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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。# q2 y9 Z% a6 ]- m
netlogo自带的social science--traffic grid这一例子当中,5 D9 i$ _" F7 y9 P2 J  `/ S
globals3 M8 P) |# v( p% h; ?
[; k" ^  S, b' g4 t: c3 K" b
  grid-x-inc               ;; the amount of patches in between two roads in the x direction- F9 p4 U" J- K7 ^
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 _/ O2 Z$ y3 G& }8 T  acceleration             ;; the constant that controls how much a car speeds up or slows down by if# y3 r4 N4 m, q# t1 |
                           ;; it is to accelerate or decelerate3 p' M2 ]; f0 t
  phase                    ;; keeps track of the phase
# Q) O) e; f6 K7 w  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure9 L" }3 c0 t, U2 i; X! w
  current-light            ;; the currently selected light4 T6 y6 F5 {3 t* w& j
  I6 l* \* D5 Q& z+ q
  ;; patch agentsets4 z5 g9 E4 i1 [  L! T4 P* t1 w
  intersections ;; agentset containing the patches that are intersections
% c  T! a1 p) t, m  roads         ;; agentset containing the patches that are roads
1 J' M6 M4 c4 W1 ~' ]8 o]
& E4 n2 E/ {& |6 S1 b6 o& W/ @& Z; p3 j0 j9 _; I9 e+ P- V
turtles-own6 I, R+ W: W6 a3 m. E
[
8 M/ {; s& T1 F0 K: A- h1 B  speed     ;; the speed of the turtle! h1 i! O% f; r
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right! d6 U# `: j6 l! @9 N
  wait-time ;; the amount of time since the last time a turtle has moved& I- Z" m, p( I$ a( j% ~9 f' T) u6 p
]  n( ?" S3 n" A$ j* ]  g

& J5 Q3 G7 c/ u' ^patches-own
( M% g, `4 S% b; |1 t[# D9 i9 d6 I0 @# |2 R& d% o6 \
  intersection?   ;; true if the patch is at the intersection of two roads
) T/ ^! O; }& o: n, F. z5 `  green-light-up? ;; true if the green light is above the intersection.  otherwise, false." t0 V9 L- d/ x& o# A' ]# }, v7 V
                  ;; false for a non-intersection patches.
% d1 j1 H0 r/ C+ L& j  my-row          ;; the row of the intersection counting from the upper left corner of the  n& U% K4 P1 ~) f8 s
                  ;; world.  -1 for non-intersection patches.
5 V4 Y- |( l3 P+ v  my-column       ;; the column of the intersection counting from the upper left corner of the
( |. F) _0 t; q- b! A; a+ o, P                  ;; world.  -1 for non-intersection patches.9 _' h* V7 p6 g* C! W/ ]  l
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% a# F6 @2 ?6 t  auto?           ;; whether or not this intersection will switch automatically.$ Q: g; |7 c$ {& \' q5 k- c
                  ;; false for non-intersection patches.
. W, `: W5 V  L( d+ w2 a]- a# e$ B7 [6 K7 D$ a- H

. h$ U, |2 l/ e* n: @0 h3 @; t4 r# Z1 [
;;;;;;;;;;;;;;;;;;;;;;
/ d3 N+ M: N- q4 x! ~;; Setup Procedures ;;
( H6 O0 r1 b% s, C6 g$ u;;;;;;;;;;;;;;;;;;;;;;
7 @1 g: I: U- K* L3 b1 v# k( `( o/ |
;; Initialize the display by giving the global and patch variables initial values.0 G) O; T$ B# h4 q/ h2 G
;; Create num-cars of turtles if there are enough road patches for one turtle to
" U1 R  p8 u3 I# t+ O  I;; be created per road patch. Set up the plots.7 ]6 C: z' t7 L1 z- I: @
to setup
( B% q  l. }9 ]; B# I" }  ca
( |/ o. v. y4 r  setup-globals
$ k: z) y- L9 A$ l4 A' }8 a- G. P: O* I
  ;; First we ask the patches to draw themselves and set up a few variables2 \5 B$ \0 R; r% }9 f0 r9 N
  setup-patches$ ^! j' S- \/ K& N
  make-current one-of intersections& u9 i5 E3 X, F  O+ [
  label-current5 c7 L; P- b& y

