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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。
$ [! G- f1 ?; H* knetlogo自带的social science--traffic grid这一例子当中,; G7 V8 V1 F: B9 X9 Y5 k' i
globals
( h! Q/ _) ]0 h' D  n% K[
$ l, G  }& _( ?+ l; g9 e9 p' f  y  grid-x-inc               ;; the amount of patches in between two roads in the x direction4 p. _6 X  ]+ \* Y, \
  grid-y-inc               ;; the amount of patches in between two roads in the y direction3 U2 W# m) ~0 B3 d7 M( F
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if2 Z0 ^+ p" E+ Z7 T: r% f+ R% v
                           ;; it is to accelerate or decelerate
4 s9 B) `: w" r2 e  phase                    ;; keeps track of the phase
" |) r/ q9 P6 R9 L" \# I  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
' ~' R1 v9 ?/ f  current-light            ;; the currently selected light* u; d4 W6 Q8 E5 w- \2 G
; w  J( B' Q5 p7 V3 H2 k
  ;; patch agentsets$ r( F+ z" i1 V( [5 N
  intersections ;; agentset containing the patches that are intersections2 h: h5 x& G# B9 h& ]5 Q
  roads         ;; agentset containing the patches that are roads
1 y0 ^8 w. F+ _8 P. q/ f]
6 ^' Y! ?3 R- t7 y8 p' h( o; G9 R  f# n6 [5 c' _$ C" @
turtles-own
! O& s% _' G& }! D/ }[4 z% U- q4 h2 \
  speed     ;; the speed of the turtle
/ v1 h* v! e' t  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
2 F; e8 k( ]. [3 F  wait-time ;; the amount of time since the last time a turtle has moved; Y4 P6 }  b! ?) M" X$ `. v. c" x4 x
]$ e1 }* F  m1 H& W$ {- Q! {9 N

; x2 R* J& D- n) F* Bpatches-own5 w2 z; T: `' B; o, q" w' e
[5 q: P* y  x$ e2 S3 }8 P
  intersection?   ;; true if the patch is at the intersection of two roads4 Y0 m0 I7 ~1 I) }3 I+ J
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.1 D7 l5 I4 x) j0 x, d" }6 i8 r
                  ;; false for a non-intersection patches.3 w$ _# R  y! k% S
  my-row          ;; the row of the intersection counting from the upper left corner of the. b% k8 q, |3 S! t. f7 Q3 e0 }5 X7 r
                  ;; world.  -1 for non-intersection patches." k/ R7 y( V) F9 m3 p0 I
  my-column       ;; the column of the intersection counting from the upper left corner of the  N6 p% ]) z" E
                  ;; world.  -1 for non-intersection patches.! i% z9 ?- N( y) v6 ?( Y
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.3 Z5 d+ n2 i0 W  O$ ?
  auto?           ;; whether or not this intersection will switch automatically., T: a% E3 B" }" ]
                  ;; false for non-intersection patches.
; t) l  c5 W$ }- }7 q4 p]4 Z; l, N0 M' R8 X; E

9 O5 p+ B6 ]1 M6 ~$ ?( X2 y9 O
7 D5 x+ t" t) G;;;;;;;;;;;;;;;;;;;;;;
; I: B% F( _/ N7 J. {;; Setup Procedures ;;
1 B! i0 }# o, Q) y) f;;;;;;;;;;;;;;;;;;;;;;
8 w2 Y/ T0 X# b" C/ D; B# e1 O* Q: c
;; Initialize the display by giving the global and patch variables initial values.$ C2 u8 @/ o7 E, D; ?
;; Create num-cars of turtles if there are enough road patches for one turtle to4 ^+ Q8 @( P. a0 D
;; be created per road patch. Set up the plots.
5 v7 i4 s0 p) U- {- S6 Gto setup
) h* v$ l) G$ V8 s- ?% W  ca$ G8 \, C  r% `( {6 A+ Q/ X
  setup-globals& g' ?& d% j8 n$ E  D* i, D
. R$ k4 y; `( q% x6 Q
  ;; First we ask the patches to draw themselves and set up a few variables, h5 V' e, s: Y$ f  \6 Y; R
  setup-patches
: R" B0 ?3 {, m( q) y% z  make-current one-of intersections5 A( o8 z  }* B3 A: K) F  C+ W
  label-current
+ B2 Q3 w; T( i" t- ]5 A& R  L! M- V  J: F' v  j
  set-default-shape turtles "car"
/ [* f- @1 m, ?  q9 i' b
" c2 K! \/ \! C3 p& S  if (num-cars > count roads)
& |7 z7 s/ i# i8 d8 e  [( l2 z5 `9 h+ ]/ }% o) ]! F
    user-message (word "There are too many cars for the amount of "- i' [. f! R- F: S
                       "road.  Either increase the amount of roads "( Z3 W0 \& T5 R
                       "by increasing the GRID-SIZE-X or "1 O; g. \6 T8 D! Z* V8 A; [- b
                       "GRID-SIZE-Y sliders, or decrease the "
6 D5 [' t+ ?2 n8 _2 `                       "number of cars by lowering the NUMBER slider.\n"  a3 U8 h1 d& v$ h1 D: Q# l" C
                       "The setup has stopped.")' Q; H; ]% Z  E* C( T
    stop
/ T- Y5 o# F) J  ]
+ D# |$ Q3 p$ ^. G2 K5 Q) g/ g7 P$ O4 z( S3 G# A- L# C
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
1 V3 L* y# p  n8 V6 Q  crt num-cars
2 n# e3 U2 B' i- ~% F  [
; r3 r$ j$ P  f/ a2 E) L    setup-cars0 g) v% E6 }& X& o3 V( ^
    set-car-color
- C- ]7 n; b) ]. ?9 s% d/ e" o& ]    record-data* d: O" p" @# ]. f
  ]1 q8 n, o/ h# e, S$ P9 u

