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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。
' I( N6 G3 @0 H% k! b1 Inetlogo自带的social science--traffic grid这一例子当中,
- V. Z7 y$ k# m+ Zglobals7 z2 V5 W7 Z  L& J% }3 s8 K! H
[
; z% Q/ y# r1 L$ M. o4 ^  grid-x-inc               ;; the amount of patches in between two roads in the x direction
2 M+ E3 u7 g: P* o: }  grid-y-inc               ;; the amount of patches in between two roads in the y direction. x% L* I. j! V! N) M9 _6 `' e4 S' m: t
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
* N# F* G/ c" W4 V- L& d& P8 N; u2 g                           ;; it is to accelerate or decelerate
4 V' O% a+ U; v+ J4 M7 G8 `  phase                    ;; keeps track of the phase, Z! _3 b! F* Q5 n9 \: c
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure1 s" p( L) z6 b, v( v+ @+ l9 c
  current-light            ;; the currently selected light8 C$ u, e% [" M5 I9 e# U

3 K; C5 ^; Y' [: q2 d9 U1 |% t; ~  ;; patch agentsets
: p" ]- N+ Q9 U2 G9 g  intersections ;; agentset containing the patches that are intersections. y5 R& o$ H2 ~1 `3 @' Y* Y
  roads         ;; agentset containing the patches that are roads$ D: g( _3 N+ d" A3 w
]/ i+ z3 m% E  F: P4 j; F# z# [7 \
# {  \, G2 k0 {. e
turtles-own' `5 u/ W+ p9 Z" C1 G# J
[
  M5 \% }' w6 m; |. B  _  speed     ;; the speed of the turtle: m; h1 E$ `0 J: o7 S! W
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
$ ~9 l- Q) Y3 Y& E  wait-time ;; the amount of time since the last time a turtle has moved# ]9 q; h0 B( ~  i, j, A
]$ [" b8 K7 h, A# v! ]0 T+ G" _
( ~& I# {+ F6 N& T7 r* I: x7 Y; N
patches-own  \$ g: Y1 w. t. w1 w) Z
[# F, S8 ?( v/ R
  intersection?   ;; true if the patch is at the intersection of two roads
/ O, `& B2 P! u) ]$ e  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
: X% ]4 z$ L2 }( ?5 @" ]6 c# j$ R3 Z                  ;; false for a non-intersection patches.
& B: `$ O/ r0 U/ ^4 w1 H$ r  my-row          ;; the row of the intersection counting from the upper left corner of the& f3 @0 c$ a& x! H" f4 M7 o
                  ;; world.  -1 for non-intersection patches.4 t" g6 L2 o2 M  f! d& D
  my-column       ;; the column of the intersection counting from the upper left corner of the
. G) u9 F' L7 W                  ;; world.  -1 for non-intersection patches.
% K/ a: w1 p$ Z. V$ ]& e) e* Y3 u  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
5 s6 e! C! n' A9 W( \6 a  auto?           ;; whether or not this intersection will switch automatically.
5 |6 c- B4 q' U3 R  q7 x# y. m: A                  ;; false for non-intersection patches.2 H7 U4 @, v% J
]$ M- m- @6 L/ ]$ ^* H7 A8 v

9 k9 V' D+ ]9 {) A: ~% x+ Z7 N" N0 [7 @4 ^
;;;;;;;;;;;;;;;;;;;;;;
0 F6 Q0 m# e1 i) M* O;; Setup Procedures ;;# n% P: m# {, R" k1 g) ~
;;;;;;;;;;;;;;;;;;;;;;; t# P" n) j0 q

