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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。$ ~- [/ a; k7 v8 ?; Z' [; ~
netlogo自带的social science--traffic grid这一例子当中,
& R3 c6 H; K  F- o  v' A) kglobals% K1 Y$ S6 k, H4 u  q+ x& R1 X2 f" {
[# j8 d% d% q; I9 Z3 S5 b
  grid-x-inc               ;; the amount of patches in between two roads in the x direction, y. r9 V/ ^+ w" X7 @, Z9 L
  grid-y-inc               ;; the amount of patches in between two roads in the y direction, N- M9 B* ~- F4 v0 r) _" Q
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if6 {& N) G) @$ g; ~% r/ V( t" }
                           ;; it is to accelerate or decelerate
, L  c$ Z2 x7 |5 {- d- G  phase                    ;; keeps track of the phase0 h0 |4 R/ [% E. `, ?
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure. [" X; g1 G1 Y7 Y
  current-light            ;; the currently selected light
; g8 P# f* R, V" N# Y% @- v" U* V, E# b! s, X- b
  ;; patch agentsets1 w2 c+ X4 Y( {/ I$ r
  intersections ;; agentset containing the patches that are intersections
, l, s1 b" ]% J6 `' B, E  roads         ;; agentset containing the patches that are roads
6 Q( u; ], e$ z7 P5 F+ _]
: z+ E; y3 U: j0 |5 T7 _% w; w# |1 m/ \+ z5 q0 U' o: c1 g
turtles-own9 H+ R- Q7 o, Y/ O
[
+ _, v; r2 O4 P5 S  speed     ;; the speed of the turtle
8 B7 j0 K( f: Q+ i  up-car?   ;; true if the turtle moves downwards and false if it moves to the right# g6 l7 M- C- `3 E& e: q
  wait-time ;; the amount of time since the last time a turtle has moved
5 G: C" K8 B6 v]  n' s& O1 n; \' {: {
  T0 m2 L& A4 F0 c8 Y: i
patches-own
3 `3 @0 T& e  }& m4 q. k[
& K, \: j* H7 {! x3 ]  intersection?   ;; true if the patch is at the intersection of two roads
1 J) `# M0 l" ]  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
" m" e* e8 Y  Q/ x                  ;; false for a non-intersection patches.
, Z  x5 _/ V& `; `: s! X  my-row          ;; the row of the intersection counting from the upper left corner of the
8 }( T. ^8 r- b  z9 b$ u3 u) d4 j                  ;; world.  -1 for non-intersection patches.
) g+ k& P- j% P1 y" \  my-column       ;; the column of the intersection counting from the upper left corner of the
" s2 j8 U8 v2 A; y3 o                  ;; world.  -1 for non-intersection patches.
& y/ y# w4 C/ O; C; K  Y% J  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ j! R% e8 }8 `5 D, i" I1 g
  auto?           ;; whether or not this intersection will switch automatically.; }4 O. t4 f% {+ x7 q3 S
                  ;; false for non-intersection patches.
. l& n5 T) a8 e+ i; ]; M2 R]
: b( d" c9 E( a! @" Q! S# ^- i$ i
" z! ^: l2 G0 C+ E& X0 K8 K
;;;;;;;;;;;;;;;;;;;;;;
) G$ x; H; h* R1 i;; Setup Procedures ;;8 Q* r% w' |8 ]* u  j" Z+ k
;;;;;;;;;;;;;;;;;;;;;;5 i7 P* i) \6 J7 E4 q% B

* e/ E& q, p& A;; Initialize the display by giving the global and patch variables initial values.
4 T% ~) i: C, N. F  O3 `: X;; Create num-cars of turtles if there are enough road patches for one turtle to
% s3 U, c* G/ b3 G  _/ P;; be created per road patch. Set up the plots.
/ [7 n$ m1 a2 N( E) i! Uto setup8 c+ v# Q! M% M6 Y5 A; [8 o: X
  ca
; n* |) [, f& i3 n$ D4 G+ t1 ~$ O  setup-globals
- d. T3 X& |, s- d* ^
3 Y- h" Z; p# y: \. X2 S$ E& X  ;; First we ask the patches to draw themselves and set up a few variables
. a5 l0 I: X  Y; Y6 u5 p! Q  setup-patches9 H2 D! L, c! c, W1 g
  make-current one-of intersections
/ O( L1 ]: u9 l  label-current' w: T+ J5 J: p1 Z4 ]
( P; A% t* ?: k5 N7 g/ v; @& Z
  set-default-shape turtles "car". T. P* r3 v6 ?8 E, T8 W

