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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。
% f/ U; a3 n9 G, }7 P3 e, J- ^netlogo自带的social science--traffic grid这一例子当中,: n; I7 J6 z4 Q/ Z" G
globals
0 a4 p( N) {8 a( u: G! c[6 o& z' X' T2 u4 B7 z3 Q( q4 R
  grid-x-inc               ;; the amount of patches in between two roads in the x direction4 T3 U: N+ f& p: S$ \
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! x- ~* g* T! g/ I  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
% t- k/ r" S6 S2 q$ Y2 p                           ;; it is to accelerate or decelerate
" W7 f( U$ _! f  phase                    ;; keeps track of the phase) S! X/ Q+ U+ E0 Z
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
9 X: i1 J; e: \. v1 Z1 V0 O, t0 k  current-light            ;; the currently selected light
; d6 T! F& r2 d2 l* [. x! Z6 P, R! G! c9 f  a! T! a# k& k
  ;; patch agentsets
6 t. i2 }' u  t: f. L& x' w  intersections ;; agentset containing the patches that are intersections
! T: B$ a6 l1 o8 `! Z1 M/ f  roads         ;; agentset containing the patches that are roads; ^- E$ k3 ^( ?5 A+ }) _" a4 T
]
, W- [0 |% w0 |/ A8 U9 h) X+ T% y1 c# b- t7 Z7 f
turtles-own
, W6 q' M. R9 n. y5 B: m4 I* X[
; k7 A/ p+ F! @  speed     ;; the speed of the turtle
) h. U$ U$ q0 i& w# U  up-car?   ;; true if the turtle moves downwards and false if it moves to the right$ L% C3 ~9 n) C: V. }8 x% |
  wait-time ;; the amount of time since the last time a turtle has moved
5 B5 O" ^, [# P& h" U6 }. u]
# P' t8 `( e6 \9 E, E1 A7 L5 Q$ `. b0 W+ r
patches-own
# O. O( h7 r* @- e& \! C[+ i2 p0 J7 m# a+ {7 g4 {
  intersection?   ;; true if the patch is at the intersection of two roads9 z  M$ D7 v0 F8 o) w9 F
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
6 ~* F0 I8 X& g$ s+ k                  ;; false for a non-intersection patches.: Z1 ~! y7 p. k" K
  my-row          ;; the row of the intersection counting from the upper left corner of the
  o- ^3 v2 A1 r( q1 R) J0 ^                  ;; world.  -1 for non-intersection patches.
7 M- \! D$ \0 D) O' f4 I  @- \  my-column       ;; the column of the intersection counting from the upper left corner of the" Y5 k1 p  }3 q' E$ _
                  ;; world.  -1 for non-intersection patches.
% ^) g" m7 b) a4 T  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 V+ m0 `0 n4 R7 L7 U
  auto?           ;; whether or not this intersection will switch automatically.+ R, A: `! ~9 U: W- u
                  ;; false for non-intersection patches.# G1 G1 `- a) _" W
]
, g: k. [: y; Q  d/ v+ \. G6 ^& e& q. Q  H; F

. v* n9 g8 t: Q, h( o;;;;;;;;;;;;;;;;;;;;;;
! |6 B2 L3 a$ e9 U$ {. l5 s' r" n;; Setup Procedures ;;
/ k4 a: A0 |" B) T& @8 f6 Q- M8 V;;;;;;;;;;;;;;;;;;;;;;% d" |% k% \4 k: m

+ T2 n, |' R2 J/ [" Y  v;; Initialize the display by giving the global and patch variables initial values.
  p: ~& X3 [8 @) q;; Create num-cars of turtles if there are enough road patches for one turtle to
" v9 W" r- r/ F% R2 {;; be created per road patch. Set up the plots.
: O5 t  _$ `8 [; G/ m2 _' x9 Dto setup0 Z$ K$ e4 G: L' L0 Q) a3 G" v
  ca
( B, N" G% o( A8 _0 ~0 s  setup-globals) e. f+ \$ L0 b6 l* n

