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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。
' p" N) G9 {. n  b3 pnetlogo自带的social science--traffic grid这一例子当中,
5 z) O/ @! g. f% l, Gglobals
/ K( i6 d0 z6 R1 r! W[. w9 O* `4 o( W  D
  grid-x-inc               ;; the amount of patches in between two roads in the x direction4 [, e3 X  O6 L0 ?' E# p
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 j& s4 P! [+ e( v* l! b0 v- t  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' H8 o' u- ?5 c' V' t% v                           ;; it is to accelerate or decelerate6 b9 ]! Q2 |8 u0 Q' \
  phase                    ;; keeps track of the phase
. k2 s+ _' P, @0 t$ Y$ P) [  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ j* c5 e5 E4 G3 v) s/ f2 N' ?  current-light            ;; the currently selected light1 t  M$ q$ g, W% f7 ?
- |# N) a7 I" I3 u
  ;; patch agentsets6 V1 c  W; F6 G, q6 D0 r
  intersections ;; agentset containing the patches that are intersections" N( h% L! o) s+ z( e
  roads         ;; agentset containing the patches that are roads/ N# I+ X+ t. ^
]" _1 f; Y3 t3 U8 a1 s

4 m+ C- i- O; s/ A: Pturtles-own0 s+ D  m; w4 g1 Y
[
- |% o3 w, M. l4 O/ W. L5 N  speed     ;; the speed of the turtle
8 ?- a* q5 j1 v$ E& C5 _) u& P  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
6 z5 c3 {- r7 |: C! P+ G% v! X  wait-time ;; the amount of time since the last time a turtle has moved- C: o' K" }( T% f0 N2 T2 ?2 v' x
]
( x. o; I, E: o% n  I& i+ L
4 I& m4 N9 Z' S2 \5 ]patches-own: O2 Y, b& P# U9 @
[$ x# j' f! K  p8 k/ ^! z
  intersection?   ;; true if the patch is at the intersection of two roads3 g8 t) z# H9 H2 Q4 K# P
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.! Y4 v8 r; d2 F
                  ;; false for a non-intersection patches.
1 ?& m" f/ n8 P  my-row          ;; the row of the intersection counting from the upper left corner of the% Z) b. V8 ]. S# X" q+ `; N# n5 ]
                  ;; world.  -1 for non-intersection patches.  j3 m! d% S' V1 a* L$ n
  my-column       ;; the column of the intersection counting from the upper left corner of the. s  c$ v, ^1 x' @* P
                  ;; world.  -1 for non-intersection patches.
2 l( t  R; x! v  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
) q5 E/ g1 c( F  auto?           ;; whether or not this intersection will switch automatically.& I7 b. P1 U& d$ i3 B$ _+ _
                  ;; false for non-intersection patches." K3 O7 Q, y+ m+ b; s
]
, }. x& B- A3 [! @# C1 m2 U
! g; D* D" x) ?2 q/ r/ X! t* S' ?% {7 w4 M
;;;;;;;;;;;;;;;;;;;;;;
* K  I; i9 d% `1 U# U;; Setup Procedures ;;
( Y4 Q! X; k3 y+ b1 W" e. A;;;;;;;;;;;;;;;;;;;;;;
2 C* \( m$ U4 Z$ E& \
1 `; M7 c5 f: [. ?9 W;; Initialize the display by giving the global and patch variables initial values.
: y: B  R4 o. s0 W5 N& Z& k1 E+ j;; Create num-cars of turtles if there are enough road patches for one turtle to+ v* X2 L2 Z! w
;; be created per road patch. Set up the plots.$ Q) x+ t8 y* ]2 o7 y5 T
to setup
. ^& u- M" L  B9 z! m& y  ca
* X- C' |* K, v" q. y( N  W  setup-globals
8 n- ?, H) ], r6 ]3 k7 R
5 ^4 V6 Q( \, R7 p, u5 C  ;; First we ask the patches to draw themselves and set up a few variables. n! ?# v% n' w1 |/ q$ \5 d
  setup-patches& A6 M; I' E- P, \
  make-current one-of intersections
4 O: s) P3 R9 X4 [. D' E( C  label-current$ w0 d" j2 O5 `
# J4 ?3 a/ t5 F1 q
  set-default-shape turtles "car"1 w& K+ a$ {- X; `  E1 G5 l

