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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。' {$ _% a: O- _& v3 [* \: V
netlogo自带的social science--traffic grid这一例子当中,
% t- O8 {# I% @8 eglobals% Y. @& n& {# Q2 R
[+ P* r3 e  V% h0 V) @* x
  grid-x-inc               ;; the amount of patches in between two roads in the x direction# b+ \' W& ]( F5 g1 ^5 i" }
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
. f( D  i, z8 G; d2 x# `% t# q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if, t- M5 @- E# f5 D2 ?% R
                           ;; it is to accelerate or decelerate
& w% J3 H; C, A3 G  phase                    ;; keeps track of the phase9 P# B! j' L9 e. O
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
( c, @/ c% x; U  current-light            ;; the currently selected light
/ q# W$ s" o: b/ O( i5 h. ~4 Q3 ?7 v( I! G  H! U. o; W
  ;; patch agentsets
2 R3 i0 B2 I! v- E% n  intersections ;; agentset containing the patches that are intersections
8 R4 T& r; ~1 u% |9 b$ x$ r  roads         ;; agentset containing the patches that are roads# O8 _7 V* n) V
]
7 x. u8 d6 d. ~: p/ I; h& V) z/ I6 O4 R" n# X5 z3 L
turtles-own
" z% ~( X5 j( B6 Q5 u  H7 V) m! z[/ D) E1 a3 V" h* i& K' f$ U$ q
  speed     ;; the speed of the turtle
* @3 N$ [% ~! o2 J6 @( c  up-car?   ;; true if the turtle moves downwards and false if it moves to the right6 P1 z4 z; q9 A) W' N# H, ?3 ^
  wait-time ;; the amount of time since the last time a turtle has moved5 k; X# y8 |% t$ i
]2 R+ @( D$ }+ ~

! A% K  _9 m7 n) M; `% C9 x! Xpatches-own
$ v& I" l9 Z7 D[$ z! D8 G% t. \
  intersection?   ;; true if the patch is at the intersection of two roads
% j* r/ {* J/ ~8 q* h  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.! b' [4 O3 p" n# |; I$ y- {% [
                  ;; false for a non-intersection patches.. o- r9 J# @' ~" t  t; H6 R
  my-row          ;; the row of the intersection counting from the upper left corner of the
( [+ _) c7 B9 b: c                  ;; world.  -1 for non-intersection patches.
  z7 K: X$ R9 @: f  my-column       ;; the column of the intersection counting from the upper left corner of the+ c! I/ C9 l: E0 W" S# _
                  ;; world.  -1 for non-intersection patches.
% k2 B' m9 D. ]+ k  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 D  c4 ^1 Y( z
  auto?           ;; whether or not this intersection will switch automatically.
8 u% h9 ?2 H% {% `1 j; }                  ;; false for non-intersection patches.; X9 d& a% V, `' F
]
. L( K" o! [5 Z/ ~( N- q& |" E, a
3 [7 F0 c5 i: t/ P) t5 n# \4 P7 _, s% r1 x+ Y# n+ `' Q  ]
;;;;;;;;;;;;;;;;;;;;;;# T- L' c* ?) I
;; Setup Procedures ;;
2 p. B% M3 \" Z' J# j. l8 J;;;;;;;;;;;;;;;;;;;;;;) ]$ n5 D+ F" J8 [
) ~* d6 b3 a! k, D' z7 L
;; Initialize the display by giving the global and patch variables initial values.: ~" r+ j' N8 t5 q
;; Create num-cars of turtles if there are enough road patches for one turtle to6 ]$ x- Z) d6 W- T9 i& d* U
;; be created per road patch. Set up the plots.
6 i+ X8 R* `" M9 Yto setup
" \' \+ w3 S+ t' t4 k% A  ca1 F5 a9 q+ g! v6 {- d5 z3 `
  setup-globals- i! u! h" |4 {( G" w- ^
5 w% Y' \+ I  r4 L& x
  ;; First we ask the patches to draw themselves and set up a few variables
# R3 z; L. @! r7 W, w  setup-patches
  b9 |( c1 Q/ n& y$ U  make-current one-of intersections
* a0 c+ v* F" ?) N  c  label-current
: N& r  x9 {) {# `9 P) @5 ?1 m  f+ p% ]3 u# ]! \" C
  set-default-shape turtles "car"! z. S3 L3 y# X" D5 j& z

