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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。
+ n- x* V! m/ _netlogo自带的social science--traffic grid这一例子当中,
$ ~* a8 C6 r8 E7 h1 a" ]globals
7 K; |7 j$ O- z" H# ^[8 Z$ F  |' n; s- L  a  f& B
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
  i* J4 v$ a- Q  x) O  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: z2 \; U5 |1 v. L" s+ G5 ~  acceleration             ;; the constant that controls how much a car speeds up or slows down by if+ r* R/ j+ Z+ D3 }5 A' N
                           ;; it is to accelerate or decelerate
. W' R9 L) d4 P2 e0 g9 {- H  phase                    ;; keeps track of the phase2 A3 u' m6 n' a3 t$ t
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure% e' }, ~- z5 l* H( \
  current-light            ;; the currently selected light
1 L% M2 B0 ]7 S; }2 [) e* c4 V
; s% j3 V, D6 B% g! z3 p  ;; patch agentsets
; d6 Z% z5 _" h  intersections ;; agentset containing the patches that are intersections; d) A+ F4 c/ e' _
  roads         ;; agentset containing the patches that are roads
" L9 R* S6 ^1 w. c]: T" F( y6 o. L6 s! S
3 t, i3 i; K' e: P8 e; G& @3 k
turtles-own
/ s& z' R. R# X/ @, r; i0 d[9 {5 ?. f4 m- n: @% j& ]: e
  speed     ;; the speed of the turtle$ n5 N$ ~3 `3 K, M! V" u
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 p5 [2 M6 [; s" _7 s; X7 r0 y
  wait-time ;; the amount of time since the last time a turtle has moved
5 i8 S" P4 `3 O6 Q4 M]
: l) t+ I! }' p3 k
% \) L0 z4 o( r  @patches-own
' Q+ h( r0 x; \6 n, R- V0 C[0 A; ~( ~: O$ }! y& @( W6 V
  intersection?   ;; true if the patch is at the intersection of two roads/ [* _7 d0 h7 L$ J& L& n& x
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false." B/ |& R/ ]0 G8 _, q0 v# m
                  ;; false for a non-intersection patches.4 y7 a% r1 m0 q- n/ V1 `
  my-row          ;; the row of the intersection counting from the upper left corner of the
( x' I. ]6 Z  T: {" V                  ;; world.  -1 for non-intersection patches.
- z( p7 \) c1 o' o- R+ ^  my-column       ;; the column of the intersection counting from the upper left corner of the
( V9 I, F* E: Y- D+ }                  ;; world.  -1 for non-intersection patches.
& H& @- A6 ]  r/ o  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
# a+ S9 k( v  T/ s) ?* M  auto?           ;; whether or not this intersection will switch automatically.
( y6 x/ o" D% K9 ~  L                  ;; false for non-intersection patches.) l6 s0 I$ m0 {, g, w9 R+ k
]% i) t7 P. m0 }# ^  _: Q
. _. }3 T7 a' n* d/ t
9 d5 u: V# {& u: I. o2 ]# ~+ O$ }
;;;;;;;;;;;;;;;;;;;;;;
# e+ Q9 E! [4 j0 L' x;; Setup Procedures ;;
8 i2 n! G9 F4 K' }2 ?0 t2 _;;;;;;;;;;;;;;;;;;;;;;8 e6 T7 W' \! a" Y, l. [

! k/ M7 C! j4 H  P+ H;; Initialize the display by giving the global and patch variables initial values.
, G, r6 R# J! s/ K! G5 `;; Create num-cars of turtles if there are enough road patches for one turtle to
) Q2 [: L( B3 W* U6 z;; be created per road patch. Set up the plots.; r( c1 a7 H- A/ D7 R! ^
to setup3 w5 q4 T3 x; ~
  ca
! Y+ P3 z  r# g4 n  setup-globals
- }% g% b/ s# _. x- |0 E) V8 G& p5 Q3 e" k5 ~+ {
  ;; First we ask the patches to draw themselves and set up a few variables
0 Q& K) k) }/ S  s6 h% x  setup-patches& ^& T. Y) o& O# a% H* z. g- M
  make-current one-of intersections
0 j/ a% ^1 x4 N( o, n  label-current) |9 t# X$ i6 W# W# b# G- ^

. l. l6 p2 o* t! k" Q  set-default-shape turtles "car"! d  {3 d* ]9 G) b2 v) H9 h

