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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。
3 l0 j% }6 D" b7 E: mnetlogo自带的social science--traffic grid这一例子当中,9 {. Z" B7 E) D0 ]
globals; h' L5 V9 M4 S, `8 x* R" o
[
* T3 Y& Q, }! [" u  q  grid-x-inc               ;; the amount of patches in between two roads in the x direction, _* x, U6 w; k: _" ~8 F# `4 o
  grid-y-inc               ;; the amount of patches in between two roads in the y direction: l& k9 E( K, L- q# s, H
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
% T9 D9 m5 i2 k/ g8 h8 ~' B                           ;; it is to accelerate or decelerate* N+ |3 G* V9 p* J7 J
  phase                    ;; keeps track of the phase
: x5 ~5 l4 L( m8 `+ K. B! ]6 O  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure( Z4 b# J: J7 f7 L4 U9 O, H2 B
  current-light            ;; the currently selected light
) g! F; {; E: H* z/ V7 f6 N2 f7 \
  ;; patch agentsets
" K* Z- n  p# o9 Z0 U5 _. }4 B  intersections ;; agentset containing the patches that are intersections
, A& _3 b. X4 u; }' q/ Y. o  roads         ;; agentset containing the patches that are roads! G/ a5 m. F" C( V$ @6 x8 Z% N
]3 i8 i- T: n7 K$ }3 u2 @8 S5 C- S
0 s/ _" e8 q8 e1 p$ ?# k) o7 _
turtles-own! l( I/ D/ K2 V' i% H3 b% x
[
7 u4 }0 `3 A2 U6 a5 w0 n  j  speed     ;; the speed of the turtle* @" y: F9 T/ b, U6 i' b
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right- T+ {2 b+ q" T7 w& `
  wait-time ;; the amount of time since the last time a turtle has moved
" z4 H" U" ]" a0 N* B. E]
( T+ O9 k. U% z1 e
2 D0 C- u4 r" }' A8 S/ npatches-own7 Z: }' }% W' ~! y5 ]/ D8 t
[; @3 p, n1 _- A8 ?3 ]
  intersection?   ;; true if the patch is at the intersection of two roads6 K( y1 m, v9 ~2 d: }# x2 i
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.4 r7 S3 o& H2 j' B. S/ [: J8 Q
                  ;; false for a non-intersection patches.$ r, O4 h1 v% d9 i
  my-row          ;; the row of the intersection counting from the upper left corner of the
7 U% e* Q2 U# {& D                  ;; world.  -1 for non-intersection patches.
$ m5 [- R( h5 ~9 V0 Z& u/ a% \  my-column       ;; the column of the intersection counting from the upper left corner of the
7 k1 ^) }; ?9 ~. a4 D" V                  ;; world.  -1 for non-intersection patches.
% m* J9 B" h0 R/ @% R  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.) G7 \: m& O0 @" l) c5 V& U
  auto?           ;; whether or not this intersection will switch automatically.
# `! [2 g+ i5 ^                  ;; false for non-intersection patches.1 Z( ?: D4 R0 |. b
]
; T; m2 y; S, [3 W5 Z  @
: S- L" c% l4 D
; e: Q- x8 g/ c' L;;;;;;;;;;;;;;;;;;;;;;4 ?4 \& t! p- H" x4 U
;; Setup Procedures ;;- P9 H9 _' K1 q$ H. K2 p
;;;;;;;;;;;;;;;;;;;;;;
: h6 v* m6 ^* C! L& q9 z, e- v0 P# u6 u. |
;; Initialize the display by giving the global and patch variables initial values., a: `0 m4 n' ^
;; Create num-cars of turtles if there are enough road patches for one turtle to5 U6 ~+ a6 y2 |. a& I& V
;; be created per road patch. Set up the plots.
0 c1 v; K; E2 a1 D0 N$ \. W; ?to setup
" S+ ?0 H( }3 N1 S0 a  ca# ?0 F2 L. s% q2 k7 n8 D0 }) p
  setup-globals
; z- _' c3 m- ]: \+ [: `" l
" K. w; \5 U  ?6 q  ;; First we ask the patches to draw themselves and set up a few variables0 S* W: c8 s7 U: L' |4 `4 |, P5 [
  setup-patches
5 o# _1 G% @2 b, ~4 M  make-current one-of intersections
4 h4 e" S; O. s6 T% T, w  label-current; }* n  ], u5 C& |# I& |( t2 t) d
' D: b6 z0 _+ ^! ~
  set-default-shape turtles "car"
3 x$ K; J. ^' s4 p5 ^+ X$ K. |* x1 b
  if (num-cars > count roads)
  c, Z: s" e6 W  [+ U5 X) s) \- U. R5 X, ]
    user-message (word "There are too many cars for the amount of "$ z* A- i* c% Q$ c/ I. o
                       "road.  Either increase the amount of roads "! a! ~) d. `9 ]1 e6 M
                       "by increasing the GRID-SIZE-X or "5 w' ~  F1 z! X# A" o
                       "GRID-SIZE-Y sliders, or decrease the "7 ^5 D, W0 P2 {  l9 L5 W
                       "number of cars by lowering the NUMBER slider.\n"  _& ~8 \  H4 B" z- B
                       "The setup has stopped.")
