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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 C0 g  r& a& L) y6 x, Vnetlogo自带的social science--traffic grid这一例子当中,
8 q$ n( I7 ^, }9 Q. F- Tglobals
" Q  v5 ^2 Z* |+ l. e# O1 ^[
" w: Y$ m2 {4 {  grid-x-inc               ;; the amount of patches in between two roads in the x direction
: i: X0 ^* O: N- ~& S5 P9 _  grid-y-inc               ;; the amount of patches in between two roads in the y direction
. l; u; F1 ~: k1 @& {  acceleration             ;; the constant that controls how much a car speeds up or slows down by if' X& U- g. K0 x2 q
                           ;; it is to accelerate or decelerate# U9 v' r( F4 M$ a, F* W1 x- `
  phase                    ;; keeps track of the phase
1 Z0 v% t. ~8 @, H4 E2 B$ W  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
6 _3 ]: @& }9 ]$ P' A  current-light            ;; the currently selected light- l8 f- p8 ?( Y* T

" |$ P- w: w5 b, l3 l6 C' ~+ d8 Z$ F& _  ;; patch agentsets/ L* E* l7 ^4 ]$ [! j
  intersections ;; agentset containing the patches that are intersections
2 d4 R5 M! B/ J8 L- ?6 U2 f+ D  roads         ;; agentset containing the patches that are roads4 H% |, N8 G" p2 ]
]
0 H( O9 {$ L  F" B) L+ i
$ D' x1 E. U& L2 m: }) tturtles-own
$ v4 P+ ~, m/ t3 j[6 b3 @; W. l+ L5 o/ q, O% i' N0 }
  speed     ;; the speed of the turtle" A7 X/ j+ |3 j0 u7 t( z; v4 \
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right" L2 |2 k- b5 l9 b
  wait-time ;; the amount of time since the last time a turtle has moved. V1 K" g2 J7 o- ]+ A( k
]3 S( T5 Y2 d. Z* L' E
6 c+ d, l, Z7 S- Z* F. P; K' \8 z
patches-own8 D. K- F6 m& \/ \) z
[
5 y0 N/ I: P+ Y- f  P  intersection?   ;; true if the patch is at the intersection of two roads0 D3 Q0 n( H$ s- j
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
) l) I8 {7 ]+ u- a8 z% T0 c                  ;; false for a non-intersection patches.
1 p& H5 V. ]. j0 C; \3 V  my-row          ;; the row of the intersection counting from the upper left corner of the
- T2 u1 V+ v5 c' d" T9 }( H& N; W7 d                  ;; world.  -1 for non-intersection patches.! n6 ~! y' V+ h* F
  my-column       ;; the column of the intersection counting from the upper left corner of the
$ _1 r; U% W! v                  ;; world.  -1 for non-intersection patches.
8 {" R- I# B; U  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.- q% u1 A. g# e! H" O2 t
  auto?           ;; whether or not this intersection will switch automatically.) o8 [+ t/ k& y* _6 |* ?$ r6 b
                  ;; false for non-intersection patches.
- A/ ?! m9 e/ h. G]
/ F1 T! K4 z( y; U; D& Q- e! k( T( @6 s

* I: Y1 ]2 U' x. e4 U3 v% K;;;;;;;;;;;;;;;;;;;;;;
) U. n0 Y3 n) B/ J;; Setup Procedures ;;
# J  Z* \9 x: d$ q6 Y1 z;;;;;;;;;;;;;;;;;;;;;;1 D1 k! [( a% ]3 j; G- y

! v2 f; {& ~2 f0 x9 T2 o;; Initialize the display by giving the global and patch variables initial values.4 S' a' G  ?! u5 f; P6 v2 q
;; Create num-cars of turtles if there are enough road patches for one turtle to
7 [: B1 M( K- L;; be created per road patch. Set up the plots.4 j" M3 a# ]  g) {7 l
to setup
2 L0 C0 s4 @" D/ x5 L  ca( N7 q+ f+ {2 ?" m/ {$ ]- F; r! Y
  setup-globals1 D! i) e7 l: T3 C9 T

8 `" h) t3 W1 |! J& W  ;; First we ask the patches to draw themselves and set up a few variables
, V1 J( S: @7 F) J# P. D* X  setup-patches0 @/ I; }" c- w" B
  make-current one-of intersections+ a% e. U7 S$ i' `! G
  label-current
! z& n( i; f7 g% @( o$ y  S5 C& o$ l) S" n: t0 S
  set-default-shape turtles "car"0 G) K: l! o. E0 h) v4 X1 q

