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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。
, Q! B& r0 S0 s* C2 E& t4 Pnetlogo自带的social science--traffic grid这一例子当中,, Z$ y% u/ l+ J, `  ]) u
globals: S# Z0 U! H) ^6 \& L2 u3 m
[
0 Z2 D8 _: Y( b) K! j" U! B  grid-x-inc               ;; the amount of patches in between two roads in the x direction& y1 `% F# C6 J; P  Y0 p  Z. v
  grid-y-inc               ;; the amount of patches in between two roads in the y direction% y- p- X4 ?  S
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 x# I8 |, N/ d1 M* B                           ;; it is to accelerate or decelerate$ A- g+ d6 B5 x1 X0 I$ {9 b
  phase                    ;; keeps track of the phase
# F3 M( l; V( ]2 Y8 l- o  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
) r4 @: U- x) _4 J" x! Q  current-light            ;; the currently selected light# Y) O. F& ~  S6 Y: X) b! P

) ~9 b# S/ t( e- M2 g  ;; patch agentsets. o6 W# p* S& M! M6 V3 Q3 c
  intersections ;; agentset containing the patches that are intersections% I# f7 N+ p  T. j, B6 b! U" P
  roads         ;; agentset containing the patches that are roads
7 [1 O# u1 q: C% x6 L) T]
3 u/ @7 n, ~! z* h1 W( T) D4 d) N) N+ B: w
turtles-own* y/ d7 X8 K" X, Z' G
[
$ q2 N/ a  E2 r) S2 c7 s8 a. X% ~  speed     ;; the speed of the turtle* J" ~! u, R. L. D% c9 g9 J
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
  w1 M) J! S5 B  wait-time ;; the amount of time since the last time a turtle has moved
9 R& G! O0 e( {+ _- j$ @. {. x' j]5 a) l9 u- g' f, S) i
7 a  g; M" C, F& B4 g( r
patches-own* u  R8 Q/ l% f+ }6 A
[2 {, a3 v) D: e) q; R' J
  intersection?   ;; true if the patch is at the intersection of two roads
- f! }/ B1 [9 Q8 n  @  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- b+ @5 a; x+ v  _2 Z% a4 r5 @& [
                  ;; false for a non-intersection patches.
# M' A. B( J2 X; m' M  my-row          ;; the row of the intersection counting from the upper left corner of the
- h8 q8 C% S0 f' X                  ;; world.  -1 for non-intersection patches.
, j$ l- f& c; T6 M: c  my-column       ;; the column of the intersection counting from the upper left corner of the2 ~. Y1 q$ M' L8 @/ b0 p5 r
                  ;; world.  -1 for non-intersection patches.
7 S5 o; }2 ~, j- B0 ?  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.3 K' W8 ?$ x) L0 w, P+ u, \
  auto?           ;; whether or not this intersection will switch automatically.
: T9 I* I9 ^! L( [                  ;; false for non-intersection patches.) s' `; k0 A: B  s$ v
]; _8 ]: V- {& Y9 Y' h$ e2 o
5 O5 w, Q% Y( J! q( R& a8 o& ^
" K6 t! H) ?6 _  K7 i+ @' B8 J
;;;;;;;;;;;;;;;;;;;;;;5 Z* z+ {$ ]) C2 x" C
;; Setup Procedures ;;
# [: M* T- T9 ?/ b4 J! M% h;;;;;;;;;;;;;;;;;;;;;;. S. O7 j' ^" t$ }: ]4 _% f
( P& N' p' S6 M
;; Initialize the display by giving the global and patch variables initial values.
: v7 N: z0 P, g. k( i$ h;; Create num-cars of turtles if there are enough road patches for one turtle to
; m2 N/ D- l' e$ {/ o;; be created per road patch. Set up the plots.
" C$ m5 {0 w* }- d8 x  R0 dto setup, ?9 b! u1 ?  m( ?. ?
  ca7 j+ N5 l% h4 ?
  setup-globals0 w8 h1 V. q5 `, h( I

& k; l+ p5 u8 x1 j  n5 P3 ]  ;; First we ask the patches to draw themselves and set up a few variables
% R# v1 }7 b8 V1 e8 s7 L  setup-patches% H- P2 I5 P" `6 k
  make-current one-of intersections- D" v0 S8 O$ |5 E. P; H
  label-current0 U9 L* j& f$ `1 _
" _6 V! {. Y  r; }' D  a- f7 P
  set-default-shape turtles "car"9 h3 k0 i' r$ ?# ^

