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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。
: Q. L: k$ V% _$ j% Unetlogo自带的social science--traffic grid这一例子当中,% Y$ T/ [6 O' g' F
globals7 s  r8 C3 E! L7 U0 [
[3 T. J7 H/ ^( a( U5 }$ L
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
0 _0 S  ]# A: o# h, T5 q  grid-y-inc               ;; the amount of patches in between two roads in the y direction8 g2 @8 L5 `. K. K
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if0 B. w  Q) R  G: w( Q) [
                           ;; it is to accelerate or decelerate. m2 q" N* F* N7 N
  phase                    ;; keeps track of the phase& N  P: [1 A+ w* e% ]& S( P6 a
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ E- U% ^  J5 Q$ s# h  current-light            ;; the currently selected light
; u* \' B: b6 u' D$ N
8 Z3 K. f7 i* f7 p6 ?  ;; patch agentsets
- x' b- M7 m! ^5 \8 T0 c  intersections ;; agentset containing the patches that are intersections
" {( [5 Q6 @2 ]1 R$ L5 y  roads         ;; agentset containing the patches that are roads! k  s/ f$ W9 x; |$ C7 o  _3 u
]
. e2 Q; S' r: J' w6 g) _- n7 K! L. @# _2 B, R$ \
turtles-own
4 `9 s+ Q) I( D[
' l; |3 W& ?- }/ M9 o  speed     ;; the speed of the turtle
8 ~  d( y3 R8 N8 |4 E  up-car?   ;; true if the turtle moves downwards and false if it moves to the right6 D' R# L; z0 ^4 i# t* S2 y3 G
  wait-time ;; the amount of time since the last time a turtle has moved5 k' e, z! c- C2 X$ C; I5 V
]
' ?( q) W5 f8 a1 e+ _
, s; t3 C) r3 z$ B' upatches-own$ e, N6 o3 D4 I' U/ P2 p9 {+ @
[, `% R, Y9 S4 g3 U
  intersection?   ;; true if the patch is at the intersection of two roads
/ Y; {+ @' f% z1 m  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
' l, ]0 p3 N/ u9 B' }2 d                  ;; false for a non-intersection patches.
* j; E/ v1 ^/ F% ^; s( U8 q  my-row          ;; the row of the intersection counting from the upper left corner of the
' B) N1 L) u  l2 H& g5 f                  ;; world.  -1 for non-intersection patches.# D! d; b) H$ @; {/ ?
  my-column       ;; the column of the intersection counting from the upper left corner of the
7 Z! C, U& A3 C4 `/ ?- k! p# |+ a% N                  ;; world.  -1 for non-intersection patches.7 y. h) }2 F, ?' j' ?6 z
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
2 s; ?& I$ J. E) R  x4 e) ~& f  auto?           ;; whether or not this intersection will switch automatically.3 N2 J  r# Z( t5 [0 U2 g, [0 p
                  ;; false for non-intersection patches.% y# X" d/ L/ G
]
: r) b3 @% ~4 Q$ \) [' ?% z
9 x2 C. S+ O; e: x+ o
) N8 B% f& E- k- G! |( d: z8 ^2 i;;;;;;;;;;;;;;;;;;;;;;
% h9 ^7 `0 U6 t+ L  f  }  m0 z" J;; Setup Procedures ;;
* J" x$ m* n7 ], j+ N1 S3 Y;;;;;;;;;;;;;;;;;;;;;;
( a0 `( D- H8 f& P, w' e6 ~; y5 F
/ R' Z6 }( P5 O; T5 S;; Initialize the display by giving the global and patch variables initial values.8 f) V/ w2 R$ F) t
;; Create num-cars of turtles if there are enough road patches for one turtle to
/ [7 K; K6 x% t* G& m. d# E;; be created per road patch. Set up the plots.. [/ N: w7 ]( Q# A7 p% _, I) o; a
to setup
. z3 p, m2 O8 }3 E4 v: N4 l& [; k# G1 m  ca. U7 A* t8 {' H5 J! h- y$ x% }
  setup-globals
( U7 p9 R+ `; L+ [# z; x8 M: M% X/ o0 K% c
  ;; First we ask the patches to draw themselves and set up a few variables
" r* @9 b: w2 G  setup-patches
9 Q0 N; Q' O% s: q  make-current one-of intersections5 x) q& U) E# ^+ ^" c. a
  label-current/ h1 p6 ~2 c2 G( W4 {
; \% @. _  t( T5 i" V
  set-default-shape turtles "car"
7 l, n% g9 F; h! Y3 [% D7 \5 C, g4 X+ x# q; r" C% v- [
  if (num-cars > count roads)* y1 R1 A( ^8 w' T% B
  [2 B; F' H$ _! u% i. A6 E' o' X. V
    user-message (word "There are too many cars for the amount of "
2 y8 G1 p6 P' _                       "road.  Either increase the amount of roads "
* J! V& c! M! ]6 h% z% e) E                       "by increasing the GRID-SIZE-X or "4 E  p6 ?; c7 {; w4 B( R
                       "GRID-SIZE-Y sliders, or decrease the "
4 X' Q( X. T; R' \                       "number of cars by lowering the NUMBER slider.\n"
' J4 ?) l2 D6 u4 V9 Y* {                       "The setup has stopped.")