6 E- f& N- v# A8 S  t/ H9 }. {4 w  if (num-cars > count roads)0 G4 K) a) R* J$ B. I& H' v2 R
  [! A3 `" e4 p" B7 B& v# ]
    user-message (word "There are too many cars for the amount of "
/ h/ O# }* u% j8 w$ M" ^" H                       "road.  Either increase the amount of roads ". p' ~' ^$ w/ l  N0 P* W* b
                       "by increasing the GRID-SIZE-X or "1 u  q$ g9 e* G& ]/ b. s
                       "GRID-SIZE-Y sliders, or decrease the "
, H+ L( J  e% d" \3 W7 Z0 R                       "number of cars by lowering the NUMBER slider.\n"/ `" x* a8 h3 l4 W+ U3 h) H* _
                       "The setup has stopped.")/ _: [% n! _' s; E. p
    stop
0 Z0 A) ^8 t8 X6 R+ j( d  ]: g7 M1 v4 B) g, [+ N5 p, p* z

8 l# @# |) R9 z) P& O  d$ h# ]6 w  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
0 ?& P: s, N" O  e1 g4 i& o& M8 S/ G( i  crt num-cars$ |: U* v. P: M2 z- R5 n' ?
  [
, R7 F& j% ?4 w& ^    setup-cars  `8 k3 B* Q- T: W  [, x
    set-car-color9 W  `$ N- W: H- x$ t* g- S6 y
    record-data  s0 @# X# t! ~+ ~8 C. D/ j1 P. c  {
  ]9 v0 {) {+ J- D  q0 {$ F" M
% J6 O4 G2 K4 `! \$ j
  ;; give the turtles an initial speed2 [8 m' l, W* A& P
  ask turtles [ set-car-speed ]: _6 B) ~8 P* C6 d

! v2 j' Z7 Y9 G' _  reset-ticks: k% e4 U$ w$ e! }% K
end
8 ?2 u( t$ b: v
9 O& {" Y$ p; Y6 ?6 e% Z;; Initialize the global variables to appropriate values5 v5 n' K1 {: S/ Z* m
to setup-globals
$ c: V3 m4 ?/ E0 X! y  set current-light nobody ;; just for now, since there are no lights yet& t& E1 p" Z7 x( C  a
  set phase 0
1 n& ?8 N' W" n% w  set num-cars-stopped 02 ^. f9 L% Z. E1 j, f
  set grid-x-inc world-width / grid-size-x- S2 v$ Z  \; F% N
  set grid-y-inc world-height / grid-size-y
/ C: q# U: i% N% W" M  t- [& {# m
- l5 L* C4 R  Q; v1 y' j8 i8 j  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% s% Z9 Y+ Z% t6 N4 p, A% U  set acceleration 0.099. F' b% E' h% O
end
/ M; o: ?9 I+ J3 _1 ?# a. ]$ e$ M0 Q3 [+ U
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,; M" ]; i% o7 x4 f' Z
;; and initialize the traffic lights to one setting. B0 l8 B* V  r0 i8 S
to setup-patches+ x$ R" s: Z& K+ P
  ;; initialize the patch-owned variables and color the patches to a base-color0 A1 G3 Y% k; L) W8 `, l! |  }
  ask patches
1 C) @3 Z* l& C  [
* }1 y; b. t1 e6 @, u! _5 i7 k  {# ~' y    set intersection? false7 [( Z) a7 J) d% k* f7 l
    set auto? false1 I/ j5 e) r" y/ A9 i) H" b
    set green-light-up? true
8 ^/ N) u' U3 [( ^: ?    set my-row -1
4 B$ h; p6 f& Y( o! B3 ^    set my-column -1+ [- |7 f# j8 O4 R
    set my-phase -10 y: ?9 o, n( L# w! W+ d" I
    set pcolor brown + 3+ S. l& M5 U7 \& p9 I5 T
  ]
0 v1 y# T! t  ]& p! v( O
+ j' f& H) R& K& D% E  ;; initialize the global variables that hold patch agentsets( P. l- T( y4 \( k4 E: h7 F  ~9 I
  set roads patches with4 [5 B! D  k6 e) |/ l
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 O$ ]3 ~6 N! u% z9 x    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 V) `; H0 ~+ g) x# O2 W  ~  set intersections roads with
4 ^3 K$ U2 U* S" t: }4 {% |    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and* {6 O) [2 m7 Y  F7 p  Z5 T
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# D! {# u; ^) ~. x& w. E; `5 E+ G0 c& Z& L. Z7 C
  ask roads [ set pcolor white ]
% I4 u2 S0 I( D+ N% H- s    setup-intersections
* D8 M5 s0 z- B, T1 F- l$ L$ T! Y2 send2 j! _; ~; w4 t0 f  M7 R
其中定义道路的句子,如下所示,是什么意思啊?2 o  @8 j" ]% f; k1 X
set roads patches with
% D4 m  k9 v- u+ c$ L: `# n    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( c+ c; ]# @/ A; D% z. N- i
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! L, X- {) e6 P; w* a4 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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