+ R8 L* E2 ]" h0 S; f! ~3 l    stop
" n. g/ U& p7 X* M/ u  ]
1 U9 W) F0 h5 I6 u; C1 @1 G
+ K1 F, D- z& Y( P' e  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color9 V) D8 N3 o$ l
  crt num-cars
$ J: k+ X# L( l, L  [
$ H" e" e, t' U  c- C) q    setup-cars
& G! z7 E2 ~! e( H    set-car-color2 R( U1 e5 E% U) L: v9 J: i, N1 U" n
    record-data
/ v* Z0 l4 s# N( W$ y/ ~; X* A9 i  ]$ s* x/ i/ ]" E

1 _: s' v* K5 ]* F9 d3 T) J  ;; give the turtles an initial speed$ `  R3 `3 ]' Q# ?
  ask turtles [ set-car-speed ]
! D1 Y! ^" c: Q1 }! E6 j8 O( V: L( G" u* Z) Z# e8 u# k
  reset-ticks# f" {0 w1 e. [9 O
end: ~* V+ `! b( X% I/ Q
3 G! X) P8 k  M2 G8 m
;; Initialize the global variables to appropriate values
: h( x: _1 O4 S# C  i. ?to setup-globals: J1 A, V3 L1 D, ?4 R4 U" h
  set current-light nobody ;; just for now, since there are no lights yet/ ^# d: _, x" V- k
  set phase 0
3 N/ u% N5 d9 c% R  set num-cars-stopped 0
+ b" S5 C8 p; m, L% q4 {0 ?) S' z+ v( {  set grid-x-inc world-width / grid-size-x/ X% ]0 B6 w* Q9 Z& z
  set grid-y-inc world-height / grid-size-y
. X* e& _5 G0 Y0 c# k) k( F' t8 P
& P3 T% Z- I& [0 N6 n6 ~' F7 H  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary9 d: j" j% B0 O' X, u, q
  set acceleration 0.099
6 u, H$ s( ]6 V: I! f& nend
1 A# k$ v6 a6 x& c" t: r9 e! I) k, r" T" j
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
8 V. d& A$ r5 _;; and initialize the traffic lights to one setting
' E5 s6 [0 y& qto setup-patches
( B" _: S( \2 q+ T6 Q  ;; initialize the patch-owned variables and color the patches to a base-color+ x% W5 Y) o# Y6 V
  ask patches
- k5 H! U  e/ j) G% M! ^6 Z- R  [- C2 A5 N6 n+ }5 D3 u) b3 H
    set intersection? false
/ l# [! i" }  _$ g  k: a    set auto? false
4 F0 W& _) u3 B: o5 o4 P5 @& ?9 L    set green-light-up? true
1 E" R; N$ p! E7 U" `# b8 {    set my-row -1/ w$ v6 B0 z5 ^9 n2 _
    set my-column -1; ]9 M- ?% k9 ]! B
    set my-phase -1
- p6 d  K5 i$ E1 o4 P, W    set pcolor brown + 3# ~) g  H8 L9 H: D) ?/ T
  ]
# L0 u# ?; p" A, l7 X: c
- K% f& S% t4 q$ D( Y! y  ;; initialize the global variables that hold patch agentsets
, w9 V  ^+ M2 P& {% @! B! D2 v1 f  set roads patches with
( [% r2 g/ o4 c. d# Z* Y% _. @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 u- O" W. _7 ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 C; T6 E: a5 w% v* J2 J
  set intersections roads with: g, s1 N0 j1 y/ ^% d5 C$ g
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and5 b6 o7 C: ]. i6 ~! o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. a' E6 m0 \. h4 j! [2 y* k
  n8 T/ P6 O& p  v0 f8 N' z6 S* Y  ask roads [ set pcolor white ]
% _$ u2 g7 _( _3 X$ b' }  u    setup-intersections8 u4 N, U, a* \3 e6 V3 g2 \- G
end& K5 ^* r" b- G0 }
其中定义道路的句子,如下所示,是什么意思啊?
# `0 J# d- Y/ d4 {4 o$ U set roads patches with: ]* l0 ?7 Q! M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, Y2 C  w0 r1 g/ J" E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: G/ E. h* z3 o8 T1 M. 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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