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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。
/ B! F* [. x" \# |netlogo自带的social science--traffic grid这一例子当中,) x/ a9 Y1 r  P* C+ w
globals
) z( h! b/ e! A8 Z! @4 B9 a[
3 w( ~+ I3 c2 L" J% P$ `7 m  grid-x-inc               ;; the amount of patches in between two roads in the x direction- d& R, [) b) O4 {
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
  u) O8 \/ c- q3 M9 I# W  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
4 g8 ]% d( T; h9 C: D! |% i. Y7 I                           ;; it is to accelerate or decelerate9 i, \, l  y; W& T# f, {& q
  phase                    ;; keeps track of the phase
- R  W$ [1 {' C' L; n& R+ ~! `& \/ v  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure1 p* z1 ?6 N/ ~, H% n
  current-light            ;; the currently selected light
, C7 H* j& Q  p! f# u4 \' ?
& Y- |0 T4 y5 Z2 ]1 g! g7 V  ;; patch agentsets
. m, ?$ P* j; [$ j2 m: h  intersections ;; agentset containing the patches that are intersections
0 B3 U* n; {2 v; C" N4 S  roads         ;; agentset containing the patches that are roads
* c5 J3 J: `) x" T1 t]
% y; P7 T" R5 U. m8 ^' ]3 J; ?! _. _! e/ S- |# e5 l9 E
turtles-own
8 W* ]3 T  _  c& ~; v[( m% P2 P0 e$ P8 m
  speed     ;; the speed of the turtle
4 |2 l! h" W8 n' |7 W8 a1 a. A4 y6 h  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
0 m0 n4 b$ @6 C& a& E* K+ o/ t. ~  wait-time ;; the amount of time since the last time a turtle has moved
( u  B2 G# M6 T. @]
2 Y5 ?: x8 K! U$ s. V+ r
$ ?& m$ o* p1 h7 b5 qpatches-own
: _6 N8 V! `2 c, b# p, \[
1 e- _# \/ x/ \, E/ x9 T  intersection?   ;; true if the patch is at the intersection of two roads
# v5 }+ \+ G7 X& b) X  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.) s) u# D7 y+ M* P
                  ;; false for a non-intersection patches.. v! L5 Q" |/ r2 Q) s- i% F. b: r
  my-row          ;; the row of the intersection counting from the upper left corner of the0 e+ Q7 m, m! o% p8 W
                  ;; world.  -1 for non-intersection patches.
$ u' q9 R( Z& X" \! r; @8 u4 L  my-column       ;; the column of the intersection counting from the upper left corner of the1 o/ p7 x. t" `- ?2 v" U1 M
                  ;; world.  -1 for non-intersection patches.  f7 h' a" |6 D3 Z
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.7 L4 C) I1 h  B9 Q" A( g9 A
  auto?           ;; whether or not this intersection will switch automatically.
" Y" I5 [5 {' u4 h  N! W& _/ T5 F4 |                  ;; false for non-intersection patches.
6 I, G$ T( W' E]; G" D8 ]1 B& ?$ h+ j0 E) U

; S7 K; ^  o) E, Z+ G4 k. N. r
( i3 m9 N- p0 ~4 r3 Y7 a3 u;;;;;;;;;;;;;;;;;;;;;;: ^* `4 |5 G- I) N: J
;; Setup Procedures ;;" R  o; F" J- ]: Y& `$ t
;;;;;;;;;;;;;;;;;;;;;;# y; q7 L+ m: q) v" z

) b0 i: f  V8 I  j;; Initialize the display by giving the global and patch variables initial values.# h+ x7 D4 M3 K* \5 ^
;; Create num-cars of turtles if there are enough road patches for one turtle to- g, z3 v( _9 E) x/ v; F* g
;; be created per road patch. Set up the plots.
+ u* v5 q" W$ U, h! sto setup
- u7 h" Z. `* c4 Z  |# o  ca+ R( ~9 h. N9 W+ I
  setup-globals+ x+ T; i! A! }4 t- I

