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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。7 q* o1 R/ R: [) T! B
netlogo自带的social science--traffic grid这一例子当中,
3 Y2 S4 F; M1 F/ k1 |- R8 d4 X1 dglobals
, f/ e4 b& N8 [! t' z[
" ~( R# P+ W+ K. N* L% X, {. G  grid-x-inc               ;; the amount of patches in between two roads in the x direction
+ ]/ U' P" Y2 }  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, ?& `  A4 t7 k1 p+ P8 J  acceleration             ;; the constant that controls how much a car speeds up or slows down by if) J' n- [8 I+ f, v8 t
                           ;; it is to accelerate or decelerate
5 E% z* N- L( ~! D! M& g7 J! @  phase                    ;; keeps track of the phase
1 ?7 T+ B# H1 @7 ^5 m' @0 ]& t( s  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ a+ X, Y) O" N  current-light            ;; the currently selected light1 t/ Q; s$ \) j/ {1 K1 L
; c& d* [" p1 I5 x7 C, Y( m5 T1 Z- ]
  ;; patch agentsets
) l! E6 b% n( {4 _# ]  intersections ;; agentset containing the patches that are intersections
* B. \3 Y9 B* w- P4 g  \) v' G) r( m  roads         ;; agentset containing the patches that are roads
  Q  p# ]3 r7 T" T5 t% K# M+ F( V], C% B" p* N, d1 M- p3 c

. N% r! d1 f6 M% h$ |% [$ @& ?: ~turtles-own
# w2 c( B$ k% M5 c* }[
" x4 j* q/ y7 j7 S  speed     ;; the speed of the turtle
  l( t" x, O+ I8 I  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
( A) e- D0 m$ r; G  wait-time ;; the amount of time since the last time a turtle has moved
1 p& u4 O+ X. y5 M5 I]; `6 @" x- v: ^: e5 a( t

# T; K+ w, V( Z' xpatches-own
  M8 e. }: d7 d! t1 F3 d7 q2 x[
- o7 _/ w! T  Z; J+ ?- H  intersection?   ;; true if the patch is at the intersection of two roads9 ]! A+ I0 A9 z# b8 K$ m
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
5 F/ y; U$ g7 H" J( f" N                  ;; false for a non-intersection patches., @8 @' M" d% C! t5 c
  my-row          ;; the row of the intersection counting from the upper left corner of the
* N: g( M* `2 e                  ;; world.  -1 for non-intersection patches.
2 P! r4 J& ~  a. h. |9 ]: U  my-column       ;; the column of the intersection counting from the upper left corner of the
  Y) t3 s& b2 C0 P                  ;; world.  -1 for non-intersection patches." i& o2 J% a8 M% ]& P5 X
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% F3 T4 X$ I, H9 e4 j# g+ Y. f5 C  auto?           ;; whether or not this intersection will switch automatically.! Z2 C! K1 ~" V8 B, t$ A
                  ;; false for non-intersection patches.
& @+ {# m) ^. q0 ~]/ R2 }8 M- f$ c$ _

$ \5 W4 P! [0 w+ |" v( F8 j" ~# h  B; |9 ^
;;;;;;;;;;;;;;;;;;;;;;! B# g- q: n. ~
;; Setup Procedures ;;" k9 d% I% O% A' f
;;;;;;;;;;;;;;;;;;;;;;& {' k, N- u+ y. W

! I' y$ b1 u0 a4 ];; Initialize the display by giving the global and patch variables initial values.
# e& E, G! V" [' {6 L; b$ Z) L;; Create num-cars of turtles if there are enough road patches for one turtle to
$ ~: W4 i) O2 Y- l;; be created per road patch. Set up the plots.  V" s" [: M2 G6 x$ d2 M
to setup
) i) o5 b( B/ Q2 C0 P  ca
) f, V: N: v4 {6 m5 ]3 i/ g4 @  setup-globals
# S& t- h6 `" `4 |! f1 ]+ A' Z( E$ ~0 F; s' C9 P+ ?! Y8 Y
  ;; First we ask the patches to draw themselves and set up a few variables
3 m1 \) W$ v- N. R  k  setup-patches
+ C4 y# L* D0 |0 b6 t, k- u  make-current one-of intersections
  j1 D' X% K; E* Z* _8 ]  label-current( s4 v5 m6 |5 L5 p! ?' x( F
" t) P* e- ]2 p% d  H3 q* s$ |. g1 }
  set-default-shape turtles "car"5 y' t% X1 O. F# `; R7 z* ?( l

