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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 K  ^* _: ^# J
netlogo自带的social science--traffic grid这一例子当中,) n5 a7 g# ~1 a1 Z
globals0 f2 x. t0 g! b9 w
[
$ u4 N) }2 Q0 v  R/ i$ N  O; B  grid-x-inc               ;; the amount of patches in between two roads in the x direction
: U1 O1 e" y* C+ l! K' H' H& f0 j3 Q  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! i: R2 Q, M& h& p# X4 r- I  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
- D4 @  Y2 u% Q# I                           ;; it is to accelerate or decelerate
. {' K9 Z- k# G3 q* I: m7 T) `* ~  phase                    ;; keeps track of the phase
: ^# {  Y  A6 J' K8 N- f  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure2 ^5 {: q9 z$ Y/ W# [. g$ x
  current-light            ;; the currently selected light1 A! g; _2 z% N$ O2 B

  \  {, ^" k6 C; f/ \1 S: D  ;; patch agentsets
4 L, s/ e0 M6 ]! O2 }% I  intersections ;; agentset containing the patches that are intersections7 s8 _  |4 `, I( \; V1 b
  roads         ;; agentset containing the patches that are roads
0 F/ N4 Q* V  K9 P]
; w: x, M$ B" P/ z3 l3 @- i5 F% O% D0 d* }+ a( M
turtles-own
& A! o7 {$ L; R( @+ d. k[
- ^1 m4 q; c* C' L1 i- ^  speed     ;; the speed of the turtle* a: t8 E: G% k; \* }
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
. X; W: C8 e9 m/ t/ m- j  wait-time ;; the amount of time since the last time a turtle has moved8 S' ]2 T5 s8 J6 z" Q: ]$ H
]
6 |( v9 R/ l+ _! P+ |& b
0 Q; Q5 p' u; w- qpatches-own
0 B) E* L8 x  n  K. l[
9 u# n, p5 n. s* n( g; p  intersection?   ;; true if the patch is at the intersection of two roads
2 [, i3 E3 U# Y8 W  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.4 y* F, p. L0 [) c- i( K
                  ;; false for a non-intersection patches.
2 y. N. w" I' n  my-row          ;; the row of the intersection counting from the upper left corner of the
9 v( T7 h" s* u6 i) t                  ;; world.  -1 for non-intersection patches.
0 w5 P5 K# u6 J# h) ?, e9 _! I' J  my-column       ;; the column of the intersection counting from the upper left corner of the8 p. p+ X$ ?; h1 T! W2 h$ O
                  ;; world.  -1 for non-intersection patches.
& _6 A4 p1 }8 {# e$ [; I  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.' Q* r2 ]/ n" t# @
  auto?           ;; whether or not this intersection will switch automatically.9 g; I# Q2 j" n" X1 a
                  ;; false for non-intersection patches.
' ~: x+ n$ }! L& S! }" ^]$ `5 C. V; Z: Z* D$ W& e3 _

, F- M  C- F' s4 _% Z( f" A' W- t0 s6 N& v% R* T
;;;;;;;;;;;;;;;;;;;;;;
* }% }% p- n; t; G;; Setup Procedures ;;" x6 @7 R  r; z2 h; ^" N% Z
;;;;;;;;;;;;;;;;;;;;;;
3 a. j8 F$ e% V; h5 w1 d
; P  H" r% f" m6 v( K2 y;; Initialize the display by giving the global and patch variables initial values.
  i, y7 i+ \" ^( z" [* I. x+ P/ |;; Create num-cars of turtles if there are enough road patches for one turtle to
2 d( O  k# C- v. o2 r;; be created per road patch. Set up the plots.9 d, `% ~5 J: G- y, j: G$ v7 x. Y
to setup4 s% t! O9 L, h6 u# Z" i
  ca, `& _$ S* A8 K  z! q
  setup-globals
2 A) b; O( v( g$ @7 K3 Q. ]2 I& f$ h' E" \# v9 }; I8 G
  ;; First we ask the patches to draw themselves and set up a few variables7 v3 ~' ]8 h- m2 [
  setup-patches" _) j* c# \8 J* t* ?% A/ Z+ N. B
  make-current one-of intersections
7 x' f% i9 z7 B4 o- D7 D  label-current" Z: U) [- h  J
# V  n) x$ Y! N! v  u, _, z& v
  set-default-shape turtles "car"
/ @6 h- T; v' G7 T6 b7 p
; i3 h& b4 I+ E  if (num-cars > count roads); O9 Y2 Y9 P5 E# O5 Z& ?
  [
' f" U% p, m5 l6 q1 G    user-message (word "There are too many cars for the amount of "9 V4 c; Z: ?* @) k, j
                       "road.  Either increase the amount of roads "* g2 x0 _$ t5 i, b+ O
                       "by increasing the GRID-SIZE-X or "
2 t- \+ H" J8 E9 O                       "GRID-SIZE-Y sliders, or decrease the "6 S. O' s: M4 b! b7 s) c
                       "number of cars by lowering the NUMBER slider.\n"& l) f! W2 Y. o, k. {* g- y: J2 g
                       "The setup has stopped.")
; L1 f& \5 o( A6 j- e    stop
4 ~; ^6 F, b  C  D, W/ |+ j  ]  ?7 i4 S) O& w! t- g" B3 o
  j9 B$ M; v5 t% }: l
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
" V: I+ ]6 S; l5 U+ ^; r* t  crt num-cars$ ~5 b# H# L* _
  [
1 n$ c. \- i( Y6 Q    setup-cars" j6 A. f8 w+ K. N7 L. f/ p
    set-car-color; O5 ?5 P# C: h* C  K
    record-data
% C% a" f' n, g( q+ ~4 A  ]9 J" N! J' k# ]  @

