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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。
6 \4 K7 I8 ]1 z: O' i8 k# q; p0 qnetlogo自带的social science--traffic grid这一例子当中,
, h5 V; q, W% z0 K8 {globals* v" O5 _: Z3 U9 V: `
[) i- }' H( u4 A3 p5 l: }
  grid-x-inc               ;; the amount of patches in between two roads in the x direction, s, m" D! o/ B6 \2 Z- W' g1 ?, t  U
  grid-y-inc               ;; the amount of patches in between two roads in the y direction! q) o& H! v. X  f- o# F. n
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
4 \3 }: I& ]% Y                           ;; it is to accelerate or decelerate
$ B; l7 b- D% d% o  phase                    ;; keeps track of the phase3 r5 `7 b2 Q8 C8 S
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
( c* I) G6 S* e2 g# C9 B$ u$ H  current-light            ;; the currently selected light, Z& |; K' }( A/ q
2 Y0 I3 ]; m( n3 F3 `- q% C
  ;; patch agentsets
9 f! ]" a  |( F7 t' }  intersections ;; agentset containing the patches that are intersections4 U( h! D' h1 n" t# y7 I5 S. V+ L
  roads         ;; agentset containing the patches that are roads
( D2 ^7 {+ c4 p* b0 i1 p]1 O. n( I; e2 p3 R6 P& k4 O

- G+ L( P4 ?4 s" zturtles-own
+ s. o' W5 U: ~% M& F[  i! p; e2 w" [% N  e
  speed     ;; the speed of the turtle. q/ Z( I0 m* B0 S' D* l: _
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right0 c$ y# O; K. M; ~
  wait-time ;; the amount of time since the last time a turtle has moved
- D$ h1 o! r9 T% A1 w]. ^. M  G) h1 Y7 m
, e$ |& D8 z" r9 M3 g7 d' ~- K
patches-own! A: G  s$ ^* ]7 M( u) b+ P
[
( w( Z3 \/ s$ V" X3 Q  intersection?   ;; true if the patch is at the intersection of two roads
' q" y  t, |- L: j9 u  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
) q4 q3 |% @# }; B. B% E+ R2 ]                  ;; false for a non-intersection patches., J+ j( ]0 w$ J" C9 p% \& \
  my-row          ;; the row of the intersection counting from the upper left corner of the
7 v8 H( I1 d3 {1 {1 v6 ^; P6 s                  ;; world.  -1 for non-intersection patches./ Z! Y) v$ A7 K. q  L
  my-column       ;; the column of the intersection counting from the upper left corner of the6 `9 n. D0 f, T7 ~3 n3 `1 l
                  ;; world.  -1 for non-intersection patches.1 L& [& E2 I7 c  P. j" A
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
) Q: N4 c0 a+ o: [/ {" f( f6 L1 F* k  auto?           ;; whether or not this intersection will switch automatically.
5 m. q5 H1 r+ B  Y                  ;; false for non-intersection patches.
1 H( m, n0 W3 k7 m8 d4 u: a]
1 h+ \) T. z  o( m
; Y: o: Y1 \- ^9 P) P6 a8 [7 g5 {8 }0 K9 x8 U
;;;;;;;;;;;;;;;;;;;;;;4 P8 v" }: `; B) z/ `1 z
;; Setup Procedures ;;1 i* d) N, W* u7 r! w1 s; `2 ?
;;;;;;;;;;;;;;;;;;;;;;/ r( y9 k7 N0 q- X( x, D

1 `' F1 ^2 w1 U;; Initialize the display by giving the global and patch variables initial values.7 K( h8 k* I& `7 V
;; Create num-cars of turtles if there are enough road patches for one turtle to* ]; D' S: ^6 Q/ d+ F+ f( W  ]# A" r
;; be created per road patch. Set up the plots., [; d3 W! O, g8 h8 A% @  \
to setup& ?% m8 @" B8 z
  ca
6 U, O& U* @2 z( g# N8 k3 b  setup-globals
$ n) h6 o( M: e0 x7 `, g& n+ I2 \8 T0 S
  ;; First we ask the patches to draw themselves and set up a few variables1 U  V9 y: P% L  S8 A; M
  setup-patches3 D  b8 h/ {" {- I% |
  make-current one-of intersections9 d) b' B: ]5 ^( Y
  label-current6 E( `  s% y9 S/ Z+ X( ^! Z: I

8 q$ ^+ F" e% a2 X" H0 o# Z! x  set-default-shape turtles "car"( v; W% d8 E. b) T

