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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。
" i, S3 n9 ?3 m( s/ ~( G' Unetlogo自带的social science--traffic grid这一例子当中,4 H6 t% @) I' O- P5 [3 n4 `( ?
globals, I2 ^) A( h* S& h
[
" |$ o7 w# t& t  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, q* D5 E5 T* Y! W4 i  grid-y-inc               ;; the amount of patches in between two roads in the y direction& N( Q! S2 y2 b8 l  {
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, W+ Q  A, e/ z- l                           ;; it is to accelerate or decelerate
0 m$ \$ H3 m  o9 S7 m/ p  phase                    ;; keeps track of the phase! r) U. ^' V  z$ O( q& T6 X
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
6 f- Z. ^  y' m  current-light            ;; the currently selected light
0 w3 S) I, R9 H4 S9 {) A
! N& M% m* y1 P7 d) k' q  ;; patch agentsets1 {" ?8 L$ x8 R' k
  intersections ;; agentset containing the patches that are intersections# F+ H: S! |8 e' C3 a6 c
  roads         ;; agentset containing the patches that are roads* _0 s2 P5 r- N
]# [8 J2 z' M0 N! I& f, M

- \# Q4 @4 t8 s* X( s8 Zturtles-own: \6 `5 s3 Q$ T/ l. L
[
+ E% f. e2 R1 j  `  speed     ;; the speed of the turtle
: h" R- N  M9 N. v3 ]! B% G  up-car?   ;; true if the turtle moves downwards and false if it moves to the right# T  |% t- Z7 c7 e7 b
  wait-time ;; the amount of time since the last time a turtle has moved
( `8 s3 i! g, D% H6 v( w9 q]! z/ x% T; w. c! J
8 D/ T) e2 G# C( R- e% }( x
patches-own
/ b7 t6 c) Y1 x3 U5 {8 D* l' L[
$ X/ m# H. j; u* w  intersection?   ;; true if the patch is at the intersection of two roads
' l) z* m* m$ G( K' t  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
# }& G3 q/ a1 ~5 S9 G                  ;; false for a non-intersection patches.
7 Q0 b2 a2 B2 i# x) G/ x+ j0 k  my-row          ;; the row of the intersection counting from the upper left corner of the% c6 z: p1 D; {; J, M) K
                  ;; world.  -1 for non-intersection patches.
* @* b+ L; Y. ^7 r7 y) s; H  my-column       ;; the column of the intersection counting from the upper left corner of the
! t7 c: |- R" Q( N                  ;; world.  -1 for non-intersection patches.  ], C/ P9 v$ O+ {
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( R/ I' ~* W" k  J* `  auto?           ;; whether or not this intersection will switch automatically.
% l; H$ p$ w" K; k( e" ~                  ;; false for non-intersection patches." p# f6 z2 J; N! ~2 y2 A2 k2 o4 z
]
( D7 p/ `, _8 A: ?4 a8 T- _1 S/ z1 a. b* n# M

& a+ u% E% d" i" a' S;;;;;;;;;;;;;;;;;;;;;;6 Q! @4 A0 g  v
;; Setup Procedures ;;3 r0 u0 ?- A- e7 c. v: r
;;;;;;;;;;;;;;;;;;;;;;
7 y9 X& g6 e+ D3 H% A) s2 m2 e9 q3 o' g% R! a: e( Y
;; Initialize the display by giving the global and patch variables initial values.
1 j1 M, e: K5 a* w, r% G;; Create num-cars of turtles if there are enough road patches for one turtle to
# c4 _( {/ g* }1 E6 n3 G;; be created per road patch. Set up the plots.
4 @) S. x* Z% _5 ?4 e+ ~to setup" J' _/ B. o! u$ f
  ca' s) r/ q0 x: r  y. {
  setup-globals
- A, }, c% N# [! f0 m# q2 l. @; }+ ~2 z* k: h: s" a
  ;; First we ask the patches to draw themselves and set up a few variables5 F+ Q) _9 z3 v* R* n
  setup-patches
; r; W' ]+ E3 q  w# F# x  make-current one-of intersections
3 ^  F) j( U1 n  label-current
1 m3 S( g8 j7 v6 l; J4 Q
" G3 e8 H/ n, }0 p- J% _" O  set-default-shape turtles "car"
$ B% |: W6 s7 H7 C; `0 l( I( j- e7 d* _* D3 g
  if (num-cars > count roads)
7 u0 [/ T0 y& k$ D0 x  [
; M" S; F3 J1 x2 \    user-message (word "There are too many cars for the amount of "; N  ^: x& Y- S
                       "road.  Either increase the amount of roads "' e( Z( F6 t+ ^5 z, L1 ^! [( h/ X% [
                       "by increasing the GRID-SIZE-X or "
% u0 x1 N9 D* l3 i3 D! h4 |/ R                       "GRID-SIZE-Y sliders, or decrease the "
& D3 W9 S4 O- f5 g* z1 z- r                       "number of cars by lowering the NUMBER slider.\n"
6 I- h7 A0 e( W5 Q% C                       "The setup has stopped.")4 V4 j: t5 K! @3 \: N/ p  F
    stop
$ g; \& j$ b* y- P/ b, O  M  ]* \4 c' @" N3 |6 m$ O/ R+ H  Z6 [

