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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。
" \2 C1 ?/ f' ~8 v4 c4 ynetlogo自带的social science--traffic grid这一例子当中,2 q9 X" @4 I3 E' ?8 G* \
globals
+ C9 Z- e9 g# ~[$ @8 u6 c0 f9 E1 H/ l
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, s. a, o4 l- O$ P& |% d1 U0 }  grid-y-inc               ;; the amount of patches in between two roads in the y direction* _: i' O9 _5 s, l) O6 b; f' g
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if3 S( L6 \3 c; O( U2 A
                           ;; it is to accelerate or decelerate
" s8 k* [1 g6 ^- W  phase                    ;; keeps track of the phase& H  a  u- V- Y7 z& c8 }1 H
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure- R& O9 `+ w9 A  u  g2 b( \- u
  current-light            ;; the currently selected light
% X" z+ Z; ]. C/ I- ?% q. l4 ]' g2 o
  ;; patch agentsets8 R. b" \1 F8 a6 |- n- Z+ X" I
  intersections ;; agentset containing the patches that are intersections
# |4 J4 O; ?; P" \- L  roads         ;; agentset containing the patches that are roads; I1 Z$ I- v9 L. Q& ~) |
]
, j; T- [+ r( g" H2 h; }0 R8 e6 C( V6 X/ H
turtles-own
: Z1 _2 F$ v( g' I; |[
2 A, C9 j+ h* q2 C; Z% s  speed     ;; the speed of the turtle4 v% A6 G$ k+ a' y
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
" H% Z8 i* g5 c1 \2 [' x  wait-time ;; the amount of time since the last time a turtle has moved
5 ^" K* S4 y) H  s]
7 M- ~8 h3 k: w7 W4 z+ s. U5 j& U
patches-own8 B8 y4 l! p* z/ E: [! p
[
8 }+ p2 `8 F4 e2 E: O  intersection?   ;; true if the patch is at the intersection of two roads
6 }* f! C0 }' E- L/ k' l  @  green-light-up? ;; true if the green light is above the intersection.  otherwise, false., ^; W  x" e4 F3 }& J5 O" n+ Z
                  ;; false for a non-intersection patches.
3 @/ y& q) p. @! ^. R  my-row          ;; the row of the intersection counting from the upper left corner of the
3 _: k& Y2 [6 a5 r! E                  ;; world.  -1 for non-intersection patches.
- K, b) \6 A: h: d. i  my-column       ;; the column of the intersection counting from the upper left corner of the- B: z! u% f4 j, d+ k- p
                  ;; world.  -1 for non-intersection patches.
' m8 H6 ?) p0 Q& y9 V; h  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
+ n" S2 q# \: {# e4 t! U  auto?           ;; whether or not this intersection will switch automatically.
3 `8 z7 u& u' R! U- h                  ;; false for non-intersection patches.
* [3 ~" |5 D+ K8 C]8 Z, @5 k: J7 t- b
* s" ~1 e; @" [

  C$ x8 W& u. K/ J5 {3 e" \% k;;;;;;;;;;;;;;;;;;;;;;0 [+ S7 z5 l( |7 j, g
;; Setup Procedures ;;. c) _! C( |0 i- z! r- u
;;;;;;;;;;;;;;;;;;;;;;4 D; Z: `4 f- u
$ k0 }( j0 a' a& a# O
;; Initialize the display by giving the global and patch variables initial values.  p( T" }- l6 H! y9 C
;; Create num-cars of turtles if there are enough road patches for one turtle to
( C- m8 l9 A: }. ^+ j;; be created per road patch. Set up the plots.6 n$ u8 @3 k; K: s9 Z; n1 J+ c2 T
to setup
5 |# f/ Z2 D1 n, }5 _  ca/ E6 f1 `* B! u6 V
  setup-globals
- o- ~* P9 M- E+ B0 `" x, N' U5 k  M8 t$ M- [7 c. E
  ;; First we ask the patches to draw themselves and set up a few variables+ g% I" S, `0 k4 P
  setup-patches5 a" Z; V! \; C
  make-current one-of intersections3 X4 |, l) c" m1 L" ~
  label-current
: a; w. \8 a) w* }. K3 ?: R: y7 u7 Z5 s$ i
  set-default-shape turtles "car"; N! N+ n, u3 l% C% `9 @
: h$ I7 d# x- [! e7 y& F) ~  t
  if (num-cars > count roads)
" _* [# L1 [- \8 S  [
+ F1 G2 Q4 E% j4 l    user-message (word "There are too many cars for the amount of "
, }' d# ]4 X8 n- A# `7 p                       "road.  Either increase the amount of roads "5 e  B& D5 s- o
                       "by increasing the GRID-SIZE-X or "
$ E0 L% [  s: {( t                       "GRID-SIZE-Y sliders, or decrease the "
& o" N2 d& T0 |/ E1 ]; H6 Z: k                       "number of cars by lowering the NUMBER slider.\n"
9 C6 D8 `8 t, r# z+ I4 |/ @                       "The setup has stopped.")
; t0 y* g0 b% B0 V. n# H    stop
/ D& `7 Y2 n1 b0 Q9 V  ]( R% ]1 D5 f( r# p! B% H: @. ?

