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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。9 }3 z# Q* l" Q# W
netlogo自带的social science--traffic grid这一例子当中,5 P( e4 q% k0 d7 [
globals7 k1 Z. i" Y: p& w' L% Z
[
- @* p" V+ M2 M0 F  grid-x-inc               ;; the amount of patches in between two roads in the x direction
1 Z+ @: y4 R+ b! o# i0 y% o  grid-y-inc               ;; the amount of patches in between two roads in the y direction% g& r$ b2 g/ p  }0 M* n& b
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
3 ?6 g# Y. A+ h: {                           ;; it is to accelerate or decelerate! }1 ]" r% }! Q! h' q( U; D0 c* E
  phase                    ;; keeps track of the phase2 b3 Z' f" [' d
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure( T* S, S# z3 }: [$ W4 v' C
  current-light            ;; the currently selected light7 K' d; K+ ]/ O7 r2 H/ E

# a. s5 C/ v$ D- K9 D# ]  ;; patch agentsets
4 o0 {1 u9 R( j! R$ K  intersections ;; agentset containing the patches that are intersections
  b6 ^$ I& r+ \$ K" I  roads         ;; agentset containing the patches that are roads4 K+ T# y5 l3 Q) [+ Y: C: q
]$ S. O3 D0 _/ |- `% y$ [& P( t8 @* E- ~

! h. B: s9 S5 B: c' F- qturtles-own( `+ ~7 S& h9 k+ |( K
[
( C" u. Z2 T  f  U- K  speed     ;; the speed of the turtle
, P( J2 U5 @+ E% n5 @9 ?0 D  \  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
% m0 p/ |) r0 a* N% g7 b/ a  wait-time ;; the amount of time since the last time a turtle has moved1 B  |3 ~7 q0 L# h* O6 o; P) n
]; [  w2 b2 r7 N6 X

$ e6 F: A# K1 G& {9 [1 P8 Zpatches-own5 s/ N, ~4 V0 j! l1 Q8 p
[
; c2 c2 M- g$ V: R5 a/ z  intersection?   ;; true if the patch is at the intersection of two roads
6 A0 v* S+ L8 o+ ]- d6 g) E' G  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.! I/ d; o* M. P  Z. o: h; Q
                  ;; false for a non-intersection patches.8 Z. c/ |7 D' D! Q6 o; W
  my-row          ;; the row of the intersection counting from the upper left corner of the
  b, d( s5 C  G& x                  ;; world.  -1 for non-intersection patches.
7 |' u. x7 l: Z6 x* m  my-column       ;; the column of the intersection counting from the upper left corner of the5 R; u# {  @, v+ i
                  ;; world.  -1 for non-intersection patches.
2 ?2 ?( H8 N! g) `; a% |% z  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  o- t$ G) s3 Q0 c3 L6 X
  auto?           ;; whether or not this intersection will switch automatically.4 e' p9 w! W2 G- K- K" K% H) d. B/ j
                  ;; false for non-intersection patches.2 R! k  K. ?+ b. W
]- G8 n( \7 N- N! @: \5 o1 M, C
0 B8 Y: `6 K' K! S# V/ O3 u

) D2 M3 J. N- _  F7 _  H;;;;;;;;;;;;;;;;;;;;;;# B) _$ d7 ~7 k' |, [- i
;; Setup Procedures ;;
3 V9 B# f2 w6 W9 X8 R;;;;;;;;;;;;;;;;;;;;;;3 h/ m! ?' ?1 L/ T# g2 N4 I$ v5 ?
$ g2 n2 e* D# B+ ?- f! G& {8 Y
;; Initialize the display by giving the global and patch variables initial values.4 \' F( J! o  Q* `' l) U
;; Create num-cars of turtles if there are enough road patches for one turtle to
! a) H1 l$ H5 U;; be created per road patch. Set up the plots.4 I  P4 E6 x5 n* S# K: n  G
to setup
7 D* ^/ j0 G+ C& G  ca* n7 ?! D% K( O; y1 J6 g' b
  setup-globals
( v' @0 p8 j" t/ U3 \& K% x* [: A& J$ R
  ;; First we ask the patches to draw themselves and set up a few variables
/ ^$ q5 U) X- H( o, w# N2 k  setup-patches, p: m0 R6 s# I  X# I$ Y1 P
  make-current one-of intersections  W7 S2 |  ?/ t: Z- o4 d6 G, H
  label-current
$ M: ^9 L5 r' p: E/ v+ ^4 O; l# h4 C4 _# `$ R& `( l) R
  set-default-shape turtles "car"
/ R) e. i, X3 Q9 l1 y* D& J$ h% t, E; W0 [% Q% i6 I# r0 W
  if (num-cars > count roads)
+ M- G/ {# B6 t' e; ]3 f  [
3 |# ?2 Q3 }) E) X  [8 J( s    user-message (word "There are too many cars for the amount of "
% V' s3 \3 \2 k. }- X$ u                       "road.  Either increase the amount of roads "
5 v& q& }3 H; _4 @                       "by increasing the GRID-SIZE-X or "
7 _' R6 F' ~/ ~( e6 r3 x: r                       "GRID-SIZE-Y sliders, or decrease the "$ I2 v  Y$ ?  b$ a
                       "number of cars by lowering the NUMBER slider.\n"
9 u6 c4 r6 Z( ]$ n4 j  s                       "The setup has stopped.")
/ z8 i2 n, D4 O* k' F/ S    stop+ `( t( z9 Q2 a& P+ w7 v
  ]0 S% l5 d7 K2 w0 z. Z' c: s, m+ }