: _8 o! {4 \' H9 a1 {! ~. u% n2 m' [  ;; First we ask the patches to draw themselves and set up a few variables7 f. g  H& ?3 b/ Y0 X
  setup-patches
5 s3 {3 q9 J0 c/ w6 {& }- Z# n  make-current one-of intersections
: p& b: U9 u0 Z* X0 Y& _  label-current
0 C3 U1 m  E7 C) x' O# ^8 d2 I( |) b
  set-default-shape turtles "car") Q6 M: f* W& x$ ]  k( y# X
: ^$ o$ Y. w& Y0 z1 n
  if (num-cars > count roads)8 K( t) t; A5 Q' c/ S+ b
  [0 X( o/ D' |0 D% g* T
    user-message (word "There are too many cars for the amount of "
' J  f; W* c+ L' P                       "road.  Either increase the amount of roads "
5 |, O' @, Y1 X. l                       "by increasing the GRID-SIZE-X or "
& a+ K! q0 ~5 V: r+ O7 f4 r: k" c                       "GRID-SIZE-Y sliders, or decrease the "( k' A' D' t& i: a& T
                       "number of cars by lowering the NUMBER slider.\n"9 `2 b. t9 _+ Z! e+ `( g$ O. |" J4 A% o4 ~
                       "The setup has stopped.")
& {  _4 x0 ?" \7 i. F    stop0 O6 g/ q8 h% m9 |7 O
  ]
4 F3 A; v6 I4 M; R; O1 A8 b# W4 Q' z! L# j: Z" B" ]
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color8 P/ u$ V, s0 Z, n! f( W+ M
  crt num-cars5 c+ |$ Z7 ~+ V; ^' }/ `! X
  [
0 Z1 X4 x; F! l    setup-cars
4 i$ R8 {; d1 Y$ U$ f    set-car-color" {/ y0 f9 ?9 J6 ]2 P9 @
    record-data8 X; T: L* A8 H
  ]' l. w; r" v- N; q7 H4 V
9 \, p5 M6 D/ b5 K" U% {& l9 G
  ;; give the turtles an initial speed
$ n% b) p/ K9 O' C0 v8 L; v. m" ~  ask turtles [ set-car-speed ]
& H6 ?4 K8 l1 C$ I& \
  k2 i& i9 j% {  reset-ticks* f) U. Z/ }! t" G8 I) m' |. Q
end1 a8 m& T5 x4 R  I
; e8 S3 E' ^* g3 v$ e
;; Initialize the global variables to appropriate values
& o( i1 k2 G% [- r- [& uto setup-globals& q% t7 p- P% f  l9 y
  set current-light nobody ;; just for now, since there are no lights yet
2 R  t* r/ b. B: U' G/ |. ~. g  set phase 0% A. H7 z  `( U+ K
  set num-cars-stopped 08 S. Y8 X3 A1 j0 G* g
  set grid-x-inc world-width / grid-size-x( v5 V  G  t) R7 p
  set grid-y-inc world-height / grid-size-y* ~+ Y+ c% ~6 C) A; L0 t6 U: ~
1 X" v7 P) h, ~/ \4 A) f2 {$ g
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
) S4 r: Z$ o" [% ]7 K- ~  set acceleration 0.0993 b; M  o6 k& _8 [* l
end% b# [5 j& V/ W( E' {2 X/ J" n

- _1 x* z6 i9 Q% v; Z# h3 R;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
4 F  J2 j$ G/ e. M;; and initialize the traffic lights to one setting
* _, [6 g  \8 }/ M( i8 G9 J+ X, ]0 [to setup-patches
" V( o! K. Y5 n0 [6 l9 G8 ~  ;; initialize the patch-owned variables and color the patches to a base-color" M9 g9 x: I: o; U
  ask patches9 d- I8 N8 l2 F, J# q; J" P4 {
  [: ]4 k6 l6 v0 o: w* E0 x& |
    set intersection? false
* a$ _# m4 t# ~    set auto? false
0 N; J, ~% e3 v    set green-light-up? true
0 C$ c: f2 a4 i6 H    set my-row -1; M2 b8 S9 I5 s5 U3 P
    set my-column -1* f5 m0 ?: d" z4 L" Z2 o3 j& N. ?
    set my-phase -1  k$ X) q. x% u0 V" j6 l
    set pcolor brown + 3$ A" Q" U  f9 j! S
  ]
% z" J/ z! p6 v* E+ Q% Q+ G4 X7 O8 ]# S# N3 T6 C0 K9 r
  ;; initialize the global variables that hold patch agentsets
+ f' K9 I+ ]4 y4 D2 x! G  set roads patches with1 y2 E+ q. S  K3 T; y: C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 L8 e& i+ }. a( Z( l  ^! y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  u% X! o, \/ y% ?9 n, q' [
  set intersections roads with
& z! D3 w+ [" G; x& k" s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and* S7 Q7 [6 h9 P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 k% I6 f$ R9 M3 }( ?7 P6 s
- Y- k* F4 i9 J0 ?
  ask roads [ set pcolor white ]; ^3 p$ l# |' U+ `' \* q* W0 S/ r
    setup-intersections2 Z' V4 P) n% D) z2 R
end- s/ |# K! @& y) }* K6 o
其中定义道路的句子,如下所示,是什么意思啊?% B0 {% A4 b# m
set roads patches with7 J* I2 V" r4 A7 g( t
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& N* T( @5 z. v* t0 Y4 G5 ~+ {
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ g: T3 p  ?) m2 g
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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