* J. u8 d; I( G% t7 ~. h1 _  if (num-cars > count roads)1 Y( r: m4 M' \  T( d
  [3 j4 d* I8 Q  C  E
    user-message (word "There are too many cars for the amount of "
( Y- n( U. d& ]6 N$ D& z9 q  c                       "road.  Either increase the amount of roads "
/ Q9 g7 ~: M( u, W) r                       "by increasing the GRID-SIZE-X or "
. w; l; J) }7 k6 D3 b                       "GRID-SIZE-Y sliders, or decrease the "5 `8 L" e/ l% P* w: ~' n7 W
                       "number of cars by lowering the NUMBER slider.\n"
) ?: A) M. x# k                       "The setup has stopped.")  X1 G; S" x1 {8 T" |
    stop6 H6 f2 v, t" R
  ]1 O$ ]% h8 C( }

" v' w" Y: @# {( w/ b  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
2 S# |) A& H& |' }  crt num-cars
0 @6 a$ L$ M) d# j  [
) Z' \+ W. Y( d# f, K    setup-cars
7 t& @+ U' }2 t% p5 A, q    set-car-color3 c7 ^' I# @9 f
    record-data
5 w1 G/ c9 U2 k/ L8 B' t: [! b  ]( l1 C* ?0 M- p
- d4 H3 ^+ n7 t# ~. ~% ]+ [
  ;; give the turtles an initial speed6 e- ^# ~+ u  o" i7 T
  ask turtles [ set-car-speed ]1 e% ]) _5 @, G
3 P/ X( [- f& l) ]
  reset-ticks
# J. D5 r4 `/ D) \/ v2 ~: ?! f' wend
, J) \9 w9 V" Q) A0 ~9 s0 ^/ M% q! d' Z" }
;; Initialize the global variables to appropriate values
. t% o/ M; m, v/ `# v' mto setup-globals8 ?& a* Z: \5 }* R+ O" ]+ j8 }% [
  set current-light nobody ;; just for now, since there are no lights yet
, l; [6 S: Z8 H; k  V) ]/ J9 s  set phase 05 I4 I( G  Y  W* Y" l
  set num-cars-stopped 0
1 O4 u* ]: s& l+ b- J) o. y5 X5 ?  set grid-x-inc world-width / grid-size-x
4 z$ K$ D( I/ u; U  set grid-y-inc world-height / grid-size-y
1 @8 P7 }# y5 J. m% v9 B( A3 k
! a) j9 t# c( j4 Q9 m  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
& T, h! i* v- ]4 e# C- B6 m; i  set acceleration 0.099# ]3 r* L7 h. s
end6 i, X" k/ X9 @; k" Y0 f

) }/ q. p6 Z) {) p7 Q5 o( s;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
* D% F' ?% X" l: T: ?;; and initialize the traffic lights to one setting
, K# G) e; V% }3 q0 T% F3 P+ cto setup-patches
  x6 m; z; s# e' V# G) P  ;; initialize the patch-owned variables and color the patches to a base-color
3 W" |9 c* t# p  ask patches( I% B% n. x; x/ z% ~( v$ l
  [1 Y* U) Y" c$ w  Z- y" |; t" o
    set intersection? false
! |8 Y* a; P8 J2 u! k4 h, k$ x8 v* T    set auto? false
! L3 a& K& T+ `# M0 u    set green-light-up? true
. H7 G1 N& K& Z4 Q/ p& B* N    set my-row -1% F7 p6 W: K4 ?7 Z) }- T" a
    set my-column -1
! I3 r2 |$ O% J8 C5 i' _    set my-phase -18 p" ~8 X3 U6 t; J
    set pcolor brown + 3% m  L- d0 t! f3 V% v) ^) ~9 l
  ]+ j/ z. i; _1 F! N4 @
/ C: B0 K7 C  s' m- X2 e* Q6 `; p; |
  ;; initialize the global variables that hold patch agentsets/ @: v4 E& d# ]( j" D. y
  set roads patches with* e/ u, f* I. z" ]( n, m/ p$ |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) w' M( M! y7 L. _) U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) Z$ q' X" {0 S- Y, {$ @# M; H
  set intersections roads with
  L! t7 u/ S' R2 b& u& E9 [- G1 v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and8 J% J) J0 U% h5 U2 C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# n" o; p9 f: U
8 R6 V' u: N( i& i2 {# h
  ask roads [ set pcolor white ]
0 O1 o' y  C. z  J! T    setup-intersections3 c+ \) O: K4 k; N3 w
end3 F! T6 [- s: e7 F7 v: K
其中定义道路的句子,如下所示,是什么意思啊?/ `4 S+ P' b* Q- j  f6 X
set roads patches with
4 y/ U9 u" r" n% e  t! h    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' {2 l' R* H! {( F# [# G    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 a) f; M" e) s1 ?& y6 c( \  L; B8 @
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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