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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。, n/ c7 [5 k! r+ I6 C$ ~
netlogo自带的social science--traffic grid这一例子当中,
( z* @# F) u2 z1 N8 @  \globals1 L* ?6 A0 b! e, t1 p# \3 b
[# v) w! |) m* h' y+ S; j$ R
  grid-x-inc               ;; the amount of patches in between two roads in the x direction0 m3 x7 e! e( B* I7 Y$ `2 o
  grid-y-inc               ;; the amount of patches in between two roads in the y direction0 O  C  ?# e; \: Z
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if/ ^0 f( q# e- {+ |# G$ v- \5 k6 o
                           ;; it is to accelerate or decelerate
0 J) ~& R+ k4 N- ?" Q4 n7 W) Y. W  phase                    ;; keeps track of the phase
- ]2 U- }2 v) T; q7 W. q& z  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure& `1 o% l" y. }
  current-light            ;; the currently selected light6 v# M, {; N6 z1 v8 q
2 P' I* P# b+ j, Y$ e  V: W9 _
  ;; patch agentsets
# o/ F( A6 v/ r; x! ]) z. G  intersections ;; agentset containing the patches that are intersections
3 V' @- `, I1 r' k4 x  roads         ;; agentset containing the patches that are roads
3 z7 p8 @8 `5 j0 a" w]
* k5 G/ h7 K+ D/ a
9 V( s$ i5 w; s+ p0 rturtles-own. G! G: e- r! T# X5 |* W
[5 w& I6 V; j, i
  speed     ;; the speed of the turtle' k' P8 a* v/ I' v5 K0 }
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 }& }* U. U0 d) ]2 L( r  wait-time ;; the amount of time since the last time a turtle has moved8 _9 s- v6 ~" S& K, ]+ t
]# Q4 [0 p. n+ r0 d/ c7 b: E! ^2 h

5 ]$ X* w& b* y# }patches-own
9 S# R+ G% j" L# t3 S+ ]$ p' _[
, y. h! n4 h% {4 O8 K: \  intersection?   ;; true if the patch is at the intersection of two roads! a  j! X$ Q  q/ ~3 x
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false., _/ R7 R3 F$ \2 C) r2 O8 u+ p$ A
                  ;; false for a non-intersection patches.: _2 ~' F% _& C
  my-row          ;; the row of the intersection counting from the upper left corner of the
$ t# |+ L; `4 G! J9 T                  ;; world.  -1 for non-intersection patches.
' x* D, p5 G5 y! i* \2 y  my-column       ;; the column of the intersection counting from the upper left corner of the+ A, V% Y2 C) |9 d) W  F- ~: N
                  ;; world.  -1 for non-intersection patches.
3 i4 s- I& }( n  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.- f6 K9 t1 v( A7 Y% Q7 {1 H
  auto?           ;; whether or not this intersection will switch automatically.; n$ z9 o6 ~3 T/ N- y/ M
                  ;; false for non-intersection patches.! d! {  {7 T( w9 S( g
]
& P/ Y( k+ E# l5 b% C5 g' w& U. D" d1 l- P, p3 {$ \7 A

/ [: T% @& h4 M: O/ y2 U4 T;;;;;;;;;;;;;;;;;;;;;;$ p! A5 U' e) l# C5 a  B' \
;; Setup Procedures ;;
' o: S0 m3 h5 {% V# q: t' b. ?;;;;;;;;;;;;;;;;;;;;;;0 i: u. l! U* j  I0 x
$ O7 d! E3 h; m$ c6 ^+ e
;; Initialize the display by giving the global and patch variables initial values.0 x/ Q9 a  a% ^1 s0 @2 z
;; Create num-cars of turtles if there are enough road patches for one turtle to2 C1 u5 H. H$ L4 Q& ~2 A# \
;; be created per road patch. Set up the plots.
; A- V* X+ {6 v7 G2 wto setup. ^0 F, d* D; f$ s# y% t# p6 U
  ca
& {# l& ?$ w/ H. y6 k  setup-globals
& u8 r' W* S. k) z2 {) e, h
5 E" \. m6 v3 E, p$ E" a9 ^8 H6 H  ;; First we ask the patches to draw themselves and set up a few variables
" X0 x1 f' Q6 ~# m/ v$ ~7 x$ n  setup-patches
$ I% N" \* M( u2 ^; g  make-current one-of intersections) [; x, X1 {& w' U) H8 p# v/ j0 J
  label-current
4 |$ x+ X! r: `; ]6 q# Q* o
4 o! I9 A6 Z' R* C! H8 b% k  set-default-shape turtles "car"6 w- O+ Q3 R0 i3 @) n" B4 N

