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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。
0 M( T: F/ e/ Lnetlogo自带的social science--traffic grid这一例子当中,
5 L6 l9 s9 c0 u2 Y5 F/ ~/ Jglobals
2 B$ g; C9 i5 Q( c[, d  Y) K1 t9 W! ?. b- U
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, x% x, l# h, `# {  grid-y-inc               ;; the amount of patches in between two roads in the y direction# q% Z  l) o* q' }1 [
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if( @6 c4 [: c% J# m
                           ;; it is to accelerate or decelerate
. v: E4 Y$ J( k, t  phase                    ;; keeps track of the phase
/ T) K8 L; \/ ]. q! [( C  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure! O1 {# @, s- {  v, T+ x
  current-light            ;; the currently selected light2 ?) o# T& p2 y9 t

/ L# l. W6 S9 F2 I  ;; patch agentsets
# g! h2 s& }1 U) c; e  intersections ;; agentset containing the patches that are intersections9 Q7 h2 Q1 S- ?! m$ d& b
  roads         ;; agentset containing the patches that are roads3 ?  S' Q/ D7 ^+ w1 W. k; ?7 b9 s
]+ U- w. I: r& N# i

- Y: W7 p3 L3 H2 q$ Fturtles-own
4 [+ s& o' k  M; w9 v& Z# m[* h7 N" B/ R! U
  speed     ;; the speed of the turtle0 k  s2 J$ g- x* X. e2 J, m3 o
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
" J% c2 H, Y) p% w5 i* {. F  wait-time ;; the amount of time since the last time a turtle has moved# W( [3 E, `0 C0 }) K3 K
]) y& Q. x' [. F6 d, F+ ~

, `" [8 T+ N: }6 l7 ]patches-own
3 h1 ^, E& z8 `3 {7 q[: O, w8 ^. _' y2 R; r* P5 q
  intersection?   ;; true if the patch is at the intersection of two roads4 ^) U  a" h) Y8 }% b" a; Y
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
! K; I: g/ ~" K/ j: T7 y/ y) {                  ;; false for a non-intersection patches.5 D# {+ B5 s6 O
  my-row          ;; the row of the intersection counting from the upper left corner of the0 \0 w$ g" s- z; U
                  ;; world.  -1 for non-intersection patches.5 M( ^' {! R3 G
  my-column       ;; the column of the intersection counting from the upper left corner of the
$ q* M( D! i0 n  L. u                  ;; world.  -1 for non-intersection patches.! `" D  @  u* G! ~
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.0 e2 k: q" {& s; n. v2 |- A
  auto?           ;; whether or not this intersection will switch automatically.4 h+ D; u" G' {( S' A
                  ;; false for non-intersection patches.4 T( E) D% V7 y, K: ~4 o
]* A. j% |/ @( X% D% J% |$ Z) ^& P

1 O4 M' c, q/ e4 ^% S6 B+ K! J+ o* q* ]& P' ]! n
;;;;;;;;;;;;;;;;;;;;;;
) H% j+ c; c" V0 h;; Setup Procedures ;;, D1 h! o; ?, G
;;;;;;;;;;;;;;;;;;;;;;
9 v9 N* D" G$ g: |# g
4 m) _$ o9 h9 K" `& W3 O$ q$ Z;; Initialize the display by giving the global and patch variables initial values.3 ~% R- ^3 n( N2 B9 L/ M$ {
;; Create num-cars of turtles if there are enough road patches for one turtle to
8 r! C! K1 l# ^  y# v;; be created per road patch. Set up the plots.
9 T8 }, W" Z1 Y5 Fto setup
1 {; G7 E' Q  O- Q. L, ]* ]  ca
* Z1 P5 j2 ]  X& H6 |* o; S  setup-globals
5 U' _* H4 V8 f# R5 F  [) A5 v  i  }* f
  ;; First we ask the patches to draw themselves and set up a few variables* B; k/ I+ y9 @  o! w2 F
  setup-patches: e) U+ w0 y. _2 ~# W# P
  make-current one-of intersections
) x/ Z/ T/ U. J  label-current0 J( K7 d1 x$ @5 k

& b, n% b8 c2 f5 f, A  set-default-shape turtles "car"' u: h0 {( v; |% b( k7 V7 n: h4 N! R  ?

