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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。. M3 K; O+ F$ v) P  u
netlogo自带的social science--traffic grid这一例子当中,) X% @. F' M: L/ n
globals+ }8 K' q" n( X" h. A! J
[9 [! }. b6 g7 w6 t1 q
  grid-x-inc               ;; the amount of patches in between two roads in the x direction) Q) L2 T6 Y( t: k' j8 v$ I
  grid-y-inc               ;; the amount of patches in between two roads in the y direction: n) f0 }2 Q7 U! c& e7 d: I
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
( X$ D# J* X3 F3 j                           ;; it is to accelerate or decelerate
$ P. r* H! }! \8 t! P8 z. i- l  v  phase                    ;; keeps track of the phase
# y6 N1 }9 A# J7 @; U$ d) u  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
3 M2 E# z; z* s4 n8 y" a7 x  current-light            ;; the currently selected light8 Z9 p  ]. Y, |5 B: _/ U: h7 m

7 L* e2 s6 g: X2 C5 {9 G: d  ;; patch agentsets
, Z# Y" K- |$ a  intersections ;; agentset containing the patches that are intersections6 A+ w" _( p2 \, [$ m' E! E
  roads         ;; agentset containing the patches that are roads
0 [2 B% z/ I3 j* c3 i3 [: d  K; M2 o]* I, x, V( ^- K! y; G* P# _

2 P5 F: @: j6 ^" K( R5 n. eturtles-own4 l" V& V5 n/ x( ], E' Q0 H3 q
[
0 j$ t7 b4 R# g0 m0 z  speed     ;; the speed of the turtle
. r8 u" Y* t8 t8 @% Z$ `5 w+ S  up-car?   ;; true if the turtle moves downwards and false if it moves to the right3 n7 p  \8 @- H  F
  wait-time ;; the amount of time since the last time a turtle has moved! [7 B: x0 q5 z1 I
]( k$ K; z$ Z1 |: Z. m. b# G: a

1 z1 C$ C( E  }" N- f% W1 Cpatches-own
9 b/ J8 Q+ b1 O8 [* E[6 R) }7 M+ C7 l' N) _
  intersection?   ;; true if the patch is at the intersection of two roads
( E7 S  i5 V" w( K2 \  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.' w+ q- Z& G$ u. l$ x& |! \/ I1 _$ i( o
                  ;; false for a non-intersection patches.
1 Z1 S$ d$ u5 T! _+ i! s, p  my-row          ;; the row of the intersection counting from the upper left corner of the- K2 W& D/ V4 {) _5 @
                  ;; world.  -1 for non-intersection patches.
% O5 g+ i: F. i' Y  my-column       ;; the column of the intersection counting from the upper left corner of the
' D- d; x; Y2 |- p; o                  ;; world.  -1 for non-intersection patches.
( Z/ X8 c( P+ G7 @. n  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.2 _& i3 M. x9 S% `1 L1 v
  auto?           ;; whether or not this intersection will switch automatically.' q# M; c6 U& _: c! k7 P- e7 Y
                  ;; false for non-intersection patches.. G0 @- O) ]+ b# w% h1 b! s, D
]
$ ~- A* p* g& n5 U3 _) Q/ y; B+ ]% ?1 A5 R/ Q; O1 i- z/ P! I. O3 c
1 Q. Q2 @1 ]3 h1 g
;;;;;;;;;;;;;;;;;;;;;;
" [# }  {7 ?3 M6 p;; Setup Procedures ;;( {5 V  c  }" L. v4 U5 W0 Y! |
;;;;;;;;;;;;;;;;;;;;;;
& u, B4 r: }5 y$ l4 {- \+ {8 j. S0 M$ r- I/ ?; f
;; Initialize the display by giving the global and patch variables initial values.2 n) ^) P# ^' q5 S
;; Create num-cars of turtles if there are enough road patches for one turtle to0 v* p; n) \5 @- h9 `
;; be created per road patch. Set up the plots.$ P+ w  S" t' j3 M2 J5 x
to setup
8 ^* {) v* _3 D6 ~  ca" B5 {1 t/ o9 {: y4 u0 B, Y0 }+ B" G
  setup-globals/ \8 t) w. y/ N+ _! [+ U# R2 A
8 ?/ C5 r# f7 R
  ;; First we ask the patches to draw themselves and set up a few variables
+ i3 X0 \" q8 U  setup-patches
, \4 G0 Q! F" [3 n' F  O  make-current one-of intersections
7 e2 \+ J0 A3 w, h( O, w, |! G  label-current8 t" |) y9 s( }- M% ~
5 O% Z+ o' G3 h5 v, }7 v" _
  set-default-shape turtles "car"
0 ?4 ?# X" c+ I9 z, y- c
+ z0 i  F) v5 g1 v' A  if (num-cars > count roads)& ?' Y- I6 E. @0 m7 c5 Z# Q
  [% P( r; N: c( [( q
    user-message (word "There are too many cars for the amount of "
, k! U+ P0 @8 ]1 B, J                       "road.  Either increase the amount of roads ". T! ~" m) o- x. x, o
                       "by increasing the GRID-SIZE-X or "
* v! p$ i+ a$ Q( f! @                       "GRID-SIZE-Y sliders, or decrease the "6 }9 l) u8 m: j0 o
                       "number of cars by lowering the NUMBER slider.\n"$ H1 W4 J8 r- M* J, E0 \, t+ Q% v
                       "The setup has stopped.")9 J3 b  e+ C- x: T- s) ?
    stop
1 f; @: ~2 `* O  ]
2 k. t6 j6 N: r/ N
- G. g& ~; c. `- p2 l( ^  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
7 a5 X7 [) J5 R; K0 M6 @  crt num-cars
. x) ?2 j; W3 h- g4 E- ~# Y  [
+ W, [. K& L$ u  s* ]# V    setup-cars
: a. C  X3 G2 w3 m. ^6 A    set-car-color9 b. V9 P" k, ?
    record-data
# ?, z& ~& O& f- @  ]
  c) c7 R. C1 d* ]# g4 f' R* Q
) v% C2 l  R/ e; p( l  ;; give the turtles an initial speed6 B. T. u5 s7 d3 J7 b* ^
  ask turtles [ set-car-speed ]* h7 v0 V5 G3 u1 m& N

