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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。) h8 u, x" ~$ y/ w) u8 ^  \% e! S
netlogo自带的social science--traffic grid这一例子当中,
, L; m( S6 [. h; L) }7 Lglobals0 n/ W6 M/ b8 V- `
[
7 h2 H5 u1 M) }4 b( N  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. H( A& B% Y$ N! k, h  grid-y-inc               ;; the amount of patches in between two roads in the y direction) M3 Z  O% H9 _, P/ N
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if: J" P. V+ Z) m: Y, w
                           ;; it is to accelerate or decelerate# R. ~. Q( V% v7 T/ _7 I
  phase                    ;; keeps track of the phase; M9 g! J  g4 T! D
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure  D' n2 W7 J! ^+ B$ v( I
  current-light            ;; the currently selected light
0 n5 t' N  c4 z4 c% I* ^+ k& K3 F& g$ M
  ;; patch agentsets# z9 V$ ?  K) a1 a1 X
  intersections ;; agentset containing the patches that are intersections* b8 t! \) }) O9 H& b2 h
  roads         ;; agentset containing the patches that are roads
7 j5 Z$ `8 y4 r$ K- Z]" k2 P% Q0 I- B: M
, b( ?& |( i0 U6 i' p
turtles-own
% M! c4 G  I% f- f[
* ^3 Q" A; f4 G5 w- W3 w# H* t6 u  speed     ;; the speed of the turtle0 t9 H7 i! n! e5 t2 `" I
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right) Z+ |) v6 J% v
  wait-time ;; the amount of time since the last time a turtle has moved( y. P9 c9 L/ K! U; S9 P3 w; o* E
]
  a8 }) \5 C* t* p. _1 U) i9 w: Y/ |& }* Y
patches-own
! a( w/ |: }  c. H3 S[
( J) I3 @) @) p2 s2 e# ?  intersection?   ;; true if the patch is at the intersection of two roads
7 W0 r$ [1 h6 L  K  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.2 ^+ d: A7 m0 G! l$ R
                  ;; false for a non-intersection patches.0 P! ^; D* }1 t. ]; Z1 U
  my-row          ;; the row of the intersection counting from the upper left corner of the9 K  Z7 h, n/ b! n8 b8 p" `6 f) B; ]
                  ;; world.  -1 for non-intersection patches.
: B* c- h7 m- b0 y9 \  my-column       ;; the column of the intersection counting from the upper left corner of the: I- M% f: X! i/ ~
                  ;; world.  -1 for non-intersection patches.
0 X: u# H) c' I  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.% |# h9 C9 y7 [3 S
  auto?           ;; whether or not this intersection will switch automatically.+ G. s! |! ]' J- ^
                  ;; false for non-intersection patches.
, H( x$ [7 r3 e7 k* H9 x' Q]
* {1 ~" ?8 V! @7 c* d) K
7 ]# P* ^  }( K3 z
. t- h9 U3 c# ~) u  ~+ J; v$ `, o;;;;;;;;;;;;;;;;;;;;;;) T) f" d" e* p; o0 d
;; Setup Procedures ;;
8 K9 ?5 U! M) T; q;;;;;;;;;;;;;;;;;;;;;;( n% K5 b1 z" ^3 a, u. J  t

) F* k6 G$ ]" u; z;; Initialize the display by giving the global and patch variables initial values.
. n) J, C. a, P;; Create num-cars of turtles if there are enough road patches for one turtle to4 v! G* V3 N& q' a, t0 R3 `
;; be created per road patch. Set up the plots.
4 d" q' l: x& B6 h  Zto setup
$ |1 G0 e& c5 J8 e$ x  ca
  l+ x" F$ U# ]! b& D  setup-globals
/ \; D4 {7 h* L/ a* R  Z$ }. p" D4 S8 c5 ?  k( i+ i% m- c5 ^, @' S& b
  ;; First we ask the patches to draw themselves and set up a few variables
& Y0 x5 t2 H# z0 g/ {* I; M  setup-patches
- Q4 ]. M( ~/ W  x: H+ C0 V  make-current one-of intersections
6 [& ]* J* B! x! P9 k5 Z8 E  label-current0 l3 ~! P- n6 B% k1 |) r7 q0 x+ L1 [* `" H

