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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 s" G: i/ z4 N$ [
netlogo自带的social science--traffic grid这一例子当中,
; ]/ \/ }* ]' m9 k# Y6 F0 }globals
+ ?3 p0 H5 e) T2 U) \[  N* ~. O- ?' n6 w. }
  grid-x-inc               ;; the amount of patches in between two roads in the x direction& {. L" K3 Q" X$ |
  grid-y-inc               ;; the amount of patches in between two roads in the y direction+ {+ G9 q) p. T) D$ S7 v( G7 n
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if. {# _7 R  c) y0 Q: ~7 h
                           ;; it is to accelerate or decelerate, s( A2 \( t* K# K
  phase                    ;; keeps track of the phase; W# V# X2 x8 j+ ^- [2 e4 A
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
- B( G8 O8 F7 P: o  current-light            ;; the currently selected light+ A$ Z) A% `6 h" m
! t/ Z5 E6 W& }* R: E3 y$ T. a% `2 U# L
  ;; patch agentsets; @) G$ G' z7 _# c6 B
  intersections ;; agentset containing the patches that are intersections& T: J% o: O1 `) \* j/ o6 O
  roads         ;; agentset containing the patches that are roads
% w3 [: ~3 F5 s) m, {]
  v. o. g; t; b: N# _) V" \% S( e/ X9 S  K; o( T
turtles-own
& \/ x" v9 O8 l4 u6 ][, s% m0 W- N) O% N; n
  speed     ;; the speed of the turtle
, x8 y2 N- J2 ^: k- R+ h( C2 e  up-car?   ;; true if the turtle moves downwards and false if it moves to the right2 m! u8 t% D0 L2 ~4 U8 f& S$ g
  wait-time ;; the amount of time since the last time a turtle has moved( M) k: N4 r9 A* H
]
9 N2 l! T+ V7 b4 s: ]3 }; J8 H$ Q$ k# P
  V4 Q/ |; `6 ?' }' R1 fpatches-own: m- z) O( r# G% w7 d& t  D
[! F, U9 A# [0 {! `) j4 F$ `
  intersection?   ;; true if the patch is at the intersection of two roads
" ]4 t- K+ n% A& F! ]% @  {) m0 L  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
3 N2 i8 S+ Z9 ~7 I5 P0 {+ W                  ;; false for a non-intersection patches.
, r* }# m4 h% E- ~. @, R% ]/ v  my-row          ;; the row of the intersection counting from the upper left corner of the
  |7 q2 ]7 e! R5 ~) X3 n1 G. _3 P/ ~5 P                  ;; world.  -1 for non-intersection patches.5 G6 r" n2 J7 v/ S. ?0 p  E
  my-column       ;; the column of the intersection counting from the upper left corner of the
! Q. D: a6 i& S) u                  ;; world.  -1 for non-intersection patches.1 r* D* d; N# s0 e( `
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.' C5 m$ o) L+ q. ^7 R; R% U/ I" ~$ P
  auto?           ;; whether or not this intersection will switch automatically.
9 J% D+ ~; ?. ~1 M3 B! b* }                  ;; false for non-intersection patches.. d6 C$ c3 w+ c# N, ^
]+ y! ~4 j) q$ p2 c6 J! r; V3 \

, Q. ~, A: C8 Q
  m# `/ h* c  h% ^" G;;;;;;;;;;;;;;;;;;;;;;
  P- q" p  F1 T0 [;; Setup Procedures ;;
4 E% u& F8 W: k( R$ Y;;;;;;;;;;;;;;;;;;;;;;
. F9 u/ u4 h5 V/ R+ N9 R0 ^( P- H
;; Initialize the display by giving the global and patch variables initial values.
  z3 j2 D' [! h;; Create num-cars of turtles if there are enough road patches for one turtle to
3 S) Z- Y* {9 k# k( B2 U1 y& M;; be created per road patch. Set up the plots.
! y: r" y# C' N9 y  S: C, q4 D# i6 jto setup
0 H8 w$ |$ |7 s  N( O  ca
1 S. @, ~5 b" J" ^, ]# o  setup-globals
2 l$ }0 J; A) e) ~
4 _; ~" J9 }4 h) ~  ;; First we ask the patches to draw themselves and set up a few variables
% E0 ?1 }4 u" ]$ F  setup-patches
( S  r! P- X( ^0 d3 f% G  make-current one-of intersections( m  d  g) j! M8 U$ v1 @) e4 W
  label-current
" Z6 P0 t- ~! W& V2 S6 a) Y
* O( b, K# b' z. h+ P) T5 f7 q  set-default-shape turtles "car"8 ~3 a8 e6 b" d, l

