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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。3 z+ r) A# z% E" R
netlogo自带的social science--traffic grid这一例子当中,/ F: O: W. K% I: G! I. Z  R8 h
globals
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  grid-x-inc               ;; the amount of patches in between two roads in the x direction' i5 @9 @: }0 R( d! W8 w( }
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
. U$ X  E, g  m- Y+ h5 G- D, n* }  acceleration             ;; the constant that controls how much a car speeds up or slows down by if& X7 K: i+ ^1 Y" P6 p
                           ;; it is to accelerate or decelerate+ G* a, c4 i  n% ?
  phase                    ;; keeps track of the phase
: F. r# X7 y+ F1 ~  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
% l6 a5 M4 D! c5 v- G  current-light            ;; the currently selected light
. c: Q. |& g# g( @. ?8 u6 E' L6 n0 |' N! a; l  t( i
  ;; patch agentsets" W. N, i* O" u
  intersections ;; agentset containing the patches that are intersections3 @  a! W6 J1 ~: ]5 j/ _
  roads         ;; agentset containing the patches that are roads
8 u4 G& g0 B- P  C5 C]; V1 R1 |  o6 ]$ j" L( t

. B. P" A7 {" m2 W  P2 hturtles-own
# `8 E* P$ k' Q, e7 a* e: r[
- @! ]' A8 B- P5 {2 r: L  speed     ;; the speed of the turtle
- h2 O  a; o% C% ^" k5 I$ @  up-car?   ;; true if the turtle moves downwards and false if it moves to the right  h' \3 O( [% R; \: _1 }
  wait-time ;; the amount of time since the last time a turtle has moved# v& C/ d3 B; c  P$ L
]/ Z- @7 z# B6 T7 c+ y) ~7 R* d

1 d6 F( o( |( Opatches-own
; U5 V& t0 d9 J7 C/ U' M9 S" `8 i[
( X1 E0 G; @" W( \: q' S% {  intersection?   ;; true if the patch is at the intersection of two roads( g: o3 }  f3 N( n. \7 V" k
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- ]$ ]$ G# r& k# C# w: `# g$ T
                  ;; false for a non-intersection patches.
5 u. z+ a/ C/ H  my-row          ;; the row of the intersection counting from the upper left corner of the0 @, [( b" ^. _" ?
                  ;; world.  -1 for non-intersection patches.8 S; y- S- T; ]8 c2 u
  my-column       ;; the column of the intersection counting from the upper left corner of the
& z+ r2 s# Z6 Y9 l                  ;; world.  -1 for non-intersection patches.
4 F9 i* F5 W5 [! J- H  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  w2 F  c. y* d' h% B+ q9 ^8 F  auto?           ;; whether or not this intersection will switch automatically.
5 y7 g) n4 a2 q# ]1 k; M                  ;; false for non-intersection patches.
8 p* n/ X6 [0 m5 ~; n6 H- P]5 ^$ `( G2 T4 g6 j3 j& Y  |+ d% E
7 `- s5 I$ d8 s. a5 M; Y1 K/ _
* T  E9 Q% p& l
;;;;;;;;;;;;;;;;;;;;;;
/ G5 a: u* h0 s( O: W4 L;; Setup Procedures ;;
+ I; z$ N& X3 i7 }7 _" F7 m. W;;;;;;;;;;;;;;;;;;;;;;
( `5 L' i7 s7 m/ T8 E. _) x4 Z+ i4 f' o- [% X2 z; M. n
;; Initialize the display by giving the global and patch variables initial values.6 M& G4 C% C# m0 M
;; Create num-cars of turtles if there are enough road patches for one turtle to
) N! g& `# g( f0 z( q4 };; be created per road patch. Set up the plots.
9 z5 H+ T% c4 m% ~* f0 dto setup' ~/ O0 X+ Q' r6 \8 V( w9 d
  ca
0 O7 o' W. L6 I8 |# K. w9 e8 |  setup-globals1 S5 ~; x& t  U2 u$ a
: F+ y3 ?4 ?; |3 g" R% T2 z! g, w
  ;; First we ask the patches to draw themselves and set up a few variables% j: U& s6 f( X- q7 ^9 t- ?
  setup-patches- E" A8 T- T4 [  _7 }" m
  make-current one-of intersections( Y% x% |- g$ I: G9 v% Z
  label-current9 h3 ^6 G, o5 V
5 S# i1 X* e5 g. v9 k" x6 o. G
  set-default-shape turtles "car"
% O" \0 \! i+ b
- H3 Q/ l$ g+ z3 G  if (num-cars > count roads): U) V- R+ z- K& G8 j) i
  [
8 j- V6 K2 n5 o    user-message (word "There are too many cars for the amount of "3 q3 X0 A# M) f6 m" M3 {9 R0 h
                       "road.  Either increase the amount of roads "9 r3 ^; n% @4 p  P. `
                       "by increasing the GRID-SIZE-X or "
" E% f1 ?; Z1 F1 s                       "GRID-SIZE-Y sliders, or decrease the "4 A& x0 ?9 U- T' D* V
                       "number of cars by lowering the NUMBER slider.\n"
0 [9 H' ?" n3 K  W! F$ s: f                       "The setup has stopped.")" z! H  g. K  j3 Z( _( U
    stop5 M& |6 Z# \" r- p: x  {  X2 o
  ]
% l1 u8 I  v) o3 J/ [$ H& l% o* ]  W6 g' s# N% n0 x' |4 Y
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color! L3 @; l5 _2 t" S6 w* H( z
  crt num-cars
% ^; v' Z, B' F" P  }: J0 I. g  [
, h9 u; D! d% H2 p$ Q1 k    setup-cars
8 S8 ^4 W9 _  Y; }) Y$ h    set-car-color$ p  I( r' k- Z# K
    record-data7 _& z; b$ Z8 N+ A' H
  ]
5 }$ K+ i% q% @+ C1 N5 e
7 |) J  V) f! d6 p  ;; give the turtles an initial speed
: |9 Y+ r& H0 K; D5 h- h# h  ask turtles [ set-car-speed ]
, B% l) i/ D5 a" q3 }( N9 `6 K
: O; \' z2 N; P% U$ M4 ]7 M  reset-ticks
- N1 C, V) {7 ~. cend5 Y% c6 Z7 M* c
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;; Initialize the global variables to appropriate values) K' z2 l0 l4 M. \
to setup-globals- X3 L7 b3 C' ]! Y% y: E$ F
  set current-light nobody ;; just for now, since there are no lights yet- Q3 C, B" W. i( p+ I
  set phase 0. `' C2 f/ Y8 a  F
  set num-cars-stopped 0
# ?6 [4 z7 P8 w  set grid-x-inc world-width / grid-size-x" ?3 y0 j% t# i. f5 ~: B7 Y- P
  set grid-y-inc world-height / grid-size-y( e- x* x. ^$ I9 C* O" M" R! o

