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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。
$ E; G7 U# d. c2 X$ w! ]netlogo自带的social science--traffic grid这一例子当中,
( m4 h, w" b9 ?  vglobals
* W% {0 A" @$ g3 I! W( z* d[2 X1 a' c* d% S" d
  grid-x-inc               ;; the amount of patches in between two roads in the x direction! P3 k0 I5 p3 c( h
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! _6 m, T/ ?1 H  U+ M' \; d4 q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if2 i+ \. n" V. }( q7 f2 r* W
                           ;; it is to accelerate or decelerate" R% y" r: M' B+ e
  phase                    ;; keeps track of the phase( N* L. a3 {2 E1 }, t8 A9 p0 e2 `$ y
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; F7 A! X  J  h, R  [$ c  current-light            ;; the currently selected light7 m# E* z6 y0 z, ]

8 h  [$ u, V7 Q* \. @  ;; patch agentsets
2 E7 p# V- C5 c9 Y  intersections ;; agentset containing the patches that are intersections$ F* y$ s; V! Q( H) K
  roads         ;; agentset containing the patches that are roads( E" E( T# Q* E- V: D$ d: }% b
]' l9 D% {9 [6 n% M5 {9 `- s9 D. F

3 D2 g0 @( W# ]+ c* t; @! pturtles-own7 [+ F6 x1 [' R" V
[
6 h+ G+ u0 p" O1 [% K6 N  speed     ;; the speed of the turtle
" y" \- @- f" P1 o/ z  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
3 j' c7 j9 P9 ~" v7 u& c  wait-time ;; the amount of time since the last time a turtle has moved. Z2 L4 q* n/ e) D" b" m
]; M7 o. S1 V8 t" u: D1 V) j% w
% V& M# [% F  u$ r2 `
patches-own8 w7 S4 M6 v+ ~+ I
[
( u# ~% a; @  V& X, d2 O  intersection?   ;; true if the patch is at the intersection of two roads$ B0 h* v+ C# X9 ~+ y3 g& `9 S
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
  C5 L# U( n1 k! w' s6 L. C: H                  ;; false for a non-intersection patches." s8 Q- B0 A% j
  my-row          ;; the row of the intersection counting from the upper left corner of the3 C5 X# c% g: @; M$ I0 ~
                  ;; world.  -1 for non-intersection patches.; B! V, c2 x' s5 X
  my-column       ;; the column of the intersection counting from the upper left corner of the9 Q9 Q- m+ u6 u( ?' Q. {
                  ;; world.  -1 for non-intersection patches./ ?  s1 C) ~) N
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
6 c* o3 L; C# }- x/ d% W( [  auto?           ;; whether or not this intersection will switch automatically.$ ~0 W; O; {* a; T
                  ;; false for non-intersection patches.6 r9 V! m  q: l
]
) W# C+ x# D. m5 u. N0 E& ^( h: H/ U7 N2 u9 O
+ X6 |, c" x7 A' a# ^" x4 k/ D5 w
;;;;;;;;;;;;;;;;;;;;;;
8 B6 m5 b7 Y9 n! y# C;; Setup Procedures ;;
0 p( o: h# L" ?# {/ u;;;;;;;;;;;;;;;;;;;;;;
6 ^0 S2 n+ G7 B0 X" Z3 ~& _) [  f' c' e- _7 R6 j  l  R
;; Initialize the display by giving the global and patch variables initial values.
% z) `/ c8 r3 f8 Z. O. G;; Create num-cars of turtles if there are enough road patches for one turtle to
; g, |" O$ A! s;; be created per road patch. Set up the plots.
# d  k% R* T/ s) I5 x! Yto setup
# ~7 U6 A6 D7 k- U5 A0 c  ca
# G9 x+ j1 `5 H$ g* I  setup-globals, C6 S4 x& t5 Y/ i0 ]. H

4 |4 n0 T4 S; c" V  |  ;; First we ask the patches to draw themselves and set up a few variables
# O" }8 D" |5 I9 \, g0 \  setup-patches
) [3 H- f7 ^, _( c/ [; k  make-current one-of intersections9 l+ Q# ?$ z  o$ {1 A. ]" {" s
  label-current
3 @3 Y. \4 z( N/ S# D
! ^! V6 }* ~6 w6 M  set-default-shape turtles "car"8 `" V. _- D- C4 m. v1 A9 t7 b! g8 D$ Z
! s, B2 a! c. k( t  e+ O6 H3 q
  if (num-cars > count roads)
% U& B' o  ?0 _* Y) M5 h  [
, o) ^/ S# {9 d    user-message (word "There are too many cars for the amount of "0 s. s1 M9 r) g
                       "road.  Either increase the amount of roads "
4 H: W1 I$ {, y. a                       "by increasing the GRID-SIZE-X or "+ o' v+ n  L* Y0 @9 d
                       "GRID-SIZE-Y sliders, or decrease the "+ d9 o: S# Z) Q$ c9 w: s
                       "number of cars by lowering the NUMBER slider.\n"" B4 y6 v, x9 o! `
                       "The setup has stopped.")
+ j0 U- W# o" u  `7 }    stop; J$ U% o! d4 l, L% w
  ]% n# Z2 s2 y% _1 b, `8 Y5 M( }

