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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。
& ^" `- [1 R8 @/ A- l# d- }0 A& Dnetlogo自带的social science--traffic grid这一例子当中,
2 P/ K! a2 F3 P' [globals
  {* P2 V/ h' E  ?& _9 g[) o; f4 r, b8 e  ]  i( C! a
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
+ Z3 z% M4 y3 e+ e+ B  V/ E2 `1 [  grid-y-inc               ;; the amount of patches in between two roads in the y direction: J' ~3 R3 V) W3 g1 n% }& Y
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* L% T2 P' d; X
                           ;; it is to accelerate or decelerate
1 [; S8 q( r" n  phase                    ;; keeps track of the phase! Z( u' H( i; E. F6 d8 d
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
( S* u1 B6 j, D4 O  current-light            ;; the currently selected light
" D! Q6 v% W0 u4 ^7 l. g/ E; ?# q
6 x/ e5 z* P( e! U# A  U9 r6 G1 _: `  ;; patch agentsets
: F5 D- C' U; n- g8 O% ~  intersections ;; agentset containing the patches that are intersections) R0 [! F8 x0 j
  roads         ;; agentset containing the patches that are roads
9 l. M# F+ A3 @! }$ M- Z) w0 e# }]
( Q" o4 ]/ k9 r3 v0 i( ~1 P+ O. K! p3 l% o- n  f
turtles-own, Y% v$ x% ]8 }9 t( @
[
' U# \( I: ^2 c7 p; i# g! Q  speed     ;; the speed of the turtle7 u. b: G$ B- G
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right2 n1 A# C/ _( m( L/ K! C
  wait-time ;; the amount of time since the last time a turtle has moved. J8 L: N1 X, l! S8 j4 t
]/ G: E! y9 {3 T

/ v/ C- e1 M& `" K$ [/ hpatches-own4 k& t& ]5 Q- C$ o0 m3 G8 {( M( n
[! v+ [7 }! C4 ]
  intersection?   ;; true if the patch is at the intersection of two roads" x4 s5 x( {* ^  Q8 Y8 C% y
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.+ o/ B$ @6 B# {) P) \
                  ;; false for a non-intersection patches.
0 E- r9 R9 A: _  ~0 D& @; X( ~  my-row          ;; the row of the intersection counting from the upper left corner of the+ c8 d4 b' \" S$ i
                  ;; world.  -1 for non-intersection patches.
. M; {6 m, v" D  Y  my-column       ;; the column of the intersection counting from the upper left corner of the' {8 L  {) u- K& t: A1 j2 b
                  ;; world.  -1 for non-intersection patches.% m: p$ o( [4 h% N
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
' E) Y2 K2 u& R+ Q6 a. _  auto?           ;; whether or not this intersection will switch automatically.6 V3 ^" F6 a& [. J3 r
                  ;; false for non-intersection patches.0 {+ [" @8 ^0 @8 ]7 k5 \
]2 z# W; o+ ^- B/ G

) P* S) h+ S; k2 \* f
: ~! V) V" W9 q. C) P6 D7 Z;;;;;;;;;;;;;;;;;;;;;;
+ x, \" P! i+ c* A$ E$ c* b: w;; Setup Procedures ;;
. I- D, I* m1 W" F;;;;;;;;;;;;;;;;;;;;;;$ C* _# ?4 W' E

8 s% g* j/ {/ d9 O0 Y;; Initialize the display by giving the global and patch variables initial values.
: r+ J" w% y' [1 B/ m;; Create num-cars of turtles if there are enough road patches for one turtle to. z4 o1 W4 b8 r4 ?  O5 l# c2 J4 c9 ]
;; be created per road patch. Set up the plots.+ ~% p. X  p$ O6 N9 H% N9 W& n
to setup
$ ?/ x" [. r" b7 s; |* R  ca
2 y0 D8 o" ~% j! Z9 a' N" J( e  setup-globals
* B; K5 o  i. U( s: R
6 X/ B8 i  Z' K1 _  ;; First we ask the patches to draw themselves and set up a few variables
! R: A+ x2 w  P  setup-patches9 g. Q; ~/ s& Y' J7 ?! u% r
  make-current one-of intersections7 y. ]7 Z9 A: P
  label-current
1 |- ~  L" g) V" X; r. p! N. Z2 V+ y: t/ j6 q
  set-default-shape turtles "car"
" S5 B0 Y0 }! K) z
* l/ Y, E# `, N# m! I  if (num-cars > count roads)% N9 L. m& ]3 P4 ~4 \5 v+ G
  [+ ?- w" X2 P& H
    user-message (word "There are too many cars for the amount of ": x4 |2 k1 I# ?' d; m) ?
                       "road.  Either increase the amount of roads "
5 e" d2 n" B& P, s                       "by increasing the GRID-SIZE-X or "( Y6 T2 D! e. w  M
                       "GRID-SIZE-Y sliders, or decrease the "
. O+ ~& o3 Y" q  z3 t$ Z                       "number of cars by lowering the NUMBER slider.\n"
$ j+ G$ Z* F; [( \                       "The setup has stopped.")& J1 Z3 `" K% U! R; I- b# r, N9 I
    stop
$ ?# [% o- }" S  ]
4 A. w" ^' S7 ]4 n. i- ~( G, ?8 `/ H4 k& Q9 h4 u% u5 D4 h  d+ E
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color3 r/ a& n$ L1 U( Q# r' q
  crt num-cars
0 g+ u5 \+ i. v2 F  [. s2 ]% m0 [5 c8 q
    setup-cars8 c0 }# t$ Z& U3 p+ V
    set-car-color0 b$ W% v. x  x
    record-data
( C( Z) W" ^/ ^  ]& d9 h5 d6 I* c$ J: z% |

