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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! t, B5 ~: t4 Tnetlogo自带的social science--traffic grid这一例子当中,
- F: H/ ^1 L, E+ Tglobals
- d$ u+ e& B& d[. M- [- u- J6 h0 S5 V( t2 M
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
: G' d; `6 t9 r, K  grid-y-inc               ;; the amount of patches in between two roads in the y direction3 d; }5 U. y& |
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if) C6 }9 @+ G" H! R
                           ;; it is to accelerate or decelerate
4 `* [! L- `) D; }' x0 l' M+ M  phase                    ;; keeps track of the phase
9 [! D! ~& A+ A  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure- d' a9 j# @( A9 B# a+ s. o/ g. F, S5 O
  current-light            ;; the currently selected light  l' R2 n& q$ q2 O2 _$ V' r! K% m
9 O( ?: C6 V( u9 J& t
  ;; patch agentsets
9 N( X0 |( J+ _# F" B. R/ p  intersections ;; agentset containing the patches that are intersections
7 Y  C: v& ]: d& P9 n* D: S  roads         ;; agentset containing the patches that are roads
! w8 q3 d4 N1 [3 G1 R  w]1 W( l$ o% b2 L! C  d( C! Z! [

( q  D! G2 ^+ E4 o1 jturtles-own" f- v0 R, v& ~3 K
[
  z- {* s5 Z) `; U* C& Q5 b& _  speed     ;; the speed of the turtle
. g. R% E& c4 t; w  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
! u; V& z2 e' u4 k' N  wait-time ;; the amount of time since the last time a turtle has moved
$ i. V* Q4 A& K]
0 U) w$ R+ Y" V0 I
# d- D) O1 j+ \, \+ \patches-own
0 i( p- E  [$ M6 ~& X[
( t: `/ {. U7 r0 N1 P" J: @% K  intersection?   ;; true if the patch is at the intersection of two roads
3 F; ]# G+ }" c$ l  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.4 }  z" \  A' Z6 [/ G  B
                  ;; false for a non-intersection patches.
, o4 w8 G6 h) p  j6 L7 [4 _8 V  my-row          ;; the row of the intersection counting from the upper left corner of the
, Q" |8 o3 D1 x                  ;; world.  -1 for non-intersection patches.
! k, `2 y7 I3 q  my-column       ;; the column of the intersection counting from the upper left corner of the
8 x) z5 |" l( P6 {  W# n                  ;; world.  -1 for non-intersection patches.) h1 ?) a" x  U
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.* Q# I6 Z4 `/ n8 H6 x1 a. p! {" h
  auto?           ;; whether or not this intersection will switch automatically.
7 j6 v! z, j4 e) h6 f0 k# ?3 c( R                  ;; false for non-intersection patches.( l. O9 J( Z$ W9 P5 s
]3 A0 V1 M7 ]4 [+ U/ G
! c+ l5 b* G+ Y3 q

/ V: f) F: Q" L9 p" ^;;;;;;;;;;;;;;;;;;;;;;
. L8 K: W+ D+ }! m;; Setup Procedures ;;, m! U2 G( j8 R1 X; _
;;;;;;;;;;;;;;;;;;;;;;
+ m( B( ~3 C+ }# p9 R/ O8 }- B9 H. ?
* s7 m# c( P$ U* d& }- C; t8 @;; Initialize the display by giving the global and patch variables initial values.( \1 E- M6 @/ U" f
;; Create num-cars of turtles if there are enough road patches for one turtle to
6 q9 s& [$ z% Q  Z;; be created per road patch. Set up the plots.1 G+ o0 l7 V/ g1 V6 b8 b+ U% l) m
to setup
2 l' ^0 s7 L, W& Y& B  ca
4 X' V1 \! N' g4 B% ~  setup-globals6 c  p* C+ E" f# S: n! \/ J
" C2 s: Q5 S9 u7 T8 G  }9 e
  ;; First we ask the patches to draw themselves and set up a few variables
1 h6 R9 Z' x  {  setup-patches
& g! D3 y% g. l7 x* S7 u  make-current one-of intersections: f8 F! ^2 r- @1 N
  label-current# h3 C% Z# c+ N0 b! ]+ l& k. {