) J7 M& U" C. h6 \1 s) d  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color. _6 W6 a- O9 @9 W+ u( n8 P. j
  crt num-cars8 G. o2 {. d% ~( T" u0 i# K" Y
  [
' J) y) t+ ~- N    setup-cars
# q8 \5 ], f0 w4 l    set-car-color  L2 D* p1 y: _  d& s9 O, g
    record-data) j" S) f) u  Q* r8 v
  ]
! y0 b" d& i! k0 ~2 [' N& y
( v, E0 ^/ [) |1 c( c  ;; give the turtles an initial speed9 G( s+ T$ F( h  i1 G- @, G( X
  ask turtles [ set-car-speed ]
9 q4 E2 o; |+ v, [4 @. I7 H& Z7 S9 g7 E; z8 H8 z- u
  reset-ticks0 |, C) ?, |+ U
end" W8 D" O; f2 p8 h" X3 A
; o) J# ?5 d! U" }; O4 U& Q# J& l# D
;; Initialize the global variables to appropriate values  J' O! c6 W% r9 j/ o" K# R
to setup-globals* e9 x3 ]7 U$ m$ O
  set current-light nobody ;; just for now, since there are no lights yet4 N. w7 S1 G4 d0 c% F
  set phase 0
% u: B3 v0 o$ E; s4 V  set num-cars-stopped 0! a. T/ k: @" B
  set grid-x-inc world-width / grid-size-x( {3 t' m# D9 J' V7 @
  set grid-y-inc world-height / grid-size-y
/ W7 R* O; o4 e8 M8 t$ X/ y* l: I' e4 i: n* S' \9 }; Y  d1 z
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 D( h3 }$ `& f; e
  set acceleration 0.099; p- c2 Q* _4 F# ?# J3 U4 k1 p
end
  G# Q5 J9 ~; r% u1 o
' S( V- N: R8 I+ I$ |7 T. F;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 ^; a/ U9 J3 H9 Q( ?+ X
;; and initialize the traffic lights to one setting# T# {3 [% g( [; T$ n
to setup-patches
' b* m+ l0 S8 z  q. G$ l3 \  ;; initialize the patch-owned variables and color the patches to a base-color
' {8 z% `4 |$ u. s) C$ L  ask patches
6 F$ w/ h) R) \) ?7 B# o  [/ l5 q) L* O# p$ @9 I; \  a
    set intersection? false+ D" a1 t! o% ]" j
    set auto? false; }2 K- H( T, }! w
    set green-light-up? true
: o# _" Z) l* e; g6 `- ?    set my-row -12 ?& @! v3 G3 S" `5 {# E" ^2 S/ {
    set my-column -1
; G5 h* t7 Q( B+ S1 @    set my-phase -11 U# `; n8 K: J' X
    set pcolor brown + 3. i5 U) Z8 Q/ Y0 Q. ^
  ]) n& d; U# H+ A4 ^
- k% \, A& t, N, _! @" B
  ;; initialize the global variables that hold patch agentsets7 @% o$ u5 K4 v5 ?
  set roads patches with/ _. F" D# C( i' O8 I6 [& z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: {0 N9 W1 z" _9 R
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ G5 d5 v  J- H9 ~7 R# m
  set intersections roads with
( n# o' U0 a* H+ t( K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
! Q" `: |& K6 t% }  n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& g. H' D( p1 O# t' t' z) h: i

0 x  ~# Z8 j1 f0 T: C  p  ask roads [ set pcolor white ]& n7 N! Z: G$ ?& e& {
    setup-intersections; ^( X+ s/ b0 o. x
end' B" ]+ d2 c. m& x& q  p
其中定义道路的句子,如下所示,是什么意思啊?
- T1 d6 A- D4 }& e, z! Z set roads patches with
- I0 O5 s: l9 W) R$ \* K$ i% w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: O0 p! H; a, F4 @: U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( m& k  t4 a+ ]* g- Z- _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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