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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。' R2 C/ H1 M  A. D! |3 `
netlogo自带的social science--traffic grid这一例子当中,
5 h) }) o: i7 q3 X* V5 _globals6 q2 k( C4 u7 {2 [% Z
[0 R" s5 w* e7 u, G, \- q
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
( [% t" I( {9 c  z. c8 e% ?  grid-y-inc               ;; the amount of patches in between two roads in the y direction
* U4 Q; ^; b0 e1 ~  acceleration             ;; the constant that controls how much a car speeds up or slows down by if# c% [: V& M5 m# f) I
                           ;; it is to accelerate or decelerate
" q$ H' [: |) b0 S! T  phase                    ;; keeps track of the phase7 k/ V3 N; B* R1 _, p  L
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
& t  p! v. P! P  current-light            ;; the currently selected light
5 s) q/ t# i. [! A& t+ n+ K) S7 P9 ^  S& X" P
  ;; patch agentsets" f7 d" m" w* h
  intersections ;; agentset containing the patches that are intersections
. S) h: G" I/ |5 ]8 K# F  roads         ;; agentset containing the patches that are roads
# d* F) J- S1 k6 K6 u% B]0 W/ P) M. i4 d

% o5 j. a+ {+ r' `( Yturtles-own
' j. C0 L; Q, A: Q6 ]- {) I[
$ W. y2 e, i# k  speed     ;; the speed of the turtle
* \) {4 ?- g1 o0 Y' u  up-car?   ;; true if the turtle moves downwards and false if it moves to the right0 Y+ L* k% S* C' o2 H
  wait-time ;; the amount of time since the last time a turtle has moved
! {7 X% ~  K: I( p]
) Q6 L9 o' y' _# o6 S1 K9 F* S+ _. j2 J
patches-own$ e. b3 r  T4 ?' e% |" O* Y. V2 `
[
& a% i9 Q3 Q4 U" w  intersection?   ;; true if the patch is at the intersection of two roads
' Y8 c: I0 C2 M/ A- ~1 r/ R  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
! ^3 `) j0 S0 x                  ;; false for a non-intersection patches.8 H( ^, S1 v& _) |7 I/ c: `' k
  my-row          ;; the row of the intersection counting from the upper left corner of the+ Q& Q; v5 y# y% S1 E! ]/ ~
                  ;; world.  -1 for non-intersection patches.
/ d" L0 J. Q& ]3 P& ~  my-column       ;; the column of the intersection counting from the upper left corner of the
0 x5 \: {9 L" c' e# ?                  ;; world.  -1 for non-intersection patches.
2 E* M3 ~. ~$ D5 A) ]' r  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
! U# Y9 e  J- w( w  auto?           ;; whether or not this intersection will switch automatically.
) q( z7 |8 I& M- ]+ G1 E. j7 {                  ;; false for non-intersection patches.7 P9 Z/ `$ A! O0 _3 ~6 r  k
]
. |, T/ \' Q8 O' N% l# W* Q2 l. ?4 A( r+ `2 _

# S8 a8 U* O1 ]/ ~; s;;;;;;;;;;;;;;;;;;;;;;
3 J3 M7 j; ~/ b6 {; |  A;; Setup Procedures ;;3 ]# _* I1 }7 \, f, |+ R
;;;;;;;;;;;;;;;;;;;;;;
; }0 i+ m) V3 K' i+ g0 A/ C! }$ V0 m+ m8 N: S5 }' k( K
;; Initialize the display by giving the global and patch variables initial values.
5 z2 K2 ]* Y) v3 K$ D. ?. O;; Create num-cars of turtles if there are enough road patches for one turtle to
: q# A1 O/ h. n& d0 Q1 n;; be created per road patch. Set up the plots.# R1 C+ Q4 b/ T
to setup8 j; B- P2 x3 A# a
  ca
' @' V/ P  R: j' L  setup-globals
8 {* `% N; a1 _) O* Y& I
3 Y* c, K! ?0 e4 Z$ S! O  ;; First we ask the patches to draw themselves and set up a few variables
4 V7 B! U2 x$ z4 U8 E1 j9 E  setup-patches
8 [7 K+ A: O- g8 `' b7 r( z  make-current one-of intersections0 }( X6 ?& v: Z3 W2 b8 f
  label-current' m  Q3 y* d; r* d9 [. X& Y: W