( I' [2 J, X9 R: Z/ V; R" |9 a: h  ;; First we ask the patches to draw themselves and set up a few variables
/ ^; N7 r5 D5 g: U" {- R  setup-patches6 q% C3 J; J$ S- J+ S
  make-current one-of intersections
7 q- b& P* O" Y0 _" H7 H. S- M  label-current. h" c7 \( I; R. `  Z, s
8 @: K. A& c% F6 d. ]7 X; X6 t. i
  set-default-shape turtles "car"
4 l8 v! @; p8 v; c' [% X: f
2 g6 R$ m. o& I' [* z4 }4 H2 ~  if (num-cars > count roads)  r9 I! m2 |6 B$ m# |4 D. f: `0 h
  [
1 N+ d: ~# `* w4 ?4 h  V+ I3 x9 ]    user-message (word "There are too many cars for the amount of "
$ t8 s4 J& L/ j4 U                       "road.  Either increase the amount of roads "1 {8 I8 m% m* k
                       "by increasing the GRID-SIZE-X or "% \) J# M  g+ X# P# t
                       "GRID-SIZE-Y sliders, or decrease the "
" R! O" p) A% [                       "number of cars by lowering the NUMBER slider.\n"
; n$ j( h) y3 B9 ^                       "The setup has stopped.")9 @5 k+ h1 G! [# S* _8 l$ u
    stop& s6 y7 v* W4 K6 S; n
  ]5 V; v4 o2 v2 R. y$ y& z
% {- l+ L* U9 \! F0 D/ J
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color# @& T8 Z" c) S6 \2 Q
  crt num-cars
5 j# n" P6 D+ @7 c& p0 W, @" ]  [0 L. Z9 g* i/ d; a% \" P, s
    setup-cars
( M( H8 {  a+ A) Q4 \6 i. U! K    set-car-color
6 p1 i! t# x6 F    record-data
/ C7 L9 `; @' R$ V  ]
/ @8 Q. q! V7 g: ~( F9 z3 R; F/ E1 }1 k( Y, w; t) P7 z
  ;; give the turtles an initial speed: r6 F+ I3 V1 ~. H0 q) D+ a0 }
  ask turtles [ set-car-speed ], |; `. f4 _3 Q# C, B6 P9 c, Q% m

. Y7 H& l+ G+ m- X8 i) e  reset-ticks
& o  d' v  O, N/ k& A; yend
' }$ m0 |/ k$ ^8 J3 m4 F  X% L* i4 Y
;; Initialize the global variables to appropriate values
: m4 e. `& d% P9 z& J' Gto setup-globals' K* T7 y& S; [) \4 k, o
  set current-light nobody ;; just for now, since there are no lights yet
. `6 B2 b- e3 a  set phase 0
5 Y7 R$ c+ }! l3 P! W1 Z( ?* m  set num-cars-stopped 0
( [& a& O( Z; A* I; e: Y* D  set grid-x-inc world-width / grid-size-x
. F3 P* P0 _) r6 x4 r5 s  set grid-y-inc world-height / grid-size-y$ t% H7 J' z% P8 E: T# F
/ o# C2 @6 ~" L7 X: T
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% p) n+ r3 a$ y$ e* N, v4 L4 ]5 R/ M  set acceleration 0.0991 W3 c( D& X4 ]2 [) e
end
+ U  r$ X$ O, j  V" U6 l
6 q" G4 B! `6 v6 D) T  D;; Make the patches have appropriate colors, set up the roads and intersections agentsets,6 f, ~! j. P  @
;; and initialize the traffic lights to one setting( _2 @. r$ R! }( L! }5 A8 z# S" g' x$ R: W
to setup-patches
$ E6 \2 z- E7 g" o  ;; initialize the patch-owned variables and color the patches to a base-color5 }; {3 }- D+ d* K2 l5 D+ k6 M
  ask patches
0 W- K" o2 b5 M0 k+ {  [
8 ?1 r) I& c. X& j9 N/ a$ _    set intersection? false# v! Y, ?, t4 d3 k
    set auto? false
3 c- M) I6 {* h+ j+ [: y    set green-light-up? true
; Q4 p# J& q3 H" |4 d% ~7 c% N5 F4 s& ~    set my-row -1/ e0 t0 ?- F) ]+ y+ I, ]7 c& N  E! P
    set my-column -1
- j5 F  i% v- e. E, _    set my-phase -1( [; V1 x, j4 q. z& R0 S+ l" l9 @
    set pcolor brown + 3
5 o* H7 L3 S5 h  ]
0 p3 E2 o0 G' P% U* H
+ I/ _0 }6 V. H1 V" S+ J  ;; initialize the global variables that hold patch agentsets5 B# X, P  S3 @; p& Q
  set roads patches with
' Z* K. n& e2 x' f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 j7 K- B! `8 K" s    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 E; [2 p! J' b6 G
  set intersections roads with, B7 ^+ J! p8 n( e0 R# M5 N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
3 ^4 w% D6 x- C% l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. G) M8 X+ d1 U' D7 v, P' \% }5 K! A: `5 y! V
  ask roads [ set pcolor white ]
+ D( T3 T  |3 \8 Q( @    setup-intersections) c& _( w# ?7 C2 n2 W
end
8 T- m- i8 r5 c5 d% e8 M3 W其中定义道路的句子,如下所示,是什么意思啊?
5 c7 s8 }6 u1 _# T, C set roads patches with
9 H) j, Y5 v# u/ v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% J& ~: Q( M( X9 H7 F3 x. v$ x
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 t4 y! H( _' F, q4 a9 W, u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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