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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 `7 S" ~. K6 [
netlogo自带的social science--traffic grid这一例子当中,* W& P- r! T* |7 J4 U0 e: X
globals
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9 x) P; t4 W: U' [- P  grid-x-inc               ;; the amount of patches in between two roads in the x direction0 b7 `7 J. q4 w) R( j4 y
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 D( x# [1 n3 x9 l$ C% P0 T0 t  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 J8 l7 e3 |5 D, l6 [3 E                           ;; it is to accelerate or decelerate# D3 \( h5 m% B/ e
  phase                    ;; keeps track of the phase8 b; f. o; n: H9 ^0 O  B7 f
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure$ j! [+ C2 h% r0 A# v7 j6 f
  current-light            ;; the currently selected light* w) J* M% K1 V

! V3 v6 O8 a& I  p( y  ;; patch agentsets* L4 c1 d; N1 m- h
  intersections ;; agentset containing the patches that are intersections( }- A, {9 }8 M( l/ }+ X9 e
  roads         ;; agentset containing the patches that are roads
6 ~+ R3 @/ n: K( `. ?# u]
- a( u+ I8 e6 J4 b4 {: D' g: ?% M: f
turtles-own
4 e  e+ e" O* f) O5 P[: z7 s/ O( |- d4 D* R
  speed     ;; the speed of the turtle
/ h! Z3 F1 G  P+ x2 X1 y  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
* C, m5 `! k: |. a) A+ A0 v/ P  wait-time ;; the amount of time since the last time a turtle has moved, x; T& u( s  j2 G9 p
]* }; ?9 E4 ?7 T- ]
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patches-own' ~+ z' b4 q3 s! e0 H; @
[
' ^# Z0 k9 Q" f. {3 H  intersection?   ;; true if the patch is at the intersection of two roads
' x  m/ U' N- S0 w# L, B' S  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- ?7 m, ?+ v, I1 m& L
                  ;; false for a non-intersection patches.
4 ^+ M5 u8 M2 T- |* P! ^1 _9 L* A  my-row          ;; the row of the intersection counting from the upper left corner of the
+ x/ x! ^$ d3 k                  ;; world.  -1 for non-intersection patches.
- ?, F; M( q$ j# Q8 T  my-column       ;; the column of the intersection counting from the upper left corner of the" y. Q# W$ S' g+ e# c  F& v
                  ;; world.  -1 for non-intersection patches.
5 S; |% U: h( L% B+ Q" t  [  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches., G; t4 [) \- U8 D" e6 F" o
  auto?           ;; whether or not this intersection will switch automatically.  T  O; k  V4 _4 h# M, X, }
                  ;; false for non-intersection patches.
9 _0 m3 b0 v# V; g]
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9 F6 E) Z$ e; e& ?7 t9 I
2 f3 ~1 i2 m1 l, t;;;;;;;;;;;;;;;;;;;;;;
- b, d$ O& c* Y- ]& \9 G;; Setup Procedures ;;
$ r7 W" b3 ~$ U% B0 f* O. J9 a;;;;;;;;;;;;;;;;;;;;;;
0 t$ v& x& E! d: f+ ?; O  j- p0 J) i
;; Initialize the display by giving the global and patch variables initial values.
+ N0 Y4 A. [( z3 W2 {;; Create num-cars of turtles if there are enough road patches for one turtle to
* W/ |8 N, B* O4 r;; be created per road patch. Set up the plots.# l, V  {) T% T+ l, [5 `$ Y$ ?4 s2 y) d
to setup
! [3 x$ W( h! J8 z  ca
) ]( z" z1 p9 K% y  setup-globals& M) Z4 f5 n- A  H( ^# C- S

) \, w' e9 E( J" t6 }$ }  ;; First we ask the patches to draw themselves and set up a few variables! K  I! t" C+ V, b6 l; F
  setup-patches
9 A7 |: [5 d+ w( e2 b7 k- e  make-current one-of intersections+ g. a$ g5 j0 _
  label-current
# b9 I- ~& w% c3 _9 F9 O/ O/ p* B5 u+ y8 J* j# X" O" m6 m
  set-default-shape turtles "car"; S+ g5 Y3 z, r5 J9 M1 C
) }6 e* t0 O# \0 @1 _
  if (num-cars > count roads)
, T- g6 m6 g/ z7 a  [& k: D7 }% h) `0 }
    user-message (word "There are too many cars for the amount of "
5 X4 ~3 C% Z1 R- ^) c                       "road.  Either increase the amount of roads "; E/ B5 U5 q6 [$ P# e) s9 W
                       "by increasing the GRID-SIZE-X or "
9 N& J: Y4 V# _+ O                       "GRID-SIZE-Y sliders, or decrease the "2 `9 b( N2 k; \, Z
                       "number of cars by lowering the NUMBER slider.\n"! ]/ q/ X( k( S) I3 H0 H, j7 a
                       "The setup has stopped.")+ `  i/ M/ c7 ]7 t, E
    stop
1 y! n2 K5 p0 C) g  ]
, D" I5 D) Z( X! N8 H% T7 o7 Q
& V: {) p, M9 n! N9 \! _  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
: R9 k9 Q- Y( u- l7 V  crt num-cars' ?9 k" @7 e3 S# O; L+ c5 _* |( m1 c
  [
: p) s/ x( v( c9 }0 ]* q5 ?    setup-cars7 R0 j2 Y( e8 n, M
    set-car-color
$ k0 e/ E/ s3 U: J* I/ }    record-data: k' ?, `# M" `' T6 k
  ]& V2 g3 N3 j( ?
