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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。
6 @+ |# e0 v0 z* N6 E" |! V2 }( @netlogo自带的social science--traffic grid这一例子当中,
  l1 |" \5 Z9 w+ D; f- n! c" sglobals
5 C+ n( X, M8 z# v7 {" J[
! H, e/ e! _2 w  grid-x-inc               ;; the amount of patches in between two roads in the x direction! k  A' H  V/ R2 n" }! [6 {
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
  |3 {3 @1 q6 ~: l: u  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
" V2 `8 y, v' x; B& \# S                           ;; it is to accelerate or decelerate0 ^- f! I/ l# N! o% T, F
  phase                    ;; keeps track of the phase/ `1 a: s' [4 }/ i9 f
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
4 a& y! U; r! @$ P0 t+ `) H  current-light            ;; the currently selected light
5 H* q  c2 L3 ^
0 ?2 V0 N% H6 `7 I  ;; patch agentsets
' @6 Z# e9 z: A; d  intersections ;; agentset containing the patches that are intersections
; H' k& u4 M4 U* W8 V5 R  roads         ;; agentset containing the patches that are roads+ P7 X/ K& Z3 V0 s4 e1 v
]! t' \; r! y5 V- d: D% h' v+ ?
( ?& I" Y% W$ {& {6 w' M2 h* F
turtles-own
! G9 Z  W; l* i& `. f3 ^$ d# h[7 T2 E) {0 R" r) ~  h# g
  speed     ;; the speed of the turtle0 j; }7 j' m, ^
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 Q( A# V" G, l1 M' k4 K
  wait-time ;; the amount of time since the last time a turtle has moved
; p8 ]4 c$ ~8 Z' L+ z5 n! M2 i]& B1 e6 E& I; t) o7 |- n+ I. F( c

$ I& e& _1 O/ ppatches-own0 ]. a  C/ u0 r! e( C) v( ^( n& ~
[
& D) z2 J! j7 ?5 C5 }, c  intersection?   ;; true if the patch is at the intersection of two roads
6 Y& [( u  t" G$ {4 \7 X  green-light-up? ;; true if the green light is above the intersection.  otherwise, false." ^- ]( ?: m- n* k
                  ;; false for a non-intersection patches.
5 Y4 P* ^) v9 ]- y: g4 a$ ]; K5 s  my-row          ;; the row of the intersection counting from the upper left corner of the
, y+ `% f1 `% ?3 a7 y9 D  c                  ;; world.  -1 for non-intersection patches.+ N8 ]/ w+ v+ V9 q3 C
  my-column       ;; the column of the intersection counting from the upper left corner of the
( W2 E4 t" B( y3 N) ^2 Z; A                  ;; world.  -1 for non-intersection patches.0 d7 Z+ t$ L& O7 Z9 |8 h' y3 v. @4 A
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches." L) x/ M) H1 r+ ?- S- t
  auto?           ;; whether or not this intersection will switch automatically., Q: P# n9 h6 a- T, _7 }
                  ;; false for non-intersection patches.
& ?" z; b9 W* [( @& O]
' N3 Z. S2 k5 I: b6 v! m5 b: J" Q" |" u1 M/ j) V  s
+ e: l# n7 {5 T0 i6 }" j4 y7 O
;;;;;;;;;;;;;;;;;;;;;;& T& L2 W1 a/ K; ~
;; Setup Procedures ;;+ ?' N; x" n5 E0 Y( W) e
;;;;;;;;;;;;;;;;;;;;;;
" Q3 W: o7 K" D" G5 Q# \
: E* ?7 T4 o. D+ h;; Initialize the display by giving the global and patch variables initial values.
0 Y1 k" Q% P' p: k% c;; Create num-cars of turtles if there are enough road patches for one turtle to. X; G6 ]  L0 S" J8 P1 z" _# {
;; be created per road patch. Set up the plots.
* ]3 @* F5 B, s* {5 Y0 |, n! @to setup4 J( @: S* ]/ K  F8 A
  ca. D5 W* Q* o/ Y& p: A; G
  setup-globals
6 c! y- M5 {7 G5 X
$ U* T9 m* D. o% S/ r  ;; First we ask the patches to draw themselves and set up a few variables) q) G! R( |% c  B4 w/ {7 C
  setup-patches7 X, p& e3 a3 S  u, H
  make-current one-of intersections, g, J) z* p* w1 T/ R, O
  label-current. B; M1 j8 Y6 i# G; r/ ?' s5 N