6 C2 x/ v9 n% C5 K3 D. D  ;; give the turtles an initial speed: L$ F3 r# j5 d7 `, y
  ask turtles [ set-car-speed ]/ ]3 F" W4 ]3 G! g. b

% I6 y3 k  j- I0 U; z% ^  reset-ticks
- u( {* @3 U& U8 D. h9 qend7 m$ X( P  Q9 P! F

6 P" K+ x- t. Q( B. d;; Initialize the global variables to appropriate values" n' D1 y) Q6 P  q8 v
to setup-globals
0 w# R0 {- X; }( B  set current-light nobody ;; just for now, since there are no lights yet
. x( D# R9 a: o( J5 ~0 t0 ^& P/ }  set phase 0) E0 J# P7 t1 ?' L$ ~, r+ _! u# R
  set num-cars-stopped 04 P" y, y* }% d. \: b8 E
  set grid-x-inc world-width / grid-size-x
5 O2 m7 K/ v' r/ @: W  set grid-y-inc world-height / grid-size-y5 h; W0 {5 ~/ p: K. j% k
/ O3 E' M5 g) h, Y3 J& V! P
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary7 X) j: N0 E( }6 C$ G/ X: v
  set acceleration 0.0996 M- s7 I! A2 u# O
end& W- ?% o! G- L& z) D

- U9 x0 v: Z5 A' O;; Make the patches have appropriate colors, set up the roads and intersections agentsets,( i# I2 m6 O& S& b1 F/ |1 ~7 T. e2 X
;; and initialize the traffic lights to one setting
1 k- c, l) L. t5 b$ [" Lto setup-patches  I" u; ?: ^4 n: M: s* a) c5 _
  ;; initialize the patch-owned variables and color the patches to a base-color# ?$ V5 d" ^5 S5 a1 Y
  ask patches
: ^! z" u. m( S& Z: v  [
8 I( `% s8 B( N, l2 ]- H    set intersection? false
! Y2 z/ _- |2 L/ l% {8 `- q7 j    set auto? false  h( m& j6 ~& v% k' Y' ]
    set green-light-up? true# q7 y2 L& ^, u+ r
    set my-row -1. h. G8 V' H9 D5 F# L* ]
    set my-column -1
/ p; o& O4 t& c7 J8 m- t) n; ~8 D1 G    set my-phase -1
1 e! K+ {8 C# G! z    set pcolor brown + 39 Y8 d9 Q1 w6 |; C" A' x% S
  ]' \# H  `# r" `, T2 n4 g! u( U
2 z0 i% i% L. q. w& l
  ;; initialize the global variables that hold patch agentsets
+ _) R- I* z! F' {" s! v% x9 `% D  set roads patches with7 X2 v, m# V) l6 U9 }
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 H0 X# k6 L$ ?+ H# @/ m. V% ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& q! a# J% ?. [/ t% d  |
  set intersections roads with/ X/ y) H- X" r, J/ s; A  R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and3 d# ~% ~# g: L* j9 J6 f4 l4 E0 c6 U# c
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 y0 f! o; B% [  ^& c' t+ R, n2 f9 Z* k: O$ l6 Z- A9 n+ a  q
  ask roads [ set pcolor white ]; G2 [$ e7 }2 n" O- f1 P' S! N
    setup-intersections  U8 g# ^4 k: C
end/ t$ y4 F3 W/ P
其中定义道路的句子,如下所示,是什么意思啊?
+ t; e- i( W* J0 g8 p1 v set roads patches with& w8 Z/ L* x! _# L4 @$ q- H: s
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 w2 g  m% \7 p: {7 n
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. O/ m! I2 A1 G
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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