7 q% d& Z6 `( z: S8 k;; Initialize the display by giving the global and patch variables initial values.
5 O, C$ o* U5 I: q2 t' A;; Create num-cars of turtles if there are enough road patches for one turtle to
5 ?/ t9 I6 f$ h& u+ F3 q;; be created per road patch. Set up the plots.
# b8 K. Q0 N/ x" Y  i. vto setup
. l, W5 U+ v# S- c  y/ r) y  ca  @6 N$ l, M: C6 z4 ~$ I1 @
  setup-globals
( `9 i' D  ~4 V  f2 n2 C2 K' R; f1 {% w
  ;; First we ask the patches to draw themselves and set up a few variables
6 O. `( J" D% e5 p  setup-patches
! P, v- [& B; k# W0 h  make-current one-of intersections
, s9 j( z) e2 C! S# j+ M2 j' h  label-current
! u* p* u0 _3 Y0 b5 s* }
' N- j* I' d9 k/ R, n  set-default-shape turtles "car"
- p4 t9 I) y% _# \4 {; ^; y- t2 g; T# H. h, I& e
  if (num-cars > count roads)
  u# u6 X8 s+ N  m' I  [2 J! Q6 d2 y; ?- ?" q
    user-message (word "There are too many cars for the amount of "
" C6 l+ I) M" t% g8 F$ z                       "road.  Either increase the amount of roads "4 G0 |: g3 T3 C, ]
                       "by increasing the GRID-SIZE-X or "
# p: B- Y( d4 ]' M, y                       "GRID-SIZE-Y sliders, or decrease the "4 z1 K) `* n# ~3 R) h5 R
                       "number of cars by lowering the NUMBER slider.\n"
5 @# \, N' n8 Y                       "The setup has stopped.")- x( G3 T  M3 w4 n) ]8 ^& v
    stop
, j3 n$ C  U/ \; n  ]( ?& t& H. k; t, H& U" x( s
2 x' A7 H! y4 t; l) g9 T% w
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
- i5 c$ X8 @' {9 L! B% Y  crt num-cars8 |0 ~# Q5 v+ z# }
  [" q& \% g& z" t1 G, {# }
    setup-cars% ]/ {  y! L+ v
    set-car-color8 S( s# {0 o" ^+ i% R/ f
    record-data
( O% [' b9 d9 C: k7 Y6 D* ~  ]( G/ K' M$ ]( l6 _) w+ l

' B- |: S/ X  i  ;; give the turtles an initial speed$ U' \: `+ [  H( Z
  ask turtles [ set-car-speed ]
' I# j4 {  ?# J- _/ P, U2 P
; _- c3 s5 h2 v9 q5 F& F2 P  reset-ticks7 x' }* Z; }2 p& B2 W7 E) J' G
end6 i! S2 J' C9 N* s

* I; _" N$ M2 B  A. g1 Q2 U;; Initialize the global variables to appropriate values  A& ~) R- e& K; ^0 r( F! H
to setup-globals# C5 h8 ~( ^& J0 N
  set current-light nobody ;; just for now, since there are no lights yet# g9 f# g, o8 y: U7 L8 H1 w8 e
  set phase 05 v$ M3 {1 q' l$ ~2 _' J+ z+ i2 i
  set num-cars-stopped 0# h* v" W( k/ w9 Y% W, e. G
  set grid-x-inc world-width / grid-size-x
) _' |0 r2 n5 ?4 o6 S* ~  set grid-y-inc world-height / grid-size-y
) b) |# _: Y' j8 _7 U- I0 e
- g' K' S, l: @: b% ~. C  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) {& S2 t6 [0 w2 g. z% G$ U
  set acceleration 0.099
) ~2 L; V- D$ D8 Jend
: a% q& ?2 B, [- V$ Q& k" G! U7 b% }. c1 t6 D( W) M% }
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
6 C6 D: W$ p0 Y;; and initialize the traffic lights to one setting; n7 u3 \. Z* Q; y7 f
to setup-patches& V5 f( N4 M! N
  ;; initialize the patch-owned variables and color the patches to a base-color
7 N: C. k; {+ i6 m- p! V/ x( ~  ask patches7 M, ?8 Q6 y: }% d
  [/ d4 O3 O, c4 d& H& @
    set intersection? false
3 Q9 x# |4 S" g& T    set auto? false& _6 l' B5 v& f- x
    set green-light-up? true7 W  H" |% D0 V3 [- u
    set my-row -1
1 q$ k" i/ H! C9 P1 q    set my-column -1. @7 _# x9 L% \& L8 g2 s3 }
    set my-phase -1
" ^& X& m4 ?8 O) B: A& n    set pcolor brown + 3- L* A( }% S; F, J/ I) \
  ]/ ~" K2 N8 n1 h  N2 r/ x7 v% f! k  e

( ~7 \; A" @, ]$ D. h0 j  I  ;; initialize the global variables that hold patch agentsets# _  h5 G: c0 h! L9 F
  set roads patches with
0 j; E! [) [7 X, z* ]4 l% Z( @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 C) A! c) v! I6 m, L. U6 A    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 m+ A% h# o9 O) d5 K% a, a  set intersections roads with
1 @: v7 M1 j  A& }; A& C  s# m& n    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and! t  k5 {% E$ ?( d: o; }/ e$ Q& S; q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ n: k/ Q/ b7 u2 v6 ~/ v) u
2 K& ^0 q( y% u# x* k7 H5 l' M4 W
  ask roads [ set pcolor white ]
  Z2 o$ v- {; B. k1 m    setup-intersections) M2 ?! j. M# `3 F4 j
end+ j! o, H' c& \; Z+ |
其中定义道路的句子,如下所示,是什么意思啊?
7 G! N$ j4 o6 q, ?8 [ set roads patches with
& Y& {, \' M+ v3 M    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. Q% \9 G1 C) X& N: x, Y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 A* Y9 q( |2 q( 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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