$ w* t" N" d+ v0 n6 B: \- p  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) S% p7 ?. X+ m
  set acceleration 0.099
: x9 |: P. ?, b% n0 o: ~end* H  e& I4 Y" }0 w* C5 D0 g2 R
! X) k2 n  O5 L
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
) d8 }9 P* Y) p  o;; and initialize the traffic lights to one setting& z4 e3 w. A3 V2 p
to setup-patches
& e0 Y1 e; q; i, ~% H' x4 e0 E  ;; initialize the patch-owned variables and color the patches to a base-color
$ e+ Q  R6 R2 M8 c' p! ?) O  ask patches
+ D  y; Y! _3 ?5 f! j" K5 X  [
! L: [1 ?9 I7 K, H4 l# s* z    set intersection? false
% h5 ]+ \6 i- I    set auto? false0 m! |2 d7 T7 z, h% O
    set green-light-up? true* c7 M0 x) j; w1 N  G0 t( d: V
    set my-row -1: Y* D& ?' \& {) e( A
    set my-column -15 H5 f" G7 G, Q! R& M
    set my-phase -17 c) {  X; ^1 J2 E: b
    set pcolor brown + 3
# Z! J  J( R2 w* t8 u  ]
2 b2 k# r2 c* F
" `$ R* V, X# V  h$ I& Q$ m  ;; initialize the global variables that hold patch agentsets% K2 ^7 s( {# ?# D- r& F/ h
  set roads patches with8 k2 T% C$ k( b+ B. N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! r1 ]2 J' |6 q: q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: V, g" {& a, k5 m
  set intersections roads with$ |7 m/ u' M8 o+ W) T( {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
+ z! ?' ^) ^3 |5 M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
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  ask roads [ set pcolor white ]6 U8 |3 s& t+ m. ~" r3 B
    setup-intersections
2 }( i/ ]5 Y+ `3 z4 c- ?) |1 ~end
9 T$ e6 Y" [4 d; z; t8 @# I# _其中定义道路的句子,如下所示,是什么意思啊?
0 h/ H4 L3 Q- j! f, \2 t: n" G set roads patches with
" K8 G* c9 \% Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 |) R8 s0 l6 h+ J  Y- B/ Q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ R7 p# t) o, o6 R3 ^  l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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