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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。4 S7 A9 ~& y3 p1 E2 f2 C
netlogo自带的social science--traffic grid这一例子当中,
0 a  h, p% ~8 z1 M! c6 Fglobals5 F. e2 C8 e: W1 W
[) A1 G- O6 W' O& |
  grid-x-inc               ;; the amount of patches in between two roads in the x direction. H9 v, E* x( u% c9 \( F
  grid-y-inc               ;; the amount of patches in between two roads in the y direction8 P6 n5 G2 s: p1 c( d' y
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
* L* k( C0 u& x* |( J) d                           ;; it is to accelerate or decelerate
1 \( \8 E, g& z* r: Z  phase                    ;; keeps track of the phase
2 y. u2 P! J$ K& ?- z; I  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure: u( j7 L* y8 w2 r; J- b) Q
  current-light            ;; the currently selected light
2 J% H/ [5 i1 X: K6 j, c6 Z
- x. |+ H) C% e  ;; patch agentsets+ S" L7 B; |) n8 g. ~
  intersections ;; agentset containing the patches that are intersections
4 D8 [3 C, ^/ ]* M  roads         ;; agentset containing the patches that are roads
) b5 y  N; r* c- b9 d. D]
- C$ V, w8 k0 F0 U3 s  W7 j8 ~5 C$ I; o& G5 }
turtles-own1 V. ~# d, e9 ~: N7 r: }9 U7 u
[: o& k4 p2 B4 h7 i. H
  speed     ;; the speed of the turtle7 g$ S2 F# L% t8 c! [& o- s* ?) T
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: f8 m; c- b2 Q8 _5 U" ?& |  wait-time ;; the amount of time since the last time a turtle has moved
/ v: y  s8 B2 X. |  x]
0 E0 i$ ]8 o) T4 K4 P; y/ W1 O- l" V  y
" X. L" r: ^0 W0 E, ]4 O7 ?, dpatches-own0 o! X# |3 ~* b+ z! o
[, g: V5 u. @# ]
  intersection?   ;; true if the patch is at the intersection of two roads4 B8 ]7 i6 f" S; m. O3 F
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
* l* r4 j5 @2 |" _) Z" Z                  ;; false for a non-intersection patches.
9 T3 Z/ `/ D3 Y( h' A  my-row          ;; the row of the intersection counting from the upper left corner of the
; Y, ~) r0 `0 e- n" c' y* f                  ;; world.  -1 for non-intersection patches.8 `- e3 q# v+ G. e( i$ V+ o; G
  my-column       ;; the column of the intersection counting from the upper left corner of the: o. A6 v( \* B. ^
                  ;; world.  -1 for non-intersection patches., S6 h! m# \/ O- M& f! ]
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.( D6 B& V$ k7 M1 A- k- I. y& ~$ R
  auto?           ;; whether or not this intersection will switch automatically.2 m- z" w8 B( j3 D0 i9 K* S+ p
                  ;; false for non-intersection patches.
' [0 d; L( i. f+ t]3 x# b) h; u; w" S+ n. ^5 B7 l

, W4 x' Y! t8 y7 S& [& W! |! T, F; M! j0 @; y9 U
;;;;;;;;;;;;;;;;;;;;;;& e) i4 h2 c7 A  N' w
;; Setup Procedures ;;1 d' w7 T5 S7 ?) T# q5 X
;;;;;;;;;;;;;;;;;;;;;;1 R8 I1 B, `5 l5 @! A4 h. k

9 k8 |2 A/ J' \;; Initialize the display by giving the global and patch variables initial values.
: D* w$ u) D- D5 R8 y;; Create num-cars of turtles if there are enough road patches for one turtle to
7 G& I  |' k% J7 q- x;; be created per road patch. Set up the plots.
- @: ?, d( B! v( N( H. Mto setup5 g5 Z4 z! q6 V3 m/ p! g0 r1 @
  ca! @( n4 M1 k( [( S; m' ]2 V; {2 |
  setup-globals5 ~8 ?( V" \) t8 N0 f, {& M5 ~

- C. _: o+ E$ r8 F  ;; First we ask the patches to draw themselves and set up a few variables
; C$ t5 ^( D/ d  setup-patches
3 {7 ]/ y% W6 h: ~) C  make-current one-of intersections2 s8 P9 \' W# Z! C1 Y$ q
  label-current
8 y* R; U5 C* b" E7 j# w$ C7 R  U+ f
) K( y& c4 @; g+ h7 Y- E  set-default-shape turtles "car"9 L' ]0 f  H5 Y3 ]4 {

