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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。, S. h. ~+ ~# ?# N2 \0 o
netlogo自带的social science--traffic grid这一例子当中,2 y& E9 ~' I& f" L5 u! b( e
globals
: w4 r, d( i/ }. @; y/ U8 z[
9 r$ A/ {1 C) q: a0 n6 l  grid-x-inc               ;; the amount of patches in between two roads in the x direction" w. k7 z; c7 I$ \- I' l
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 {+ p5 I8 m! ~, O4 N  acceleration             ;; the constant that controls how much a car speeds up or slows down by if% |* w1 I5 i" W$ w4 I4 k: q4 M
                           ;; it is to accelerate or decelerate
1 t% `* ~/ o% R/ M5 H  phase                    ;; keeps track of the phase
7 u. b3 w/ ^9 t  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
6 q5 a6 z. a6 X, x- B$ ]  current-light            ;; the currently selected light
! H+ H/ r3 P2 f9 W' P4 y* Z  H5 l2 `+ D& U( t, Y. o
  ;; patch agentsets, g$ `+ ]+ c+ ?0 E
  intersections ;; agentset containing the patches that are intersections! P8 U+ W+ P4 C! G; J
  roads         ;; agentset containing the patches that are roads
: K. U8 q- n5 u' C0 A  f5 A1 ]]
) V" D2 p" G) w) g0 Q' I, t: p& H4 }. z0 C! q
turtles-own: K; ^) K3 W* [: p0 n
[
8 a- D& _- f3 {) t9 e  speed     ;; the speed of the turtle
9 j9 D. a8 ^7 J/ d  n  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
/ L0 H& v: R. ], x2 n) e  wait-time ;; the amount of time since the last time a turtle has moved
! ?  Z0 [6 |3 A6 C, O( ]7 e]5 Q0 H: A$ d+ s* ?* Z5 O7 X, b

! k, k6 \! u: G2 b* g" N0 wpatches-own
  s6 C, N* y1 W) u[
( h' R3 t+ r/ f" T  intersection?   ;; true if the patch is at the intersection of two roads
. A3 H6 _) J) q2 y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
7 y# X, O' J& H: r$ _( J. N                  ;; false for a non-intersection patches.; }1 Q  z) o3 A
  my-row          ;; the row of the intersection counting from the upper left corner of the
6 H9 H, ~, P: C3 a3 _, d  ?                  ;; world.  -1 for non-intersection patches.
8 @; n; S, J  I' r9 e: q  my-column       ;; the column of the intersection counting from the upper left corner of the
, |3 r+ c" J2 |- |                  ;; world.  -1 for non-intersection patches.1 g- v7 a$ G+ x. z& d
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.8 \+ O& s( P  g) J
  auto?           ;; whether or not this intersection will switch automatically.
# ?% H1 I9 V1 \! S) I( F                  ;; false for non-intersection patches.
( a: M% u; k8 Q, ]% g' _3 P]
+ F% b9 f2 ~: g+ K- \2 u0 W  ], e9 C
% g8 I, X- y# A: l
;;;;;;;;;;;;;;;;;;;;;;: j  w& _( m) m. V9 ]0 H$ ?" j0 V4 r
;; Setup Procedures ;;" ]+ G0 C0 X. }9 h  e" ]! ]% N
;;;;;;;;;;;;;;;;;;;;;;
; o3 p  y! i8 m+ {  x2 n: K& ^# o3 u
;; Initialize the display by giving the global and patch variables initial values.0 v  s& C0 r) h3 }3 r. ~0 K  K. Y& U
;; Create num-cars of turtles if there are enough road patches for one turtle to; u, O4 x( p! z$ S4 C4 a
;; be created per road patch. Set up the plots.6 N% G% g# I' b: L' H
to setup* D8 g2 D% Z, E  g
  ca
  o7 A, T4 ]/ ~  setup-globals
' f8 l$ d2 F) U: G9 {. X+ V; `" c  f9 q  n0 w. e1 g; e
  ;; First we ask the patches to draw themselves and set up a few variables+ `. H5 u  g2 e# E
  setup-patches
3 g. P# Y: [  [+ ?2 _3 O$ Z  make-current one-of intersections# U8 a! C. v' i; n" q, ~/ m
  label-current
" ~+ u! y; T1 T- O5 I# Y; }/ g6 S, y" P  V/ n' ?* `' F; J( Z+ v1 L
  set-default-shape turtles "car"! Y3 W$ p/ U; \) \& a- U) Z; K2 l. {; g
2 P8 d8 Y3 U4 ^; e5 _% _
  if (num-cars > count roads)0 h" g* c7 |% I+ s& g: I5 L
  [
: X- ^9 m9 @" N3 M9 C" _! b    user-message (word "There are too many cars for the amount of "
) w) ?5 m& @7 P) G& |. h                       "road.  Either increase the amount of roads "3 T& i, Y& X5 S# I' h! t- V
                       "by increasing the GRID-SIZE-X or "
+ g* [& |  f' R- V                       "GRID-SIZE-Y sliders, or decrease the "
; ~  _. [- N, \2 x                       "number of cars by lowering the NUMBER slider.\n"