) G+ ^' u( h* A" B  ;; give the turtles an initial speed' ?/ T/ x4 V6 r- k# F5 s9 R  S
  ask turtles [ set-car-speed ]
! k' H4 ?# b. [
& I9 d! X! R+ I* S& A. v  reset-ticks
9 u- H) {$ F3 N+ e& [end8 A" q: ?% n2 M. O
' A' c+ u7 T5 M( X) M- {& p* r
;; Initialize the global variables to appropriate values
% b$ ]1 d) V" `to setup-globals
, V0 h" [8 H/ D8 L$ W" `  set current-light nobody ;; just for now, since there are no lights yet$ @) m3 h) P' ?# c2 ?
  set phase 0
, A/ Y: q, X) S. m  set num-cars-stopped 0* V. D9 W3 Z" r% Q% I! O
  set grid-x-inc world-width / grid-size-x
$ Q# E& t, y& j* B  set grid-y-inc world-height / grid-size-y1 ^4 P* X9 @/ B2 b) h
% l, e( y5 c) x5 j% _* `( j* I# a
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary: i  n. F' Z4 m( X/ Y( S6 ~
  set acceleration 0.099/ H# d7 M; v: p$ [( `% U1 H
end
/ p5 l$ `$ s* V" f6 W3 R6 H  b6 W& O/ L2 ~; `
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,: s; v+ @) M- H. @0 z# J; H$ L
;; and initialize the traffic lights to one setting
( H: L0 s8 \9 ~to setup-patches
4 Z+ T8 Y) q+ |( J  ;; initialize the patch-owned variables and color the patches to a base-color* H2 s# t, m( ^- o
  ask patches
' F3 {& T0 B. w- |/ k  B4 B1 {8 `  [! ]6 K! a- a6 l  n1 |/ M% F
    set intersection? false4 F) b& Y6 f6 r
    set auto? false
) p5 \+ m; b" G1 X    set green-light-up? true
) t2 ^3 q9 h3 T+ {+ q+ B' m    set my-row -1! G+ u+ i1 e+ P" j9 A4 L% L1 f
    set my-column -1
7 A9 N4 C& @1 e+ c! N    set my-phase -1* T+ P% Z* b2 K  O7 f; O
    set pcolor brown + 3+ C2 D( K( T4 r
  ]8 B# v$ X5 j5 @/ e  M: [, F
) F5 C0 z2 ~- i4 f# P1 _) @
  ;; initialize the global variables that hold patch agentsets0 W4 d( ]9 M' f5 ]% e
  set roads patches with
. H3 B: V3 h6 U  r6 K- _( k; b    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ D' J, J$ o, M% @8 }  ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 ^' p! J7 l3 r7 S  set intersections roads with
+ @3 o1 r% x. N2 R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
' B  P: d9 E3 R, }  r: J    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ D2 Z9 d; D3 d& g, X9 |) g8 d! q  H
  ask roads [ set pcolor white ]
# G% {; v  {3 S- W) v5 N    setup-intersections
( c# r" }1 O- o$ \# y/ D2 l; |end
9 j6 I; Q/ C) T+ F其中定义道路的句子,如下所示,是什么意思啊?
1 V3 q( ~7 h# D4 a set roads patches with
7 K( V9 ?' [+ g! y! U: f1 X  i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: k1 B- U0 e$ y8 S( E  c0 j# O) c
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) v- J. Q. j8 ^: C* C" ]" h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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