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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。/ w/ H! X) I0 x) u' C
netlogo自带的social science--traffic grid这一例子当中,9 a' M' o1 Z* C0 H* X, l* |
globals
) i8 x. l- d8 Q, q& g[3 Q  D+ T4 H  Z& l8 A$ l& g" s
  grid-x-inc               ;; the amount of patches in between two roads in the x direction. x: A5 j0 J6 [. j# i
  grid-y-inc               ;; the amount of patches in between two roads in the y direction$ U9 B" x- a  {* U9 @% V
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
* V5 M8 k+ O, V                           ;; it is to accelerate or decelerate. R9 o  @$ X0 Y& h, x
  phase                    ;; keeps track of the phase
6 x+ g- b) k/ I3 T2 I4 j( ^  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure+ y' g# M5 }5 @% k- f1 k
  current-light            ;; the currently selected light  n( @4 \$ J* D0 C- _

& U9 Y0 P' ^: T0 P& f$ I2 d  ;; patch agentsets
  ?3 C5 @9 ]( _7 O8 }3 E$ z3 ?  intersections ;; agentset containing the patches that are intersections
- I$ S2 B& Z4 ]! Q$ d. A8 h  roads         ;; agentset containing the patches that are roads. U- k- n' [5 K7 Y6 Z) J
]9 Y' p  z* d, r9 y

+ s" K9 u2 I" f7 Lturtles-own
$ z+ b! c" k9 }[
3 J! _1 \2 R# }  speed     ;; the speed of the turtle' U" V1 |0 f) d. T0 `: k
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
1 M: Y' y. t+ A3 s; J! U7 Q  wait-time ;; the amount of time since the last time a turtle has moved
) s; ]. @+ O$ u# `# [: U]! c6 [( c& k# G  D8 Y' @( h5 n

/ u% G/ m. Z2 H4 l0 |1 @patches-own
. K) s4 |5 n+ A" n+ S9 A[; n; {5 n0 R1 t. `4 _
  intersection?   ;; true if the patch is at the intersection of two roads
: V/ u4 N) G/ L" ?2 t/ v+ K% t  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 _' G* ?9 m. C: ^. f# [& ~
                  ;; false for a non-intersection patches.3 u; i, D! d) c) _
  my-row          ;; the row of the intersection counting from the upper left corner of the
7 V; q# g% L2 A! [" D# R                  ;; world.  -1 for non-intersection patches.; U5 p0 w. o, w: `: Y! L4 E
  my-column       ;; the column of the intersection counting from the upper left corner of the
# a1 }8 `9 L  u5 b( Q- o                  ;; world.  -1 for non-intersection patches.
, J/ A$ H/ H, ~* p1 I8 t. [! J( J8 X  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% H5 x3 k5 o+ @  ^8 l) a  auto?           ;; whether or not this intersection will switch automatically.# ]2 s0 w7 U! N. E
                  ;; false for non-intersection patches.9 b! Z% v& B# F. M$ H5 T) y7 K
]
0 C8 l7 F( Q$ ?2 d6 g1 |. V, F/ O/ S0 I, C5 D: f( b7 D- n

+ V( }) j* g0 B7 H1 W/ t6 D;;;;;;;;;;;;;;;;;;;;;;
2 |" s6 I7 s$ I; n, ~% M: l, ];; Setup Procedures ;;, _- z* H1 }% x9 C1 G
;;;;;;;;;;;;;;;;;;;;;;; _9 a& x# |, J1 C: I

- u+ M8 g' m. k1 r3 ~;; Initialize the display by giving the global and patch variables initial values.  [) U& @# T9 m# Y1 X% J8 v
;; Create num-cars of turtles if there are enough road patches for one turtle to4 A, W0 v$ A3 A( r
;; be created per road patch. Set up the plots.
% x) H4 G& ]0 l" J! K* wto setup: d' S2 U4 H' S
  ca
0 ^& P; `3 p! t# t1 a7 n+ X7 `  setup-globals. v' y) |& T  n