+ a8 X% r7 f) l9 w7 d  if (num-cars > count roads)1 s+ ^' W/ w8 {9 W; F' \) @
  [
0 \  @, H) t5 [* d$ d  r/ D    user-message (word "There are too many cars for the amount of "
! v: `3 v& e) `                       "road.  Either increase the amount of roads "
( R8 w) }. r2 e1 A: ~, t' _3 m                       "by increasing the GRID-SIZE-X or "! q& U, c' k  J# R6 X5 q
                       "GRID-SIZE-Y sliders, or decrease the "
7 ]0 B0 f9 K, M: i1 G7 o6 l8 |5 J                       "number of cars by lowering the NUMBER slider.\n"4 _( @3 z/ [: V$ |# F
                       "The setup has stopped.")& E2 T! q% T- N/ a
    stop
6 h! Y: h& O' V& T% w# O1 l  ]  X- r7 ~* g( Z2 }3 M

& F: ^- T! y, M* h3 ^  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color& M0 B6 m8 R( m4 y: x
  crt num-cars$ M  C; n" N' s6 r  e# ^' v. j
  [! t: i, U4 I+ ~8 ?# [
    setup-cars
1 j& U+ D, ^) P) S4 j! D    set-car-color
$ J+ _4 W1 p8 P1 I$ U    record-data: H- Y9 I' {: n- u
  ]3 N  ^2 a$ p2 O: l9 C) `  Q
4 P( [3 T$ s. V5 ?' W7 w: P
  ;; give the turtles an initial speed1 r& o  m5 @& ~3 ]
  ask turtles [ set-car-speed ]0 N1 M3 H% o8 K% v1 P4 f6 \
, ^5 j) L# ^2 F3 A; [% ~
  reset-ticks
: s9 I; \" v4 O7 U9 o+ |' ]end
4 W- L, n' s. d* o( u# T( q4 n& y* s7 K0 P  K1 o" d' M( ^+ a8 m
;; Initialize the global variables to appropriate values4 p1 t& h# i7 z  S- _7 P
to setup-globals+ W: g8 [2 n7 E9 l
  set current-light nobody ;; just for now, since there are no lights yet  l% |% s; l. ?' y& N2 h3 b
  set phase 0- z+ R" x# {0 w8 O" H8 k$ T; T
  set num-cars-stopped 0
7 F5 v6 D- d" H, o/ D% u  {  set grid-x-inc world-width / grid-size-x
/ |( T8 H! g0 S0 {" T/ T  set grid-y-inc world-height / grid-size-y
5 b8 L" C1 {% f2 F6 ^+ W
7 |$ V3 [1 h$ g; E) x  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary0 H3 I$ F  J$ u3 O7 h" n9 b4 i$ ^3 Z
  set acceleration 0.099
! L# Q% R; C; Mend0 I, L5 E/ f) }" `2 {7 h9 ?
* [1 p; a8 \% s( ?* m' e: A
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
& W& f* Y9 S  j# [2 ];; and initialize the traffic lights to one setting+ u* C* ?" A) w) J
to setup-patches# o+ j( l0 [5 G, J
  ;; initialize the patch-owned variables and color the patches to a base-color
& t9 ]* [4 ~" `% o7 w* P  ask patches
* C, H2 f/ X* w  [
0 Y8 @* P$ z: B5 f    set intersection? false+ Z+ f. T$ e( o& u" Z
    set auto? false% z% B  X4 ~$ y: y
    set green-light-up? true
  f3 ]! u3 a/ G& C, H# c8 H    set my-row -11 U- o" U, _5 s2 t/ u
    set my-column -15 |, M+ K2 K3 d
    set my-phase -1
8 D7 G6 z8 M6 }: [$ Q# r    set pcolor brown + 3
6 d9 w/ ]( i% P* O4 @- W  Q0 w0 G  ]
7 D3 W9 {+ \9 J
. T! u2 \: i, p4 a' g3 X  ;; initialize the global variables that hold patch agentsets( O; i+ n. ?7 M' g; e
  set roads patches with$ u1 P; E; w% b7 D8 O3 e- [
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 l; r" Q+ {! G, i# ^$ V$ x. m
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 n5 q9 e* s' }3 X5 y5 E4 l2 t! T  set intersections roads with
- [" Z. K, u/ |8 @, d& I/ K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 Z4 D. H) \" Q- ^) p
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 V4 F. L8 U- O: v
( p- ~0 p) ?  v$ l# ?2 t
  ask roads [ set pcolor white ]
7 w1 ~/ m4 W; b5 x0 S+ C: n/ e! I    setup-intersections
# L7 @& d( z' i& D7 h$ E3 r4 R, Hend
3 |- z. q( D. e1 M' w2 h3 N! V+ Z) E其中定义道路的句子,如下所示,是什么意思啊?& f5 H( A0 i1 u
set roads patches with" z. H( p7 f2 v& u9 R: K# d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ {( M7 N$ K9 c" p% g  M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 e6 A# E% i/ F0 z3 q* |: O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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