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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。0 `8 P: H. E4 n6 S0 o1 g
netlogo自带的social science--traffic grid这一例子当中,
; J+ g" ?. ?1 Y) `2 f3 Kglobals4 F) F; P7 G4 w9 f9 V5 M
[1 o! ?( ?" p" F5 V1 V' H7 O2 K" j, [" P) O
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
7 H+ }# r1 f' |  L& Z  grid-y-inc               ;; the amount of patches in between two roads in the y direction0 d) R; f* b8 `, [# E- W% p
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
+ D7 t. i5 |" H8 m- N. V/ B                           ;; it is to accelerate or decelerate2 C5 K6 W0 O. [6 s9 B7 ?; n
  phase                    ;; keeps track of the phase
; Y* v- A8 L% c% `$ x1 R* x- ^  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
3 V* P' S, `$ ^3 [" ^- G  e  current-light            ;; the currently selected light
( `, `- T+ \, Y' G
7 d: L+ W3 N; F6 K, i. ?) ?' D  ;; patch agentsets0 t8 b" v" V4 X$ H' r0 g
  intersections ;; agentset containing the patches that are intersections
2 O1 N4 d3 H2 [5 p* y( R  roads         ;; agentset containing the patches that are roads
4 h; b+ j3 o/ [7 b# g6 J5 }" }7 f]/ L' ]) h! h) ^3 T: a5 y

2 Z7 [$ p3 P) @turtles-own) K  ?: P8 O* C1 ]  G! a
[
; k5 `- o6 [# E5 c  speed     ;; the speed of the turtle7 Z5 y) V( t: q- m$ h) `
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right; m; [8 ~2 c5 z1 j4 j
  wait-time ;; the amount of time since the last time a turtle has moved) C1 w( y6 D7 U3 Y& p8 V5 k
]
  M! n5 {8 J" B8 Y; j! R1 _
8 P: q! z$ y! T4 J1 B( zpatches-own
3 e8 i$ K: O4 r' `# b[+ Z. x2 I' G8 ^2 B( q
  intersection?   ;; true if the patch is at the intersection of two roads
( N! U. p) z+ W0 F  k. D  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
5 l# S+ t+ Q9 g) Q% j. t                  ;; false for a non-intersection patches.8 X% F* g% X1 }6 s* d
  my-row          ;; the row of the intersection counting from the upper left corner of the: C) Y' W( H; `9 r- B% @7 Q; N- q
                  ;; world.  -1 for non-intersection patches.
' I6 o# E4 g. d  G/ o  my-column       ;; the column of the intersection counting from the upper left corner of the$ `6 A+ h, f+ Y) Q. d  i  n! X4 D
                  ;; world.  -1 for non-intersection patches.- ^, J0 m) C9 ?  M) A) f: Z
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
3 n2 q/ {4 K" B' V/ _# U7 S) n  auto?           ;; whether or not this intersection will switch automatically.$ @1 |  r! [5 ?8 G9 I3 n
                  ;; false for non-intersection patches.
$ f, U/ m( S( L# K& Q]
2 v$ |9 B% x, a6 }5 H! V# v# E5 v) S2 H; y

- e$ F' ^: Z3 m- Q0 v* v, R' s;;;;;;;;;;;;;;;;;;;;;;5 A/ r! g6 s' Z: _
;; Setup Procedures ;;
2 e7 a! c7 C4 F8 w+ l- t;;;;;;;;;;;;;;;;;;;;;;8 M3 X: V3 e- T
' C- i' s! x  r& Y7 A
;; Initialize the display by giving the global and patch variables initial values." c- J' _( Q) g7 v
;; Create num-cars of turtles if there are enough road patches for one turtle to2 ~: G! Z7 @' ~  o
;; be created per road patch. Set up the plots.2 V- M" t; ~4 H1 W: w7 x
to setup
( X) V; K' `, Q1 k3 ]+ N" J0 u9 A  ca
* I* D! l& X- i5 K; M% J7 ~9 k  setup-globals
. R6 o! T  _9 P, U% I3 T: N& P: d4 x4 N- {! U. g# K  J; W( k( \
  ;; First we ask the patches to draw themselves and set up a few variables" C: T2 k4 O  L& Q
  setup-patches
% o4 y5 ?  o. a+ W& J  a  make-current one-of intersections! D$ p: ?6 N$ R) `+ w
  label-current  g# o$ Y! Z. u& n* F

