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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。' o# w' O/ d" `: ~6 f; f1 A/ v
netlogo自带的social science--traffic grid这一例子当中,
4 b" K0 g, l: A) W5 V6 `8 _globals
' B, l+ h% _8 h' H  V[
5 q. ^/ F9 a1 A3 b8 x8 t/ |  grid-x-inc               ;; the amount of patches in between two roads in the x direction
* e8 F. h6 i4 `# i  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: X  Y; q9 {, d* p0 s$ P  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 P, L& }# ^2 a7 ~+ j7 q% w8 J( M                           ;; it is to accelerate or decelerate
$ R% }- h' |% b" `  phase                    ;; keeps track of the phase
# K! j3 g+ X1 O4 h  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 |, l% U9 C( `' }5 d  K
  current-light            ;; the currently selected light
) X' K( r$ x4 |! p! J, L$ t! e; [  f% P$ M
  ;; patch agentsets
9 b! M  _! c$ T1 [' m8 ~  intersections ;; agentset containing the patches that are intersections% [  n9 R2 ^) [" i9 U$ M
  roads         ;; agentset containing the patches that are roads' c6 v: T, Q" R( x2 G* l* H# O, ?
]
/ ~2 U9 D2 a1 W4 ]  J/ @8 a
* K; N; ^! \& ^; I8 `5 t3 ]8 w- Aturtles-own# e  T* e/ o5 l7 H- u3 ?& {( r7 ~: L
[
9 M* C3 v6 i; `7 |% n! ^  speed     ;; the speed of the turtle
2 t5 _8 |) |! a% @/ ]0 j- u% l  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
& E+ t1 ^" c$ I$ z, X3 V0 O1 \0 b  wait-time ;; the amount of time since the last time a turtle has moved! R; j6 U, k: p5 f# A' \8 _
]
3 v4 S" @/ v% N4 y- |( e7 Q: s1 B% k' G9 }" T/ Q
patches-own( @8 `) o5 j: j
[
6 D4 x9 y, F/ [! j  intersection?   ;; true if the patch is at the intersection of two roads  b) E: b  {8 y  B9 Q$ ^
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- |. U2 E: U5 Q- l
                  ;; false for a non-intersection patches.5 T" j9 F+ h  o& t8 e7 u
  my-row          ;; the row of the intersection counting from the upper left corner of the1 K9 |( T8 _$ i" X: |: C
                  ;; world.  -1 for non-intersection patches.5 B* z3 a, z0 k: F5 _  g
  my-column       ;; the column of the intersection counting from the upper left corner of the/ H9 o6 ?$ E4 w/ B5 S9 ]) v
                  ;; world.  -1 for non-intersection patches.
1 N* S, D7 {8 l" x  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
0 S  S2 A( I* L4 a: u  auto?           ;; whether or not this intersection will switch automatically.
( K& Y0 S5 ]: d  ^: ]: |                  ;; false for non-intersection patches.+ j: U2 N+ O! q2 m7 g
]
% c+ a  c2 Q& p1 x" ~
: @7 Q: u. P& o$ ?" U! p. R0 R
7 D# D2 n6 L2 n6 R% Q6 e;;;;;;;;;;;;;;;;;;;;;;
  t' p6 N/ ?3 c  \;; Setup Procedures ;;
0 a( A8 K* ?/ G  |, b( R" ]3 ];;;;;;;;;;;;;;;;;;;;;;
: m2 a# F& e& O2 @+ z4 F
" i1 s+ ~' s0 s- q  }( ^;; Initialize the display by giving the global and patch variables initial values.0 \0 o: d8 M6 t- u+ {  M
;; Create num-cars of turtles if there are enough road patches for one turtle to& ^/ l& ^; O/ _+ W
;; be created per road patch. Set up the plots.
/ S/ |$ m: N' O0 e  v1 c. \to setup
7 l/ a* O1 @* v. h5 o. V# m  ca
, N; I# U7 g% d* `  setup-globals
/ E/ {, e3 P" c2 c8 M9 S
! ]7 I: C# r* ]% d) b  ;; First we ask the patches to draw themselves and set up a few variables3 I- ^/ t% p, ~9 O% x
  setup-patches: ^7 G7 O0 T% y2 o
  make-current one-of intersections
% o2 \' a0 I& W9 m2 C( ]4 J  label-current
/ K& K& U& ]7 P. b& W2 t7 A, U4 h6 h$ ^7 x7 |
  set-default-shape turtles "car"
& J2 E3 v. n- C  W
' n. B. j- `9 h  H% C7 f& f  if (num-cars > count roads)9 h1 ?. `  D# U/ _
  [: S3 Y  `8 x# S9 {2 \% _, X
    user-message (word "There are too many cars for the amount of "
; i/ y, E7 i. D- `. R4 O                       "road.  Either increase the amount of roads "' @, K! j  F; O9 v0 s# W' I
                       "by increasing the GRID-SIZE-X or "4 F. u& T: M1 E
                       "GRID-SIZE-Y sliders, or decrease the "
) c2 B- r# O8 q, |% l' v) g                       "number of cars by lowering the NUMBER slider.\n"4 s7 g) m- v- s
                       "The setup has stopped.")