* s, g' H! Z( }3 x/ u
  ;; give the turtles an initial speed$ ?* d" h4 O- o; t4 i+ j$ B4 [$ {
  ask turtles [ set-car-speed ]
2 V5 [, W, E7 w) b
) ~  K& b6 P) u8 {" B* `% u. O: S5 r2 m  reset-ticks" P: v5 l% F& r  I9 f4 q0 D  P
end
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;; Initialize the global variables to appropriate values8 p4 s# y1 i; p) {9 `2 {
to setup-globals/ u5 ?5 ~  T* ]2 P
  set current-light nobody ;; just for now, since there are no lights yet
1 e8 I. n: B& U4 c& v- l$ z  set phase 0
: e. d9 v$ l2 s& p& L. I" d  set num-cars-stopped 0
7 @* b' C" q5 {, V7 x5 b! t: Y  set grid-x-inc world-width / grid-size-x: e" G) S& y1 I. T' k
  set grid-y-inc world-height / grid-size-y
8 ?8 _( K+ _" _* ]
8 ], w; B3 h% p1 U8 h  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% S4 P. n7 x1 e, n$ O  set acceleration 0.099
2 K0 b) e2 c$ X4 j+ Y( v' gend
  l& @7 d( W  _8 p/ }' y" n/ G. G
9 p9 e; R+ `6 p$ X. M* b9 a$ w;; Make the patches have appropriate colors, set up the roads and intersections agentsets,% q; O+ Z% u) q) @
;; and initialize the traffic lights to one setting" }# X; s4 J7 ~
to setup-patches) o: I- m3 D* s/ @' \
  ;; initialize the patch-owned variables and color the patches to a base-color
; c8 v5 g! A  R: v+ f  ask patches2 X, V% Y, e9 q2 q: ?9 V
  [
4 K: A% `; ^" S' Z    set intersection? false# F3 m$ S7 z* K* ]+ ]" S; _9 K
    set auto? false$ z) X8 ]' X$ p/ |& `3 K# Y
    set green-light-up? true
6 P$ C9 Y& Z3 `7 X9 y    set my-row -1
% X" l# j% ?0 e* p    set my-column -1
: m: ~8 A$ v8 G% l    set my-phase -1
1 D$ O* q. o" C4 z    set pcolor brown + 3  _" \  D, j2 ], d, i
  ]
9 F+ S+ F7 r# U8 s0 v, r3 }2 u( K6 U8 {+ T! `+ D+ g1 k/ h
  ;; initialize the global variables that hold patch agentsets
3 D' r$ w" F# U+ G" ~6 ]  set roads patches with
0 H. R: }$ S; A3 |  \' J; y) I    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. ^0 V5 \: P! S$ Y# I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* m' T3 F8 K6 d) s" \7 m) n# }
  set intersections roads with3 k+ U" ^' ]. U! F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
' Y4 @  @8 e! f, ^5 Z) M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ t  w/ H5 U" a
. S8 C3 U! b  O: S% Z  ask roads [ set pcolor white ]
3 H; j$ I0 h1 U" m8 C1 N) D! v8 M. E    setup-intersections
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其中定义道路的句子,如下所示,是什么意思啊?
/ H6 B; z  n$ ?1 \, |) k8 d9 h set roads patches with/ E) t' ?0 @, s% x4 ^0 _* w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 d. U9 D5 ~. c& ^7 C) ?& A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  l& Q4 p1 e' c" c8 A8 s  t
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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