1 T% L. S3 e* J' G- `  if (num-cars > count roads)
2 r9 h0 `$ X9 C* Q  [1 R: @+ e, @# G' W
    user-message (word "There are too many cars for the amount of "+ }" T/ H8 }, ^1 }4 F+ p6 f
                       "road.  Either increase the amount of roads "
& l& H( j% w& }$ Y' d$ N+ `! U                       "by increasing the GRID-SIZE-X or "
$ _4 b5 t* {5 [. T, h1 A; {. h9 y                       "GRID-SIZE-Y sliders, or decrease the "
3 J4 l9 c/ ?) E% Q6 ~+ _                       "number of cars by lowering the NUMBER slider.\n"
5 I; ~" [' r9 j; _4 \* ?                       "The setup has stopped.")0 ]& ?: d7 F; n
    stop
" e4 @1 I  y3 ~5 a0 S  ]
) {2 j; b7 x9 t/ b! y9 C7 k$ M2 u0 n0 ?9 t$ T0 V
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color+ H3 B9 D" I* m! M9 |/ [4 @- p" S
  crt num-cars
. G% s# [' u7 p+ R$ c  [6 c) Y' M( m9 P
    setup-cars6 i4 X- l: t5 p0 c8 B
    set-car-color+ D9 B9 |& M+ v' A5 k
    record-data
, _3 \+ Z2 k; F* b, H: |* k! J  ]; o( t: {: O2 j* B- Z
- v4 v% O! F6 F: B
  ;; give the turtles an initial speed5 z* j: v* d) K3 N
  ask turtles [ set-car-speed ]7 v* d, O; ~! Y) x5 ]
# z7 S( Z# @2 A* B7 O' h$ ^
  reset-ticks
) c, T6 r5 |, }end4 s, h$ v. n* ^" a; u2 s' ^
, O# z0 f/ n" r9 Z' Y
;; Initialize the global variables to appropriate values, m. ~4 ]$ e$ ^
to setup-globals& f0 P. n6 E/ t8 d, `
  set current-light nobody ;; just for now, since there are no lights yet3 r$ E( W9 p5 }% j7 k/ |3 B7 N
  set phase 0/ M# v8 T9 n; T! c$ k6 x
  set num-cars-stopped 0% G5 u% G6 l8 u: p7 G
  set grid-x-inc world-width / grid-size-x. i5 b4 n; A1 `: z5 z0 L# t& v* l
  set grid-y-inc world-height / grid-size-y& U( B4 P  X8 N. i; V  }+ N( V" s
) t1 E3 }: _: u% {: }! Z. ^
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary' n- G; T7 f% A. X; [
  set acceleration 0.0995 r2 U- E. D' H- h
end0 C" q6 @* C, @- O& n$ r  r$ G
) }  t- {0 c* K! B1 {
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
! ]  N" g0 `/ @;; and initialize the traffic lights to one setting
% j; C7 t' b) Y( Wto setup-patches7 @7 l- e  J9 B) ]8 e+ l# C
  ;; initialize the patch-owned variables and color the patches to a base-color% A; j' |  h  T6 p/ u
  ask patches
5 ?( P% q8 t$ ]/ U  [
+ \& U/ l$ B9 C, r    set intersection? false* ~  z) ]' a, V3 X: v
    set auto? false0 g; \* d) v/ S% G/ R
    set green-light-up? true
  c" v: u5 F7 p( b- _6 W    set my-row -19 ^/ w# r1 X4 f5 s3 \
    set my-column -1
/ O2 ]2 s' E0 y0 _9 e    set my-phase -1
, `$ a8 j- F8 w  h    set pcolor brown + 3
( e0 N7 }8 U* r% T0 d: M* M  ]
8 q: p+ N. ]  V* h& I) D4 H9 F: c. w2 S: i4 J, x& E! z, R5 l6 l
  ;; initialize the global variables that hold patch agentsets
+ v& I, x0 H+ E7 s8 @% A$ X! Z  set roads patches with
, d$ D% U. m$ S4 H; F) }. {2 X6 u' |    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( ]# m2 F( u) c: C7 B% r" z% T. j    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% C4 @/ |2 n. x/ j7 t. [  set intersections roads with
3 I( [- {* g0 Y5 k1 q3 }& C  t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and7 }+ ?; c% L1 x$ Y1 `
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& i' V/ v: a7 ~8 r' N2 j) H& k0 H

# t8 `+ l% L: G9 p  ask roads [ set pcolor white ]
" E' h: e7 R/ N- I0 n    setup-intersections
/ K( Q* ~& S, F! b( W! G6 Iend* ?: M, o1 q! q7 D+ I+ R
其中定义道路的句子,如下所示,是什么意思啊?
" X% Z( y, Q0 Z- I0 ] set roads patches with
. u9 y6 F( h$ [0 z6 L4 k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  S  n$ u  g) |5 V0 p, r3 }' n. H% Z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 f* `' W5 g$ H6 T+ L$ s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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