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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。
7 j  }/ S0 Y+ e- r7 c$ E' y4 Q1 i( onetlogo自带的social science--traffic grid这一例子当中,
- k( N' ^( J7 D9 w, zglobals# V; |, [( m0 J. E% W
[
7 g7 F" @% v  L% z# ?  grid-x-inc               ;; the amount of patches in between two roads in the x direction
+ R# g( u7 M/ \) i  grid-y-inc               ;; the amount of patches in between two roads in the y direction
/ J& P5 t+ y' d+ @  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
- h2 ~8 b; z) D' [; w. ^                           ;; it is to accelerate or decelerate
% f) Z9 \( c, {- A  phase                    ;; keeps track of the phase% h3 A' R) t4 S4 _. y
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
! w. j* R: n- D5 T" |  current-light            ;; the currently selected light9 X6 I. I3 P# h' I1 H

* W3 K( f5 B( {( Y" E: {8 q  ;; patch agentsets3 O  ]; q3 w! g5 O- i
  intersections ;; agentset containing the patches that are intersections* q0 _6 N  S! v- Z
  roads         ;; agentset containing the patches that are roads
+ |0 n7 x( X! ^! V6 H2 x6 z]  m8 S; ?% g3 v

) l0 F* e+ t1 a  p7 k) \turtles-own1 R( }2 V7 r7 Y% ?
[
3 _5 T; i  V6 Y  speed     ;; the speed of the turtle
# w; e! {( p7 R5 Y" j* ?! E  up-car?   ;; true if the turtle moves downwards and false if it moves to the right# v: O* p' Z' @
  wait-time ;; the amount of time since the last time a turtle has moved# f7 A9 o4 u% m5 w! g) I( ?
]3 f/ O. R- G! l- W7 d
+ C9 P3 s* y" b; `) y( Z6 q9 w
patches-own4 w. T6 ?5 M' M
[, e" g& Y; L" L' x$ K: }8 e
  intersection?   ;; true if the patch is at the intersection of two roads
1 O+ t/ W; Q" c, ?  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
3 Y  l1 X0 a% T5 H- T+ J5 N                  ;; false for a non-intersection patches.
& V8 [  d9 n5 w, Q3 o) {  my-row          ;; the row of the intersection counting from the upper left corner of the
7 P5 c$ R0 D/ ]- G5 {- M                  ;; world.  -1 for non-intersection patches.
1 ]: Y1 H& k7 O& l+ a, M0 f& V  my-column       ;; the column of the intersection counting from the upper left corner of the
; t/ {* h. x, i% W% r! W                  ;; world.  -1 for non-intersection patches.3 g; x8 b! F! N3 {
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.9 A0 t* ~# R/ L- ^9 h
  auto?           ;; whether or not this intersection will switch automatically.( B3 B5 Y. h1 |8 u% _) V
                  ;; false for non-intersection patches.$ m! t7 J2 [+ x
]+ V: G+ s: j9 C1 l2 B

; g0 i9 L8 a* Z7 B: @. u# H8 \( Y  J2 H9 u! F
;;;;;;;;;;;;;;;;;;;;;;6 j6 {6 N* U" p
;; Setup Procedures ;;! }2 J$ Y: B; j/ l* m5 j  Q/ E3 N
;;;;;;;;;;;;;;;;;;;;;;
9 |: A1 n. q# `
. W9 Q1 V: O0 @+ ^' _. p;; Initialize the display by giving the global and patch variables initial values.
3 C6 r$ p4 O5 d: s3 l  n  X0 };; Create num-cars of turtles if there are enough road patches for one turtle to" L+ u. I7 O& Y
;; be created per road patch. Set up the plots.
+ r  L4 E1 T2 t1 xto setup: Z, ]  o( @: h
  ca  z$ g% `" J; F  h/ \; Y8 N; S8 C
  setup-globals
& F( \0 u! }! b) c  K' V* Q1 s! @% w% `& Z. q3 Q
  ;; First we ask the patches to draw themselves and set up a few variables  I: k, y" X6 n- j
  setup-patches0 x6 ^8 j6 `6 ~; h7 [% B" u
  make-current one-of intersections
+ D( _6 j2 }% B$ f* L  label-current
1 q2 D# ]$ F7 H2 e5 j1 R9 X' s' K; F% ]" ?' e& k+ l2 H5 q
  set-default-shape turtles "car"
# ~  ^% O  B! h- o6 H1 p. @6 X/ I6 p8 w  N5 k
  if (num-cars > count roads)7 L* ^& y: |: B4 G5 H5 m) M
  [
; u! E! u: Y2 Z$ X; \    user-message (word "There are too many cars for the amount of "
9 l2 E0 g% o5 u; v! f4 P& P                       "road.  Either increase the amount of roads "& G" @2 m/ z) Q* p- @& T' \
                       "by increasing the GRID-SIZE-X or "
" g1 ?* B' u" A- g' _                       "GRID-SIZE-Y sliders, or decrease the "; e) l. G3 B; T- ~) W9 K
                       "number of cars by lowering the NUMBER slider.\n"* x# |+ R8 w5 _
                       "The setup has stopped.")9 I2 A5 W2 ~7 p3 x: ]: Z8 _% f
    stop
- h9 n) l0 X& ^/ H  ]( J$ e6 A8 {* S/ J7 T

