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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。
. r/ G, Z& I( Q0 Y% k# |& Pnetlogo自带的social science--traffic grid这一例子当中,
4 \! g2 @; b  sglobals
  h1 O/ _/ k4 i) z& ^- F5 s[# D' w! ]) z# x/ \9 {- ?
  grid-x-inc               ;; the amount of patches in between two roads in the x direction+ _! @# M4 e/ m& J9 o  J' q
  grid-y-inc               ;; the amount of patches in between two roads in the y direction6 {3 k. J. _- Z; b, F/ z+ V! }" s% V
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if% w! K" Z1 O: g0 V- k
                           ;; it is to accelerate or decelerate
$ k. @' Q/ h, C2 F  phase                    ;; keeps track of the phase3 _" x' z! S& H6 q" b$ H4 @
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 f% ~+ L. V  b( z, H5 N5 O- Q
  current-light            ;; the currently selected light
* n, C* N3 a2 r  r* U; @! B* v9 U/ Q7 @/ m/ F- \+ u
  ;; patch agentsets  f; B* }/ U5 |6 U/ o- z& w/ N  C( h& c
  intersections ;; agentset containing the patches that are intersections" M( P( v) a: a% F& g' y
  roads         ;; agentset containing the patches that are roads& ?2 u+ A% I: [2 b" t$ w
]
, `% T/ j4 x. e9 i' g
+ K( G8 |; c" v& N( ^& Iturtles-own
6 @  ]+ P6 {& Q2 _- Z. \[" L" O- p3 |! I  u4 G7 N
  speed     ;; the speed of the turtle
  s# ~4 h2 P1 B0 _' N  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
# d; Q+ P/ P9 h0 Y  wait-time ;; the amount of time since the last time a turtle has moved1 l, ]9 [' p" S0 Z( C* o- m
]5 z0 u7 w2 ^3 C: t; |  T5 a7 Y

7 j8 p$ G( |7 R$ v: ~8 E  T9 G" hpatches-own/ E( u3 v* h  r$ P$ J2 c4 n. t8 x
[  [9 |, l! u, }, P% P: @6 M% G4 ]* l
  intersection?   ;; true if the patch is at the intersection of two roads
, u! I! H1 Y4 R7 I5 M  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
, Q5 s- W" i2 x+ R! x4 E0 g                  ;; false for a non-intersection patches.
+ |3 ?' c- |, o# w! p  my-row          ;; the row of the intersection counting from the upper left corner of the
9 [5 B& ^# ?& V# p! M                  ;; world.  -1 for non-intersection patches.
4 W& ^1 s8 r  I2 `, Z: i  my-column       ;; the column of the intersection counting from the upper left corner of the
$ P* U* ]; U& C& P                  ;; world.  -1 for non-intersection patches.
+ X' E( Q$ C8 G  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.1 S$ E6 u; X, O" ~' P0 D" v9 Z3 V
  auto?           ;; whether or not this intersection will switch automatically.
# L+ A& S2 h2 n3 \# A. v$ U9 z                  ;; false for non-intersection patches.
& n: A3 i* r' {9 {" `3 \/ u8 X]
, I: [$ P+ R4 L# e" H% t) u' S/ O6 V  l! N5 |$ n& g9 B
) w6 i' s# ]& f1 v$ Z+ g
;;;;;;;;;;;;;;;;;;;;;;
. P& M9 [5 A/ x5 C' X7 y;; Setup Procedures ;;
! W' D! X3 q1 H6 G# g;;;;;;;;;;;;;;;;;;;;;;( P6 F4 p8 \) B' o' I) J( `