+ @5 b* _9 ^2 z# Q/ C  a    stop
5 L2 n" L2 H4 A4 q, k. b  ]  F% u5 [. l& r2 ]# M/ H, g

# I" C; U% E% h7 U/ [: v9 j2 z  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color* c, V& Y. F! [. g/ ~: K  z
  crt num-cars
) T, E$ S& y# r$ |# ?  [. h: `8 U' u& X9 _* Y
    setup-cars7 B! a" O8 t! H: i" S4 B" A  y8 R
    set-car-color
- X; D9 Z0 o) T  I+ l    record-data
* E$ u, z$ H) _1 q  ]
% c; C* N  y- U3 J) Z) F* ?! V6 L  H6 C% }8 P8 O
  ;; give the turtles an initial speed
; e$ L; a6 X  _  u* f2 @9 j  ask turtles [ set-car-speed ]+ F: H1 ~0 ?9 @2 @+ A3 D' X
: e8 E( H8 r) K2 ]+ s4 U
  reset-ticks
- \8 O7 E% N0 L. [5 M0 Kend
  u, [. O5 D3 s* G  s) M$ y% Z( O3 Q% u; G# u
;; Initialize the global variables to appropriate values
8 ~0 p: H  U9 @; i' ~to setup-globals
& b# u8 q( ^6 d' F. U  R* ^  set current-light nobody ;; just for now, since there are no lights yet
) r1 Y9 E9 n, h4 Z  set phase 0* O- k9 L& Z8 s( T
  set num-cars-stopped 0% n/ V( _/ n4 S6 f
  set grid-x-inc world-width / grid-size-x
! T  y( p/ \. T& @" c' r  set grid-y-inc world-height / grid-size-y) V0 V( O' G) S, J+ J

7 D4 @( v: K* r( G+ ^. L& v" a  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
- Z& M7 ~9 @( M) |1 X" K; |  set acceleration 0.0993 D, Q5 f" ^, y0 @: ^
end
. I1 Q+ J* z# p5 ~+ u6 R! ~+ k' q* H# J# _. e
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,, W9 S) o! Z, Z2 H7 Q9 r  g
;; and initialize the traffic lights to one setting$ X) F; Q" b, |9 h4 [" G2 o
to setup-patches
/ Y# u* B, g  ~# V: B0 }* ?  ;; initialize the patch-owned variables and color the patches to a base-color3 Q) }9 e+ _( k6 M- a6 G; G
  ask patches- ~- Z3 g: r# F% u2 T6 ~  T  P+ x7 x
  [7 |: ]- g! L7 o
    set intersection? false
5 P2 N6 ?8 I( x8 h) ~    set auto? false" T/ D: @& f; [2 l7 ]1 h: ?
    set green-light-up? true# m( Q, A$ l8 A
    set my-row -15 a8 e, U% K" d" |
    set my-column -1& S. ^. m! Y/ f- y& M; q0 a- v7 [6 N5 m6 h
    set my-phase -13 h- ?% h; x7 k: j# {$ q
    set pcolor brown + 3
$ j% d  a$ c% `1 q+ g' y3 c- F  ]
/ D+ O# ]" O8 ^/ Q0 f5 @- y8 \) F2 I( p
  ;; initialize the global variables that hold patch agentsets
4 J7 h. [! ?4 Z& H" p  set roads patches with
! L* T/ ^2 I  N5 b    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! v, v# a* i/ ~2 ^) c
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- _5 m$ J6 o& D7 w  ?
  set intersections roads with9 l3 p( Z6 q* G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and2 j1 P: Q( o7 z) q+ @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# E7 `; x7 r4 ]( d- N2 J7 |0 }7 a6 b* V0 @+ p
  ask roads [ set pcolor white ]1 H; {) X6 O9 J
    setup-intersections
) Z7 D8 n) t) H- U! ~end' T/ y2 K' ^& S+ O
其中定义道路的句子,如下所示,是什么意思啊?
9 W- S, o7 B+ ` set roads patches with
! U- @3 c* x+ W: p" Z5 ~% M    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 E3 l! F. I- {' P# u) R    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! e& v) ^4 b* s- 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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