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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。
8 J& H+ M- \& {$ \+ Anetlogo自带的social science--traffic grid这一例子当中,
8 W6 R* K2 V9 r* L1 ]! jglobals
" G( c- J1 t. O[
2 l. \6 O6 F/ G) O! T  grid-x-inc               ;; the amount of patches in between two roads in the x direction
3 G9 r8 n, i4 P$ v1 b5 |  grid-y-inc               ;; the amount of patches in between two roads in the y direction
  x3 h" P/ w5 K! F$ \9 }' a5 y  acceleration             ;; the constant that controls how much a car speeds up or slows down by if5 k% @+ m8 M" J( ]4 V
                           ;; it is to accelerate or decelerate
% P5 P1 a7 \/ V. S+ O0 k  phase                    ;; keeps track of the phase
' l1 q* s( s3 [3 e8 @2 \( ?+ H  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
0 T0 Z; |* ~+ l: S0 R  current-light            ;; the currently selected light
3 o& k$ w0 Y7 G. ?% I; i
2 Q! u. Y* S2 q7 B  ;; patch agentsets# k+ g3 n  Q5 N; u: n8 a
  intersections ;; agentset containing the patches that are intersections
# C! M! }0 V; C% x3 g3 |6 J; t1 @  roads         ;; agentset containing the patches that are roads
1 ^* k( k% \& y( o1 |9 x, j0 s]* w/ F" O) N$ E/ c9 N

; U5 w2 s. V6 }9 k# {  ~5 I$ Hturtles-own
1 t/ L/ b4 j' v) l[& ^4 s& K/ f4 @% A+ x7 x9 P
  speed     ;; the speed of the turtle
* f! l+ m: B1 w* a: j1 l7 N  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& h: I' v7 G" X/ w' }
  wait-time ;; the amount of time since the last time a turtle has moved
4 w- f: Z- }) S2 D, v1 u4 Q% F! _]
. v* `) S* X" v9 [) b4 N. v) K6 [) R. @0 \: R5 `- u: e
patches-own- Z: L1 w' H  K& P
[
% L3 h3 c# K: m5 U8 ~  S  intersection?   ;; true if the patch is at the intersection of two roads# q. G$ g0 B) r1 D+ |
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
$ ~" ]6 w; o; x6 l                  ;; false for a non-intersection patches.
" C2 j3 |2 W6 m0 ]& K. n  my-row          ;; the row of the intersection counting from the upper left corner of the9 S/ c' r1 W3 s, q. h
                  ;; world.  -1 for non-intersection patches.
5 A* @* S+ L% ~' R  my-column       ;; the column of the intersection counting from the upper left corner of the
) Z  r/ i( i1 t8 N# k' a: V                  ;; world.  -1 for non-intersection patches.# E/ q9 d9 _6 K; v% Q# A; K& f" D
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
1 p  d2 k2 c/ s4 Q  auto?           ;; whether or not this intersection will switch automatically.
6 w* D; h% `% W( y- s$ A                  ;; false for non-intersection patches., A* A3 [; u5 F+ L% [
]
. f  e9 O2 m0 [0 v7 v( x" Z% T
* W) H6 |: t: F" Z2 ?- E7 `9 j  K/ C" {6 R& M( ~
;;;;;;;;;;;;;;;;;;;;;;
& y6 |7 Y+ j: e4 W/ X6 P) \, @. i* M;; Setup Procedures ;;8 Q2 {5 `8 w. C( ?
;;;;;;;;;;;;;;;;;;;;;;
/ Q, a6 j" J+ [; N, h5 b
5 j/ L( `) h. K1 Q! Y+ };; Initialize the display by giving the global and patch variables initial values.: P/ v. f2 H6 y1 a& K+ y. W  e0 U- z+ V
;; Create num-cars of turtles if there are enough road patches for one turtle to" d9 h# e/ `6 n/ w- F
;; be created per road patch. Set up the plots., X; R8 g; Q  Z# O8 V; X+ H  M
to setup, D4 Q1 F4 W4 g* R# _" Z
  ca
- d+ W+ x) _: }' Y6 N2 T  setup-globals' v+ ]/ y) U) [
7 \. l  ?3 Y+ s4 s
  ;; First we ask the patches to draw themselves and set up a few variables
) t! L7 q+ ~; D) L" i  setup-patches
7 i' A: H. [1 t0 I  F" \3 i# C  t  make-current one-of intersections. c: K8 C  x* S2 X" g
  label-current
# J  c( \  h" X4 v% Y# E/ y9 x
* M; A: N9 Y  s0 S& P- ~  set-default-shape turtles "car"9 X0 g, x! J% T7 G( i1 z9 T2 ~