; e  R6 u1 j# m( I8 g/ J) _; J  reset-ticks; @( {* \/ B' [! O4 L7 r2 V8 s$ a  r5 ]7 O
end
. ^! r" U0 F9 H4 G# c: Y% G& R9 ^6 M
4 H8 q: O* i' N& x;; Initialize the global variables to appropriate values" x( @( ?; {8 ?
to setup-globals
% K: W. _! \+ B, d* ?: S& Y1 f  set current-light nobody ;; just for now, since there are no lights yet# [. X) H/ a! S( [# D5 \3 N
  set phase 0
2 n1 P  f  @4 W  set num-cars-stopped 0- P$ N4 ^5 U) X2 j, q
  set grid-x-inc world-width / grid-size-x
9 j9 o# Q, W$ C+ Y1 {6 K& n  set grid-y-inc world-height / grid-size-y8 R& b! p# N/ H1 Z
' S' }: B2 V) C: s
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
) Y6 `7 Q0 k+ x8 m. S% g  set acceleration 0.099
" \2 D# `% ]1 [" S# G  fend( Z9 g. p# M; H' i+ D" n

. |! J3 g9 C; y- l2 n;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
* W" N7 w- U5 f0 F0 f+ q% I0 j; x. Q;; and initialize the traffic lights to one setting
8 G; s# `# }  P9 u- F3 uto setup-patches
; W3 y& Y4 Q5 c' Q$ o! \  ;; initialize the patch-owned variables and color the patches to a base-color
5 H9 ]- V1 T, p) N8 b  ask patches
+ b/ B* i" K) y( F  Y! o8 Z  [. M# r: k1 _# e, [* x' {
    set intersection? false2 @9 R9 m! \$ X$ _" g" p# s& g( J
    set auto? false$ F9 i6 f8 J! J% _% X' E
    set green-light-up? true
9 U! W5 M9 M4 |5 N    set my-row -1' t, \2 S5 h4 e; V7 [9 c) }
    set my-column -15 t9 r4 J! W. D6 z8 i1 i
    set my-phase -1" l# r2 `% x7 D- `9 s4 Z
    set pcolor brown + 3
6 M$ Q: q0 l+ w* z, e  K  ]' B- k7 \& S, d6 t& G1 L! I6 w
6 |; J- }5 f6 e) W+ Y: S8 I% P/ t
  ;; initialize the global variables that hold patch agentsets
2 _2 A& |% m4 o$ e9 l4 L  set roads patches with
" p+ a& O) y3 }* {6 ~    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) u$ A! g) O, A& l0 _( w" O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) g+ ]5 q9 q1 ^: d  set intersections roads with
2 \% m! d3 g7 t9 c    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
& S0 a# p+ c! U* M+ k    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( i/ \# Y( r4 j$ P

- |  {/ a2 D1 t& S" \  ask roads [ set pcolor white ]
" X5 ^- X: g: Y3 v2 k    setup-intersections( X4 l7 ^3 s: E# l) r
end, F3 ]0 }! ]/ E; E+ W
其中定义道路的句子,如下所示,是什么意思啊?
  s" Z( Y9 B: \' `. h  N0 ~ set roads patches with
' @' W" D4 S$ S, ~5 W8 u& e, `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* S" M% ^4 I2 O- x- S* w
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 z, e8 S; f( q1 E5 H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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