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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。* R2 O1 ?3 d- t; p4 o  S
netlogo自带的social science--traffic grid这一例子当中,
. ~) }1 _! D2 e2 h# Vglobals
' I6 \  f% R/ W9 z* [$ `( n4 _1 N[
$ ~6 D! T/ Q: {" l4 e7 \& r) F. n0 [  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 q3 b6 l1 E8 M! w9 ?& T
  grid-y-inc               ;; the amount of patches in between two roads in the y direction- D1 {$ W0 N4 {8 c
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
( V! G  M" n) R5 T; M/ z                           ;; it is to accelerate or decelerate
0 e2 k* J0 ?0 y; `) V5 X; u- j  phase                    ;; keeps track of the phase
6 `7 ~  J8 g( h7 ]- y* k  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
0 s, C: {& O1 K4 S/ e8 j& w  current-light            ;; the currently selected light% \) Q" Y, l! e
9 a* p; o, K! U6 P" l9 ?- f5 G
  ;; patch agentsets
$ Z! Y6 i0 A# n  intersections ;; agentset containing the patches that are intersections
' G* W/ x2 a9 u, d4 t6 k# D5 b% w  roads         ;; agentset containing the patches that are roads. p5 b7 y9 {1 w* }6 `
]
) i5 C2 ?$ f0 U7 }0 ^* o1 C
; I5 ^5 S+ `8 G& Uturtles-own
4 u* u9 K/ i6 O, [' u7 I[6 a/ X, |/ I! k% `# w1 Z1 Y
  speed     ;; the speed of the turtle
. v* Q8 f9 U9 ]1 b# `* Z1 x- l, ^  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 g/ B! v. f5 s: i' W. `
  wait-time ;; the amount of time since the last time a turtle has moved/ U& l2 h2 r* K+ W
]) V' y& R- {8 U4 k& j5 @
' ]0 {% L( Z2 c0 M: }
patches-own
8 r8 E+ E) S2 z- [) K0 t[
. _4 g9 L* H5 }3 {  intersection?   ;; true if the patch is at the intersection of two roads
8 F4 y$ z2 c4 g7 A+ l  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.. j4 e0 D  k2 u: p% H' T3 j
                  ;; false for a non-intersection patches.
3 q+ C2 B( T" n- T. L1 n* X  my-row          ;; the row of the intersection counting from the upper left corner of the
# B  G: Z9 t& D9 K* A; U- M8 |( \                  ;; world.  -1 for non-intersection patches.
% L, x) U4 b" ]1 x% g  J  my-column       ;; the column of the intersection counting from the upper left corner of the) c: h- P* s3 W8 h, u
                  ;; world.  -1 for non-intersection patches.
! U3 L0 _' p+ E/ {& G% q  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.8 p* `) X, B+ \1 a! ^8 z4 h* \
  auto?           ;; whether or not this intersection will switch automatically.
% Y& x# R& I' H% A2 J, e& W                  ;; false for non-intersection patches.2 p7 p% e# o& J2 p, B4 A
]- k6 c- i# |6 L% {6 ^

$ m, ]. k( g( h# Y4 c9 W* A6 O- A
1 x/ E- b' u1 a9 M  W" ~3 i/ X;;;;;;;;;;;;;;;;;;;;;;
: m" z5 M8 Z$ x( _9 f# C) u;; Setup Procedures ;;+ }" g# ]3 v8 d$ G( Y* q3 \( _6 \: ~
;;;;;;;;;;;;;;;;;;;;;;
* Z0 ^7 i  J! Y% b( ~( s7 }) {
' Y( }3 u' G0 E: Y& o0 ^! S;; Initialize the display by giving the global and patch variables initial values.
