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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。0 }# {' t; e+ y( S9 w
netlogo自带的social science--traffic grid这一例子当中,) W% [/ ]. B6 V
globals
" G5 X# s# ?; m# @  g[$ J8 l; V% _  S4 J
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
: H% H5 [" O# t8 l7 ]. l6 n  grid-y-inc               ;; the amount of patches in between two roads in the y direction, R  ?% E' q! F' g2 o4 s
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
% \: k' d; K7 M                           ;; it is to accelerate or decelerate
7 x+ |5 \2 c. d  o  phase                    ;; keeps track of the phase
! b; G8 m+ I) p  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure( `, A7 G1 y2 K8 v5 E
  current-light            ;; the currently selected light7 ~( _5 s. p& ?% [# ]

; _/ Q/ q' w8 G  ;; patch agentsets
3 `: I7 W. Z4 u4 @/ s. U  intersections ;; agentset containing the patches that are intersections+ e4 {! E, f7 ?1 i/ w$ `1 S& v
  roads         ;; agentset containing the patches that are roads
' G# g3 c8 K4 ~) w3 [2 N]
% \) L) m: X# [$ p# H  d; W6 H0 s4 E  [9 d  a6 _: e* e
turtles-own6 r7 n+ B7 G$ b4 ]
[3 {+ N+ ?; N7 H) p! m, \' b
  speed     ;; the speed of the turtle
. L" ~% |. T( k; T9 {1 W, W  up-car?   ;; true if the turtle moves downwards and false if it moves to the right6 `; W- ]" i- \4 w
  wait-time ;; the amount of time since the last time a turtle has moved
: @* Y3 v- Q9 X]
, C0 {1 m7 |9 `* q' G$ i2 V5 B
* F& B$ i7 y, I4 ]4 ~+ ?: Hpatches-own% i2 N1 @) ~$ y& e' ~5 @# v) o
[
/ j8 \' C% O; y7 O  L" |  intersection?   ;; true if the patch is at the intersection of two roads
5 o! z/ \/ _* g$ ^  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.8 @: t) g3 L5 P; i, h" ^
                  ;; false for a non-intersection patches.
3 D+ Q! ^* \8 d- ]( l  my-row          ;; the row of the intersection counting from the upper left corner of the% {! r& L9 o/ _! g( b* P9 f
                  ;; world.  -1 for non-intersection patches.
( e: e2 q0 o4 W, U6 ~  my-column       ;; the column of the intersection counting from the upper left corner of the
# O8 [+ W8 J$ }& x  Y6 c                  ;; world.  -1 for non-intersection patches.
- ^$ {. Q! |( |  `7 q  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.( E" C7 |5 z) G, G" W0 }
  auto?           ;; whether or not this intersection will switch automatically.
: m6 E) G" Q6 e  G$ y; c1 ]1 r                  ;; false for non-intersection patches.6 [2 b" F1 L: n, j3 k
]0 j2 Z; ~. k' b3 y( V3 ~
* y# V) `& n2 G# {+ l9 k# Y

" q! v) p* @. d- P* l" Q& Z;;;;;;;;;;;;;;;;;;;;;;
) t) }! E! q0 ^, L, q# V;; Setup Procedures ;;
$ E( a) U4 e1 I;;;;;;;;;;;;;;;;;;;;;;
. Y  [) \3 H3 v: F% F" F7 v! B0 z* J* R
;; Initialize the display by giving the global and patch variables initial values.3 I& e/ A% S8 G: P2 D
;; Create num-cars of turtles if there are enough road patches for one turtle to
* w( p" a; a  N9 ^;; be created per road patch. Set up the plots.
3 H' e9 X" P. _3 Vto setup5 n6 x% q/ p1 q' m1 l1 y
  ca: G! w$ l/ T. L. `' [
  setup-globals
; L) Q( e  t0 z9 ?4 A. u. p
  S  ^8 k5 z& p6 n6 w2 m; O  ;; First we ask the patches to draw themselves and set up a few variables& `* h4 n9 p9 ]) I5 P- {) g" Y
  setup-patches
! F- |4 t% S. ]" s5 {: L  make-current one-of intersections
" z* N. k- y& b! f5 K2 _  label-current* K  s0 H4 h" q# ~  s
; G# c; f% Z8 H+ u1 k) }
  set-default-shape turtles "car"- s+ h, e! [' T2 V1 l! |

