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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。
; s9 q3 ?8 @: bnetlogo自带的social science--traffic grid这一例子当中,  T# t0 k* v$ C( \8 ?: j
globals
0 \. S2 M) ^9 p, W/ N" _- @8 z[( e) q4 O  T2 B/ h$ Z: {$ ^- s
  grid-x-inc               ;; the amount of patches in between two roads in the x direction  O# O; D* g- J  I
  grid-y-inc               ;; the amount of patches in between two roads in the y direction$ U& n. Y0 e' G" H
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
# ?7 D: j* b  v                           ;; it is to accelerate or decelerate
5 h3 K4 ~: y. B7 x4 U  phase                    ;; keeps track of the phase
4 h" w7 t! p* r" L2 _8 a4 |  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure( Z! \" q: w! u* X0 o% n3 n
  current-light            ;; the currently selected light# [- }/ c$ e! N3 t# U# C; ?

  g" b# d' X: f' R. Q/ w0 j  ;; patch agentsets* f! j3 d4 n/ [. r
  intersections ;; agentset containing the patches that are intersections
: n/ j! Q+ P+ j- J  roads         ;; agentset containing the patches that are roads
0 ?+ y: R" Z0 |]4 K; e  n9 {0 F) G

# a3 t4 o7 m, K" e, }7 L1 l" @3 eturtles-own
" z4 Q) {3 b, C( m[, L7 V7 E8 C% @; Z: f5 ~& z! y
  speed     ;; the speed of the turtle
- Q: E" u0 z2 z7 j' g; \  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 b+ Y0 ~' V0 u5 i* J% D7 v
  wait-time ;; the amount of time since the last time a turtle has moved
/ b# B' {' v4 X6 O! n]$ l, v( c! q6 _

) w/ S2 g2 I5 X9 S1 E( @8 mpatches-own! B$ L( j' }) W( K
[1 D& Q1 v+ ~, j; c1 t& l; X
  intersection?   ;; true if the patch is at the intersection of two roads
! P0 `- j5 H  f  H* r) y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
. V6 E) ^3 ]) T2 n+ W                  ;; false for a non-intersection patches.8 y$ |! t0 }7 }9 {! b
  my-row          ;; the row of the intersection counting from the upper left corner of the, y6 X9 q- L+ ]: E; o( [
                  ;; world.  -1 for non-intersection patches.
; A3 w7 K# s! e2 c0 P& X  my-column       ;; the column of the intersection counting from the upper left corner of the
/ ^7 H7 n& n/ n! y8 N, Q0 r- M9 v                  ;; world.  -1 for non-intersection patches.
0 N7 d; Q* l- H  j/ d) n  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
' H, J' `) e0 F" j3 Q; B  auto?           ;; whether or not this intersection will switch automatically.
/ M5 ]4 _. B9 C  K6 g                  ;; false for non-intersection patches.
" b( o  {* s. L, R- `! m]
: c0 X6 N+ z# ~% K  A4 p5 g" i& e4 d; I) r* z, c9 B
( m* i# G. m1 q2 |: R+ \- f; g
;;;;;;;;;;;;;;;;;;;;;;) B* j# ]& I1 D* v
;; Setup Procedures ;;" W' r! \; z) B7 U
;;;;;;;;;;;;;;;;;;;;;;+ R# v( X8 N( h
% j8 r. A2 ^3 O7 ~4 }7 q1 E
;; Initialize the display by giving the global and patch variables initial values.9 N1 f2 h7 I# z1 K& P
;; Create num-cars of turtles if there are enough road patches for one turtle to
6 f  P# l! W3 l# Y% `;; be created per road patch. Set up the plots.9 h: J# Q) O4 s6 s7 C
to setup
4 |) Y' q1 {0 W/ \/ r) f3 i  ca! S. Y* B, ~, x1 h$ [2 R
  setup-globals
9 U2 R) K$ t. D3 `4 q. O2 Z9 J* E, L9 f$ v' p
  ;; First we ask the patches to draw themselves and set up a few variables' Q, v3 k! i$ {. _+ m1 j6 D% d! O9 |
  setup-patches
! }" ~# y9 Z7 q* l! E8 S  make-current one-of intersections* Y: F& c: \8 B3 w" d, k
  label-current
  k9 ?" k0 ], [5 f! F" X) S7 T" e6 Q3 j( A, A- q
  set-default-shape turtles "car"
7 z8 O: t3 p" a) m& ^( Z7 l+ q& K" F6 q  X
  if (num-cars > count roads)
9 P+ }9 r. I0 I5 }  [
9 n5 F& G: l  H  o! O* s4 d, W% l    user-message (word "There are too many cars for the amount of "
% z1 \, d2 l2 }                       "road.  Either increase the amount of roads ", N! o4 J4 D1 P) l9 d. O( ^
                       "by increasing the GRID-SIZE-X or "
8 @; l. D$ Z0 p                       "GRID-SIZE-Y sliders, or decrease the "/ c; E. B9 i) p2 K1 A
                       "number of cars by lowering the NUMBER slider.\n"
3 h& l# k1 i# R6 a( T; o# {                       "The setup has stopped.")! H! x: o3 y$ S8 T  k
    stop
- A- V$ w0 N/ T' j7 l3 Q  ]: F3 X1 I" P; R2 C1 H- E7 n8 p
: e; p; d! f! G' X! _- A1 ^' \& J+ c
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color7 k( I4 V) o2 S7 C4 z7 f" ^
  crt num-cars
. a4 f6 K" [" M1 J! o; J/ N& ?  [& }: d1 E, E1 |; i/ p& Y
    setup-cars' w2 [% A& q1 ]6 e" D4 K3 j: |
    set-car-color
- E, b1 [7 l" {5 I. g; X    record-data
  Q* e) v; s& {$ F. s8 V$ p& l  ]- v+ I  n, T. G; s) a2 T4 v  ^% V  P