, f! j& f3 h) H  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
, ~3 z1 q8 a% k6 ]9 V& q, Q  crt num-cars
! d0 M& P8 J! h; q( o  M0 l) F! K  [
; n- o  \  C" X$ @    setup-cars: I" ~$ q5 W' M' a4 o
    set-car-color
9 U6 ?# M. G4 [4 }" N    record-data, ~3 A7 w6 [/ i( B! m. c
  ]5 \7 x: _8 S) b9 |

+ O3 X9 G! o1 H6 _  ;; give the turtles an initial speed! C) B1 Y# V  t8 s/ h) h
  ask turtles [ set-car-speed ]/ ^: |. _% B3 z8 z/ l, E) f# Q

; S& E0 r3 Q0 w8 p7 f+ o  reset-ticks
+ X2 c9 Z) @  b  mend
  ?. l, f4 [, \. \2 x
& ~; o# t) b8 |  \% ?;; Initialize the global variables to appropriate values
5 s3 }8 O7 q; B) Z' W* P/ _8 Eto setup-globals# t( I) m: m% c. N
  set current-light nobody ;; just for now, since there are no lights yet
2 ]/ k% K1 m  ~5 z" j  set phase 0
, {; ^' r9 G) l, b3 o0 U, M  set num-cars-stopped 0
0 N3 C1 L. d8 _  z+ M/ n' X& b  set grid-x-inc world-width / grid-size-x+ k2 s0 \7 c& o- U% g% \0 k% s( L
  set grid-y-inc world-height / grid-size-y
8 x! M* V) R7 G/ m
2 p2 y5 U  e! H: N$ g: M  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
1 K6 s6 j) y2 @  set acceleration 0.099
, }9 U! W# \4 s6 V& Z  A2 P) Oend
. i' k& W+ ^: x5 h$ }- d! `3 d8 H, r) W6 a4 [% S; `
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 K# ]  N! p$ ~1 i$ g;; and initialize the traffic lights to one setting
- ~8 [7 o3 {7 C$ l6 y/ X# |to setup-patches
# ^' d( i& R& t% B2 P. |  X/ B# G  ;; initialize the patch-owned variables and color the patches to a base-color6 o& j  u& [1 ^. u8 j
  ask patches
% m1 y9 g6 f: ^# D  c/ g& ?) D1 c  [1 ?1 Y- `: u0 x, R' S  \  U
    set intersection? false2 d8 m! w9 O, V
    set auto? false( ~! v& w3 `# E- w  W8 V
    set green-light-up? true6 q# a% |* S# G  P
    set my-row -1  u6 T* C2 k* F
    set my-column -1, Q. V9 T; l+ J+ Z9 D4 _9 X# `
    set my-phase -1! u  @8 w8 g; F/ [$ Y
    set pcolor brown + 3% d0 F( e  I# e# F
  ]$ e! D! l+ E5 `, T

, N  j/ m; W! m% Y- }" z  W  ;; initialize the global variables that hold patch agentsets" X% K$ c, [3 p7 o0 D7 w2 h3 f' N
  set roads patches with
- o' F8 ]7 _. c( d- Z6 v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: v: U5 ]% ]* y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 d- u: ^- R( l) O  set intersections roads with
% _! W7 y/ g& X$ h. @4 }    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and& A7 g6 W# @- r5 q/ A+ F7 M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 l/ ?& d9 m  p# m( }
1 _! R; O' f8 D- a% ]  ask roads [ set pcolor white ]8 |0 u+ l# {# S4 _
    setup-intersections7 U) [& S2 j  S
end
- d, y7 K6 z' |& g+ `其中定义道路的句子,如下所示,是什么意思啊?- g& }9 G0 a3 [3 |. U( x% p
set roads patches with
1 ~5 H/ x6 Q9 i4 d    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* O/ w: P! _+ x1 q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 f/ d5 \/ _2 g. u
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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