  M% l0 r+ {5 V$ M$ L4 P  if (num-cars > count roads)- [+ c2 a5 t$ f6 Z% Y9 z7 j
  [
1 p! m( S; F# v) ~" ?    user-message (word "There are too many cars for the amount of "
' `4 }1 P( _) ^. B- ^9 p* P                       "road.  Either increase the amount of roads ", f' R6 X' v0 j% }
                       "by increasing the GRID-SIZE-X or "
+ f% h; s1 [! W0 y8 L6 Z0 p                       "GRID-SIZE-Y sliders, or decrease the "
0 }( j6 O/ R6 J1 O( o1 V' G                       "number of cars by lowering the NUMBER slider.\n"
' x( n5 C: }9 u2 o& C2 Q9 e                       "The setup has stopped.")/ E; n" ]" F6 ~& ~( t
    stop
  S$ l, ?1 p  f& t8 S/ \. i, j  ]
7 A+ O2 u3 [4 P, v) a: d/ E' l4 O" q- Y# t" T: C( [
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
# f4 w1 B' {- v- l3 m0 q8 e  crt num-cars
0 c$ r$ E5 k1 R" _( G  A; E) Y, d  [) j) T) d( q9 x+ ?2 @/ E
    setup-cars$ @- v2 _; t( G3 L, \+ L
    set-car-color4 F* U: L0 \" T" O1 u
    record-data2 }/ ^: k4 M! I. ^. N$ h
  ]
( _; \) S3 |1 L4 w! i& G) ^8 Z7 V  {3 ^1 k! i# p0 F! l
  ;; give the turtles an initial speed( Q7 v9 Z/ C: `' v$ a
  ask turtles [ set-car-speed ]) I, C0 s4 z# E) t4 p6 C
7 {# e) c0 U' j/ N0 `" v
  reset-ticks9 \& ^" K/ \" a. A, @' i
end% d- R4 l  z% j3 ^% r/ F$ |
1 I3 O1 n) O5 }! s* `" }, F- j9 H. z
;; Initialize the global variables to appropriate values: h$ l, N0 ^4 w' S
to setup-globals  K2 |: [$ M6 D" U
  set current-light nobody ;; just for now, since there are no lights yet9 O4 d% G/ f. y- A% u
  set phase 05 @9 }$ [6 J3 E) L
  set num-cars-stopped 00 p" p/ a$ x. f1 c/ X8 b
  set grid-x-inc world-width / grid-size-x  A* x4 I3 R$ c5 G2 E
  set grid-y-inc world-height / grid-size-y/ o' p* g; L2 x# Y

6 [- G8 F. r3 p, q5 s/ g5 u  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary* N& N2 o7 ~$ M" X* F- y
  set acceleration 0.099# X1 }2 p( o& Z  }, b6 W
end
) _0 C7 _: c, ]5 h* Y. z% n$ t; z( j
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
7 r, }1 s. Y8 W4 J;; and initialize the traffic lights to one setting: C* r- q5 h8 P5 L6 m# ~
to setup-patches
8 b0 v" C; A) x  i: U  ;; initialize the patch-owned variables and color the patches to a base-color2 p6 y* n' j/ D
  ask patches) q  a8 }0 c$ r) h; U
  [! ~0 \- Y: i. f! l2 E2 J
    set intersection? false" c: V) ~% s& u+ P2 q) k( R
    set auto? false# h  o1 J. z+ I. D
    set green-light-up? true. Q2 w6 k- G5 w" S3 s
    set my-row -1
3 Y9 f- \; u- L0 M) w$ \    set my-column -1( o8 U& K. C4 u7 G/ ?2 p! B4 ?% r7 ]4 O
    set my-phase -1& R; A% H, ^  j1 ]# \
    set pcolor brown + 3
& m; r2 O% ^. D7 @7 [' C6 [  ]
5 D! y9 L# m5 }# H* \  H: s! M& s9 K: c+ {, G
  ;; initialize the global variables that hold patch agentsets+ h2 o3 c$ f: F5 i# u; |! w
  set roads patches with
! M. X! r/ h; }/ B# {    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 p$ w& M! _2 P: c; L; Z% E) ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( _& k6 W6 i  g& g# s  set intersections roads with( L, f0 O$ y+ s- s$ M4 n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
$ B/ P3 r$ a5 `/ t* k; I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 w* _2 i7 y8 S5 e  T$ A& a
( W9 l2 J; `5 M  ask roads [ set pcolor white ]
5 f. J# \; |1 c$ [    setup-intersections
5 _) O9 Q& @* j3 o% p' lend) ?. T8 v* Y# @5 n1 I
其中定义道路的句子,如下所示,是什么意思啊?0 s' I4 f2 X6 K# H2 }
set roads patches with. K" P. f& z' Q. D7 V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( o1 E1 J& I! ?% j7 H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ i. j! p: v5 ]' ?1 O' |3 l# I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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