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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 H% |! c) q2 e5 x
netlogo自带的social science--traffic grid这一例子当中,& o/ Q3 R1 h" g" N/ b$ L
globals
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  grid-x-inc               ;; the amount of patches in between two roads in the x direction+ M' |9 K( D( E+ b9 n* u
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 E) G' h: q( A& j& W: S6 ^0 b% c5 f  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
8 _4 W4 U/ T' O1 P. H                           ;; it is to accelerate or decelerate( E7 u& U5 s' E
  phase                    ;; keeps track of the phase
- p. i. T4 ?  C0 y" T  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
2 @$ \6 O; s; I( k* G6 l  current-light            ;; the currently selected light: s* ~: u* g# N2 e* n, A
7 l' X/ ?& O5 P. {
  ;; patch agentsets" F0 E0 O" Q# i# Q! X
  intersections ;; agentset containing the patches that are intersections" V$ w. Z  H/ F2 |% A* ~% s9 W, F, G
  roads         ;; agentset containing the patches that are roads
9 C) V/ D/ b. Q* T]% Z3 P# {( K3 j1 z

: j6 C+ J* d' I3 G% yturtles-own2 ?% a6 y. B3 h, H5 {
[$ S2 `" }3 r7 g2 g' f
  speed     ;; the speed of the turtle
( w; \5 D3 N9 L( z" ~! [  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
" t. b# ^# Y6 I0 z  wait-time ;; the amount of time since the last time a turtle has moved
9 b( s0 |3 w$ L4 M]# g2 E- W& J9 d2 [. F1 W' E! A

6 q6 S* D4 g/ W7 c8 Dpatches-own
4 Z6 A7 @% Y( x' v[" E7 }* W% q2 d% ^# V
  intersection?   ;; true if the patch is at the intersection of two roads
7 e6 M5 S! T* b, ]& Y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
1 C! ^, ^' i$ ^                  ;; false for a non-intersection patches.8 I! \! e9 p4 |5 E0 G
  my-row          ;; the row of the intersection counting from the upper left corner of the5 ?; Q, z9 e6 @5 f; ?% O1 C
                  ;; world.  -1 for non-intersection patches.0 W& M: Q3 U. j, I3 j0 _( s6 o
  my-column       ;; the column of the intersection counting from the upper left corner of the
* p6 g- P3 |) [# J& E. J                  ;; world.  -1 for non-intersection patches.! x5 G0 w! U$ U- k# f3 ^
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
9 E1 a$ I6 j; D1 {  auto?           ;; whether or not this intersection will switch automatically.
* H$ S1 Q: L5 O( Q0 }7 u1 [                  ;; false for non-intersection patches.
- U. _8 ^4 r4 x, n! l3 }" B5 l]3 J/ C: y& y0 f
: g# z) b3 J- q  U; \* A

9 k- ^  }7 ]& @# b5 C/ z) k;;;;;;;;;;;;;;;;;;;;;;
7 X0 o  a( Z4 [3 V+ |;; Setup Procedures ;;
& U7 F  N% M+ P/ ?5 G& K;;;;;;;;;;;;;;;;;;;;;;
8 F4 T$ j5 p+ a: b% q: s
! X6 I' B- [8 A. j* I) J9 [;; Initialize the display by giving the global and patch variables initial values.6 t5 K' t- F$ z1 u0 L, v4 l0 L
;; Create num-cars of turtles if there are enough road patches for one turtle to$ \! h3 L) M3 c4 ~: t2 S
;; be created per road patch. Set up the plots.
1 Q# `9 [# P# h& O1 u8 |to setup
/ J$ Z& v: Z. \9 a  ca9 e3 o& `" ]& |# a4 N
  setup-globals
+ s- n2 g+ J# X  M, A. P; x) i$ t8 C) {/ V
  ;; First we ask the patches to draw themselves and set up a few variables$ y  G, T! b7 _, M* m
  setup-patches
& d% a- G) U& U2 d, p  make-current one-of intersections
6 U) j1 O( F0 E. ?5 L  label-current
3 ~" Q" v8 w7 P9 R8 J: K2 D4 G5 M1 N9 \! h1 P( K
  set-default-shape turtles "car"8 _1 Q2 @: j4 R