& W7 |! c3 y0 b3 w  ;; give the turtles an initial speed8 y  j$ ?  }8 p
  ask turtles [ set-car-speed ]/ z# u3 |4 g5 r$ G5 J

0 J  w) O) }0 E$ H, \  reset-ticks. o9 \5 ^" x  J3 d2 e( h  t
end
6 ~: p9 x/ S; L- W7 P
* E% ]! x# o+ h: z* n;; Initialize the global variables to appropriate values
' L; U& Q7 [" m8 W1 |( \to setup-globals3 j! Z' l; H# o5 r9 E" c6 B8 }
  set current-light nobody ;; just for now, since there are no lights yet! X8 ~3 D$ M6 {* w( C
  set phase 0; J* n- D! x2 `- }; W. m2 C7 W! @
  set num-cars-stopped 0
  m. q( L) V, s% r$ V  set grid-x-inc world-width / grid-size-x& R8 x$ w7 m* P0 d' N, Z
  set grid-y-inc world-height / grid-size-y7 L5 N. q6 C, R
1 L% C! e+ G1 M& F: p7 m- O6 u+ }
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
. y, Z4 v8 ?* A9 R  set acceleration 0.099
3 X0 V! T, i8 R8 R, p3 Z# }end6 t0 a# A- x& ~  n( _& F: V' i
1 \+ r! ]" x! @4 n& C' T) I! y
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
3 ]9 F8 b  G/ a( K;; and initialize the traffic lights to one setting
" H6 z0 ~) o# ]8 b- ^9 |" xto setup-patches
+ V: \" O& i" E, o  ;; initialize the patch-owned variables and color the patches to a base-color1 J0 [2 `6 O5 u9 Q5 N* V5 N
  ask patches9 R4 C4 ~" d5 e3 ?; Q7 s. X
  [, g6 }% ]9 U* W/ U) N
    set intersection? false8 b" S( E/ J- i0 o/ Z
    set auto? false' [4 |7 u1 w$ I& C% H7 `4 F! h& `
    set green-light-up? true: M7 Z# Z1 |+ y& _/ T1 q
    set my-row -1! t; F: z# S9 m  B4 Y2 `
    set my-column -1( o/ j$ A- e) M6 |
    set my-phase -1: X: U4 g0 o6 k+ d  S6 \, t
    set pcolor brown + 3
7 U* E) @2 ~4 f. y3 i9 X8 ?  ]
  b6 o( C6 ]' L( o) }' c4 E; z# c( S! ^
  ;; initialize the global variables that hold patch agentsets
* M! v. M5 t& r( |  set roads patches with2 a% u7 q. e3 ]! y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 o( Q3 q( {( @7 y: s$ x, d* E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 h) T7 O) J# B! u- o
  set intersections roads with
' S* e' r$ ], \. N1 ^. [    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
- E" g- e/ a7 c* v& k( V9 }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  x. c4 ^- H6 \7 z6 |* C

. i" T+ f" A7 K# l. O, Y( ]  ask roads [ set pcolor white ]7 Y& i! F% j6 f  J: c
    setup-intersections3 w$ V% H) T! a3 h. ^) H
end
4 H: d3 @; s* k6 T其中定义道路的句子,如下所示,是什么意思啊?
& b2 U* z  ?) U$ Y& K set roads patches with5 _( O* E& E5 C- P0 b
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) h' e0 ]! [' m* y9 H+ D0 L- N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 y) f3 K# M0 G( r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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