2 m+ l% f8 U1 x1 n! |4 T, O# y  if (num-cars > count roads), e. w/ `- O# ]5 T. X
  [
9 R( k+ A( y8 e1 k' ]5 N    user-message (word "There are too many cars for the amount of "" R, }0 J! v4 L2 x; _+ ?
                       "road.  Either increase the amount of roads "5 g. h7 r6 f, [5 V, w
                       "by increasing the GRID-SIZE-X or "
$ S/ u& i5 N/ Y                       "GRID-SIZE-Y sliders, or decrease the "
. M  Q. V! D$ G( a- I                       "number of cars by lowering the NUMBER slider.\n"
3 v' E( ]9 R, O4 `$ I& j6 r3 a                       "The setup has stopped.")
4 r0 O, o7 l6 b1 x" t" b    stop" u- @) o  n) S! z$ R6 m5 G
  ]9 U! d0 e# o, p! `# k& `

5 X. j& w$ N2 t1 q- Q$ k  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
, W1 X6 s2 d& {  crt num-cars* ?6 c2 R! a! r1 H* R
  [
$ y: i9 r9 l2 w, C) d$ T: D    setup-cars- @3 Y/ V- M) V0 b$ I
    set-car-color6 C" @/ `; X5 Q1 a( U/ |* X0 B
    record-data5 a1 |: a7 E: C- ^7 p7 W" {) B
  ]+ @, Z  w6 x( m( h* k
/ S' \/ Y- R6 p2 z# {# j1 `
  ;; give the turtles an initial speed  q! n- o# G& u
  ask turtles [ set-car-speed ]- ^; N5 {% m1 }: W; O

6 d5 s" Z& O) k& p: A3 P  reset-ticks
% T9 G- ^6 a* m6 {2 J( }7 I* _( Lend
6 x: ]0 k$ P, H4 F8 f' n6 A7 j3 X' s
;; Initialize the global variables to appropriate values/ A+ X9 A9 m5 F7 S0 n- f  \
to setup-globals
2 t6 x8 R0 y+ Z" o  set current-light nobody ;; just for now, since there are no lights yet
! F1 t5 E" N$ k8 M! C: g* P  e  set phase 0: o$ H, f4 L$ W1 ?; l
  set num-cars-stopped 0( X8 o( c; ?* x5 P
  set grid-x-inc world-width / grid-size-x+ p* m  g1 _# R/ A& l9 d0 G
  set grid-y-inc world-height / grid-size-y. }1 }) ^' g" c7 {0 X9 ~7 u

0 u. X3 y0 Q. E% u/ ^6 z  U  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary! d* Q, ]" @6 B: W' m7 g
  set acceleration 0.099, b4 c8 x$ u  W# d* a  J
end( i8 P4 Z7 {( y5 w+ H1 L/ ?

4 ^" t# ?4 g$ H4 a2 g* V: {% j;; Make the patches have appropriate colors, set up the roads and intersections agentsets,8 d* u+ Z& w7 L" ^  Z; _
;; and initialize the traffic lights to one setting
9 A0 P" z/ a0 R) ~8 {to setup-patches# w! I0 o- v) Z$ R  v1 \/ o$ y
  ;; initialize the patch-owned variables and color the patches to a base-color
. s* ?7 }( M7 A# l9 a: T8 f  ask patches
/ }7 d  C& e1 o$ x$ j# l2 d$ m  [& x; i8 R3 o- U, `! M
    set intersection? false3 Z+ A+ a- u4 ^% e7 I) X
    set auto? false
# Z' e& T0 K2 j, ~/ ~    set green-light-up? true$ g4 U* b3 R. V7 w! w" F
    set my-row -13 C% O! a9 [0 V
    set my-column -1
9 c/ U: j' `/ M    set my-phase -1
4 m% v/ Q% {/ V/ ]5 Z    set pcolor brown + 3
2 {1 d- `; H; Z; Z  ]
% r3 A$ M% M4 v. j
) `; L3 O8 |' ~! i% l4 f, F  ;; initialize the global variables that hold patch agentsets
' p( T. _6 P6 k" b0 [" Q' V; ~  set roads patches with
) p$ j" j! W/ V; Y3 G# M1 l5 }1 F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( q, p& H( F# W$ r+ J7 E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 A, C& a0 h7 J
  set intersections roads with- q  D3 n2 l! s/ q" V0 o+ z8 n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ |4 m8 @" h' z1 d% c9 q& P( Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- L6 E+ a& }) y. H6 k( s
9 U3 ~! e- A3 a( R
  ask roads [ set pcolor white ]; w5 Z4 L9 I' `/ x/ U' C  k
    setup-intersections6 e+ \+ k# m6 f" J% m
end  B3 I. n6 u( C3 |2 O5 w
其中定义道路的句子,如下所示,是什么意思啊?8 [6 _: ?1 u6 V; }0 Z
set roads patches with
; X% V% l4 x0 |# z& s% Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' ?, q7 C3 F5 T/ g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' }& z; K3 ]& I0 ~2 t  W
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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