6 j, V- @2 z, m* R    stop
6 Q2 \8 d3 P3 k2 L  ]3 P: v8 q8 R4 u

% E! T. D. N9 q/ `7 n, f; u  h  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color( q! \- G$ [1 e- C  V0 R1 D# N
  crt num-cars
2 P/ j3 G: a1 ~$ B* n+ S' C  [$ J2 i& e# ?" Y0 f9 G
    setup-cars
2 q( j9 J+ n3 v- N( _    set-car-color
4 r8 v' _& p; v  M; a) z: W) C    record-data' I3 H( \1 n7 B/ p( m  v1 @
  ]' \9 s$ }2 I" f# X$ w8 ?+ L

$ \8 `) G0 F: M$ E9 T  ;; give the turtles an initial speed
% G4 L# ]. x5 L% K% N  ask turtles [ set-car-speed ]
% o3 A! H$ r- m1 G0 x4 [0 P) N% k. y
  reset-ticks( T! B8 z7 u; {( z7 {0 ]
end! @0 k+ f& X+ u# _0 ?
* ], _. g1 o8 t5 `" \2 [" x7 u
;; Initialize the global variables to appropriate values
; x5 S  J+ v$ C" {. N; o4 Yto setup-globals
( e: c) D; P9 L1 @. t  set current-light nobody ;; just for now, since there are no lights yet
! p& ~" s2 e2 D- f. |; e6 C' b  set phase 0* c( K+ V$ P& }
  set num-cars-stopped 0# Z) b4 i( @: m# `; ^5 d9 Y
  set grid-x-inc world-width / grid-size-x5 J# Q0 d) q3 V$ v3 _
  set grid-y-inc world-height / grid-size-y/ ?3 \# N4 g. ?& t, o5 ^
6 ?( r5 o/ B. }: L' l
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
: W  s$ [8 o% q# C- x) ~! U  set acceleration 0.099
# m/ @3 k8 P" n" @6 C/ wend: _% i$ M6 M6 S$ R
. h- x- M8 G: X5 c
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,+ t, f+ h' {8 y. [1 x! @
;; and initialize the traffic lights to one setting
: U" c$ M- q; g# r3 F$ V4 D( H, Hto setup-patches
4 p2 _) r+ n( d' D; R, K4 f* Y4 p* O  ;; initialize the patch-owned variables and color the patches to a base-color- X+ A6 a0 u5 }+ C
  ask patches
8 `5 o! R6 w! s0 }. i. `7 s  [
' R+ \( t4 @$ d. W    set intersection? false3 \3 \% ^4 J  y6 F( V8 a
    set auto? false
2 M  \, f+ J* k) y    set green-light-up? true) L& _  m1 `2 c& @8 U+ @
    set my-row -1* K2 X& a; N1 Q( x3 S/ J
    set my-column -1
5 Z- ?8 w3 F" o7 ~' v0 [6 L    set my-phase -1$ p- o  w% Q) }* V1 f3 H5 x3 N
    set pcolor brown + 3& ]" n1 t4 U$ w
  ]( h. E5 N/ i% p$ `" b" [* B8 o
8 y6 ^0 U/ ~: r  e3 w$ h7 |
  ;; initialize the global variables that hold patch agentsets
7 C8 O- X& G7 g( b0 b# r2 i  set roads patches with+ s2 E& M: ^0 s2 \2 M8 x3 J- G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- R. g* _+ u4 Q7 T+ i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ x4 k' H: U6 z4 T  Q- U- X  set intersections roads with: Y! `; T1 U( C5 j' U1 L7 R, }
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and9 e: G: N+ R, j/ X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 r7 l0 M- G' R! P1 m4 R  q0 K
& H/ M% m! }) K4 V
  ask roads [ set pcolor white ]. x. y* F7 F4 i0 M$ [8 q
    setup-intersections8 n8 T$ K( r% |: l4 X/ E$ D
end# o& M; D' u3 d* H  @$ ]
其中定义道路的句子,如下所示,是什么意思啊?
4 t+ q* I' T& C5 e set roads patches with
9 g4 {8 `% D+ P# {( C    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  y$ J# }4 n/ C3 \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ J4 o8 w+ T( z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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