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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。
. ]" M9 @# @( M0 ^7 V' i4 Dnetlogo自带的social science--traffic grid这一例子当中,
% S$ E( D) t3 Yglobals
3 m% W+ i4 K9 T[9 y0 s' y4 @; Z; B
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. @6 j5 ]$ C5 T  grid-y-inc               ;; the amount of patches in between two roads in the y direction( T# k8 H  U9 `  x  ]# x
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if3 Q) e1 W4 r3 c' v- U  M8 H
                           ;; it is to accelerate or decelerate
0 \! c! A% @! D. b$ t1 {  phase                    ;; keeps track of the phase
4 Z1 H+ ^3 e" U  l- _9 n1 N  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure0 h6 L; C/ r# Q' o; s) \
  current-light            ;; the currently selected light
( d0 E8 m* `! M( M" `& U; |$ d* o5 H3 I$ p
  ;; patch agentsets/ @' t  a+ G( p; ?) z- i
  intersections ;; agentset containing the patches that are intersections
: H) P6 H4 P( ]" d+ j6 P: `* K  roads         ;; agentset containing the patches that are roads3 I& X' X0 V. k; @4 [; ^! `0 a$ F
]
/ {7 f4 J$ g* o6 i1 V& F1 Q/ d- ^+ `8 G1 w, P% A. D7 t! S
turtles-own
* G) {( N/ [1 f/ h/ A[
) A8 P5 P! j+ |/ w  speed     ;; the speed of the turtle: r, o9 V$ R+ {( m
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
- ^4 E1 `' x/ J( n  wait-time ;; the amount of time since the last time a turtle has moved% R; I, C9 d& Y3 ~1 `, N6 N
]$ {% o$ h3 U9 k6 c+ \% z  x, i
, v; y0 Z7 E' ]& ]) |  m
patches-own
. N. e2 G/ {+ _! y3 T: G[3 u+ n1 G9 x4 H+ c( l
  intersection?   ;; true if the patch is at the intersection of two roads" m! y7 O' Y( {6 K' \& E
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( e5 m- {0 D2 G) `! H) n                  ;; false for a non-intersection patches.
. |3 o6 s% g4 a8 T& ?# a  my-row          ;; the row of the intersection counting from the upper left corner of the& x" r3 y# a$ L1 G. `8 l/ }, k0 q0 |
                  ;; world.  -1 for non-intersection patches.& H. C1 |9 k0 w+ o6 E
  my-column       ;; the column of the intersection counting from the upper left corner of the
0 I" S2 q! b( S! g' o* V                  ;; world.  -1 for non-intersection patches.
& J! ?7 l  B: }4 {7 s3 p+ U  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.+ t% I$ r6 v* `
  auto?           ;; whether or not this intersection will switch automatically.6 {" h1 @2 r8 n, y
                  ;; false for non-intersection patches.
8 `, x4 `' {2 y4 X' }]
5 M% K3 s1 k; D' D, j# Z& g$ e  Q6 z$ ^+ N. A0 q. |# S
4 n; _# F' D" e$ j# {) b
;;;;;;;;;;;;;;;;;;;;;;6 r! X1 q8 \2 h! J
;; Setup Procedures ;;
( A. l6 q$ Z4 }& d, f8 [;;;;;;;;;;;;;;;;;;;;;;
% _; V/ G. U3 `. e$ |0 E% _" [) b  U- h# R7 R, n) I$ K- p0 O
;; Initialize the display by giving the global and patch variables initial values.
% _/ ]# p' G7 F+ n1 J5 n2 X; v4 G;; Create num-cars of turtles if there are enough road patches for one turtle to: Z6 ]9 Z! ]* }; X2 w( C0 L
;; be created per road patch. Set up the plots.
9 [, f5 o4 Y: h8 V; {8 _to setup9 e9 `; R/ P7 R) m% W8 X7 Y- }
  ca
( D* b# X5 z( l/ v. H, C% Z  setup-globals+ P: m, n8 I; E
) n( w: g: x$ P$ u1 x2 @
  ;; First we ask the patches to draw themselves and set up a few variables
/ X2 ~( N1 M. i7 C5 `8 B1 j" ]7 j8 m  setup-patches
0 S0 \0 `' |2 Z' K( d0 L  make-current one-of intersections# G/ |4 {2 h) c- w9 z: C/ d# {
  label-current
  T" ]# r) D. R' J3 x% ^
6 K! J- _! h1 C' l/ N  set-default-shape turtles "car"
/ ^/ X7 m. T+ Y/ U0 ^0 i5 U: y0 K9 l3 ~& S+ _  D
  if (num-cars > count roads)
9 u5 f/ \0 O5 N6 b) c# t& E* N5 _  [
1 r2 _0 g6 l% P7 A    user-message (word "There are too many cars for the amount of "3 u6 o; j9 R" R/ a3 D' _4 Z8 N' c
                       "road.  Either increase the amount of roads "
2 C9 T! n7 ~; U) _! Y; W                       "by increasing the GRID-SIZE-X or "  E# q, b1 T+ \; `: k9 L
                       "GRID-SIZE-Y sliders, or decrease the "3 |% w- ^5 u  f3 b, n
                       "number of cars by lowering the NUMBER slider.\n"
4 D) C/ X$ U- X2 n2 i0 A                       "The setup has stopped.")
" T; T2 a. n& y+ I/ B5 J    stop
, Q  w0 U" E4 ?' |, v# }  ]6 ?; B5 [. Y+ Y, G0 q