, K( Y  j: o% m8 _9 N+ G8 j  if (num-cars > count roads)( m$ s. Q5 X( o4 ?- _
  [
% ^3 c* r, }$ p; B0 g    user-message (word "There are too many cars for the amount of "
& `8 C( L6 B/ m& }; t" b' c8 f                       "road.  Either increase the amount of roads "3 I& u- A; T& F( U* X- _* A: g7 I' D
                       "by increasing the GRID-SIZE-X or "
! m# h0 h+ K/ j; _8 K7 I( T                       "GRID-SIZE-Y sliders, or decrease the "9 [) _0 `& R1 l/ E+ [# Z
                       "number of cars by lowering the NUMBER slider.\n"
3 g% U# ^, w0 ]8 u8 h                       "The setup has stopped.")' \6 i, v) E/ D& ?) g- c
    stop7 t4 C3 P) b2 W; h" Q' z3 A- u
  ]7 x5 k( w/ u, x: _
$ h0 P' c- e' I( L' F2 g/ d) O+ X8 N
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color# U- n. F" E% e5 g1 [
  crt num-cars: ]- K) l" R" S; k% A
  [. n# Y1 Z: w& ]0 d' a8 R
    setup-cars
' S- n; e( X2 P    set-car-color
8 S+ G5 V1 r4 M4 K7 R" [    record-data
. G2 |; R# \3 t8 d7 Z5 i0 G  ]
0 ?8 J8 d6 D# Y+ _1 d, J$ F1 U$ T7 f8 e; w
  ;; give the turtles an initial speed. l/ n! V1 @8 ]! ^1 \% R; V' h
  ask turtles [ set-car-speed ]
7 I6 O6 n) |; L% t3 a: K% _- S+ C$ l2 o
  reset-ticks' D* D- [1 g  y! \6 q
end
# ~$ B* d* a+ d3 I, a, e1 s' y3 ^0 j1 C5 i( g
;; Initialize the global variables to appropriate values
( u: g9 ?# B7 T; M) u! z% `to setup-globals% B4 P* O2 Z" J
  set current-light nobody ;; just for now, since there are no lights yet
+ s& U0 S! G6 d! t7 ?, c  V: k& k, X  set phase 0  ~6 F  P7 i/ l2 M! R
  set num-cars-stopped 0# [( j2 h% d% u( ^
  set grid-x-inc world-width / grid-size-x/ _% Y' N# G! d3 c% q; T- h, e/ M
  set grid-y-inc world-height / grid-size-y4 p: {. `* b5 |

: r4 e  b& t! w3 {" I" n  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
4 X9 R  M" Y2 G  set acceleration 0.099
3 n( ?6 C. H' iend- i% v  ~3 }  B
( a" p6 J9 q: P7 ]8 ?1 m/ B
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,7 L$ @' K( z! {6 n6 {. k  M. O4 |
;; and initialize the traffic lights to one setting
* G6 H" S1 G  D, i& Bto setup-patches2 y' [, Q6 n& f# Y" t( E% k3 m
  ;; initialize the patch-owned variables and color the patches to a base-color0 R# V6 V# {+ G" k9 b
  ask patches
3 T7 ?* C/ b( o5 y6 W8 X  [
* b' c8 T0 u  j! _( U    set intersection? false
5 v. a3 D, i+ b! O4 @, I: f' z    set auto? false( w- d) o8 r4 U5 {  i
    set green-light-up? true; k$ P, h1 y; [% |
    set my-row -12 c: y2 `: c+ p" t4 e$ J4 O: x
    set my-column -1$ [$ Z- f8 S( B
    set my-phase -1! ]+ U2 T2 Y: t
    set pcolor brown + 3
/ X9 U8 w" q9 F& ^  ]" m1 \' N" S+ t, h5 r3 Y/ h) _7 B

/ k: T( m) _6 I( N9 k) H1 J  ;; initialize the global variables that hold patch agentsets
) b' |/ |0 i4 P9 g. u6 s  set roads patches with# |7 f7 z; d* f
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! d. A2 l6 Z5 F( w5 z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( @: Q8 y6 S8 ?3 j4 }: y; p  set intersections roads with* I5 j2 C" u& o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and" @+ H4 p: q" d! W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 \: d; E6 t' b! v/ ]3 f: h; t
, w1 W* {. I4 w. `; E+ g) P- c
  ask roads [ set pcolor white ]0 q* |3 Y8 i6 n4 S# ~7 V" E4 d
    setup-intersections
8 ~% D; g! o/ V5 h1 Tend, ?' B+ K3 C- c8 X6 q
其中定义道路的句子,如下所示,是什么意思啊?
) Q3 x0 T+ p) `3 y4 p set roads patches with
8 o, g9 Q* w" P- w  R3 ]/ I    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 J6 W. U" E' Y8 P0 q" v& K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. n( F0 N; Y/ ?& s0 X% 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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