0 X; }7 E0 K* k                       "The setup has stopped.")
* }8 [$ u' E6 N6 J, @- n4 i    stop
/ L7 [# B' k$ J1 c. ~  ]
6 `9 |% D6 }% h6 p. u! r% s: v, D  k: x4 M! O% q
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color' {# u* d8 E! A. M" d/ Q# P2 `7 v1 c
  crt num-cars
5 E# q# A/ }( [( ?7 M! I: x4 e  [
1 |5 z8 L! ~9 Q    setup-cars
$ {- E. A* I4 b( w2 t    set-car-color
+ b6 E/ i" H, x6 O& o: r  C    record-data
, ]* p; ^. C6 E5 f  ]
$ X6 p0 b: K# S: y7 D4 q+ c0 V0 n; R/ E4 v" V! X# @/ _
  ;; give the turtles an initial speed$ {* _; L3 Z+ F, r8 x1 \% e
  ask turtles [ set-car-speed ]
% f5 P2 b* c  o3 F# C5 W- L/ N% P/ j- ]6 O2 H' n
  reset-ticks
: @( g. v$ Z# Z& hend% n( |# N; ]4 E# W# o
3 _% f( j0 r4 h; i1 M
;; Initialize the global variables to appropriate values/ r+ A* `) @3 i+ ^3 K
to setup-globals3 q4 \: R' J/ b; a6 {1 ^
  set current-light nobody ;; just for now, since there are no lights yet* c0 ], C0 z5 h6 g
  set phase 0
$ b6 N' ]0 S; ~! |  set num-cars-stopped 0, U" k" l' k1 W4 R9 V% Y. `% P% n
  set grid-x-inc world-width / grid-size-x
$ O7 t) q* G8 ?3 d; C0 h& p  set grid-y-inc world-height / grid-size-y
, I) T' x/ s! j/ M  i
4 ~) Y3 G# k- j6 H* X/ ^+ M  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) @9 k+ L( l$ P
  set acceleration 0.099  e8 j' j, E( L
end
$ ]; e3 E9 @1 [1 g* f: u5 _! }7 ]* X( _  g) W) j
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
' v3 a% @0 ]8 w& O, a  o;; and initialize the traffic lights to one setting
0 E" u" [+ J% ^5 T7 {5 D/ E* qto setup-patches
. q3 m+ Z2 k+ }& |3 h  ;; initialize the patch-owned variables and color the patches to a base-color# S  ]) x# e$ d! j
  ask patches% ^$ ?& O8 o+ `: e7 H& z
  [/ \- c1 W2 A% C' X
    set intersection? false
4 o0 Y: L1 n+ o& ~' P    set auto? false' `% q, p2 ]1 G
    set green-light-up? true
7 h/ P& n# Z4 @* C0 t' g& i" H. {$ r    set my-row -1. u$ d  E% {/ X  @6 W
    set my-column -11 B2 s6 u. c# q  Y: ?& g; p5 D# E3 V
    set my-phase -1$ ~* n$ s  ^8 [! B
    set pcolor brown + 3
3 B. F( j+ [$ j" y  {* ?  ]6 {6 W" [2 {' S

! \  @6 l1 m3 I8 {  R5 R) ]  ;; initialize the global variables that hold patch agentsets
  o% P! P2 J! Q  set roads patches with
( e+ j' A4 Q" ]9 L' ?# T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 O9 B! n: b3 m1 o  E: D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" M" A$ g# u1 J! W5 U. k4 m
  set intersections roads with- [) m1 a* T( \" v, x/ l3 x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
# F/ x  D- W9 {7 C    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 p6 ~' C0 I: h5 r  W* ]5 l  i5 V0 \+ k
  ask roads [ set pcolor white ]2 g9 F9 B0 b9 z8 V
    setup-intersections5 b  D% Y! v5 M  s! G$ L$ A( @
end
, S1 O5 e0 Q% Q: u其中定义道路的句子,如下所示,是什么意思啊?
4 k# c# }$ C  j; q; O: x set roads patches with  {! @2 U' y7 F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ y( g$ @. `. c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 A7 M4 b1 Z1 t1 e8 _/ t- F* 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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