  V! ], ~  l, N7 h9 \4 `  set-default-shape turtles "car"
, e% q9 B7 x% D9 ^" E; \9 w! z. p( h, @5 A; O6 O. T# }2 {
  if (num-cars > count roads)8 r" O, q' g1 U: Y3 X
  [
2 y: z- [. l! Z7 T    user-message (word "There are too many cars for the amount of "$ h8 G1 g0 [2 Y" Q/ g6 T& |7 P
                       "road.  Either increase the amount of roads "
- Z0 W* I+ M8 J6 d$ f                       "by increasing the GRID-SIZE-X or ") b6 I, ^8 R+ Q
                       "GRID-SIZE-Y sliders, or decrease the "
$ m2 g1 U) E* Y* s                       "number of cars by lowering the NUMBER slider.\n"
: O; ?9 `" O' e) p! x% w; N                       "The setup has stopped.")
  w; K3 b  x% f* r  j; c0 C- `    stop
6 E9 |) J5 S& w% \* N1 ?" i3 r  ]/ l# M; W2 e+ |5 z7 _7 N8 ~

5 a1 \. `. Q8 D8 _7 k# n  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color, a* d4 H+ [5 g) A
  crt num-cars
2 m7 x  N; C! g; v/ e6 g  [- k1 l$ }9 E- e# ]; t6 c
    setup-cars0 x: \5 G$ d% o* E
    set-car-color6 T  X) W* a4 p1 u# s  Y
    record-data! M1 Q' e7 I7 V
  ]: Y$ y. h5 f9 l  O9 I
. g* b  Q: N5 B5 n1 ^
  ;; give the turtles an initial speed
! g8 p! A$ Z9 X8 l; a  ask turtles [ set-car-speed ]
) h8 @3 ?0 e# J1 e* A  M! n4 B! }* g; E5 |
  reset-ticks7 f! Q' y2 l6 `* s; E3 B" S
end
# R. X; u4 @9 J2 V
1 E$ I' q4 l' I! V;; Initialize the global variables to appropriate values, u, F* r- ?9 w- v4 C6 Y2 R. c
to setup-globals
9 }; h+ B" i7 Y( j  s8 v$ X( v) V  set current-light nobody ;; just for now, since there are no lights yet
7 I. v. |1 Y+ r. D. [3 H  set phase 0
. b. ]5 L; ~# l/ ^  set num-cars-stopped 0# J4 P( G  h; i5 c
  set grid-x-inc world-width / grid-size-x$ f& ^, _: Y- K  }: H' _' E
  set grid-y-inc world-height / grid-size-y* N  k, E. u& }# Y2 M% h5 @

- H4 r4 m9 j: {  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
: p+ H% P& g2 H5 j. b( k  set acceleration 0.099) x* L3 o% ^+ C
end# V0 W  j: h, l2 T* o
" @0 @3 y7 f8 o4 q
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,5 b1 ~' d7 ^5 ?# A$ q% n
;; and initialize the traffic lights to one setting
$ w) w: l$ t9 J9 y- ~5 z: ]/ U( Vto setup-patches
6 K9 {0 P4 s7 L+ x5 m* X. G  ;; initialize the patch-owned variables and color the patches to a base-color+ ]& q! y: x) @" P$ ?
  ask patches- ^4 l. v) x* U* s
  [5 S1 F4 A+ ~8 I* j
    set intersection? false" h  g6 ~" l9 o5 A/ |; z2 Q4 }
    set auto? false  I; p: W, u( F
    set green-light-up? true( p5 c: L4 B" g  q" e  G9 s
    set my-row -1, Q+ L# r0 _3 |& O, K3 x9 r
    set my-column -1
9 b/ O; G8 q. Q9 l" e    set my-phase -1" d2 e) z9 c- y6 u, ^1 W
    set pcolor brown + 3
4 T. L( b, z/ M* z3 E- O3 q  ]% P9 |" }- [3 I# a

. O4 H% {  O- y, @1 H* N  ;; initialize the global variables that hold patch agentsets* e$ N, \# n5 A$ D4 ~
  set roads patches with% z+ F$ J  g" a( k- w; W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. Z* H; O) W7 J0 u* J7 W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: V5 G; ^1 s! d- S, R  set intersections roads with7 o% B$ |5 _$ i" p
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and  i! z0 n. \+ }) w' h5 t  E+ H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ F" H. L# h. l  [
+ f: \+ @$ ^* d) T  ask roads [ set pcolor white ]
8 p% p( R9 e/ |. P  C    setup-intersections
) x4 Y& f% g% Aend7 M8 P5 n- O2 Y% w1 b
其中定义道路的句子,如下所示,是什么意思啊?
+ |8 N/ @) o; f& ~2 Q6 Z set roads patches with
0 `+ H$ P: q  Z3 a# S) ~% T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. A/ h8 c8 `: F    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ o) s6 O' K( s. _' P( q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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