$ C& q3 N& ?; [" R4 J  set-default-shape turtles "car"9 m! s! c/ D; q

1 S  @3 N4 R8 q1 S  if (num-cars > count roads); m/ S4 R' G  [6 E( ?
  [
: a) J% D0 m/ i6 G6 L) X, }    user-message (word "There are too many cars for the amount of "1 v( X* z! q- k' B8 w* J
                       "road.  Either increase the amount of roads "
5 v8 Z" g; x/ t. @                       "by increasing the GRID-SIZE-X or "
! H" J: l! v+ q9 X                       "GRID-SIZE-Y sliders, or decrease the ", f+ }" t( }1 J$ ]. x
                       "number of cars by lowering the NUMBER slider.\n"# K/ D( _# G# I% M
                       "The setup has stopped.")
! ], x, n5 ?% P; D. D    stop
4 Q( I: |* J" M$ |/ D  ]# a& ~- _6 u) U( n5 l6 H

. d5 Q# [; B, C. S( R  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color* p+ T0 U2 E6 `, [
  crt num-cars
6 S3 B% [! K+ o  R8 k; K  [
5 |# Q3 X: z/ N) G( o, @5 X/ N    setup-cars
2 A: ?4 s9 i" W: s7 ^1 R) d    set-car-color
- }1 y0 X1 I5 k6 Y0 D    record-data/ Z" ~3 F: {! ~# r  b
  ]( P  v% M/ e# s2 N, ^. J

& L* n1 B) j+ }  n! c6 H- q  ;; give the turtles an initial speed
2 g7 v3 ^* U( l$ W8 \  ask turtles [ set-car-speed ]- h2 Z. @8 h! q* o

/ p- Q% U! Z1 W  reset-ticks- M  N$ J  @- @7 Z
end6 b( c+ m+ o! B: U8 E& W# Q, i
; e! B4 i. d6 k6 ^( |
;; Initialize the global variables to appropriate values6 [9 t$ X! z- F' s6 A- g% D- j
to setup-globals
! _/ N/ Z* U0 f& N7 {3 m1 |  set current-light nobody ;; just for now, since there are no lights yet; }, n: F# U2 e$ x+ a. A
  set phase 09 b- Y0 Y' s+ D) N8 j  I
  set num-cars-stopped 0( |( {: m: J1 b: J
  set grid-x-inc world-width / grid-size-x
( y# y! e3 D- x  set grid-y-inc world-height / grid-size-y" p8 K& Z3 a& W
1 F8 |" c! U! f! s4 [2 s% N6 B7 X, S4 b
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary- E7 u: v6 U2 d2 g, _
  set acceleration 0.099$ {/ N# a+ W* [- a! W
end
9 ]7 B8 E( y* @0 ~2 y9 g* s' ^( h2 _/ }+ [0 ]
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ A, {4 n8 v9 |0 ?$ L
;; and initialize the traffic lights to one setting( d" M% ^( b( E, Y# s7 e" q
to setup-patches
- V/ k; P) h' B: ?  ;; initialize the patch-owned variables and color the patches to a base-color
# ^( g8 S9 d, q& V$ b  ask patches
2 ^/ t9 q) z' n$ H; d  [
  y: D) [) r" N8 z7 N3 O1 ?    set intersection? false
" w5 C# `# c. f5 b9 s( l& U* |    set auto? false% F5 a; L7 Z9 n# H4 {& [
    set green-light-up? true
5 D3 d9 U1 F! p9 A# }0 y! i    set my-row -1
  f1 e. X" P. k2 r    set my-column -1* u" A+ v9 ~3 V2 E% v
    set my-phase -1
- r2 G8 `0 C6 D    set pcolor brown + 3
9 P! z- F6 }; ]  ]
9 B# {8 ^" k( @8 I6 C. L/ Y7 l" u! l. S; L' \
  ;; initialize the global variables that hold patch agentsets
3 M$ J. V$ p. Z0 U# ~& B7 l) X* d  set roads patches with
. z& j( |, K0 A# F4 G" \) ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 T# r* s0 D6 y( t* [
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ B5 G$ j5 P6 |  D; G4 T
  set intersections roads with
* k9 _6 i1 u' R( @" |7 g3 l7 j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
9 @/ N' B6 p% `' ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. k3 l- d, ^: m7 K. |" q! z3 i+ M! w
  ask roads [ set pcolor white ]7 I3 w) U7 m4 H5 [  j* i4 @
    setup-intersections
8 q& |2 a: D# {) ^3 ^+ Y3 E0 Cend
- R, A) |' E" w  }+ S其中定义道路的句子,如下所示,是什么意思啊?
, y5 A' c2 W! r8 R7 o/ N/ V% B set roads patches with
. t9 L4 }/ R3 s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: J# y- e$ x/ E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% ]$ Z# u: |6 d+ ?  q& ?" ?) j/ @- c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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