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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。% o# i' @) M3 G. R8 t! a1 A& w
netlogo自带的social science--traffic grid这一例子当中,( w. c0 F% [2 {( H& e6 Z
globals" s2 Q. }- d( ^& x. w( c3 S9 r
[% w! L' Z5 o6 y% w
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
5 M  e! J% I/ [0 n/ D' K. T# P/ u  grid-y-inc               ;; the amount of patches in between two roads in the y direction
% o9 }3 _* Q3 i# H2 k( ]/ r7 c) Q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if3 ^/ F: D  C/ X' W
                           ;; it is to accelerate or decelerate' Z( S, q6 G; e9 h- {
  phase                    ;; keeps track of the phase
8 D% l4 z! S2 @2 v6 {* v& F4 f  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ v$ c# i. {( S* J- D. J  current-light            ;; the currently selected light
+ D( O4 B% w& v) F
7 {- {! z* m; y  g7 O  ;; patch agentsets0 L% M. g+ k- Y/ L* z0 J* a1 j
  intersections ;; agentset containing the patches that are intersections
( w- E7 e# A" ~1 w/ a0 N  roads         ;; agentset containing the patches that are roads* A: C' I# v% n' z5 o
], ~' A/ u3 S8 L) |6 V* }
% b0 b+ q) d' L- d8 t9 \2 X/ F( `: d% n
turtles-own
* j1 R3 @  m+ [: L* w2 M3 T3 l[
% C# R. J3 t; P9 U2 I  speed     ;; the speed of the turtle
3 O) N3 j0 y9 p* T0 O  up-car?   ;; true if the turtle moves downwards and false if it moves to the right  |% H5 F: W0 ~1 j; P
  wait-time ;; the amount of time since the last time a turtle has moved2 b3 R7 N! h1 K. j! D5 u* b8 _5 c
]
5 Y* l& l. m3 P7 @$ i7 i$ a1 \' W
patches-own
8 q' P8 c2 v8 ^3 J( q( V[0 q/ L1 l: i5 E1 D! \7 b# W+ e9 K
  intersection?   ;; true if the patch is at the intersection of two roads
/ ]+ d" w' B  I! X, R* n% f  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
: |/ a$ O" k6 v                  ;; false for a non-intersection patches.) |( K9 ~9 Z$ h
  my-row          ;; the row of the intersection counting from the upper left corner of the1 w; l" i2 r2 L; h6 s2 @+ W7 r
                  ;; world.  -1 for non-intersection patches.
6 K% ~: A! M& t  my-column       ;; the column of the intersection counting from the upper left corner of the
* W1 f9 T0 _' N; l3 Q1 `+ R                  ;; world.  -1 for non-intersection patches.
% K) H8 R  m7 M9 F  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
3 C' R7 P( _" m, g" p; J# e  auto?           ;; whether or not this intersection will switch automatically.
% Q' q* r2 q: m6 i4 D  Y                  ;; false for non-intersection patches.
$ p. I/ c( J/ R$ X3 M7 ]]
' {0 Y1 @6 s- o1 P8 C8 J' W% s' q; [; F5 n9 O1 b3 E5 b! s- V

/ S( @% H6 W, x% S9 W;;;;;;;;;;;;;;;;;;;;;;
/ O5 e! v1 U2 B;; Setup Procedures ;;9 @/ D! X( y+ v: ]! t! e
;;;;;;;;;;;;;;;;;;;;;;) P/ {2 A- z& T% |

' u) g! F. D" n" g* H- \. d;; Initialize the display by giving the global and patch variables initial values.
* l7 I3 c% B* R3 @( x;; Create num-cars of turtles if there are enough road patches for one turtle to
. h+ H3 ~4 i6 f: m  N7 p% p;; be created per road patch. Set up the plots., D8 v9 v# I" l- s6 r, m" N
to setup
, V( o# D9 O, j: R7 l! n, V, x  ca
7 Q, x# M! d! G6 j- o  setup-globals
7 v! M2 p' s/ m7 N1 V( b" Q3 g5 y
  ;; First we ask the patches to draw themselves and set up a few variables
& M1 A+ i  V1 G- L$ y  setup-patches
5 W, E1 M  F+ Z8 X9 J, l  make-current one-of intersections7 y" X$ D2 _& ?: S* h
  label-current# K# ~$ Q4 O3 k! m

! h! g# e3 B8 R/ M2 r' }  set-default-shape turtles "car"/ ?8 }: R7 T8 h* [0 k% ~4 a2 g