5 ~* {% D. ^  Q0 n;; Initialize the display by giving the global and patch variables initial values.
# D* F. w0 }; O( c7 H;; Create num-cars of turtles if there are enough road patches for one turtle to
5 R0 ~, I; O* {7 v# v$ ]" l  Q" W;; be created per road patch. Set up the plots.8 _3 b' L: N$ z4 l; b9 p  ~
to setup
, ?. t1 y4 X% G# V# b( i  ca
2 y0 [" o  z) I; V5 [  setup-globals
/ x8 ~  |% W, {% a; I/ {' O, T4 X! C1 p0 `; u* \
  ;; First we ask the patches to draw themselves and set up a few variables
& t3 d% w+ t9 u/ y4 E/ I7 f  setup-patches9 K; h: j) ?/ O# M% L% X
  make-current one-of intersections! e3 P9 `% a) |) K& s, G2 A
  label-current
- e6 ?) u' }4 o$ k
0 L  F8 S5 z: l! {6 i  set-default-shape turtles "car"7 U% r, n0 N% |  r6 t
4 j  I) X" |7 @- }5 S
  if (num-cars > count roads)
- G4 h7 K( _" z  [4 c' P: J/ o$ F# u1 Q: X
    user-message (word "There are too many cars for the amount of "
* r# x& q) H2 m4 z; Q% M2 a9 W( C5 T+ B1 H                       "road.  Either increase the amount of roads "
' Y7 D: P7 t3 g. [! a3 {                       "by increasing the GRID-SIZE-X or "7 ~: E8 _. t3 ~+ Z6 A  r/ D
                       "GRID-SIZE-Y sliders, or decrease the "# r. t* C5 e$ Z5 `$ z
                       "number of cars by lowering the NUMBER slider.\n"
1 U& F# p/ M" R3 h( P+ |                       "The setup has stopped.")
4 @' Q/ Q: a: t* C3 r    stop. }' Y6 a$ o- n
  ]5 p4 m8 p' F! o) z7 r( T, F! t5 Q
: D6 Z: B8 w4 [  V# z$ Y  ?. I5 q
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
6 \; R& B$ O& _  @& @4 B  crt num-cars& d( j( _0 R6 K6 s) S* k
  [/ W+ t; J5 e# s
    setup-cars* T: _' E8 }; Q! @- w  v" J* ~! q
    set-car-color- ]+ E, r  k9 s. i( B/ E8 X: S
    record-data$ y# E1 |& K( _3 r
  ]
* f7 v2 F5 [! C0 P# u) j9 b3 q" I0 Q$ f' \
  ;; give the turtles an initial speed
2 A$ V) \3 q$ M8 b2 Y  ask turtles [ set-car-speed ]
* U$ m3 q4 u: ?& t4 m0 @
+ z% @/ a' _( Q1 l* S& t  reset-ticks
. g" p* h, m! a* Hend
" {. g$ g# x3 X! ]: C
% p/ n3 k0 s8 u; f: S+ h( ?;; Initialize the global variables to appropriate values: w1 U6 H3 ~0 x$ c; r* ]
to setup-globals+ }  ^# B3 I/ u( Y
  set current-light nobody ;; just for now, since there are no lights yet: M0 u* F# a0 S) V. j
  set phase 00 o* R5 o  \7 j+ ?, G2 q
  set num-cars-stopped 0( P9 Z) ]# Q; B; G
  set grid-x-inc world-width / grid-size-x
  ]; ]4 c1 L4 x6 {" G% V$ R# }  set grid-y-inc world-height / grid-size-y4 ]+ E8 D0 K5 f( z+ r1 g* n

/ M7 H; d! M& V% n# c9 \9 u  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary( A5 }; ]" n" [% A, m0 k: f
  set acceleration 0.0999 u5 v* K* ]- z# U+ k- e, U
end9 b, O/ Q$ O0 h) f- k' A/ G

/ x% I+ W, g! D* `  X+ m8 ~;; Make the patches have appropriate colors, set up the roads and intersections agentsets,. u: t8 W1 G, i% A
;; and initialize the traffic lights to one setting
7 \, q) [: _; p: I; Sto setup-patches. z$ T: H% i& e$ K# j
  ;; initialize the patch-owned variables and color the patches to a base-color8 s0 V9 A3 B' Y6 f3 q( l
  ask patches
3 {( k/ e  B% J, B! y4 A% S  [/ [1 W; J% t6 c5 z- O
    set intersection? false
( w/ R- I0 ~  P2 i/ h5 a8 E    set auto? false
' z& r% e& C! H/ J8 s* M7 R    set green-light-up? true
1 y' |" A. F9 Z    set my-row -1
& S) {. D5 n& u3 `& U' g2 v    set my-column -1
! G  p5 i: l  K9 j3 H9 _- f; h    set my-phase -1
6 N* C7 M4 M; w6 ]. g/ a    set pcolor brown + 30 I- F8 F) ?! G3 ]; S
  ]
8 R& \$ w' I( }+ s
# F, h4 v  y8 f7 R  ;; initialize the global variables that hold patch agentsets
4 t- Y0 L  n3 ^: |0 E0 J: u% d  set roads patches with9 u# |9 x! x) G' n, l$ l% c2 _
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, `! \5 k# ^/ Q2 [
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% K2 m3 K5 r9 D0 b6 ^( K9 h7 |. r, _
  set intersections roads with4 t$ }7 k5 b- S. H
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
3 k. e' \) A  O, e    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- d& q( `0 `9 e* y) j
0 K( [$ C+ h1 A6 s1 o' F
  ask roads [ set pcolor white ]
$ H. f+ y/ _1 D+ W* Y: J    setup-intersections
& i/ ~) ?% B+ k' p1 G7 Jend7 z# X# A0 Q9 I0 i
其中定义道路的句子,如下所示,是什么意思啊?
+ z5 _8 s/ w4 Z( y set roads patches with  D& S. m" y0 m
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ X, Z+ \7 H7 f) q6 _
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], @+ g! M( m4 a( H( g! K
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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