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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。  ]# U) v6 q. t
netlogo自带的social science--traffic grid这一例子当中,% p! B% w1 T! H- Z% P" q( ^7 g
globals+ A& E7 d0 v6 m; G8 R' t
[" M, @2 c* T) j; q5 ], f# n) ?
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
& d' `' g0 Q$ |/ c  grid-y-inc               ;; the amount of patches in between two roads in the y direction2 S$ G  [3 m! @
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
7 l* j+ `" q9 `0 C* f+ L                           ;; it is to accelerate or decelerate. R+ q, k* I4 [4 z. x3 a
  phase                    ;; keeps track of the phase
0 b8 r' \, H- q) t' B  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
& {0 r- ]' z- z  current-light            ;; the currently selected light; A$ a# u  b1 a8 Y1 ]! g* V' N3 w! M6 p
5 x: w% h! X7 |: f& W$ j7 h0 G# @
  ;; patch agentsets- P$ B( W, F  v8 n' e( G
  intersections ;; agentset containing the patches that are intersections# S( P' B* h' K3 ?4 l; @! g( v' Q
  roads         ;; agentset containing the patches that are roads
" d" m" k1 N6 \( ~/ @& F]
/ S; p, @$ E, A# [. o5 M
& k' N/ c; ^' `# z/ Oturtles-own
2 b$ _7 f. T, P4 {: ?[
3 i. ^' k5 ^4 i9 @  i  speed     ;; the speed of the turtle- O: C: Y2 B! z  J4 Q* o
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right1 J: M% W; t! K, ^3 y' G
  wait-time ;; the amount of time since the last time a turtle has moved
$ Y* b# k4 B9 r/ z% q8 V* }]' D6 @( ^- m" L, u8 v% t5 s

/ i) ]/ B2 e) _2 F7 Npatches-own
3 ~5 l$ q. ]1 w[
; X' G" M: t1 F# N  intersection?   ;; true if the patch is at the intersection of two roads+ Y+ \8 ]0 C& [0 f+ a" l
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.0 \# C4 A2 p6 j5 \0 D- Y, _! U/ u
                  ;; false for a non-intersection patches.; ?" i  u) R& w4 S. ^
  my-row          ;; the row of the intersection counting from the upper left corner of the- B: G5 R+ w: i
                  ;; world.  -1 for non-intersection patches.) k7 ?6 B( t: }
  my-column       ;; the column of the intersection counting from the upper left corner of the
5 U8 B9 D- n' r8 [                  ;; world.  -1 for non-intersection patches.
9 C/ I3 Z( i, e# ~  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# ]+ S$ N1 X& l
  auto?           ;; whether or not this intersection will switch automatically.- e6 Z+ `6 I8 o5 X. {# l' Y1 \
                  ;; false for non-intersection patches.
' J1 T: A6 x) n]
2 N8 y# {2 y) S9 ~
. E& N# w- |% n
1 H. E4 y* C9 n6 };;;;;;;;;;;;;;;;;;;;;;
" ^# c9 ?7 T( ?% b0 a;; Setup Procedures ;;
: @% K: D& h: [;;;;;;;;;;;;;;;;;;;;;;
$ K! @, P: \2 X' `( f( n
) _% O/ i# X# s/ [# K& k' m+ z;; Initialize the display by giving the global and patch variables initial values.( O4 U8 H8 h/ [
;; Create num-cars of turtles if there are enough road patches for one turtle to
5 ]+ K4 {" e, h* a' N' b  S;; be created per road patch. Set up the plots.+ p% t/ Z- u7 F9 {* G1 t5 s
to setup
! m8 d# h- T. ?8 g6 }% k  ca
% J# w) T4 S& i. j5 ~  setup-globals
; F4 S" b: ]% h3 S* ~5 O  W$ z6 S: [4 Y( ]' T
  ;; First we ask the patches to draw themselves and set up a few variables5 ]3 D" @. p5 ~! G- q/ M  X
  setup-patches
9 }% u' @: d* m' w, F; k  make-current one-of intersections' b" r( p2 @  s+ B/ \. L
  label-current4 D4 p0 q1 z+ J+ K
7 m5 U; D3 F2 p' N4 O1 j
  set-default-shape turtles "car"! b  \  h1 e. W. `" l2 W
1 u- A  y4 w/ p  w& e
  if (num-cars > count roads)
# f% H, `! q+ h2 F/ ]7 [% O  [. [( a9 k, ~8 J% c' A4 i4 @' N
    user-message (word "There are too many cars for the amount of "