3 U1 L7 o+ n" t1 g8 Y  if (num-cars > count roads)
. U7 I8 D; k8 H0 D' e7 C8 f  [2 X8 f# Y7 j7 L* f5 A; Q- b% t
    user-message (word "There are too many cars for the amount of "
0 M7 \# K( T2 \1 A# j. n% [                       "road.  Either increase the amount of roads "7 H4 i* \) q: X- J2 o5 ~9 U# d5 f
                       "by increasing the GRID-SIZE-X or "/ G: l8 M, i7 k
                       "GRID-SIZE-Y sliders, or decrease the "7 r$ Q- P( V1 s8 |, L6 t% G9 W
                       "number of cars by lowering the NUMBER slider.\n"
, g8 T0 }0 m; y                       "The setup has stopped.")# E; m6 U* h- }3 G: y
    stop
# N$ p# s; l: k$ Y: y2 N  ]
, ?( A2 A& p5 N8 ]3 s4 w6 x( i5 A. e# u" I3 F
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
* y% ^2 z: C' R3 `  crt num-cars
2 x0 W5 @$ ^* A. f$ T7 f/ D  [
0 a. h7 n* u2 j! p    setup-cars
/ Y( n. p& Q' ?+ b( m4 m5 m    set-car-color5 s* Q+ P/ n8 A; W% r2 h
    record-data; y/ j+ T& T% T  r% c7 [
  ]
! O( V# |0 p; a. R4 I: ]& F) p$ b2 Z. f/ o4 Y
  ;; give the turtles an initial speed# S" N5 V% y1 k0 m
  ask turtles [ set-car-speed ]: |; y  C5 H  I, a  g; ?

' K# }8 x4 j8 g+ m* X) c  reset-ticks
$ W5 |* O: m3 yend
: `+ W* D0 w; G8 m( x' X# K5 ~
- Q* N+ L: ~4 y4 j, ~' O;; Initialize the global variables to appropriate values8 p* ?! o4 T; i5 ?- i) K7 h- z
to setup-globals
4 X; ?* M& Y; G$ j% `+ N  set current-light nobody ;; just for now, since there are no lights yet+ C7 u5 p% z  V( x. q* k* E
  set phase 0$ w" W; {  J7 I4 K- F5 D2 N. r6 R
  set num-cars-stopped 0
  N9 @& E) O; k( ]& S! R6 n7 p: c( J  set grid-x-inc world-width / grid-size-x5 r! y5 \+ H. ]4 j0 C+ _
  set grid-y-inc world-height / grid-size-y) i3 H5 s) W5 R* d! f% @
# Y, `/ _- T; c  k- j: b- m
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary0 ]  k( H" L' B' e+ w0 I4 ?# ]) X
  set acceleration 0.099( B3 q% l7 G5 l, x  j% T6 h1 d
end; H* I  U( l: A/ ~& o
) s" F9 G0 H  K" o
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
+ f, n; \4 i0 _& X1 y;; and initialize the traffic lights to one setting% o: f6 d1 w: I2 h4 [3 x: \- P
to setup-patches
" }( a5 n2 J# V1 O  ;; initialize the patch-owned variables and color the patches to a base-color
1 P4 p- _4 F1 e6 F  ask patches$ N, t  u& S1 E/ a2 u7 ^
  [+ `+ c+ E- Z- Z( q1 w& J
    set intersection? false/ k5 U* B- K1 n7 @
    set auto? false# y, u2 }; J# t! e/ c2 h) c- i
    set green-light-up? true
3 A& A! I0 S7 j6 c  g1 ~    set my-row -1
, v3 j% F! G8 {7 H5 @1 T6 a, G6 s" `    set my-column -1
# z0 |" H* `" e1 e- J8 }    set my-phase -1
1 l8 c6 Y" Q  b( s9 m$ P% ^2 O    set pcolor brown + 3
& I# Z4 A$ u1 x9 P$ s9 J$ i  ]
( v) q9 x( ~2 E# c8 k  L! j/ ~/ j. J( k
  ;; initialize the global variables that hold patch agentsets
, S" W& g0 \9 _  set roads patches with% `  c7 e5 w8 s# F* K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 G! c! ~) L. Q6 ]& y2 f    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 G+ t# @! y9 F/ X9 r# N7 ]
  set intersections roads with
. f8 G: N9 M% c" J. y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
: @3 g2 c8 r) K7 \- J) z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% G7 |5 ?  |) P9 N- H; y2 B! l( t
0 Y* y/ @- z2 g) u! n: t6 b  ask roads [ set pcolor white ]9 g# `8 B# ]" j
    setup-intersections' o- d/ ?, i* a6 j
end
. R2 w7 p. K8 p4 y) N# i其中定义道路的句子,如下所示,是什么意思啊?) P1 _! G2 _, j8 J  z7 t
set roads patches with$ t, t' q, S9 s' r
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 T- S" g4 N4 R5 X! [2 ^, h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% I0 x% u- P( I4 A" U# M, E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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