1 J& u/ a( L7 b  ;; give the turtles an initial speed
- H$ O6 @& @, c! ^* y- ?  ask turtles [ set-car-speed ]
) X( _- }2 v1 f; I3 |, g0 E2 Z5 O! a2 V0 T$ P
  reset-ticks
- Z% E' V+ R% n7 y& q  c" p9 q" R( Lend8 |9 P1 O+ x$ j- s# h' _

* G# E! e, ]1 _& S0 Q0 Q;; Initialize the global variables to appropriate values
: t6 m( Z5 c5 A( [to setup-globals7 k9 F' [$ T$ _8 [6 c+ t" p
  set current-light nobody ;; just for now, since there are no lights yet& A; I1 o. Q, i( t( `" U2 w
  set phase 0$ q; A$ g/ a  v% q  Z
  set num-cars-stopped 0
1 N: r+ r  z' d4 Q  set grid-x-inc world-width / grid-size-x+ C% ?1 g& o' ?  N
  set grid-y-inc world-height / grid-size-y
: L' _; Q: g5 A1 k1 ]1 v$ G: G  f) u$ ]- Y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
( [2 p4 l2 f; A( x  set acceleration 0.099) @" z5 G! }  |8 v: m/ O6 i+ Z
end3 z4 s$ X8 ]( U* o
4 L1 T9 o1 Y9 L; U4 s: X; M3 |" f
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
! h: E( v! G  x" D$ t. G;; and initialize the traffic lights to one setting9 ]/ I; O( {& k2 d" R5 d' G
to setup-patches- W' G! _8 N7 ]+ S8 \  \
  ;; initialize the patch-owned variables and color the patches to a base-color
) h- E9 H+ Z/ c# I  ask patches
( ]* A. W9 Y' T9 ?' a  [
5 k- e& ]* {% ^" z    set intersection? false
6 u# i, j9 f0 H: D0 `    set auto? false
( v% ~: m' K+ u" X    set green-light-up? true
) l/ Y7 s+ |) k+ t3 S/ @2 f* i    set my-row -1
9 D- c9 s/ }& O5 T    set my-column -1& {, a9 y; d( ~! v1 F( a' I
    set my-phase -1
" V/ h0 w! p2 J! C    set pcolor brown + 37 ?% B# Q5 m# M9 Q; b& X& u
  ]* y/ d9 T" V2 @. i
( a* v! z" k: [: O
  ;; initialize the global variables that hold patch agentsets
* D; W0 `8 D- A$ X  set roads patches with
) V% T( v- Y, ~. Q% R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  i7 l4 W3 ~, p
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* y! @- M' T! r4 \  set intersections roads with- `' _% R& B3 ~1 z: N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and# ^, n) C5 Q5 v' P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 {" D* u' m. Y) t. \
' {8 P/ [& o* i; _+ ]! t( b: e0 _  ask roads [ set pcolor white ]; G: Z( e) R3 l0 O# t. E/ ~
    setup-intersections1 d5 p5 B7 h* v- R9 B; k2 K2 t/ D+ c
end( G, h3 f$ o. L! E1 i& l
其中定义道路的句子,如下所示,是什么意思啊?+ _7 y8 y( j: L& A  x, p2 s
set roads patches with
5 h$ `( u7 z. w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# ?8 R: _' Q2 r  f4 ]5 x& \: b
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: K/ ~, L# P! X/ ]& I
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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