  q" j% f' T# s  }  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color6 ]- G& D7 B7 J; h
  crt num-cars
! x& S/ G+ z" _7 k* ]. N" U5 v) G$ l! r  [
5 u* w" k1 C9 c/ a    setup-cars5 |( d# ^% z6 g- G' T4 z8 T
    set-car-color" |) u0 J* l7 P2 X# h9 J+ B
    record-data
' R4 {2 l- i; c( g8 t- E2 K  ]
5 q+ n% j4 L3 Z& G7 D5 }) l8 _
! ?; S2 ]- I5 B9 d1 S3 z- q  ;; give the turtles an initial speed2 Y0 X- D( m# Y. E6 Y. O
  ask turtles [ set-car-speed ]
9 h% W. J. c: A! c& e" v! ]& k0 l% [* @# u5 U5 @; V/ W" m7 K
  reset-ticks
0 |0 x' e) i+ W. I1 Y! nend
! Q: S, F' E1 Z/ d' l7 H0 ~+ h
; F! z9 q( k' L7 C;; Initialize the global variables to appropriate values
( l4 G5 G# D& X" R( h# Ito setup-globals) b+ ~0 g0 R& ~* p/ o- l
  set current-light nobody ;; just for now, since there are no lights yet0 Y- X( U) G5 V' W0 B* @! B; ^% s$ K
  set phase 02 }( c- z+ j& Z
  set num-cars-stopped 03 s# j4 M3 b9 |& @; ], F$ K
  set grid-x-inc world-width / grid-size-x( d* R9 a- b: M' [( Y/ M/ _
  set grid-y-inc world-height / grid-size-y% q; r9 ^+ c4 D3 i! h

. |5 w# m% w- _& J' v0 C: I& r: N  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary* q6 r  o3 P5 {1 [' B8 l
  set acceleration 0.099
0 ^' `3 q# ?( E* yend
1 ^# w) ]8 |. t) [7 L4 c% O- ~
8 G7 r1 P7 t; o/ n6 |! Y4 u;; Make the patches have appropriate colors, set up the roads and intersections agentsets,# |0 H" A+ Y/ Z' f
;; and initialize the traffic lights to one setting' p" D& {5 v  \
to setup-patches* f) P  O. O' Q6 s* }$ X" g  X
  ;; initialize the patch-owned variables and color the patches to a base-color# `! ]* G, O: X! {# w' W
  ask patches( V; T% x$ i5 o3 ?
  [
) v2 r9 k; w$ u' p& T9 x4 K    set intersection? false' f- H; R* J/ Y! d
    set auto? false( J. e* l! F1 L' \$ {( P' W% I
    set green-light-up? true
; J6 t, i/ J7 s. s" @  d1 F    set my-row -1  a; V$ j( N% [$ I9 a
    set my-column -1
; h/ V6 ~7 \8 A- d' G- O5 ]    set my-phase -18 x+ v+ P  C' Q* z6 ^& G: C6 j
    set pcolor brown + 33 q5 O8 x  N. R5 T7 p) R
  ]
6 C  B; {$ ^% C: t9 B& a# O$ d! ~
! ~+ N8 s2 c! b# o) ^8 n* [  ;; initialize the global variables that hold patch agentsets
- D1 n2 P' w- [8 m' i  set roads patches with! \$ {2 g6 y; \6 |* ~
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 K' \3 `1 t: c. }; W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' C$ T. L2 g6 W0 E
  set intersections roads with6 w2 ^6 ~: n2 i8 |! S
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
: _9 p; y! b0 m3 |# y4 _4 c# r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 C" `5 v, z' B8 P0 y, o4 B( _$ l: i+ H
  ask roads [ set pcolor white ]
' w) s8 V% u- P/ n  ]3 M4 j8 v    setup-intersections2 |7 F+ Y% Q2 v# H3 e' B' {
end* R% X  F  i$ {! T0 Q: B; B
其中定义道路的句子,如下所示,是什么意思啊?% G; O  ]! h, z6 r; s9 J
set roads patches with6 [" A' C) V# T! t; R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- Y) E( N" b4 t) e) }) f/ @0 _2 E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 o6 p3 h. X, \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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