! N0 ]' A4 p# L, t    set my-row -1) t* f. s$ S# I
    set my-column -1# C4 V+ T8 F: o
    set my-phase -1
% i# a% Q% ]7 b$ v' N    set pcolor brown + 3
0 E" `9 b2 P: Z: O6 h9 M. N% k9 E  ]/ B6 s, Q( A- \( g6 _

& z# ^6 ?' Q1 ]% t" R: o  ;; initialize the global variables that hold patch agentsets
& U7 F9 Y, a: v3 p' y: Y  set roads patches with* Z( w& L! g, @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ D) Z, E8 `9 B8 y6 L* A0 l8 h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 p' N8 S6 R5 n6 ~
  set intersections roads with1 u8 A6 k  a  G5 U. B' s/ J  y; o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
  Q1 v6 [& J( T) F1 O7 Z- c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( u& Q/ d! ~, h' G( @# p
; h* w# M4 B/ L! B) a- B  ask roads [ set pcolor white ]' |+ b/ Z6 [% o! f7 U' r
    setup-intersections1 |. i2 a3 a" n8 o
end
0 c1 A7 e3 V/ L) a: _- U7 N9 [8 ?其中定义道路的句子,如下所示,是什么意思啊?" W8 Q/ m2 @, m/ h9 n% S
set roads patches with
# b. r; h8 h1 Q3 c7 q. `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: ~% [  J! Q" p& S: r6 a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 z/ G  A( e7 r7 j2 E( l8 B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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