- {- t: z6 K( t; J$ z  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color# q, K- E, e9 N* g' J9 ?4 W; D6 D
  crt num-cars% A7 w5 t9 N# U: z
  [
- o2 ]9 f1 [  E. k, Y    setup-cars) ?9 K$ {+ a/ a' v" w2 g/ T) }
    set-car-color. G) Y7 V/ X6 z. d- h. u' B
    record-data
7 C3 k: O( [2 {0 j% q) K  ]; v1 [  _. L5 j2 h* L  B$ R

9 W$ j6 k( f8 \: y4 f  y! V- n  ;; give the turtles an initial speed
% s5 W/ b% q2 B/ {+ K& k  ask turtles [ set-car-speed ]
5 J$ Y5 p6 Z1 ^6 W  h
/ D$ d0 I, [8 \8 t/ [  reset-ticks9 X5 m+ W$ Q2 l- s8 H+ ]
end+ y! Y2 }- g( G! i6 i2 h
1 L  Z  r4 ]4 I# ]8 @8 Y* S/ _
;; Initialize the global variables to appropriate values
4 }& H0 O4 Z  V! nto setup-globals
3 j# E6 |2 H7 O- B: N  set current-light nobody ;; just for now, since there are no lights yet
! ?% a3 S8 ], k* |% \  set phase 0: G( p" p4 |& w2 z# ~9 @
  set num-cars-stopped 0) u4 L. _% q; m7 _' w* }  E9 m
  set grid-x-inc world-width / grid-size-x8 Z* y! R9 l3 k
  set grid-y-inc world-height / grid-size-y) F1 C6 B! P) `* v

% F  X6 F/ h) Z9 {  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
5 l, f8 G6 m, v9 V. x. y  X  set acceleration 0.099+ d, d- R" L; J4 h& w; u
end
' f2 J: J9 `$ A, I  r6 v, f; q% N6 K! F/ B1 f
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 e/ g, d% h# e# i# j
;; and initialize the traffic lights to one setting  g5 a; E$ [& ^: e6 A+ h7 m! q) C
to setup-patches8 r1 v+ O" E1 C% K! |
  ;; initialize the patch-owned variables and color the patches to a base-color/ ^! ~, k* r; J3 `
  ask patches
% ~# u* J8 f9 L  p8 Y1 V  [- r5 U! |( A( s$ y  x
    set intersection? false" Z  L5 ?( @$ |, K* H
    set auto? false, c" V) y5 `- a6 |7 _: ~
    set green-light-up? true
- S. z( q. h) s    set my-row -1
- w/ d% a+ m: K  k  u$ T    set my-column -1
& s. Y: @" n$ s4 k( D+ G1 F    set my-phase -1
; n: N' a/ \* _% W. l$ x    set pcolor brown + 36 u9 x; I5 z$ U  F% G/ X
  ]5 Y$ X8 a" C; I( ~8 Q

; M* \. ~, b( t# b$ I7 j# L/ ?  ;; initialize the global variables that hold patch agentsets
5 `0 H- o# g6 b- C0 x/ q- S  set roads patches with: m* ]: O6 h* C5 G) g
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" x9 o' B, s$ Q' K8 D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" W4 k+ h1 S( D. Z5 w
  set intersections roads with  P9 U  q" n. X. s, l1 h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ F* ^8 Q& \/ n8 `) m
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 a2 r: ]6 @7 l
' x1 V7 M* x6 d- o& s. D, h5 j  ask roads [ set pcolor white ]2 d' S# A1 J) i2 D
    setup-intersections
! F# Y$ x7 [+ P; x1 F! ]+ m6 @2 Mend( x5 @- Z% y1 ~. ~
其中定义道路的句子,如下所示,是什么意思啊?
/ H8 T$ I* C7 ] set roads patches with+ E+ S. J4 _7 a
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 V: O& L% b9 P# Z! t: d    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, {9 t% S! B1 m) e9 B# C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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