" _; e, ]+ f9 z. j$ r* o;; Create num-cars of turtles if there are enough road patches for one turtle to
% Z( L1 K$ F) `2 p0 e2 L;; be created per road patch. Set up the plots.8 |+ `2 d$ X' s7 k/ j! P) k
to setup
9 V5 c  H$ b6 s7 X6 f# Z  ca% G' x9 I% r- A& t; p) d
  setup-globals
/ K% h7 C  s) J6 ^9 k# I2 J1 k+ x2 F
  ;; First we ask the patches to draw themselves and set up a few variables1 h4 y4 C  e3 |9 q0 P& q; ^
  setup-patches
# e  Q' c8 j( {) j: j  make-current one-of intersections8 N' G% f) }# z3 p4 y
  label-current2 g1 ~, l4 r  i! m" w
* ]0 ?, y3 j( \+ E3 l* N
  set-default-shape turtles "car") _6 o) ?4 j9 G
3 f2 W  `, @2 y$ }
  if (num-cars > count roads)$ |0 G, ?& r2 j6 i) f4 _+ Q
  [
. a% q- W* U  {! z, G9 D    user-message (word "There are too many cars for the amount of "; V  c: a( o, p, K5 O
                       "road.  Either increase the amount of roads "
( u0 j6 }  V' C( f( S8 P2 q7 M                       "by increasing the GRID-SIZE-X or "6 G. g) o  b3 I0 w5 W
                       "GRID-SIZE-Y sliders, or decrease the "
: y6 q+ R& T( V3 U                       "number of cars by lowering the NUMBER slider.\n"
! r& M# ^$ F& \! f: C$ R2 S                       "The setup has stopped.")/ q6 L/ |( s6 r# Y; U
    stop
2 \+ }8 `  [/ @, h# _2 _1 w( b  ]5 m7 a5 r0 n. _" `) U' t  u% K
" B; ~7 ?7 g! ~+ f/ ^7 ]
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
( ~# `2 g! I# v8 r& {5 h4 @  crt num-cars
* ?7 }) I3 T+ z  [
- D9 N- Q' L4 K: v- C; H    setup-cars, Q2 ?1 f. f, M6 T
    set-car-color9 F. w  Y5 J' L1 @& `4 |1 |
    record-data7 u$ h; d) N6 c" d  r2 B
  ]" e! J) r+ i. r

5 c  N- {( o$ Q3 i9 M& F8 `" n  ;; give the turtles an initial speed/ r$ [# ?' D& c! z# }
  ask turtles [ set-car-speed ]
$ P: i' H' g( k& y, @- T0 E+ t* k: J. x0 Y( A
  reset-ticks" m- @8 \6 i5 n
end
& j' ]0 v7 y9 j5 G( }
( K! {6 {3 \  |9 c;; Initialize the global variables to appropriate values
5 j( u0 @4 L3 o4 }" v3 Z, |5 tto setup-globals
# \8 c5 ?, _* _1 A  j" S- n/ @  set current-light nobody ;; just for now, since there are no lights yet; {% A; `  L, Z* e1 O! d; K
  set phase 0/ w  t/ d- b1 t1 W6 d
  set num-cars-stopped 0# t9 l( a4 ~- I" K" t, p1 v
  set grid-x-inc world-width / grid-size-x. E( }/ u' S% [8 z' ^- H
  set grid-y-inc world-height / grid-size-y1 |, g  i2 _0 Q
/ A  t0 E$ A: B: g! y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
* q7 N! w/ `5 o2 b: b" x4 Z  set acceleration 0.099
4 q, i9 q0 `# C& ~0 O. s) rend
) P3 i( F1 s4 k% k
! c% o* k* n( V: T1 C" E8 t;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 }5 x7 J5 J6 J3 v;; and initialize the traffic lights to one setting" B( }8 q# Y+ h7 C
to setup-patches
) s- \$ w" k& m. C# Z& w" q  ;; initialize the patch-owned variables and color the patches to a base-color& h, V6 |( a1 _, D5 P$ D5 y0 i  ?' h# o
  ask patches
: _( h* A: L- w7 \/ F# s/ `5 m  [
: @- X6 w2 [) @0 }9 B% o& L    set intersection? false
0 U# j  O, H% w: o9 E& R0 {    set auto? false
7 }& }, [$ o/ R+ O; ~- ?7 A( X    set green-light-up? true
; g% ~: S5 H9 U    set my-row -1
8 E; \, D' v3 \) E    set my-column -1
8 m, i. e' g4 f+ q; h" E% J    set my-phase -1
- S0 s) ]: w, ^2 `; x9 Q' b    set pcolor brown + 3& `, }+ j6 F' ?) i2 `
  ]1 Q/ [# r8 Z/ J( O4 D
% ?$ ?: B8 N2 h1 i; l, S# R" U
  ;; initialize the global variables that hold patch agentsets5 `" F2 J- \6 H, U; W
  set roads patches with2 w: z, X5 \5 {$ L6 X" g; T+ a5 P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) T) i% e2 j! Q  @. c0 B1 }
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 h. ~0 b" ]' ]$ h  set intersections roads with: s, R& ?- e  g  B1 ?
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
; r% l& D: N  V    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, ^$ f1 H) `8 G. G1 a
5 h8 H1 w( X4 w% [4 Y# v' K! s  ask roads [ set pcolor white ]
6 C" N* S* {; }. k7 h: p, X) O& i7 c. ]    setup-intersections4 _) S5 x6 o. k/ m$ y6 X
end- l, u' \+ o, M% @' s! F$ e/ p
其中定义道路的句子,如下所示,是什么意思啊?
" G' m$ f3 A1 k% H3 ^2 u set roads patches with
7 \3 z) Q& z, l3 K4 o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& @& s. V. I. T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 p4 A. `  e" r" v( V$ 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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