1 k/ Z4 s/ t" u8 S8 j; b: {1 j  if (num-cars > count roads); S0 E7 w9 O% B3 ]! X- u
  [
7 W2 B- ]& u: T, z# X: S: f    user-message (word "There are too many cars for the amount of "
; d0 ?/ `& y& q9 I3 ^                       "road.  Either increase the amount of roads "( q6 V0 h4 f: U- Y$ R, v* |
                       "by increasing the GRID-SIZE-X or "
* D2 C8 @/ I1 u0 @                       "GRID-SIZE-Y sliders, or decrease the "% J1 S9 B3 p4 A% x2 r" y
                       "number of cars by lowering the NUMBER slider.\n"
2 X6 S" m" E" D3 i" j+ z2 z                       "The setup has stopped."): `+ ?7 n) c  j, ~/ e7 r
    stop5 }! q6 Z3 i. v$ U& a
  ]
; n7 Q3 P! ^0 K* r2 U, e# N4 K
: l: H- K' R) R, \* @3 D" ~9 x  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: D% K* i5 e+ m! ~
  crt num-cars
5 k4 I- p. s; v3 s  [
8 A# H# E/ L) D4 O) |    setup-cars! P* P8 g8 Z9 x4 D4 V. R, S( E
    set-car-color
9 l9 i; t8 s9 R% r' N/ z    record-data
: y2 U) F" L& A9 |& a9 y* g& |5 i1 ~  ]
) ~; @! ?! \3 i: @( G
4 ?5 i9 ?) g# u1 f7 H& a, S7 g  ;; give the turtles an initial speed0 Z9 Z! b$ f+ _
  ask turtles [ set-car-speed ]% ?- g7 L$ Y7 H) U
5 r6 s" a# M* t
  reset-ticks
% V2 Q* Y7 Z+ _) t1 C* L" j/ Vend
# M9 N5 |  c  g% {3 |* d! w( C# I5 G3 A! R' @1 k/ r
;; Initialize the global variables to appropriate values! {0 H5 r+ m' }, q' L& P. n0 V
to setup-globals% w0 r6 n& T, k. M8 q9 K7 K( n$ A# Z
  set current-light nobody ;; just for now, since there are no lights yet
" y6 k' x7 O2 P2 h6 g  set phase 0* f& d4 q& W+ h2 `% d) Q
  set num-cars-stopped 0
- x, l" r0 K* m! K  set grid-x-inc world-width / grid-size-x3 h$ q) h9 V: O0 r
  set grid-y-inc world-height / grid-size-y
8 o% V4 J$ }; I& o. R# ~
/ P& j7 i; n1 d. V- c  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
" n1 j8 b( C; P6 `$ }  set acceleration 0.099
; i* b9 v5 O: o5 z! c* eend
- w$ d# ?6 r3 p# a+ Y' P0 j2 {3 q' l" z8 h# e/ d
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 O+ Y$ R+ f5 L/ R;; and initialize the traffic lights to one setting
. ]. \9 `2 e& U( R) m0 i/ d9 ito setup-patches! I8 `) g1 o! f
  ;; initialize the patch-owned variables and color the patches to a base-color
. {8 ~. k$ t+ o( Q9 W  ask patches+ p- }% w# F# O" s( y( B# g+ d
  [
6 Q2 W8 L& a5 }! S! \( J# S* \# V( Q    set intersection? false  [- n+ H$ l1 H9 q. {. {' \9 z( T
    set auto? false
2 U: F. H$ Y& p* q6 ~" p9 l' A    set green-light-up? true' x3 c/ b4 B" q
    set my-row -1- M1 P% y7 A+ M
    set my-column -18 m) c+ Z! b( @# H' a. F
    set my-phase -1( H1 Q1 c% S9 F2 W& _
    set pcolor brown + 3
6 E/ a2 ^' x; F- t) G" Z  ]$ x$ U. o: S$ f1 q8 e

- M0 S$ `. t% ^- Y, d8 _  ;; initialize the global variables that hold patch agentsets
4 e/ j) r5 ^8 r# ^+ ]5 }$ L  set roads patches with
& B. N4 x6 P2 d- U) u* m    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- _; k  r; S8 ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 J3 w7 @- [) Q  set intersections roads with% {0 p) {' ]0 V2 ]9 A; k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
- v' j% l7 j( t+ d6 ~4 U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# Y# A; ?3 ]/ T' I+ C
# |1 ~& I) L2 U8 q
  ask roads [ set pcolor white ]: J" H$ g- B/ ^" K1 a5 b+ w
    setup-intersections
8 t! q+ K- [& y% U) _end
. \- O) w% j1 b' N, R2 x其中定义道路的句子,如下所示,是什么意思啊?: q3 n. W' ]# l6 [  y
set roads patches with
0 |( s: S% V5 S5 t1 K& d; ?    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% W' x2 V5 s* Y2 F& t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 h( g/ e1 x6 O; _& k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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