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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。
+ B4 k- U3 k- _, g* ^netlogo自带的social science--traffic grid这一例子当中,+ g1 ?  F0 T% X) H& J9 z
globals
  g- `. k$ i+ k( w1 T[4 @8 E3 V- T( b- e; x0 J
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
! c  O' H, o8 b+ \5 A( E  grid-y-inc               ;; the amount of patches in between two roads in the y direction, r, h9 f6 I7 E4 H8 i+ _/ S, ?
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
: Y4 ~% W* p5 A7 \2 }                           ;; it is to accelerate or decelerate
* ^3 W" j( j- i* d- L  phase                    ;; keeps track of the phase  l* D3 l- q5 W
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure6 t% b- c, l4 q6 }1 F: S: d- ]
  current-light            ;; the currently selected light/ h* O0 R1 i. O0 w% m0 K, |

& V- H( K5 b7 w& O  ;; patch agentsets9 B/ Q: s3 V9 x) a* D3 \
  intersections ;; agentset containing the patches that are intersections
! K; O& I! Q6 e- H8 H  roads         ;; agentset containing the patches that are roads/ c+ w, M" c( Y/ {, I" S6 d
]
$ h, |4 q2 \( F2 Y( |3 q/ o! `  N0 {5 S1 |- {2 j
turtles-own8 u2 X0 U7 j0 W. J
[( K5 j5 c8 \! Z( u; q( L3 m/ S
  speed     ;; the speed of the turtle+ W/ D0 U2 I# L3 R, J0 b
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, U' f; O8 H0 m
  wait-time ;; the amount of time since the last time a turtle has moved6 Q. ]0 Y3 L- @; P( X- Q
]& f# q$ F2 a7 G" G( k: c
2 F) m$ [8 n+ f& D/ V$ C2 p
patches-own5 c3 l+ t# v' [0 p1 g
[
: K: t& F9 _# |( w  intersection?   ;; true if the patch is at the intersection of two roads
; n; M* _1 {+ S  I' l9 F  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
; g2 l) {# T; Q* ?  A' |                  ;; false for a non-intersection patches.
, P2 L: Z, h# j4 ^: R2 e+ j  my-row          ;; the row of the intersection counting from the upper left corner of the
2 B9 B+ q* s7 a& d, m" ]9 F$ C                  ;; world.  -1 for non-intersection patches.
- Q! A+ b' `; ^9 F  my-column       ;; the column of the intersection counting from the upper left corner of the# ~# ^( L3 m! O: T
                  ;; world.  -1 for non-intersection patches.; C, W( V9 c# _: `* o+ n( o8 ^1 {
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
+ H  V$ m3 O6 K  auto?           ;; whether or not this intersection will switch automatically./ L; U% h, J1 v: U) _& a
                  ;; false for non-intersection patches.
6 x) F6 t; R" L, ^. v]
( P2 V/ w* T+ J% j; N4 `2 c! k/ G8 C) p* g$ ~3 A

- B( L$ c8 O# K- y5 P;;;;;;;;;;;;;;;;;;;;;;
8 O- ~" O' n7 d( W# U) ~;; Setup Procedures ;;
* ], f+ v6 d6 N, _, [/ R; Q3 Q$ G+ B3 S;;;;;;;;;;;;;;;;;;;;;;
+ l  z% z% @7 o5 u. c+ E5 x! r4 C
;; Initialize the display by giving the global and patch variables initial values.3 R$ `: w1 x' P" |2 W8 n. K. _
;; Create num-cars of turtles if there are enough road patches for one turtle to
* r  F0 }  d3 u7 E;; be created per road patch. Set up the plots.
: t: E! X; {3 y3 O2 ~: bto setup
  J: l0 w0 W+ J1 C+ G  ca) o% L4 d  u/ T
  setup-globals
9 Q; F3 y7 B) m% e7 s  p! ^
3 w4 N  }6 e, I' {9 V% T  ;; First we ask the patches to draw themselves and set up a few variables# I6 l9 v  y6 @* R& Z8 ]* L/ m" t# X, }
  setup-patches) A9 b, T5 H2 x  {
  make-current one-of intersections
: q' q( U: x  q  d0 r  label-current9 ]  m; {( {, h9 `/ N; {) e