# d; t# k  V& _" e3 W  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  \, s! h7 y  ]- v7 `( s  crt num-cars0 Z, }, \. I3 A3 c3 A
  [! R8 t: _$ a" L' I1 X
    setup-cars% D3 M5 y0 S$ X( \% n- P% H
    set-car-color- \; C' J. ^: y: J* x" P/ f$ e
    record-data5 f# J  C. x$ \3 I+ K) y6 w1 p# v
  ]1 [+ w3 c* H. e! O% A* h4 c
: i, N7 Q" b3 r! f- p
  ;; give the turtles an initial speed
; e  p5 k! t! ~5 B( v# ]: p1 u  ask turtles [ set-car-speed ]
4 N2 J' i; Q6 R& |: C) w: e0 w4 R) E2 v- J
  reset-ticks: ]6 h. U" ~3 `$ K
end8 q" Q3 e9 g1 |% V) K. z

2 y2 T: x  g. y7 k3 t, r* p;; Initialize the global variables to appropriate values
7 T+ t- }- a+ W, I/ W6 z: d$ n( c5 ]( G% Lto setup-globals. U8 ~) o/ S! h  o
  set current-light nobody ;; just for now, since there are no lights yet
  a0 C3 R: y6 s7 d+ [" W% K, K  set phase 06 W/ `% o1 l7 q
  set num-cars-stopped 0" Q- A; z' g9 {  I3 T$ a
  set grid-x-inc world-width / grid-size-x
/ h* a' a% N5 `0 _, N0 Y  set grid-y-inc world-height / grid-size-y
* f2 N3 R  z/ w/ b9 c, \0 T
' }( i5 s6 V% G: m2 q  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary6 ?5 u1 w: R$ {" ?/ @
  set acceleration 0.099' l; F! s8 Z- y$ y* {1 P. e
end
$ f( L+ q* g* J8 J$ `
/ J% l4 G4 h/ h/ d;; Make the patches have appropriate colors, set up the roads and intersections agentsets,( i' u& q2 e9 I/ q3 z
;; and initialize the traffic lights to one setting
4 t3 k! h9 z6 c/ g7 zto setup-patches9 i; _0 S7 O% h5 `% F# i, ?4 K8 K
  ;; initialize the patch-owned variables and color the patches to a base-color
1 \: N# H! o# y* k  ask patches
# O2 |" l( Z2 H& v  s% |  [8 O* l$ z" u( }4 V4 W) V0 [4 |
    set intersection? false
/ u2 v2 Z8 v8 B, a; g0 U' @- m    set auto? false
4 J0 n% @: W; c. J/ T    set green-light-up? true0 Z8 C" d9 {4 A) y
    set my-row -1; s7 j6 z* S7 s# U3 S
    set my-column -1
9 l  }' D* v+ f# P) t    set my-phase -11 I  e7 A. V, L3 r- W: Q# Y/ [
    set pcolor brown + 3
' s. a8 F- r3 f5 _: ?  ]
, ~. q% o: l- m2 l7 {8 R  M/ a) T# d3 D2 k: l& c
  ;; initialize the global variables that hold patch agentsets2 X: t: g7 ]  v2 _; K
  set roads patches with4 O& z  [3 r& Y) B4 ^, d4 b) d5 ]1 C6 \
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 x3 b5 P8 Y6 G/ g$ e3 v4 S' b
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 s% @2 s7 I- s: k: \: q
  set intersections roads with( e5 q& {7 n5 {7 V( h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
, [  T$ m: r  z; y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) `/ l! C# V$ Q8 n) L2 @0 E' K! I8 C; \9 k
  ask roads [ set pcolor white ]# l9 e1 }3 G: p7 P$ @$ i/ K
    setup-intersections2 |+ x" |3 e8 {* R! Y7 T9 v. f; U
end+ o) r( t( L2 z( |! S2 y! I+ W  t7 z( _
其中定义道路的句子,如下所示,是什么意思啊?
5 u0 `9 v3 [: U0 E: c+ ]6 \5 T set roads patches with
) \( e( }& b. z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) ?( D% W3 p! P3 M( t5 w8 P# r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% |5 F, g2 j  f$ v7 U. i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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