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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。+ C, H/ M5 v! P7 H( t
netlogo自带的social science--traffic grid这一例子当中,
! A6 C) H: _9 P+ \globals2 q; c! d9 E; n0 Z
[* Y) J+ U6 e! }5 S5 N
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
1 Q3 B0 W9 I# L, R  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 b$ ^$ S4 }7 M+ d6 P5 u  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
4 _4 z4 H( Q* N) ?8 d; v                           ;; it is to accelerate or decelerate
, ^. G9 G$ B- l8 Y0 @  phase                    ;; keeps track of the phase0 m; D) {9 z3 e9 [8 i# e6 u8 ]
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ Q* S  n0 H5 ~+ O" M  a  current-light            ;; the currently selected light* P0 n3 S: ^4 ?. w

& o  ]$ q1 I4 `7 [  ;; patch agentsets" l. e/ y$ ?. [
  intersections ;; agentset containing the patches that are intersections
3 d* }" w+ K1 t  roads         ;; agentset containing the patches that are roads+ M* A1 Q, C( d
]% ]  t& }: |" w) r) ^4 n
$ c) H( ?) S+ `2 c- [! f# c
turtles-own
# _7 [% `# m, q! E! |[
% V7 v6 M/ a' s/ s# F  speed     ;; the speed of the turtle
, f" L1 L% `( D- t' Q, @! L  up-car?   ;; true if the turtle moves downwards and false if it moves to the right. \! q: R% S& X6 c9 @8 {& G8 s
  wait-time ;; the amount of time since the last time a turtle has moved
% C/ t3 I( l% n- N]
/ H1 r/ h! @& L3 Q0 `7 F* M( `* G
; R1 P+ l" s" zpatches-own2 u3 U  C2 ~+ f( J1 ^/ \( y
[
- ?$ Z4 Q: {; Y. v* c& [2 t  intersection?   ;; true if the patch is at the intersection of two roads
9 D) l' g6 f5 x6 m# `7 q1 }  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 o$ y5 n. m  @( K& I, h3 @( I                  ;; false for a non-intersection patches., U1 s/ H, g* P6 [- k
  my-row          ;; the row of the intersection counting from the upper left corner of the
  B" ?" B; m) Z; \' F                  ;; world.  -1 for non-intersection patches., v9 `' c2 Z. F& C) }4 p, U; m; N
  my-column       ;; the column of the intersection counting from the upper left corner of the$ ]! J. q2 `' q  R. {
                  ;; world.  -1 for non-intersection patches.
; H- q7 G" O2 R( T# G: [+ w  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
7 `. O; z6 i1 v( L6 \$ x) N  auto?           ;; whether or not this intersection will switch automatically.
! l; {5 e; ^( Y" ]! }0 V3 C                  ;; false for non-intersection patches.# Q  F1 S/ l& b- |- K/ r! R5 x
]
) O9 q# Q: ?" x4 U6 a3 g5 D+ X1 d" r* Q( q1 ]
. h! |& B) w3 B1 e# p; }
;;;;;;;;;;;;;;;;;;;;;;
3 z6 c& |/ i# ^% P3 _7 L;; Setup Procedures ;;
! y% G( Y! T. P; Q;;;;;;;;;;;;;;;;;;;;;;  W; x4 T! V! I: w/ y1 a
5 M( f$ n% d! i# ?1 m) i* P
;; Initialize the display by giving the global and patch variables initial values.
. W' c4 P& E5 Q: X6 A9 J;; Create num-cars of turtles if there are enough road patches for one turtle to5 b" M( z' f( h" l. T
;; be created per road patch. Set up the plots.( N6 k5 E0 b9 n
to setup
. e; t- _' g# J% A# K. ~  ca% [- [6 q/ G& r" r
  setup-globals, W+ P  S7 G' f" b3 H
' Z! C6 O9 M/ P6 q
  ;; First we ask the patches to draw themselves and set up a few variables( k( P$ v2 S5 o+ G4 V
  setup-patches& W( R" r7 p! {6 W9 k3 b7 k
  make-current one-of intersections# I+ c9 C  ^+ z& \& n% L/ E
  label-current. `! v7 n! P6 ^4 G" [0 j
! [# i7 @. L. f, f
  set-default-shape turtles "car"
2 M" n) k& }# ~/ W3 ?' ^& H; M7 ]# C) X( ]) T* d. m2 t2 j
  if (num-cars > count roads)3 T  k+ v) d) q7 T% A4 J
  [
# ?3 G: M8 s0 w    user-message (word "There are too many cars for the amount of "% r+ U8 z0 ?5 M( v- y: _6 E. b+ I
                       "road.  Either increase the amount of roads "
0 m9 }% b( J$ t                       "by increasing the GRID-SIZE-X or "- l! Q/ x" \! O( s9 w1 j5 ^7 x
                       "GRID-SIZE-Y sliders, or decrease the "
+ J& j9 _. S7 M: a                       "number of cars by lowering the NUMBER slider.\n"
; d1 j/ u  y! u; K5 {                       "The setup has stopped.")) J) A2 n0 M$ p0 J% Q" u( Q
    stop: l% N/ b7 s& f' Q8 u9 f+ q: n
  ]
/ c( E  z. {7 [& s. Z/ B4 B  g8 i7 I" c1 L; F. P# ~& n: N5 c# ^* {
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
0 |" Q0 H' N) B1 b! p- ]! P  crt num-cars
( G& H5 N$ O3 p$ n# b0 P! [  [4 L9 [9 x2 A7 l7 d9 G
    setup-cars
. A" ]% @, I6 f# ?5 |    set-car-color' |2 O/ _8 I, G- c# V1 p! R) a
    record-data
! s+ m" M6 }) k4 [. {$ a  ]
9 G# F, p2 ?! M3 @1 N/ ^; H: r/ N. t, d2 m! T
  ;; give the turtles an initial speed* |: P- P9 |9 i  k4 m# A- M
  ask turtles [ set-car-speed ]
* f3 m9 k" Y" l' _3 x+ i
& S- L9 B4 z; s8 l  reset-ticks
/ x8 s- O& i; `5 Z4 hend6 w. j6 _) j0 Q7 g