- L. E/ S0 S5 M  ;; First we ask the patches to draw themselves and set up a few variables
$ [; b- D8 ]! B( J- ^. O4 y/ T  setup-patches) c0 f" T3 [. D0 ]. m4 M
  make-current one-of intersections
3 W* j' d1 c. Z) F! B  label-current
# F& X5 k  S0 u  m6 K0 X+ e- n/ J! i$ L/ i
  set-default-shape turtles "car"
, O( }: Z# a. O+ h+ c3 g/ o  G" m9 p% i# e5 t
  if (num-cars > count roads)
! p/ m$ y0 i" S! p  [
8 U7 D& A, P+ _5 A. L0 P" D! w    user-message (word "There are too many cars for the amount of "' R+ `! K: E$ D# w
                       "road.  Either increase the amount of roads ", K: K* y4 W- |
                       "by increasing the GRID-SIZE-X or "7 ?1 D% z+ x+ F" i; L
                       "GRID-SIZE-Y sliders, or decrease the "5 n% R3 `: P1 A+ L  v
                       "number of cars by lowering the NUMBER slider.\n"+ |5 }% v3 ]! P; N
                       "The setup has stopped.")
6 Z& A; K+ c; V4 s  f0 V+ T$ [# }" N    stop
( ]0 Z- X7 ]  z2 \" f2 V  ]
6 L5 r2 Y2 f9 x, k4 T- }  j4 k
( M7 k9 ]# T! G8 c5 w0 m1 K  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
" |! C9 `# y% ?  crt num-cars
/ j) ?- `1 w9 w9 w+ _  [
  C% P' W6 J( ?5 A& D    setup-cars( D; M  k1 o/ c  c! }3 t1 r7 N& H
    set-car-color: G7 q- g/ N0 u' o# w
    record-data( s7 `7 w7 p* X$ Q- G9 g
  ]
! K. M; y( [- H5 G+ I2 r* N. ?
( o; f! B* z8 M6 u3 S5 y/ `  ;; give the turtles an initial speed. |; U4 o' P1 h: }1 [8 p7 [
  ask turtles [ set-car-speed ]9 z6 f9 \, y: f
1 N, ?9 A  K1 T( c+ A
  reset-ticks
: U' U* ^( ~6 y6 I  I. u. z+ d+ aend3 n. o- ]$ j# V" Z5 B! m& i

" ?; u! n( _, `* S7 u;; Initialize the global variables to appropriate values
- i- _8 a6 a  \! j# M% Nto setup-globals
* R) {- n. h& g  set current-light nobody ;; just for now, since there are no lights yet; }& x9 D6 \& A; S- U
  set phase 0- ^2 w2 ]' N6 k) W: o
  set num-cars-stopped 0
- k( z+ F! q, E  set grid-x-inc world-width / grid-size-x
' f6 J( T) e# H: D9 a0 g7 B  set grid-y-inc world-height / grid-size-y/ v3 t) U( I: Y/ S1 s0 C. f  A- l
6 R$ B  R8 F0 p; ]- x
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary; J. z. }) R0 p, s  ^
  set acceleration 0.099/ f' e0 k- h! m! h6 ~
end
2 b5 }4 y1 S7 k5 a, q' Q' g% `7 d4 T7 R2 l
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,+ @# A8 q8 t) r
;; and initialize the traffic lights to one setting
/ W$ p) {4 H" s& ~to setup-patches' Y8 w+ B5 K" q+ o8 m6 i9 a
  ;; initialize the patch-owned variables and color the patches to a base-color
5 S% }0 A: I: D8 l* i0 l  ask patches
* x$ @( e" x6 |' _* B; G( \  [
- H0 Q3 m) g; W) J0 q- d    set intersection? false! z9 i) i( _8 ~
    set auto? false2 l, L" F  T' f+ M
    set green-light-up? true
, p5 ]' g6 s" H( I2 H    set my-row -1& L  x2 \% Y) X, L4 \
    set my-column -1
' Q$ ]8 Q" p3 H! s0 U3 \; T    set my-phase -1
  y8 s  @7 G( Y    set pcolor brown + 3& @& W7 p4 U& ]
  ]
4 A) v1 P8 \6 W6 v4 k' R- N, j3 p" s7 x
  ;; initialize the global variables that hold patch agentsets
& _' N* V" ^! ?  set roads patches with
1 h/ `; ]/ v: |9 ?    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 G8 f7 }( Q+ A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! a; z6 z  a" V4 d" D3 P
  set intersections roads with4 \# v* P2 `  F) p8 Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and" X4 v1 `* z  C8 V4 E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! @. ^+ Z4 R: X* K1 X/ O: D& _

7 C/ P4 ]) a& G; q- M- {  ask roads [ set pcolor white ]
4 Z9 T3 D6 m6 }/ p    setup-intersections
; u* ]* F9 d! q( D' [7 tend
6 l. j. d; @/ I  S其中定义道路的句子,如下所示,是什么意思啊?
& f! o' b( F/ s  n# z) m set roads patches with. p+ d- F2 R/ }3 ~8 j0 a- N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 b, ~( c" A7 f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% a8 B+ X. z' @& f
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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