. o' H1 J& n" A! D5 k' ?, T% ~  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: T; r2 Z, E1 s; t
  crt num-cars- K9 z" v! Y+ g5 O
  [$ F2 t% `, ^. x- J( A  F
    setup-cars7 ], Z! M) S! Q( O3 Y/ L! N' m: ?
    set-car-color
  m/ Q* `8 h. z- u: |    record-data4 @1 b! f9 ?! O8 N% l- n
  ]2 p, S+ @8 F3 U2 D' }
8 L5 \) c5 Q4 t2 r
  ;; give the turtles an initial speed
  _1 \5 S& E' I/ w% l! U& f! Y  ask turtles [ set-car-speed ]
! ]% a) j! o$ L6 w& P2 [7 J( L! K* ?1 ~) A  h0 G2 T" G: r/ M% z0 U
  reset-ticks; Z, }% v! D4 Z# u1 J
end
* w$ i. C, e  e# r/ g
# ?4 p. V9 e6 F. s  C;; Initialize the global variables to appropriate values
% S. J% C' u' |" h$ Dto setup-globals  ^2 p6 u" C1 J, h
  set current-light nobody ;; just for now, since there are no lights yet
9 p2 T( I0 z5 {1 P6 P  set phase 0
6 o, R  P) y9 _8 Z' F( A6 X  set num-cars-stopped 07 A; I5 a- m7 F. h. `# W; U7 T$ j
  set grid-x-inc world-width / grid-size-x6 d/ P: ?3 j7 M4 E; u. D
  set grid-y-inc world-height / grid-size-y" i' }9 X9 L% \

7 h( r, O9 t3 n" r( I( E& b  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
: j# _0 |- V5 b9 f, Z  set acceleration 0.099
, G; v- k- B- t. A. x) ?end
( j: C4 A; \( C& h; U, P% c2 t' m8 M( _) j# B, w; t
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
. p' V" c! u) |. r+ A3 Y8 E, I;; and initialize the traffic lights to one setting
1 M0 T) q2 Y, D8 Mto setup-patches
' T: y+ Y# a% b" \' b  ;; initialize the patch-owned variables and color the patches to a base-color2 m' a$ l, M3 s: C
  ask patches
- y6 @1 K& B6 @5 r' k0 }' d  [
# u" H& M+ v& j5 q' d2 O# a' C/ h    set intersection? false! U" ]7 M: B3 [5 |( p9 d
    set auto? false% g8 x1 |' ?( p* x
    set green-light-up? true
$ @" G9 ^# K- n0 v4 G    set my-row -1
& k: M. e4 I# U$ D" e0 O( e" u    set my-column -1
5 N; N: t+ x0 B# ?% A, d    set my-phase -1
0 E9 G/ R' p5 w  P5 h  e    set pcolor brown + 3
6 y+ [# n" ^( f  ]5 P. t/ H8 m, c' @

4 P' V8 z  y4 t+ P; w  ;; initialize the global variables that hold patch agentsets
: G$ K- Q" O/ [) [6 ^  set roads patches with5 i, d0 b1 r0 O  d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' c# D: W$ i- L9 k6 I' c, m% C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 }1 u& s2 f1 M( L  set intersections roads with1 R( f+ c# ~* z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and* F7 `1 Y; I$ h# }) O  H& {) r& \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 r' f% _) s# V  \# x
" f. v" z  |, Z* h" P  ask roads [ set pcolor white ]+ \, ]0 h; G* s, U/ l
    setup-intersections2 i& t: h/ C/ y7 M4 Y5 I# d
end0 X8 j! C7 n% E: v" W
其中定义道路的句子,如下所示,是什么意思啊?  B* k! x8 ^: t" b) V% V' h5 Y
set roads patches with+ U& ~, B: M& R8 @4 R' q3 a6 ~
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 R0 ^( c! v2 y1 \# K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! i5 {& N. d3 G5 H, Y
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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