+ Y! Q/ G. r% M- s5 G8 S: L  if (num-cars > count roads)
: t1 C' x  U; r9 n. p3 U  [
  P3 D6 |5 J9 j) Z    user-message (word "There are too many cars for the amount of "$ |/ }9 u2 j3 A7 L2 H
                       "road.  Either increase the amount of roads "7 v2 ]7 c/ S  c# r
                       "by increasing the GRID-SIZE-X or "( p1 b& F  t( J% X
                       "GRID-SIZE-Y sliders, or decrease the "2 \! Y* f. w: m2 j; q5 t0 I1 z+ y* s
                       "number of cars by lowering the NUMBER slider.\n"
4 P7 n; d2 Q' M                       "The setup has stopped.")8 f6 L+ ]& d2 ~( _# X* H; ^- Y( h
    stop
) V1 q( ~6 M- j+ X* {  ]
- ?6 h8 S& x& ]0 T! t3 y
! x; A+ M, x2 O( n1 b3 j  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
. p" ~5 S2 Z# G% |, q( i, m; T  crt num-cars
4 G/ g7 u' X2 {) Y  [- g$ l% T6 S, @; x/ k  f+ p
    setup-cars
9 U2 Z+ j+ l' Y8 g% y' v* W    set-car-color5 }" c5 O# h! I# ^. A& ?& t
    record-data
- N9 d- q" i# Y" W  ]* r+ E& z" P' v# Z. B) I2 p

0 \' T2 i' j- s& \  ;; give the turtles an initial speed# Z+ P+ e  {- f6 \& S4 E
  ask turtles [ set-car-speed ]
6 F, V6 `% H& \$ C& b7 E; B
7 k+ r& Y8 o5 K9 }0 H- R  reset-ticks
9 h/ s; s: C( h# Y7 B" o9 Qend
6 N/ I8 d% E1 e0 L. i' ~7 ~8 G. R+ r3 Q" m/ J9 J2 ]  C
;; Initialize the global variables to appropriate values' N( s: Q/ M+ H& l& \1 ^6 f
to setup-globals$ x2 D( |. G1 _* T  b  k. W
  set current-light nobody ;; just for now, since there are no lights yet
" e& X* c  ]. Z6 c8 {' K  set phase 00 Q. ]( k5 R' V# d0 M8 t9 v
  set num-cars-stopped 0
" Y. P8 A  F+ P' v  set grid-x-inc world-width / grid-size-x+ i: f, F. o" y. e8 j
  set grid-y-inc world-height / grid-size-y
2 L, @9 A) Q3 X2 V; p7 s) U) Z3 z: q5 B  v2 y/ m6 \) Q) l
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary$ x3 M6 ~- M/ F( [* S) U) }. t
  set acceleration 0.0999 Y9 |5 q' ?$ j/ B& {/ F7 o3 i5 F- K
end  Z/ z/ e3 q! A9 y5 |8 j

; {5 l! K% _+ n;; Make the patches have appropriate colors, set up the roads and intersections agentsets,- n, Y, O1 f8 I2 L+ x* p
;; and initialize the traffic lights to one setting
3 R# m. _9 ]) f8 J2 C3 Bto setup-patches% w4 L- |8 G6 d! M# ]' x. `
  ;; initialize the patch-owned variables and color the patches to a base-color
6 R. Z  S, p$ J$ L  ask patches; V2 R: S% c# S$ I
  [- _8 c3 x7 p3 f" |# t& `
    set intersection? false' U5 V4 z( P' U1 N1 @
    set auto? false- c) g7 i8 J! ?3 m* o2 {0 Y
    set green-light-up? true+ \4 d6 }  C/ Y! c
    set my-row -1' g/ ~# h; R, J" B$ I: Y/ x/ U
    set my-column -1
5 w) r6 e- q. Q    set my-phase -1
# p1 P! W; [" W: n( V* |    set pcolor brown + 3; v- |; Y# ?; g0 M) q
  ]  [- x% ]0 k$ w+ w) h1 r: F

0 A4 \/ `2 l2 G! ~6 G  W: g  ;; initialize the global variables that hold patch agentsets
) C. S3 O6 }1 A# H5 \! [8 ?8 |  F  set roads patches with
7 ?& Q5 b7 T/ n0 p0 L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 ]- h- Q# F2 _0 k4 b
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: N' c6 w3 {4 q1 e7 @
  set intersections roads with6 |6 O8 q8 i, `
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and1 v1 a. h( O2 s1 N$ |3 H$ ^) K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ D* V/ r. U1 H% {' q8 e* P3 z+ K& L0 z7 I
  ask roads [ set pcolor white ]: s3 m  J4 Z/ g' n: `
    setup-intersections! g- w, e$ {# Q+ B: x* `
end0 g8 W8 v& o- \0 v
其中定义道路的句子,如下所示,是什么意思啊?
9 h4 v" N1 D: l1 ~5 X set roads patches with& s4 G; l8 v2 z5 A$ I. e) H
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# u) ^( R% D7 K! b$ V    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) r8 T" J" V/ 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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