# D0 h% ^- ?" w: z  if (num-cars > count roads), B0 O$ x# d+ \1 a7 g
  [
+ D. v5 a" O6 \3 d+ R) i% ?    user-message (word "There are too many cars for the amount of "
! Z; a1 ?9 j5 p& a% P6 `: t                       "road.  Either increase the amount of roads "3 u8 m7 y* ]! {  }" t# X
                       "by increasing the GRID-SIZE-X or ": |" h* d$ I1 q0 N/ k4 ^; ]1 f- x
                       "GRID-SIZE-Y sliders, or decrease the "$ |, I! q. B5 C* Y9 j' q" ]: T9 C
                       "number of cars by lowering the NUMBER slider.\n": H9 {4 E9 L# h8 h# T) {5 Y
                       "The setup has stopped."). w+ R4 X( o8 t9 _
    stop$ a* u5 Q: _9 H7 D' l" E
  ]
- k& t2 j% c' U& V& g4 D( T: D4 J& J/ J' H& y6 b- Y. ^
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
- ]$ d8 H" b( r: T  crt num-cars
, Z7 B0 d: b: d" c  [! {2 O, Q/ {  Y- l
    setup-cars4 N3 s, x. f$ h% I1 \
    set-car-color
9 `1 ~: i1 J2 k/ P; k+ K% Q  c1 I    record-data4 Y8 k0 E/ G8 g
  ], Q* v4 I7 I$ n$ m

) U6 B2 v; ?; s; F" V  ;; give the turtles an initial speed: c1 ^& P: Q& b
  ask turtles [ set-car-speed ]6 E9 a$ m6 r/ ?1 t9 w
# ~5 L5 Z( A2 V; s  J
  reset-ticks
  q" e; z, f7 |" C- r' }1 D9 ?end. z4 L' C& Q# `& y2 Q# H* s2 {$ m: Q

: g& R2 Z5 Z) \2 s& h;; Initialize the global variables to appropriate values
1 o$ ?/ _( z; V) i3 K0 W0 t8 \to setup-globals' C. u$ W+ `# l" ~0 u. {5 {
  set current-light nobody ;; just for now, since there are no lights yet
% _- P$ a9 o7 D  set phase 0
  y0 R- Y2 T! \: A1 {( z, |  set num-cars-stopped 0
; H, s+ U7 \1 T% z: m3 D4 E  set grid-x-inc world-width / grid-size-x; [) D6 @+ E: x& |8 y6 H
  set grid-y-inc world-height / grid-size-y
' r& O! z9 s8 @, P% X, G
4 p" j7 }4 T) v: ~4 J  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
! O3 i2 a, `1 ~, m. e  set acceleration 0.099/ ^& H* V+ e, C: i+ O+ b
end
1 D3 f$ A: [  P: U' w
. |) O1 C" {/ p! Q0 Q2 _  P;; Make the patches have appropriate colors, set up the roads and intersections agentsets,& {  E. Z, y8 w: g
;; and initialize the traffic lights to one setting; V2 g. L. q1 ^" s1 Y: R
to setup-patches) {- m5 q: O% U2 R) f* O
  ;; initialize the patch-owned variables and color the patches to a base-color; k* P( R7 X  d9 A5 J; _
  ask patches  `6 Y# u' G8 G4 |( U$ z" b
  [+ c9 l. m9 O. f* L2 T( s/ V9 B! I
    set intersection? false/ D' B6 J; G/ f' @
    set auto? false
" E$ \& I2 j$ Q    set green-light-up? true
5 C; s# @2 ]9 b6 m+ o' O    set my-row -1
9 {, j- _/ N' A4 ~; h4 [+ w/ ]    set my-column -1, U! J2 T/ A* }9 O
    set my-phase -1
( o  w9 F) F$ g7 H3 g/ [    set pcolor brown + 3
/ Y" F; V4 L/ p' r& U2 S1 R  ]
6 e9 S0 q: Y: h, ]8 m
8 k% s5 w6 X: a  ;; initialize the global variables that hold patch agentsets% y) r& ~* r2 n1 J3 |: ?9 v
  set roads patches with
/ W- A, A- z- \6 F3 ]9 s" c    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: ^. R, F5 _( s5 y! Q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 A  m4 K7 _$ R0 Q0 o) \0 D7 Y  set intersections roads with1 m6 I: O2 g5 }
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ v# o& ]6 J! L1 z& v- E7 o% r; X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 V8 J. r" \: z. J) B; F
6 \) f: P2 L* X& x/ t, d4 H  ask roads [ set pcolor white ]' f! j6 Z( w. ]
    setup-intersections
0 Y& v( s, i' f; G- o$ {3 e% zend
! _' ~# m' D, w7 s. J其中定义道路的句子,如下所示,是什么意思啊?
( k& l4 T1 M9 H1 m* S set roads patches with' D3 P  s5 W& P/ _8 i
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 V! c( v# Z8 g8 R: j9 L    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! @8 I4 [, `8 L5 r* {+ i! b2 v/ x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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