1 I5 F2 V6 G8 ?. b* y" b/ F                       "road.  Either increase the amount of roads "
8 s- R6 p, m" g                       "by increasing the GRID-SIZE-X or "
1 E. ?& E, j8 a* D% J- |                       "GRID-SIZE-Y sliders, or decrease the "" _9 v9 M6 Z9 R* h) v
                       "number of cars by lowering the NUMBER slider.\n"4 r% y5 m- n7 ^, A7 Y  s4 a7 K' g2 a
                       "The setup has stopped.")6 X+ N! s8 Q/ }( R( L- f4 }
    stop
% M5 F! O# J- _/ a" z. y  ]
) s1 c7 W0 u4 m- y
1 T7 y. U' Z! o5 t  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
( h& ^) g0 k& x8 i% v0 _0 P  crt num-cars
7 \5 P! O3 r4 ?+ X7 _  [
7 }  }1 i6 E* c. P( |    setup-cars
2 ^# q1 @- m3 G    set-car-color( C( ?" n  G6 K3 S; E- Q6 k
    record-data
9 m- p$ \& O/ `3 H( f$ b- F  ]
  R+ k3 Q9 j, n. M& L9 v) }% [" f! f; H! A
  ;; give the turtles an initial speed  j3 h" x( S5 ^! P% a6 N$ y
  ask turtles [ set-car-speed ]2 F; z0 ?- b2 P8 k9 F

# D# S4 c1 A# e% p+ g: b& X9 K1 r  reset-ticks
+ ], B. W0 I+ N* M* ~& }end
- I6 d2 p; N/ i; |2 ^7 `' J6 m# Q; s: y( D0 u' C& I* O
;; Initialize the global variables to appropriate values: p% w% M: ?5 U# D( P( Q
to setup-globals
" D  l: v( ]5 L" y) X5 Z/ E# Y( E  set current-light nobody ;; just for now, since there are no lights yet
' v& }+ u. I) ]1 w4 N! E  set phase 0
  }. X; S" P3 w3 M( q/ B" j  set num-cars-stopped 0+ C  d" X3 z6 X8 P
  set grid-x-inc world-width / grid-size-x( n7 e* \! C' A1 R/ U+ o5 [4 l
  set grid-y-inc world-height / grid-size-y! [# S) T7 }  h/ U% J; P
* a# w0 g/ U9 R. N9 Z5 L
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
- j* A2 j. U* r. t$ C  set acceleration 0.099
+ V* x7 U/ o, P8 {end  }; R' S" T; v$ _0 v9 F* l) Y
2 |, ^1 r) c5 r" v& D* |! @
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
) O& I5 q! e9 I" B4 ~2 j- O! g;; and initialize the traffic lights to one setting- D5 N/ X; b# |; U: L: R
to setup-patches
5 `2 m" ]0 o( ?1 o3 i  ;; initialize the patch-owned variables and color the patches to a base-color
8 V3 I8 e8 n3 ^  ask patches
. p: s/ B8 Z3 a0 F* i% f  [1 ]% _) N1 W: n2 u, E4 C
    set intersection? false
& j- O& W, F  s    set auto? false( E+ x1 q* t( \# h! g# n6 t/ q0 y
    set green-light-up? true  p: m: H' h! V' l9 A, w! _
    set my-row -1
/ j: A( s/ N/ s  a# e    set my-column -1+ z! g$ _% `7 e3 ~( |9 F: g4 l
    set my-phase -1
8 {) y: A" b3 ^; ?% O! _8 ^    set pcolor brown + 3
$ U/ P( P* A1 w! e5 ^6 Y7 l; f  ]+ i) h- q7 y9 X- t) v1 t
# ^0 Z% o6 _6 W% y$ _; D$ d
  ;; initialize the global variables that hold patch agentsets( r2 v  k3 t* [+ U
  set roads patches with
7 c0 R$ Z' n7 O# N    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% a& x! g9 b% h7 s& k7 ^
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% {8 \' z. X/ `/ ~/ I  n  c  set intersections roads with: C8 E! X1 S& U+ q& z# r1 ~
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
* C9 E2 f+ p  z5 G& X+ J  b; }. k    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  z( w: r+ ]1 {3 ]
, o9 _8 @2 u6 Y- W! N3 N+ u. I2 h  ask roads [ set pcolor white ]
+ H8 h" a" H& B; l8 s    setup-intersections7 N% ~& d: u1 ~: l/ J  }2 ~# Z0 h& S
end, C( E  ~2 S6 Y( A. Z" F+ Z# T0 m; m  \
其中定义道路的句子,如下所示,是什么意思啊?
2 E$ x! }3 {# O! i7 Y$ d set roads patches with
$ z  |: T2 S! f9 c% [4 \3 l) e    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! c+ j; Y- K+ ]( G0 C- v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) z( B: i% h; \% v, R1 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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