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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。- m1 r4 s: {. J  F
netlogo自带的social science--traffic grid这一例子当中,
( y6 b# K) A9 p5 @  W8 Tglobals8 A4 e3 t3 ]1 w
[
0 r) s! G' @" Y) @9 V# o, p& D. w  grid-x-inc               ;; the amount of patches in between two roads in the x direction. z% m; m  d$ |2 a4 m' G' ^7 q" I1 ~# j
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) E9 A: e, L8 o  a  acceleration             ;; the constant that controls how much a car speeds up or slows down by if' A+ H- j& r4 C% h. `, c: }3 W
                           ;; it is to accelerate or decelerate
# f) ^% W; X6 a& m, t/ C: s  phase                    ;; keeps track of the phase# D, H& v, x4 v3 c4 ^
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# k' W9 v5 s' V2 R( g2 _8 g: A
  current-light            ;; the currently selected light% `, u2 h3 n5 U; g8 {4 _2 Y; f

, P3 w& O; o) `/ C6 o# ?( C( V# N  ;; patch agentsets" z7 T, v  p9 m, E8 Y# |0 O
  intersections ;; agentset containing the patches that are intersections4 _" |5 e6 j6 W2 R: }% ^- P
  roads         ;; agentset containing the patches that are roads
) q5 x- L0 g4 z8 K9 E3 S]5 Y6 E# U7 m0 x4 F- k
4 x3 c& ^( F) ]* j  x% |
turtles-own
2 v% d: J# B  N9 U% T[7 h5 o! W$ D  X/ x* p
  speed     ;; the speed of the turtle3 x" _0 V% z- ~$ [9 @3 W
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
& |, _% ~& V, A; Z* d' V. {% l# O  wait-time ;; the amount of time since the last time a turtle has moved( |6 Q, \* |7 k. Z& S; E
]
  e2 l. j2 R, O3 Z1 d, @6 l; n# M" |( Q  v) B( T
patches-own4 W6 D( }6 d2 i9 Y; P
[
) a& g8 v5 H. H. H/ |% t  intersection?   ;; true if the patch is at the intersection of two roads+ F; n# X& B5 u& H4 W' `5 x& F
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.  I# g+ F- K3 b4 F1 A' M5 t
                  ;; false for a non-intersection patches.3 M( }9 J5 p( H  ~0 e9 ?7 V+ O
  my-row          ;; the row of the intersection counting from the upper left corner of the0 t% M3 M' |7 R( V
                  ;; world.  -1 for non-intersection patches.5 r0 ~( N# o2 T4 b# q( M& n+ f6 Q
  my-column       ;; the column of the intersection counting from the upper left corner of the
0 a5 a% f8 w6 ^( k0 B: N                  ;; world.  -1 for non-intersection patches.
, Q# T8 j1 \' t/ V; I8 v$ G8 Q  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches./ O2 a; I' ^# n0 z
  auto?           ;; whether or not this intersection will switch automatically.
$ ^$ M, C: J5 w0 Q                  ;; false for non-intersection patches.
( E( u0 w6 n, f9 g]$ t; N: ?+ d/ `

, B! W7 h/ r4 c
6 ~# l/ G) P2 V# c# Q;;;;;;;;;;;;;;;;;;;;;;
6 g. B6 o1 J# [5 ]. b;; Setup Procedures ;;) |! q8 X$ f  m0 v
;;;;;;;;;;;;;;;;;;;;;;
  m; ^7 N4 f/ H0 v) z$ U. `3 ^) S8 T6 e$ q6 T4 f3 U
;; Initialize the display by giving the global and patch variables initial values.
- `  d2 {' b3 I;; Create num-cars of turtles if there are enough road patches for one turtle to
* V$ i  G2 l6 d8 O7 s: H;; be created per road patch. Set up the plots.4 ]9 Y% O* B. R
to setup
/ y* ~0 C4 I0 X7 C; ~5 q- k6 Y  ca
  Q) k! d& ]# }  setup-globals1 i% \5 h2 L8 |7 B5 n

* {; O. N" j. {2 G+ }  ;; First we ask the patches to draw themselves and set up a few variables
/ l0 Z: L; {  {; d# h8 L" j  }5 z  setup-patches
' `$ x5 {. w1 C5 S6 R" j  make-current one-of intersections
0 `5 F! z& F/ }  label-current& u3 O5 R5 X- N

