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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。
+ ?) ?9 p0 d! @  r* l& pnetlogo自带的social science--traffic grid这一例子当中,
( d6 L" h# p" G9 D/ D$ g  Y' ~globals
. f* ?" m& b5 `1 O4 \# L: \0 o1 g[# \+ L; H% P' P
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
5 v/ p- s; o) X3 x  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 `$ @5 i6 t/ _7 t2 }! ?, X  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 Q5 a1 _& w9 s                           ;; it is to accelerate or decelerate7 c& e8 d( p7 a/ W
  phase                    ;; keeps track of the phase
, n& b2 V% L& l3 D" x7 v/ y: \* I  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure8 T: i8 J9 {1 b+ A! |) {
  current-light            ;; the currently selected light
! @5 _8 ?) P: U: a5 ?5 x9 H
4 H* ]4 g" ~( D) ]  ;; patch agentsets+ W- U: ?4 H. C/ P: ^  Q1 B
  intersections ;; agentset containing the patches that are intersections% _8 V! w2 L% v
  roads         ;; agentset containing the patches that are roads
# n) N0 @3 I4 N+ V' F]
: J0 \' t* k8 |9 d/ F% Z8 y, {' a: }: E( n# J
turtles-own
; Y- N- H+ g: e- S  o" h[% T) D  J/ \: H# t, V! _
  speed     ;; the speed of the turtle8 W1 S9 X) O+ b; x8 t: M6 k
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 N1 y4 |5 T% [/ B! c( L3 L' v
  wait-time ;; the amount of time since the last time a turtle has moved" B( @  c1 ^1 D1 @0 w+ S+ K2 {% H
]
! u/ h1 x$ d: e6 z" ~+ U
; [' ]& C* g7 Q: l: x7 dpatches-own
5 I1 e; z/ p) l% y  Q[
- a$ F& H: Y$ i% @  intersection?   ;; true if the patch is at the intersection of two roads
/ U& ~* @1 K2 B1 R3 o" a# H/ U  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
: s3 ^- h, ]% R0 e$ C( ]6 |                  ;; false for a non-intersection patches.
% O9 f  S' e6 X. o  my-row          ;; the row of the intersection counting from the upper left corner of the6 g  `3 f$ N" @; x/ Z. A( ]! x" s
                  ;; world.  -1 for non-intersection patches.! Q: h' |2 }" s5 s! p" l) h
  my-column       ;; the column of the intersection counting from the upper left corner of the
% u0 ~" O: h0 @                  ;; world.  -1 for non-intersection patches." X/ `8 Z+ N5 n+ i9 [
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ x- a* M& v/ f1 q. L
  auto?           ;; whether or not this intersection will switch automatically.
" A  G, ~& x+ e  D! U0 ^- l, g                  ;; false for non-intersection patches.) o0 u2 l& o4 b2 \4 K
]
5 _: p# g$ Q( g$ c' m% r
1 z' y4 D4 r' `, e
% g2 F3 E- a( R5 S4 |$ };;;;;;;;;;;;;;;;;;;;;;
$ B: P& }$ O; @2 q% T* y+ d- n;; Setup Procedures ;;6 K! q$ s  N0 N. e
;;;;;;;;;;;;;;;;;;;;;;6 K5 B0 x& X- f
) j8 q! U% C1 Y9 x! s3 `
;; Initialize the display by giving the global and patch variables initial values.- v: R( ]6 K1 t; s) ^7 M" c
;; Create num-cars of turtles if there are enough road patches for one turtle to
$ U" }- ]" o1 q- N) a6 l4 ];; be created per road patch. Set up the plots.
/ E  l0 n! ?# K; |" f; ]2 V6 fto setup5 Y" X2 e& x! U4 _
  ca
; [3 K- N0 G( y- u/ O  setup-globals
1 _% P/ x- w. A9 w' w2 f
8 L5 c* l  j! X4 q  ?  ;; First we ask the patches to draw themselves and set up a few variables
" g) N# O( a0 N  setup-patches
9 n5 T% }0 ]; f% ^% ~+ }  make-current one-of intersections
+ z9 F" o( u4 I  label-current
+ [# J8 U  u7 {9 |0 K, J& Z: a+ s! `  w7 M9 |% Q; y/ K
  set-default-shape turtles "car"
7 Y; p& I$ F( m1 O
* J) G$ y5 B, x& t; q& l/ |  if (num-cars > count roads)
: ^/ W( x$ U: i/ w1 Q' s4 _  [6 O) v: o' a( V. V3 E
    user-message (word "There are too many cars for the amount of "2 J0 c0 c5 t8 Q8 H$ K% D9 i) s: r
                       "road.  Either increase the amount of roads "
  ^% ^# }% \3 v% G                       "by increasing the GRID-SIZE-X or "
' x( {( N" o, [) n                       "GRID-SIZE-Y sliders, or decrease the "
8 ~& ?- D& D* |                       "number of cars by lowering the NUMBER slider.\n"2 b4 F2 B9 _: g4 o% z! a$ U- v
                       "The setup has stopped.")