" K6 R/ B) z# e1 Z  if (num-cars > count roads)
8 \0 U6 b2 `7 D$ Q  [  O; ?% z: Q5 \9 f' d4 C" U: v
    user-message (word "There are too many cars for the amount of "; _4 K: t% b  O. d5 _8 S
                       "road.  Either increase the amount of roads "- \; b; ]* w. H( R
                       "by increasing the GRID-SIZE-X or "
, C# u; w' ]6 e8 ^) o1 |                       "GRID-SIZE-Y sliders, or decrease the "! P' f% _$ T* ?0 A, M
                       "number of cars by lowering the NUMBER slider.\n"" y& z, q( b9 Y/ m2 g( {
                       "The setup has stopped.")
  C; ~" {: E/ H- p    stop- q$ x/ M' G" _& E1 Q4 P
  ]/ ~2 ]: D( e, U: K& f
! ~, x& R( {2 ?1 T
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
6 f3 f& L. q# G0 r+ d- c  crt num-cars& P2 ?& @( @. L' P
  [7 _5 `0 ^5 d, q, F1 n% P
    setup-cars
. g: V6 G3 P* B5 Q/ t" n* e. C    set-car-color) R6 m# h4 O7 }) Q7 _; Z
    record-data
- c2 {: z- H" s# k' B  ]
3 H) n1 d% y$ n' z  x. B# H
1 Z5 U7 i7 v( b" Y  ;; give the turtles an initial speed
# J$ S4 V( i0 j2 `8 x% }6 B( L  ask turtles [ set-car-speed ]+ o" L1 M8 T, g8 A' A0 R8 Q$ ~. @
; ^4 x; S, R$ `9 L9 S$ `( _) b
  reset-ticks- ^' a2 n; x1 x6 I6 q/ I( f3 Z
end
6 }0 l! `/ N: E% {: v8 s
3 \! A; d( i8 _;; Initialize the global variables to appropriate values
, g  m7 }5 D4 _4 oto setup-globals
2 ]: A! s6 d. E  o; ^  set current-light nobody ;; just for now, since there are no lights yet
0 Y9 d& j6 G* p1 I  set phase 0
6 G1 I% I6 l* w9 h; o  set num-cars-stopped 0$ k/ ^' N/ P" ?! G& M6 l7 u% G1 _
  set grid-x-inc world-width / grid-size-x
7 x( C4 t* y5 ]3 v  set grid-y-inc world-height / grid-size-y' G* J( F1 U! ]) m4 O

  F( R/ N1 S2 ]1 k% E/ h  A  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
5 v5 J9 b  n$ I# t5 k( N  set acceleration 0.099
0 H) E+ K: _+ f% O; U- [end
; \  N( o: ]! S
9 ]! r7 c* Y6 W# S. d' j2 ~% U3 `;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
, q0 t5 R4 j8 c1 K6 l2 k5 g- I& q5 {;; and initialize the traffic lights to one setting% z5 N) U( B& B& j# K4 u
to setup-patches  F: I& `/ R' f& n3 z
  ;; initialize the patch-owned variables and color the patches to a base-color
/ D" }2 ~. P- H: \" N3 T  ask patches( [4 t/ D# ~; @, T$ j
  [2 E; @) ]% y9 U* z  v
    set intersection? false
; z" @& E+ I8 R, q  d1 }    set auto? false
5 Q+ o+ I. A* D    set green-light-up? true- D8 _( C- F: B9 V  g$ t
    set my-row -16 {9 q! @( V, _& q7 ?7 z6 x
    set my-column -16 D7 t+ c  J8 B/ c
    set my-phase -1( o# I8 {& B5 Q, `* d" A
    set pcolor brown + 32 F9 r% \( M! G8 r; H5 f
  ]! f2 x6 q* A6 q( k; m

- Y1 q) `& b% U2 @  n' r; F. E  ;; initialize the global variables that hold patch agentsets6 k. b2 i# }3 U6 X. |2 m" R' X
  set roads patches with
, d0 b' A9 U' _+ b6 F  A9 F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. I- F8 h9 E- y, l8 A* Z9 y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* E% [1 u2 P8 H0 m2 a; w* E9 x6 \  set intersections roads with
8 k8 c& `6 Y+ Z7 F! I7 {    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
) x8 M6 N- L- g/ s    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 ^, u' N6 t8 P  I1 l

: j% Y3 V/ \# N6 Y% u( |  ask roads [ set pcolor white ]- b8 G# B( x7 T! N$ U2 |5 d( j
    setup-intersections/ r- M- T" c# L( w& Q9 P
end6 U9 Q5 Q' Z; v# Q0 A4 u8 W" b& g7 [
其中定义道路的句子,如下所示,是什么意思啊?
6 a9 I1 h+ Q* z( a5 ^% r. b. M set roads patches with
0 g8 x% L; A% h% {    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 U+ h8 r2 e9 B6 {! [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 a. [- B2 f' z6 D7 R$ S+ w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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