3 |/ O) ^& Q6 r# q- f# h# R  if (num-cars > count roads)9 r0 [; n6 b) p7 H/ [) k
  [
  L" \  x* Y- r8 w    user-message (word "There are too many cars for the amount of "& L8 y# q. @! l$ G  j
                       "road.  Either increase the amount of roads "
5 s6 K9 q0 ?9 x7 p6 [                       "by increasing the GRID-SIZE-X or "& Y/ k$ S- H5 ~7 L  l
                       "GRID-SIZE-Y sliders, or decrease the ") F. _: r# k9 e; E8 d
                       "number of cars by lowering the NUMBER slider.\n"
5 m! ~  N% T* D0 @8 U                       "The setup has stopped.")
! f4 z" v  t0 B3 u    stop
% L* Y- g: L7 |) ~/ R  ]
) c; a2 b* [8 B- h0 m4 E) z/ l6 N' C0 e/ H; s/ {6 s
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
. r1 {$ x, _( _  K$ w3 d  crt num-cars8 {+ ?" O  g; K: \8 }
  [7 D$ E  ]# d& K3 m! ?
    setup-cars/ d% ]; j3 o) ?- G/ N$ q9 Z" G& V6 Y
    set-car-color
/ E, M# h2 Y6 w+ H8 Z    record-data
- ^/ i% @) u2 g  ]+ u7 a6 p, t0 A
' a3 J! m5 ~& u- b! ^/ \
  ;; give the turtles an initial speed4 \9 L( q8 w! y
  ask turtles [ set-car-speed ]
: W( @3 o# F- L+ G/ L- A- n( e  P# n
  reset-ticks
; I2 k3 g1 t, m7 i% Aend
9 Y, L: G9 l2 z5 Z& \
: T. T; @( `2 }$ f;; Initialize the global variables to appropriate values0 `, c6 c0 o+ b3 i& p& d1 N
to setup-globals
) A* q, ?! k1 I  set current-light nobody ;; just for now, since there are no lights yet
  m3 I) @, d- q+ o% r1 h# E  set phase 00 o; M2 {0 J0 I2 Y4 Y- d
  set num-cars-stopped 02 l, F0 C+ s7 c8 t
  set grid-x-inc world-width / grid-size-x
! A4 [5 C+ t' f& g  set grid-y-inc world-height / grid-size-y' q5 ^  b6 e; \& c( F2 f
4 k4 X6 M0 Q  z
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary9 u3 t9 K% B7 S& Q8 n
  set acceleration 0.099
3 r, M" w9 g2 `" ^end" o, a; ]! m- j8 \' X
! `& Q$ b; g+ q- Z3 Y
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,9 l8 [0 c4 b1 m/ M
;; and initialize the traffic lights to one setting6 U; C8 ?3 Z  w) @" t5 O
to setup-patches
8 h: u* V8 w0 p- q" u  ;; initialize the patch-owned variables and color the patches to a base-color
) B- k- z( W9 B  \  X% W  ask patches
3 q6 F! R( |) H8 M& A  [
, F2 ]  x1 k$ v6 U1 I% G    set intersection? false+ D( q1 b# M- ^
    set auto? false1 S4 o8 b- [  E/ @3 h
    set green-light-up? true
; V: F( z5 k% n# q9 Z    set my-row -1
; A, C- Z0 F0 x. W. f( S8 |+ I    set my-column -1
5 G0 g/ h3 G# r1 H0 u+ `    set my-phase -10 P) C: s4 d6 U! P* A
    set pcolor brown + 33 [+ V" S, c$ d' a! y
  ]
" i2 h- N& b$ r4 o1 K! n6 d2 Q4 l% W6 N! k- {4 K% T
  ;; initialize the global variables that hold patch agentsets
' F+ T7 L7 G9 A4 T; K# X" A  set roads patches with6 q5 K8 o# L  ~5 ]- K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ m% ]' E' i3 k: S" B# f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ O" c; [% O2 |( m+ I
  set intersections roads with
5 l; \" @+ Z0 K* X3 E0 e5 A    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
; |9 }2 W- _, a% h6 T2 O) _( i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& m- @% b1 \& k2 [% B6 m9 Q& O. \4 ^3 }+ C) A6 U5 R
  ask roads [ set pcolor white ]
. j! N: g3 h3 K    setup-intersections
. u8 }+ u9 j7 D2 S. |: vend
# Q' _* v4 s3 e! Y% g# K* \其中定义道路的句子,如下所示,是什么意思啊?3 t! W. f! l# K0 i* c4 o3 D+ q
set roads patches with
5 j5 T' l2 s$ B8 T( y. ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- a+ ]2 z; m( J6 {; L
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! N! C4 P. U4 e+ |( ~- ?5 c9 |9 W. D
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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