4 r. E4 {. Z6 j) S. j  set-default-shape turtles "car"
' V- P7 z: h" V7 J
# A4 X4 {6 W& M' p9 N  if (num-cars > count roads). u" X" c% |4 h; I2 A
  [- m2 W% n  l" z* L9 Q0 P! K" w
    user-message (word "There are too many cars for the amount of ") a! W. @% w4 D1 s7 y
                       "road.  Either increase the amount of roads "( K+ F  A2 w2 [+ z1 F0 o4 e
                       "by increasing the GRID-SIZE-X or "
, _6 G% o4 y9 P9 i* i) D  \                       "GRID-SIZE-Y sliders, or decrease the ") X2 m7 l4 m5 P9 n2 _, n8 G  j
                       "number of cars by lowering the NUMBER slider.\n"
& r2 c! X2 m# C! g, ~( k8 V9 g& u                       "The setup has stopped.")5 ~% F& M' v* T% n8 [% B, j
    stop
: h, ?8 c; c' \7 U$ a  h  ]
) W3 ]8 n  j' |0 T9 s: ^# T
7 u% v' F7 f' m9 e+ R0 w9 y+ H  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
8 Y7 q/ \  {+ `* I* l  crt num-cars* O$ m2 @( ^* Q4 A, _
  [
, p6 B0 b" D7 ^4 [    setup-cars  K9 w; @( Q  `' E0 @1 x- }
    set-car-color# O* t% T) U# X, J, V% o
    record-data
( h2 A# o3 a  M8 `  R# h  ]& @1 L5 A3 b7 D' X% s/ Z% W

) ~( j/ X' I0 w9 ^  Y  ;; give the turtles an initial speed
. U4 \4 r- N4 m" e; c, e1 T  ask turtles [ set-car-speed ]7 o3 L; c. A6 o3 G, E* t' w

: t  M, H  _) a0 z: P' D  reset-ticks# N/ X$ q  S( u* ~# q
end
$ A- q+ E6 x2 ?- o: \: P) P
" {, S# U1 {/ m$ r" P  B: Q;; Initialize the global variables to appropriate values$ q+ _  n7 x$ O2 q" e) \$ x/ P
to setup-globals' J: K% K9 \+ x. ~6 w
  set current-light nobody ;; just for now, since there are no lights yet
8 ~8 F) y) L% T5 c  I3 S2 p  set phase 0
4 x* t7 f$ h; A  R, j  set num-cars-stopped 0
! k: r, {/ m+ H5 x  set grid-x-inc world-width / grid-size-x
" }- u' ?; h* a# }# E" }( I; \2 l  set grid-y-inc world-height / grid-size-y' ~8 M0 G& }. }0 u& Z

* X0 u' u# |5 J6 x% \  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 F7 Y6 o0 E$ A# c* B- ~0 I
  set acceleration 0.099
6 d3 l. i% s9 ~" f& h0 ]end! T5 n0 [/ k1 X

8 z  Z9 V2 K- Y9 s! f;; Make the patches have appropriate colors, set up the roads and intersections agentsets,7 x( h& p% J3 [: b* T
;; and initialize the traffic lights to one setting
! [1 @, k7 N: R$ e8 A( hto setup-patches
. w9 L, N" |' \9 V  ;; initialize the patch-owned variables and color the patches to a base-color
0 B1 i$ A' ]* {2 {4 z# |4 H  ask patches
3 u1 S# c  K9 k5 {1 h+ g8 r  [( d; q3 u: V5 [- Z( t% j7 q
    set intersection? false
  v+ y9 x* l* `9 p6 U- x' ?" C* o9 B    set auto? false
/ m6 B- t0 s( A$ {# U    set green-light-up? true
! ]2 E# a) n) I! G    set my-row -1
0 Z  a! H: z/ f: E% x0 E( Z    set my-column -1
+ _+ Q- y) n5 {& A    set my-phase -1
  }* d3 G/ l- o/ q1 x  v    set pcolor brown + 3; R) Y; w( X5 N1 M4 v
  ]: K6 c( j* R* M% }# y3 T

# H# n% U  B# m4 O  ;; initialize the global variables that hold patch agentsets' f. T0 G! E1 {& z
  set roads patches with
" n3 J- b( r$ D0 E* `& `3 V* \    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 W2 U: i) `' s( I1 m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 X3 N5 x, g0 e% ?* i9 j
  set intersections roads with
" ?' L- o( r7 m0 _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
( \- i* Z# F1 E5 \) z, G; R    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' C; J5 l" ?3 {$ N1 y/ g* @8 H9 Y! i9 D- i+ s+ l2 r2 g3 R. a
  ask roads [ set pcolor white ]" h$ Q) |) R  f9 S2 {7 O, z# h0 Q; M
    setup-intersections+ Z- k5 |4 d8 [0 v8 L
end
3 e( O! o5 b; X; `$ z. d1 ^1 ^其中定义道路的句子,如下所示,是什么意思啊?/ ~( w0 y9 N0 @% k3 o- E- r
set roads patches with
2 o! U0 b3 C9 T! o8 Z' I* Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 b  e$ t* M, `    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, B! W9 D+ v* [6 J5 p, y" m; |! Y0 ^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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