; H' \. g3 N% }  set-default-shape turtles "car"
( u& c5 G& j3 s9 D$ d$ [2 c5 f2 P% j; C
  if (num-cars > count roads)
; i" ?! i1 l7 [6 |+ _" r: i  [
0 Q6 T/ I3 f  D5 r& q! u9 ~6 t    user-message (word "There are too many cars for the amount of ": i7 y- ?8 X) G
                       "road.  Either increase the amount of roads "5 ?1 `$ k1 ?2 G2 U  @3 b
                       "by increasing the GRID-SIZE-X or "
6 g2 n/ K: E, V0 _                       "GRID-SIZE-Y sliders, or decrease the "* J, H1 a8 C% Q. r5 Z% q
                       "number of cars by lowering the NUMBER slider.\n"
1 q$ z6 ]- _  z( g' h                       "The setup has stopped.")
4 T8 ~. y1 ]- d& |    stop
) w' b. J, O3 j7 i4 B  ]
. S$ A/ ~/ d) H2 t" |% Y2 H% a' s7 c8 t7 U0 i
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color+ v  w! P2 m, W' Z7 _2 E0 i
  crt num-cars! L1 f* f1 W: A: s& z
  [
# I% h$ x# y8 y% i# V  Y4 f    setup-cars
$ d5 e* x% f' l$ W; Q    set-car-color8 ]- s1 H, I6 T* t: o
    record-data6 ]) u( }% @1 Q8 X& A
  ]
3 A6 k2 y* g* T, ]2 e& L1 s$ [
0 r6 O, ?8 ^3 z: r+ {6 F  ;; give the turtles an initial speed* D0 X" D' `. A1 {: u% ~
  ask turtles [ set-car-speed ]7 p+ b1 M' e. T

( y7 r. r0 f5 _+ I2 D) X  reset-ticks
% q/ y% \! q! r* G. Kend
. J2 I1 U7 e) F) O# t8 C1 F  k' `1 `' h7 N& C+ k9 O
;; Initialize the global variables to appropriate values- D7 ^( N% M$ Y$ C4 ]& x" P
to setup-globals8 B6 E4 P. f3 R1 M* H
  set current-light nobody ;; just for now, since there are no lights yet! `! `0 ~6 t& E7 t& I: c
  set phase 0
: ], J% h! `; Q# M- h! D( i9 I4 b9 L  set num-cars-stopped 0' J' n7 o0 F) Q  @4 a) _
  set grid-x-inc world-width / grid-size-x
, M; F  v7 d- d- V8 V* E  Q9 C  set grid-y-inc world-height / grid-size-y
. A+ U! s+ W# J1 X, p6 s, u8 m6 J2 R" e3 C- o
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
1 `" Q' }3 v% v5 |! w  set acceleration 0.099
& [+ J9 i# d8 eend# q; `- \; v# u/ i/ i) _

1 n( C( n& @% V' F;; Make the patches have appropriate colors, set up the roads and intersections agentsets,  g& ^4 x* [& o% x9 a* Q$ Y( w
;; and initialize the traffic lights to one setting
( J4 j* n  k! \to setup-patches7 D6 y5 L4 K: v
  ;; initialize the patch-owned variables and color the patches to a base-color" ]% C2 E" l: ?! W, B5 S
  ask patches; _' V8 `& D! f& Y# [' ?
  [
+ Q9 M2 C3 F% W4 R2 a) r    set intersection? false1 o& l" k$ G3 T% g% f3 n
    set auto? false
5 I7 c3 p) f2 G/ T' b    set green-light-up? true5 V0 z9 `% |+ ?
    set my-row -1& _8 z' J# q! d3 F. a) [  L* L9 W  ~
    set my-column -1
. |/ _, G) e3 q4 D, C4 `, k9 C    set my-phase -1. t- D, x) {- J& `- b
    set pcolor brown + 3
+ }* q* ~# m, s" `- t% w0 A7 E  ]3 S) N  i/ m" N6 }# n
3 L4 n. E+ y! |0 z) e
  ;; initialize the global variables that hold patch agentsets
$ q- {* z- u8 d$ r% A. \: F  set roads patches with2 i7 d0 D- ?& ~2 w! U/ k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" V- Y  |# @& b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 b" j$ n1 X( Y9 z; S+ R8 |  set intersections roads with
5 p  w1 X) z0 \# B2 c4 y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" ?- m7 E* u1 H+ g3 S: p- J2 c4 C0 l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 D* I) ?1 ?- b# B

  A; ?" ]3 J9 w- T: y; I( V2 u# r0 {  ask roads [ set pcolor white ]4 \9 f/ a/ _, B. x6 U6 P
    setup-intersections, E. x) a  r5 P0 l- ^4 ^' p; d8 k
end
& b7 \7 u2 V6 v1 W其中定义道路的句子,如下所示,是什么意思啊?2 m) c$ L! p6 l+ E6 C  N5 F- {
set roads patches with' e4 g6 j. ~! c. d" ^! s
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 o6 _8 f) n' w
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ ^& ]$ H4 G  W: {( E( L, i
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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