" Y! W  D" U7 p& C% l  set-default-shape turtles "car"
9 ~) j$ c/ f! O* V- L; |$ o: ]' N. w" R5 O* V5 F& k7 e
  if (num-cars > count roads)
% [/ ?8 ]- M, ~, v/ q  [! e& ]# ?4 M% [  r2 A- n- N
    user-message (word "There are too many cars for the amount of ": D% {- M/ B, d: q; d3 g
                       "road.  Either increase the amount of roads "
0 Q# l' ]' h' Z: R0 l  `8 K/ K                       "by increasing the GRID-SIZE-X or "& h, Z, r; d  M* c
                       "GRID-SIZE-Y sliders, or decrease the "
/ G' O( E9 u1 _                       "number of cars by lowering the NUMBER slider.\n"
- {9 Z8 Y$ n7 V$ D$ C. Y6 z& k                       "The setup has stopped.")
3 U, q1 \. V: v    stop
+ m/ I- i- z- i5 ~& }% s5 w  h  ]
) |1 ?9 d7 G: D9 _2 q4 O; G" l5 @/ l  f' W% v
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
% D/ o0 K, V0 h) c  crt num-cars
: G0 T! t0 A9 ]; }8 N  [
% t( _- J6 e, o' n3 K    setup-cars
# b' r2 c* e; P! A# A    set-car-color, q) P& \* h' w5 p0 W
    record-data
: |: F- ~( Q# t: {/ v- k8 n& A  ]
6 w5 R& a# R" v- ?7 y/ M- q  C
6 Q' U- `* e( J% w% O  ;; give the turtles an initial speed. A. w! S8 W% C1 b* P; i
  ask turtles [ set-car-speed ]: ^9 [+ w% @3 ~' L* ?

: q5 R% m0 j) \% w; b  reset-ticks+ c& ?8 U1 b! k& B% J
end' u+ V: L& Z- z! b
! f4 _8 ]4 M; n
;; Initialize the global variables to appropriate values4 o2 w% G. K- ]2 V
to setup-globals
2 S2 `, _' m: J: Q# o4 G  set current-light nobody ;; just for now, since there are no lights yet
8 R9 `+ O! M7 e) R  set phase 0
3 T9 i3 a  d$ R  set num-cars-stopped 0
9 S; b* X( P7 {6 m/ G, x3 a7 r  set grid-x-inc world-width / grid-size-x& z) q& H  f7 b
  set grid-y-inc world-height / grid-size-y, T2 _3 j1 {) L/ j3 T
: M1 G- t' N% G6 P9 g
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
& @( H1 h! u3 Y4 t  set acceleration 0.0994 `- {% m& w0 `/ ^4 a
end
' q' G" {* L, g$ }8 n: ]6 X9 C4 V- B/ g4 }' o$ j* Q
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,/ d" Y$ h8 z9 p) }& y
;; and initialize the traffic lights to one setting6 a) `2 r0 r& p$ @9 X4 K
to setup-patches+ h4 {1 p- X7 N6 E6 [4 A+ v
  ;; initialize the patch-owned variables and color the patches to a base-color
, [- a/ T! ^! U5 \  ask patches' ]: E, _' s$ m6 g+ V8 n
  [0 D4 z9 T, S& J! `4 }
    set intersection? false, G  i$ [8 q, J, y( F1 _5 j
    set auto? false
+ ?; b; J2 A) U- ~  R5 [6 n( U    set green-light-up? true( u8 w; o8 W6 t; q9 l
    set my-row -1
, r- P3 t/ L4 x  P    set my-column -1; R( ^6 e2 j: V; ~1 s
    set my-phase -1
1 B  a& ]) r0 C3 c    set pcolor brown + 3
( E4 J& B" B" |* u" q  ]
/ ^: ?8 K$ F, Z5 k9 q
& h9 V! |3 d/ r+ K* |8 U+ p" k  ;; initialize the global variables that hold patch agentsets. j* ~/ @, c2 ~. _' G2 J7 P& k6 F
  set roads patches with( |0 O3 {8 J: F) F* s, ~4 c
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  R+ f; W0 @1 y% P/ j7 Z! ?  Y( ?. Y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 g' ]( @+ U& Q* }4 v5 j: g
  set intersections roads with' o0 p6 u, t- S. g
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
: s- {( [* X9 [, z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ D' n. W, a! t: V( {8 v% p8 W) f' g; m1 w! S
  ask roads [ set pcolor white ]# M' F( L5 V# n) U7 |  v
    setup-intersections
8 |$ ^9 y% U" q( p% Vend2 O; {2 y* ^( {- U3 t. {
其中定义道路的句子,如下所示,是什么意思啊?2 i* u0 y$ ^% c3 L. T) @4 S
set roads patches with/ N1 W7 r3 L" F" F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  w5 f+ X+ j: |; V! x4 D/ N3 I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- p) i) o& A; O6 w, 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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