5 M8 ]  F3 D# w2 r& u& `    stop
" W! I$ d: P% L* g. n3 U7 }  ]" i2 ?4 P( `/ Q6 [' [- l7 V; S
( N7 v9 `  g: L
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  ~) S3 |, U' N/ @& f  crt num-cars
3 v! _+ k- l- H  [
( i# c* U. J) V& U8 [    setup-cars
7 M0 Y3 `) W3 V% K    set-car-color
9 Y" ?$ z* N* x    record-data8 S. u3 Q8 s7 u! C; b& j. `6 k1 W
  ]$ P& H  e7 u% a  Q
/ z" W- s. s  Q  J0 ~& W5 b
  ;; give the turtles an initial speed( `8 Y* W; ^& P7 C3 ?% ~7 g1 l
  ask turtles [ set-car-speed ]
' ^( _' H" o$ Q+ S- @' o
/ x# g: X  r' J8 h2 P5 ~  reset-ticks
( c6 H0 x& [; ]8 z2 u) F+ M+ Qend. I( b" G6 H# A5 c: d
3 e8 |* F5 f4 C, ^
;; Initialize the global variables to appropriate values$ U% `6 ~/ @$ B# C$ z6 @
to setup-globals9 e- e( c; z0 ^6 M6 c+ a
  set current-light nobody ;; just for now, since there are no lights yet& D/ P# o8 n8 V8 n& w. O5 Y- S
  set phase 0; J: [3 \+ T4 {  q  c& ?
  set num-cars-stopped 0
$ D. b1 P) M! Z! |: T  R2 k  q  set grid-x-inc world-width / grid-size-x% U' I. {3 _5 F. M
  set grid-y-inc world-height / grid-size-y
6 p1 q" w; w, @2 ]3 G& _0 k/ G5 U1 o( ~+ l- v' }4 A2 g$ D
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
4 ^0 C* \. ~% ]' p! q- V$ U$ |  set acceleration 0.099
( |8 ]9 k& W, O% h' @. ~! Iend
/ o  s: n% D+ Y# f$ k
( y# l+ k. `6 D+ D" `8 E;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
3 S% r# @+ L3 k, ~# t0 x;; and initialize the traffic lights to one setting* J& o- v" {  O* l
to setup-patches9 \- H5 W4 |0 L$ H; _. l* U
  ;; initialize the patch-owned variables and color the patches to a base-color
' r8 U; r: E, M  t  ask patches
: T* h3 {# @" T7 K2 f/ t: i8 C& e  [+ O. r5 ~  z+ W. b% k! m- p
    set intersection? false% e. f" w$ @: j5 A/ l+ m( C
    set auto? false- Q2 B# n" l' ?9 ]) t
    set green-light-up? true
; X! x+ l( T7 x    set my-row -19 S* ^6 X: G& @
    set my-column -1
. E5 U) y4 C! j5 a! B1 E7 U6 _    set my-phase -17 ~/ }9 }7 N/ c% p: `2 k. K+ D* O
    set pcolor brown + 3: n1 T9 ~2 y, Y8 Y, R
  ]
- m1 r! e: ~4 {" }; B" g% A
; b" Y) @+ B3 X  R  ;; initialize the global variables that hold patch agentsets
7 k" [* N: I/ u  set roads patches with! s' d7 H* `- a, E" e! C% W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' N+ M1 ]; m, L/ {# z, l' L; k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* @' {* E9 I* P. ^0 q% c  G  set intersections roads with* c4 `! I3 ~* {- ?) L- ^8 H
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ l1 A$ O9 e4 x* V/ s
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. c7 P! s2 G: j9 g: C" s5 `
; Q* w/ j) |+ P, ^# g$ e  ask roads [ set pcolor white ]5 [% T/ W  D3 x) m  M) [$ f
    setup-intersections. m5 F' r9 `, i2 ]+ M1 _
end2 e5 D3 P  D, `0 _5 h0 i
其中定义道路的句子,如下所示,是什么意思啊?7 q5 P; O* R3 X9 H
set roads patches with
8 O7 u2 x$ a: Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 u* l. w) ~. }4 f' }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& t3 y$ S# U, I: T: J, I) J
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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