3 l6 K0 v& A& A1 f" |* R* w  set-default-shape turtles "car"7 N) {) r. [& Z6 K8 j
0 b0 i& \, O0 w9 Y0 G  \% q( X+ j( F
  if (num-cars > count roads)" S4 |/ C9 c6 v/ r
  [( o/ [; h/ r3 _& }7 d! I4 X
    user-message (word "There are too many cars for the amount of ". H$ M* T9 |: {* h5 C
                       "road.  Either increase the amount of roads "' ^- H' k; D, s( Q' ?/ J+ }
                       "by increasing the GRID-SIZE-X or "
4 r/ K5 u5 q' }7 t  R8 z                       "GRID-SIZE-Y sliders, or decrease the "
1 g& T  P. j0 A3 j0 l5 g, j                       "number of cars by lowering the NUMBER slider.\n"
* ~* V, R* U8 S% |1 v3 q% T' c                       "The setup has stopped.")) ]. l8 Q$ J4 Q
    stop8 \! t; F2 f% b  v6 n# h! I
  ]6 }& M( ?$ [( Q, E
1 ~8 x, d% b& U% H# I- v" a. O) Z
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
/ O+ G0 \8 K. p/ T3 p+ S9 N  crt num-cars
4 \& ^  m" @; z" o5 {/ `  [
7 r/ i0 @2 f) ?) s    setup-cars
" K; V6 @  {* S5 O$ K8 _0 s    set-car-color
1 M, ~- e: E1 E0 B$ P+ q    record-data- Q6 {; x5 k6 h( o
  ]
7 v% k5 `7 `& T* R4 B- Z
8 i0 L' q# A7 s; |: Y  ;; give the turtles an initial speed
' `1 j4 ?+ r! B6 \& T6 d4 `. l  ask turtles [ set-car-speed ]8 b& K8 o: l7 r$ O+ m, D

" b" z# q2 S9 Q8 L' Q  reset-ticks1 S" L2 \- I( K9 f/ |4 _- ?
end
* M- [# k6 p3 Y# w  C/ S8 H. o( S  `+ D( ~' @- c6 t; L
;; Initialize the global variables to appropriate values/ G4 {3 K0 r9 H+ r) D$ x7 a
to setup-globals
4 F8 x4 ?2 W" r' m/ r  set current-light nobody ;; just for now, since there are no lights yet
! _8 g' F4 W( H  H! B3 p8 |4 b0 a2 L  set phase 0: V, L  l" r2 }' {% ]! u
  set num-cars-stopped 0# ?) R7 T+ i' y  m, _6 x* a4 r0 ^1 @
  set grid-x-inc world-width / grid-size-x6 \% A1 A: D7 V* H- w
  set grid-y-inc world-height / grid-size-y4 U( q( i. g8 c( P6 G& i1 x

  W7 q3 h4 n9 V) F4 _  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
, V  M9 V# m0 f# O' B' V0 `  set acceleration 0.099
/ e' G. L: S& L6 k+ v/ e2 `end/ E$ x: s+ i4 J- A; T+ \7 O: F
3 W. j3 |- ]$ f% u0 h; X! O/ Y; \/ [
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
" K5 A9 s$ C8 h4 s' `* M;; and initialize the traffic lights to one setting
3 H  y$ \0 p, ^/ X- A$ f: dto setup-patches/ r) a* h4 B1 Z, }
  ;; initialize the patch-owned variables and color the patches to a base-color3 Z6 F! k6 X- e" H# f1 V% }
  ask patches) s2 ]7 ^: f; P( U# a) F' y6 w  M" z0 ~2 j
  [; u  o; A! G( q" f
    set intersection? false
- G! f6 v: v" V* H# a% Y! T    set auto? false4 h& J3 D1 L+ ]' ?$ ~8 E0 W
    set green-light-up? true; H( J) |( D+ N
    set my-row -1
; q8 }( w. B8 i- u+ ?$ E9 S    set my-column -1
6 W- s. V. B' n+ Y' u8 \; u/ X    set my-phase -1
% S! w  b  r& M7 m9 c    set pcolor brown + 39 f0 z# x# m& Y7 e- d
  ]
  J/ G  K: W; {1 ^; n  [
/ y& T7 e) s& {: S  ;; initialize the global variables that hold patch agentsets( \0 s9 A9 ~4 [& v/ x
  set roads patches with
/ k9 b. F. a4 ^* c2 E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* H& p; f, ]; f2 t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 g1 m* G. J" j$ H* [
  set intersections roads with" J' i+ O8 C3 }, z& r+ ?) y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
) L3 g% e! S& f7 X6 R    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% T1 P; M: w( x
8 I6 f0 u; {1 w" N  ask roads [ set pcolor white ]
' [* a% k+ v  Q  }    setup-intersections
) c1 Z, _# B/ d: ]( |% vend
9 x) n: c) k+ D' v其中定义道路的句子,如下所示,是什么意思啊?
6 \- U7 m( }" X set roads patches with1 k0 a+ j+ M( \6 M) S0 J+ @: Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% |: d5 c7 \/ ^% d# `6 b: i6 F3 K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# G3 R7 Y' V# t! q% O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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