' X0 f" U4 O* L$ l0 K;; Initialize the global variables to appropriate values) v# f1 T* F+ ]1 ?
to setup-globals
8 ]+ Z6 [7 Y2 E7 d+ ?: y! t  set current-light nobody ;; just for now, since there are no lights yet
0 s* Q7 F9 ^, @& I8 r& n  set phase 0# S9 u" u8 R+ R4 h- l
  set num-cars-stopped 0" k3 M8 B" b- [% C
  set grid-x-inc world-width / grid-size-x$ p$ g$ U9 Q! E9 i, T% Q! c
  set grid-y-inc world-height / grid-size-y/ F) j4 N& u4 R# |

, x; ~! ]) |/ [$ m  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary8 w/ F$ q1 t. y0 j) l
  set acceleration 0.099) Y* a6 ?0 L# j* q
end; X. `" b% B4 I3 S( }5 v" \

, O. T' X9 J3 w# O;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
$ K+ t  p! C, q$ c6 [7 ~;; and initialize the traffic lights to one setting  e' i$ x; y4 b% _- a7 C1 i
to setup-patches
" E9 }# Y, n0 Q  ;; initialize the patch-owned variables and color the patches to a base-color  ?/ _2 i* Q8 `6 e
  ask patches
$ o0 T; u9 D4 y+ C  N  [
* t2 X  Q$ l) X9 Y    set intersection? false+ H$ M* }3 w) ?) x
    set auto? false5 ^5 t: f6 Y& k1 n/ c: M2 F
    set green-light-up? true
% o9 a* D( y/ V, d& z0 z    set my-row -1- ^: _1 U9 x9 z# _
    set my-column -1% Z+ j( ~# n! u: v# m: v0 ^9 q
    set my-phase -1' U6 D! D0 Y( X! f! J1 j
    set pcolor brown + 3
5 P( }+ \) \9 v5 n  ]
. Q( W, l8 f) p& b; Y" b! |: e+ a# ]' p/ b9 @$ B7 X
  ;; initialize the global variables that hold patch agentsets' Z. @$ Y, X+ H
  set roads patches with8 v* C, `4 F9 E0 j& Y- f/ G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  q$ I% W  L" Q; ~6 a* l( b* h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* B% c  N6 H: f$ _  set intersections roads with
4 O: v, g7 `2 u8 p6 _/ K3 n! r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% z7 c! _0 \1 U& J) k+ a0 d6 X$ x    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" t6 ?6 {* g$ [- u; I: ]3 d" X

% f8 U" K5 M: [( s) U  ask roads [ set pcolor white ]
* c, A# f! R$ N+ `6 r    setup-intersections. ~3 Z/ N( r' y/ s3 T
end
- A. s8 H* @4 d  T& x) B其中定义道路的句子,如下所示,是什么意思啊?( {# t" t- w# R( q+ s
set roads patches with
# P, m1 f9 {- N0 k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 t" h: i& x; Q3 v5 e$ |+ K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 ~2 ]- x! u9 [. ?. [* _, e
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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