! j$ p' X% j* _8 Y% Z  if (num-cars > count roads)
2 u. f0 K( l; l& g  @. O  [& V: j' f# N5 S. G# V. S" Q/ h# ?
    user-message (word "There are too many cars for the amount of ": M/ ^+ o0 a, V) L0 i9 }, H% S
                       "road.  Either increase the amount of roads ") |+ }* ~3 H: b) c3 V6 ^
                       "by increasing the GRID-SIZE-X or "
4 h) F: ]7 U& s* _( C3 Y- \) P  E                       "GRID-SIZE-Y sliders, or decrease the "
- F+ k* l9 d& C+ c" s) e  t                       "number of cars by lowering the NUMBER slider.\n") J9 T& W: x  z" J* D& G
                       "The setup has stopped.")
6 c6 a* q- Q: F% L4 p    stop
" c/ h) Q9 j: `9 W' n) \  B% ~! D; X  ]9 E5 F1 @$ [7 i7 z& \
# y/ X9 O& F# m0 U1 g% R
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color) k+ z9 U9 F7 ~* D# h- E
  crt num-cars
# V: B0 V9 }6 A; R9 y  [: P  [  S7 ^9 g# k* J% ^; r$ Q
    setup-cars
4 N7 J% k8 k) A' \, L- W# I2 h2 g+ `    set-car-color
' O0 B* u' j8 d9 s    record-data
8 I5 e1 S# R4 @& K  ]/ }: S7 b, ~) ^, b

: M% ]3 m0 e1 t' M5 U5 @! Q; t$ Y  j  ;; give the turtles an initial speed
8 t- ?% X- ?, E/ h( k  ask turtles [ set-car-speed ]/ r' e& _' Z* G

9 u' f# l' A+ j$ U- T  reset-ticks
( w  K: x6 P  M2 Nend" J6 S( V% i% r8 o$ `0 \2 ^

: y; o# E; z9 W, y% W9 J3 Z% D;; Initialize the global variables to appropriate values
! j9 ]. d# u8 Cto setup-globals1 k0 `! ?0 c. P9 \9 ?
  set current-light nobody ;; just for now, since there are no lights yet; s* I$ _4 K5 G( A! {- S
  set phase 01 X  U/ Q4 Z9 X2 c  I* a
  set num-cars-stopped 0
) X  y: t* H% b5 O7 N8 \6 @% N  set grid-x-inc world-width / grid-size-x
; ^0 w+ U* N2 v% t% r  set grid-y-inc world-height / grid-size-y( v0 a# n0 N6 |5 q8 S: ?! f, \
$ E4 T% n, M0 c$ j' F
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 L3 r% A# y$ u3 n1 U
  set acceleration 0.099. D% s; L1 g6 @2 ~& c8 A
end2 c& \( t( O$ `& }4 F: L2 B& Z

4 L) y# f, R2 Y;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
) t8 M" @/ B! Z;; and initialize the traffic lights to one setting- J8 y; H# n% ?
to setup-patches5 U) ]( a- {$ M1 E+ R: J: X- `; }
  ;; initialize the patch-owned variables and color the patches to a base-color
7 t" D& w6 H7 w" E  ask patches% m) ]# l9 Y) t1 F4 T
  [
7 b. f0 r! S% k: R2 {/ j/ p; ?    set intersection? false
& p3 o, p3 h9 P- K! n! x5 A% Y3 a    set auto? false
: x5 e7 r4 l' z% n1 q4 V. @' m    set green-light-up? true
( l! o; e: @0 f  |    set my-row -1' p, ]% W% A& L9 {
    set my-column -1
- ]( N( Y' b. n7 h4 L# c, v6 C; Y    set my-phase -1
: w! j* U7 N6 F3 |    set pcolor brown + 33 @- U& l; a4 Z: w
  ]0 e: S3 X2 {2 M8 [/ h8 k
, n' x9 _, U7 _0 o- G
  ;; initialize the global variables that hold patch agentsets/ J& U4 G3 V5 z) U. a( i' A4 f
  set roads patches with) j) h) _8 G& R% \' z) t. [) v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 [. c0 E- t( n1 i. I: C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! r* s2 _0 w! J$ h8 h  set intersections roads with
8 I1 l5 O( l* K; ]- k4 M, p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and3 e2 g- y( @3 ~& v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 v3 R% h0 M( P  j) R
& S6 V8 t$ p; S5 B& k
  ask roads [ set pcolor white ]* @2 v  c  K+ k( G- d/ q& y
    setup-intersections1 {& n4 e# a7 @8 ^3 q2 ~
end
: |& ]  F& V7 l$ h其中定义道路的句子,如下所示,是什么意思啊?
: u9 F4 a- q. \ set roads patches with! U4 z) O; D# ~6 P* @( X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) `4 F/ d5 [1 C/ V! F1 B
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. p% N' i% ?( R
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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