+ e1 D' O0 U# M  set-default-shape turtles "car"
" v- `2 W6 m2 w6 l# q
0 o: s' x! _# Z) ?  if (num-cars > count roads)
* K; C  i+ O% S  [- A6 j3 C5 M$ y& ^
    user-message (word "There are too many cars for the amount of "
* R; e! }0 H5 {* J5 y" k                       "road.  Either increase the amount of roads "0 Q# ?: r3 r& H8 G0 [3 t
                       "by increasing the GRID-SIZE-X or "
5 O8 [: i" C" |% ~: {                       "GRID-SIZE-Y sliders, or decrease the "# u8 I; v: H1 c6 W5 a3 h
                       "number of cars by lowering the NUMBER slider.\n"1 {7 r0 X& {" I# n
                       "The setup has stopped.")
3 |* I  @8 i/ M& |    stop
) j7 S: x' j0 b  ]
4 |" ?; X0 }' R, F: q  J, C2 m2 ?$ E+ J* r! I; L7 i
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
5 ~0 k: g; j1 [0 L$ e  crt num-cars% R% D, M  d- T; w  U2 I8 V0 U8 h
  [
& }* O, O# ~; [$ @# z8 m    setup-cars
4 p+ T( \) i: w9 g: `' y& U    set-car-color, m: p* @6 g( J2 Y& Z# O4 S
    record-data
. f8 u( B. I& ?6 {) s7 w( D  ]
  _* L9 F3 A7 K9 s$ ^$ P) L
& Y5 E. C/ s2 s0 f$ v  ;; give the turtles an initial speed
  F; U) ~7 g! x* G& `6 }$ m. n  ask turtles [ set-car-speed ]
- K/ v% n% Z% x3 L5 {$ f" v& d5 a) ~* V$ w' D! v5 F
  reset-ticks, P( W  i- Q: x  h. B
end
( Z9 `1 b, i! H6 l$ I  d6 `. a
. a8 N9 g. k/ ?7 w;; Initialize the global variables to appropriate values+ e$ x8 A7 T) |+ T2 ?& H
to setup-globals: K- a/ Q7 E* i2 `! @" R/ U
  set current-light nobody ;; just for now, since there are no lights yet) t$ i/ J5 U; n: ?' @
  set phase 0
' F# r/ p: l* E( a; @  set num-cars-stopped 0$ n! i3 O, v( ]8 }8 k2 p& K
  set grid-x-inc world-width / grid-size-x
) ^, o% v+ a: _9 [" C  set grid-y-inc world-height / grid-size-y
6 H: q/ Y6 K* \  f1 |. J# a
9 y: t4 S2 l* E: @4 @3 F- W5 V  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
9 P0 I$ v, Z: C$ v6 k  set acceleration 0.099
7 R% r* O  w: Y: j  t9 yend1 ~' h* J; K: ?# q

4 K4 j( w3 G1 k1 H! b. Z2 X4 g;; Make the patches have appropriate colors, set up the roads and intersections agentsets,- q' M1 c$ K# x9 x$ u
;; and initialize the traffic lights to one setting" f5 o& i& m' W6 p) T2 w
to setup-patches
! A* G, A/ _3 q0 k7 Z+ {* r& H  ;; initialize the patch-owned variables and color the patches to a base-color
  {, N* l4 T# a3 y  ask patches
2 L2 a; Y$ q2 C: M4 P0 X# ^  [
$ q' \) f; J# t. J# i& H" _% f    set intersection? false
- E& v5 v1 l! m* {' [! U; B    set auto? false* M* V3 i1 T: I
    set green-light-up? true
1 R! @' k, t: `! f3 y    set my-row -1
, z9 P- E. R2 |2 `    set my-column -1
) A6 T1 x* E1 h! r: _) c, x    set my-phase -1
  ]! p  p% @4 g7 |; E6 P    set pcolor brown + 3$ ?% L- O5 M% J, m3 F. Q
  ]
1 o4 W0 s# F2 p7 u: i" A
* K6 t2 F7 c* f9 a  I  ;; initialize the global variables that hold patch agentsets2 L2 I; K: W2 [1 M6 \% U1 R
  set roads patches with; T: t5 \. R4 l! K' T) x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* N6 U/ W6 N+ n  K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* E) Q: j& G& k! \  set intersections roads with2 r5 i* h. h5 f2 F0 X. \
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 \5 }) E; o' |* Z0 v4 |/ }
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 A, [6 f' y" @5 a; v7 ~0 i2 ]7 b" u

6 c, K& {, A' p$ R% Y" B, F2 @5 l  ask roads [ set pcolor white ]/ t0 b4 W* J6 j2 Z' C+ k' s/ C1 T
    setup-intersections
( E( e) O9 O+ Y) a1 g% i8 Uend, @1 s5 B) H" R
其中定义道路的句子,如下所示,是什么意思啊?
+ j7 g7 Y: A7 G. ^% n set roads patches with0 c3 B( q' g8 ]( G5 w4 `$ U- i2 u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* \' K8 H& O& M) Z5 w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" z# n( p4 \) ]1 W- w% E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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