- q# E+ d  `/ N6 ~  if (num-cars > count roads)9 \% a1 |; x. J! D, n! p
  [
; l1 A2 U: q/ `# ^" @  w- e    user-message (word "There are too many cars for the amount of "
; B1 P; A" u7 w                       "road.  Either increase the amount of roads "
: P4 @: F; W8 u# |, L# J* H" W                       "by increasing the GRID-SIZE-X or "
1 t; E5 H+ J" R6 h                       "GRID-SIZE-Y sliders, or decrease the "
5 _* F9 s  s$ Z' Q- @$ x; j, A                       "number of cars by lowering the NUMBER slider.\n"
) i4 I8 L# P# k5 {% v; ~                       "The setup has stopped.")2 @5 r4 T' I" v: O) X3 V) F
    stop4 w5 G$ D: e, O, t
  ]2 R- w% Q! U  c' t0 m: b  o/ t

4 [! l, y9 n/ Z  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color5 b' W0 A0 }. j. K; A, s
  crt num-cars1 c: b. U. I) f7 v( }0 g7 T
  [/ V: U4 M0 Z9 E2 h
    setup-cars, {* a6 b: `2 t# _0 U
    set-car-color
0 \0 O( a8 u1 Y0 y0 b+ g8 B    record-data
0 A+ e* t. A8 P4 A4 h( F  ]) T" h1 t+ B' l/ g  j7 V
/ h' @7 E, W! ^1 M. j+ O9 b: b4 J
  ;; give the turtles an initial speed2 \/ w$ p' y" t1 G9 V
  ask turtles [ set-car-speed ]
" x+ Q0 j) n9 J. }
4 X9 o  ]; _5 ~4 [* ]  reset-ticks; E8 v4 W( Q1 G
end7 F* j1 F7 w: K3 N0 ?5 m% b3 O' R8 Q
- W1 s1 ]. I) ~6 d
;; Initialize the global variables to appropriate values: J0 }/ X8 p. q
to setup-globals# ?* O0 B1 U, \
  set current-light nobody ;; just for now, since there are no lights yet
- U1 G) P9 _! x2 @1 _  set phase 05 M3 x% V! i- a
  set num-cars-stopped 0- P" x: O/ w& j# b6 b7 ?
  set grid-x-inc world-width / grid-size-x
1 l; \  \* M) o; A+ l' \3 y# d  set grid-y-inc world-height / grid-size-y
+ t- Q# A' N1 b# O& X
* `: Q9 X. x# a0 G  z. [2 h% N  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
& D' D. ~' u) L% c8 l4 b8 `/ ^  set acceleration 0.099
" J- B7 S- q, C. I7 Zend
& O7 U, e1 e" C& V
3 n1 p' j" x. G;; Make the patches have appropriate colors, set up the roads and intersections agentsets,2 I# ?0 N2 b" s" `
;; and initialize the traffic lights to one setting6 L/ s- U" C4 k$ K+ R# @
to setup-patches
( }% B$ p/ w7 l  ;; initialize the patch-owned variables and color the patches to a base-color0 a6 _% F3 @3 a/ `# P
  ask patches: o+ c  r+ h& o: g
  [
3 q% N0 `( J! _7 n    set intersection? false
: K% E5 ~8 m/ [8 q    set auto? false1 q1 f  ~& U) Q
    set green-light-up? true
4 B, b# J+ w1 Y% n$ v/ y$ M    set my-row -1
9 o' E. h+ C' J8 B- A; N    set my-column -1/ G- i# _- y% s' ]( D! ?
    set my-phase -1" I5 K2 ]7 d& ?# g# H( U
    set pcolor brown + 3
6 I8 s6 ~2 H/ O4 n  ]6 s: A1 g# x: p# V1 J, i! m, b
8 D7 K. B( G4 o/ w: ?* ]# E
  ;; initialize the global variables that hold patch agentsets: }) v. c7 k0 f! h, }9 K% z+ l
  set roads patches with
& ]/ j5 i0 ~1 |2 G4 O' [* l5 a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: r) o: p$ g: m6 |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 T# ?: M( d9 u+ W* w* T  b9 F7 ^
  set intersections roads with
# p) ?# l* l* N- D/ E9 |1 d$ `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
  S1 [+ H: B3 [( ~: F; R    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( P* d0 A3 t3 d  K1 x0 p
& s+ C2 N/ O% f$ N  ask roads [ set pcolor white ]# D& \, j6 K  ^- _$ y! Z
    setup-intersections% Y; g7 M1 D1 k! h2 c
end
6 H; i( `! X! i其中定义道路的句子,如下所示,是什么意思啊?4 k9 {, @+ m/ X4 X: O2 q: w
set roads patches with
5 E, c* r4 U8 l' K. S+ a- m3 {    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 T  T7 Z1 c# d6 c8 r8 k* L2 Z$ R3 t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 l& c& T2 g# O( r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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