+ C8 h, o  r3 D; x" U! ]) W  if (num-cars > count roads)# u( S3 c" v( Z8 J, |: _
  [
: R, Z4 }% l% F' P7 V  i3 V: {$ g    user-message (word "There are too many cars for the amount of "
. H) l9 u. J0 d. |* I8 \                       "road.  Either increase the amount of roads "4 y' f. q& L) c7 x% {4 d: V9 X2 M' J- Q
                       "by increasing the GRID-SIZE-X or "
! L# W$ g# D$ t4 V                       "GRID-SIZE-Y sliders, or decrease the "
5 e! y# }3 s( P/ e                       "number of cars by lowering the NUMBER slider.\n"' D. I  ^" n6 @/ r: z' O
                       "The setup has stopped.")
6 h2 L0 V# z  E- s, Z0 R    stop
/ T3 N: o0 U) W. M; {- H! `$ k  ]
+ g6 ]; T" G3 {9 H  E6 Q& \5 Q, ]" W2 X/ m( ^: V2 v
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color+ w% e( ?% k8 T$ L
  crt num-cars4 |1 c- c3 z% B9 L! |/ N8 N3 U$ `7 l
  [6 N- H) R7 `- d. T3 a  I
    setup-cars
+ G9 I# S! p$ H0 a; G, H$ z    set-car-color
. {5 ?8 N& \' q) {    record-data# k* t$ \2 t1 x& @, s* x8 H+ `
  ]
# j0 \' R# c* C8 B
7 U) x3 b* m; h: ^8 D  ;; give the turtles an initial speed0 _9 H4 @) o8 H, U- c! \
  ask turtles [ set-car-speed ]3 ?% l; p* D; ]2 ^+ ?7 ^
) }9 q' X- v* D9 q% w+ k) d5 U
  reset-ticks2 t8 h, u, y+ T9 \2 I/ r  U
end
, r# `7 b5 z. F: v+ S% ]. B. ?1 S
. j% W$ @9 g# n! p, ?0 l;; Initialize the global variables to appropriate values
: l, c# n( b" O3 ]: dto setup-globals
5 ]+ v7 a" ~& ~0 G  set current-light nobody ;; just for now, since there are no lights yet
9 H" F' M1 Q9 B  set phase 07 i. X4 R- |9 r
  set num-cars-stopped 0
4 Q: q" x) ?! s: w; |  o4 D: P; C  set grid-x-inc world-width / grid-size-x' U$ e+ k3 P; {# v! Y
  set grid-y-inc world-height / grid-size-y8 c3 _1 N- Q+ J/ |5 q

; E, [5 E/ ]3 H* a  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary" a3 U: B. b- \: d
  set acceleration 0.0992 E' f5 Q. q/ ?+ V$ R
end# {8 G& U4 v$ D

+ Q* x, j$ V. d4 a& }& A1 z;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
* e+ R( K* p* B, N$ q+ @;; and initialize the traffic lights to one setting
" V/ ]- c) b3 r' _to setup-patches4 ^$ F! S4 t' p+ b* J
  ;; initialize the patch-owned variables and color the patches to a base-color2 B- s% f1 j  R( Q! O# S* x
  ask patches
4 x- k, Z8 X4 }+ i  [- z" P6 D# u2 Z$ z" K3 M
    set intersection? false
, c! C$ q& a5 }- ?. y% G    set auto? false2 t0 @; [& \7 d& t2 h6 L
    set green-light-up? true/ Y* N5 K+ [" ]0 D3 d
    set my-row -1
. {3 P; L7 ]/ V    set my-column -1- f3 g& t' S2 o- c0 f. m1 [  U
    set my-phase -1
6 Y/ ^. r% |5 ~7 L" x  L, W7 {    set pcolor brown + 3; ?; ?, M, r& W/ c) r" Q6 n! I
  ]+ g3 g6 }/ o7 ~7 D* V! o
3 x2 _5 R6 U5 w  S2 ]
  ;; initialize the global variables that hold patch agentsets$ I. k0 S7 F5 T9 `0 \* }
  set roads patches with/ F. c* n* g' U7 }
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 @+ T' K: V: v$ p$ |2 f    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ Y6 M+ S$ e* X6 Y  J: _  set intersections roads with0 ~8 i, b5 P8 T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
, @, I& a+ {3 T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& a+ U/ s. v# v* T1 j: M/ N$ e( V  a7 h9 A0 g
  ask roads [ set pcolor white ]+ w8 c( b" P8 R) ?
    setup-intersections
4 `# S% Z0 h$ v, X9 dend
5 F$ v! C" {$ q0 P7 n其中定义道路的句子,如下所示,是什么意思啊?
5 d+ b* P  U9 b, l4 o/ } set roads patches with& h: D9 g/ z7 v$ l; f# ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ u/ Y' d. X* j; D; n# v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& I; a/ D3 d' j( p8 S: S& n" C# t) H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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