1 n) Y( V+ ]; r4 a3 J  set-default-shape turtles "car"0 K+ A! H" S" l' v3 G8 f

) [* H5 V; h+ x% I' u* x( _7 _  if (num-cars > count roads)* K! G" r5 @& |; {3 f4 x
  [
6 J- k4 U/ @- G, C) U5 ^( l    user-message (word "There are too many cars for the amount of "
- A8 x: x9 ^9 S# e                       "road.  Either increase the amount of roads "
5 ^1 h( n: ^6 T2 |" D                       "by increasing the GRID-SIZE-X or "
% M' {8 z" h5 M' h5 W/ _3 c                       "GRID-SIZE-Y sliders, or decrease the "
  |, G$ o9 H& v6 K                       "number of cars by lowering the NUMBER slider.\n"
% M8 A. R3 k* ~3 ^1 g7 B4 l                       "The setup has stopped.")
% n) M3 F! n1 {$ B1 B) j2 _/ I    stop7 M2 ?# Y+ y) @* m3 T. W
  ]6 O& Y" P+ h* A! M8 X
/ w1 M6 \: m8 m
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color  e: A# {, r' k% k4 O& s
  crt num-cars1 j- t+ x, q2 h, `2 r
  [2 I' J0 R8 k: B# T
    setup-cars
' }0 q2 v: x9 x5 y3 d& A5 W    set-car-color1 t/ F* t0 M" H# z4 A2 D. O1 M+ E
    record-data; J2 O; r' {9 u" g" P1 N9 L
  ]
" T, ?3 X9 e9 P9 _4 L  |
1 @) W- w7 {3 V9 L9 F9 ~7 F7 j  ;; give the turtles an initial speed
7 a9 ?4 O/ O  Y  ask turtles [ set-car-speed ]
! W( m9 v5 Z0 t0 Y5 o
  a5 d. W0 _+ J* f5 X  reset-ticks
& {" s' `; E% ]/ ~1 `& xend2 s6 b- G3 ?/ Q9 R/ v) B' c+ H
2 c& O& r" M. e- F/ i) E
;; Initialize the global variables to appropriate values
2 y! B9 k$ v* j7 K  K0 b+ x) Hto setup-globals
/ o9 Y3 {8 a! e9 Z/ t7 C" E4 O% [  set current-light nobody ;; just for now, since there are no lights yet. Q, E* T& N( ~" v4 r8 M6 O0 x
  set phase 0
" e/ Y& ]! Z+ ]1 d% h" k- G1 O  set num-cars-stopped 0
$ P# Q3 h; [# W8 M1 b& K* @  set grid-x-inc world-width / grid-size-x
: @- K/ `) u$ c8 ]/ d& w3 A# }  set grid-y-inc world-height / grid-size-y
6 |; [6 Q& l3 g0 s* w$ z1 m; r) n! h6 f3 d. l% \
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
' _' E" |; @3 \# u4 |5 ]  set acceleration 0.099
% {. Q1 b4 V7 rend' Z& `. W9 R! y5 ?# `# }& n

7 a! {9 i" M; U; N0 k4 F8 {;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
* C" _" E/ [& @;; and initialize the traffic lights to one setting
$ ^1 v- c4 I3 m+ ?- lto setup-patches
* ?3 e4 W. k' |; h! W8 b  ;; initialize the patch-owned variables and color the patches to a base-color
7 J1 _# t6 Z6 m% ?. J  ask patches
, J8 Y$ V* }  ?& F  [
$ a/ c# a3 K1 ]% R+ K- Q' }5 x    set intersection? false
7 X7 T! H5 b: i9 [- [- G    set auto? false( B' g' J- Y4 W2 U1 V/ i- B5 T6 s
    set green-light-up? true* ^4 p- i, ?6 p5 G
    set my-row -1- J2 U: R6 v. q/ z' X3 ~
    set my-column -1) x3 j3 Y& y5 _9 X/ G
    set my-phase -1
" p+ n$ a9 N: N    set pcolor brown + 3+ G1 A* Y: y6 i9 R4 u
  ]1 y' F& B8 H; ^+ A* S2 L. J
9 B, b+ a* N/ Q/ `& k3 Z
  ;; initialize the global variables that hold patch agentsets  f0 }  }% t. Z8 _" b6 a
  set roads patches with" i0 i" y+ e& I, t% p6 b) ~3 I# F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# k0 _* Z: `$ M1 A- e# \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ |; L- \& Y8 z: ^! I0 s3 [
  set intersections roads with- s" n( v& E. @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ K4 U; }: V0 t8 _, g- C8 K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 m/ Q* I, Y9 K& `$ i. k: f
: `* R: E/ Q$ y0 y8 x  ask roads [ set pcolor white ]
. L# F; X* H9 p    setup-intersections* ?6 S1 i: H" `
end& M" B- |6 i. d8 g
其中定义道路的句子,如下所示,是什么意思啊?5 a" I% e- C& g3 I. x- E
set roads patches with
! J! b( l: ~3 I4 X+ V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! O; K7 z& V; b4 d7 p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 w0 N1 _0 X: k( S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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