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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。: K, ^! S  l0 c
netlogo自带的social science--traffic grid这一例子当中,$ C& s( _. Q! f
globals
( U9 m0 Z$ s- S" T[0 n# E6 P2 o& b
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
! j( Y8 ~. U* `) |5 h  grid-y-inc               ;; the amount of patches in between two roads in the y direction  I( ]1 v+ Q8 N: B9 u
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
  |# F8 S8 H$ s; W                           ;; it is to accelerate or decelerate
( @- r0 C+ }5 o6 O* m& D  phase                    ;; keeps track of the phase
6 z% h( A7 Y0 d6 r7 V  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
6 K1 s: w) Y! Z5 @' l; w$ |  current-light            ;; the currently selected light1 |) \% R! d% B- j! V$ ?' k

, k) ~$ L" P  m! Z  ;; patch agentsets
1 R" b2 u7 @8 {: x7 k  intersections ;; agentset containing the patches that are intersections
: a# x/ P2 S7 J9 b  roads         ;; agentset containing the patches that are roads
- _8 \" M. C/ t]% |7 m8 V5 @3 W( F4 p# D% s# L* Q
9 h* M4 w7 z8 b( v+ o. t' {2 w
turtles-own; Y% g% a7 h% X, Q. I7 r2 F& z7 @
[; |  Z" m" u7 r( v0 q% D7 X
  speed     ;; the speed of the turtle
# Z. ]& S. ^0 D: i  up-car?   ;; true if the turtle moves downwards and false if it moves to the right- m; m5 y& V* _* G/ Y6 ?
  wait-time ;; the amount of time since the last time a turtle has moved3 n" X- E- l3 x5 k0 `
], M- {5 v+ I6 h1 T' `. B. `( l

# ~3 J  n0 e% N. Spatches-own7 A) u4 s. D. X4 D2 O% O
[
1 f- {' G3 q6 y" p' w; e9 `( N% D  intersection?   ;; true if the patch is at the intersection of two roads+ ]* l4 ?& o) ^$ u4 S7 x* U
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.4 j( s5 j) ]0 T6 ~) J
                  ;; false for a non-intersection patches.
1 S" b" {" V* T3 S# U4 U- V) r  my-row          ;; the row of the intersection counting from the upper left corner of the% `/ M9 l1 {+ B/ }
                  ;; world.  -1 for non-intersection patches.
5 P( e- y. p3 H0 u; V1 A6 m  my-column       ;; the column of the intersection counting from the upper left corner of the
3 w3 ^  r/ z" z$ L5 v1 u                  ;; world.  -1 for non-intersection patches.
  q+ L$ ~  e* i% {2 J  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
+ I$ U4 D7 O, Z: T/ g  u  auto?           ;; whether or not this intersection will switch automatically.
! f' [% `# _) |. S. w4 J8 i. I$ i                  ;; false for non-intersection patches., y, D4 W) t( ?+ q  }
]
& W/ p  U$ N( U3 S5 v) U; V# u! p* `# C1 P' M

. ^6 N, B2 O1 @/ P7 N" B;;;;;;;;;;;;;;;;;;;;;;
% D# M% Z, v. h& c% c9 V) ]! `4 U;; Setup Procedures ;;7 K7 g7 \% y2 n" x% x
;;;;;;;;;;;;;;;;;;;;;;
- e( C: ?1 n, L( k9 [
7 y: u% K. c" [6 Y. h;; Initialize the display by giving the global and patch variables initial values.- G: l( s$ D3 k2 c( n4 F7 c; f! n) s4 R! g
;; Create num-cars of turtles if there are enough road patches for one turtle to+ }4 m8 C" M$ v# E+ G) ~; u. s
;; be created per road patch. Set up the plots.
9 h, P3 e. J9 }. }' y" s# Kto setup
! e1 b5 r. |! j5 Y  ca2 F9 O9 Y# \  y. F
  setup-globals
9 r% M4 ], S; J. w' p2 d; \9 Y, B" d1 e8 T) v4 o! W# q, w9 T
  ;; First we ask the patches to draw themselves and set up a few variables
. _; `. K3 W% H1 a1 T  setup-patches& {% [6 i/ t" ]% i
  make-current one-of intersections4 [1 X! v. n& T3 L7 t# x
  label-current
: B9 O2 L, X9 }% S& p
) Z* ?# V0 I8 v7 R  set-default-shape turtles "car"
+ P* Y( |6 Y7 c' ?4 V! `, f$ q6 x) O" m7 ~! l
  if (num-cars > count roads)9 Z& b; r5 w* j" `
  [$ M. M. F) U. {5 D$ G9 J; m/ I% }
    user-message (word "There are too many cars for the amount of "
( A+ d) n! @# k3 [                       "road.  Either increase the amount of roads "
* D$ E* n# E. \4 y+ g. |  U7 j                       "by increasing the GRID-SIZE-X or "
1 W: p' w9 h! ~- m- E8 j' j0 r  d                       "GRID-SIZE-Y sliders, or decrease the "7 M; `5 C/ K2 R- N/ F
                       "number of cars by lowering the NUMBER slider.\n"
' F( Q3 b5 m6 n# \7 u                       "The setup has stopped.")
* H0 Y4 r% ^, D, K    stop# N% h/ w; |6 u/ S9 |" a
  ]
! U5 i2 Y$ Q5 ~1 c8 r/ g6 c$ E: m
1 r3 f4 v  @1 v3 G  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
1 p0 W# f6 ?) v% ^- |: Y  crt num-cars
! ^2 T3 N. q: ]7 H  [
, C; M& [! j, K$ B" g" J% @5 l    setup-cars
" S2 l; X/ T- E9 J    set-car-color- i$ ], A7 r9 |; q# G) e
    record-data' A/ u) a7 H7 I9 E& }: @! e8 t" ]
  ]* N2 y0 K9 t1 k' T+ k5 K% l0 X
% t) Y8 k  G( D; ?) v! E1 J8 y
  ;; give the turtles an initial speed4 v$ m, X, m9 c, f
  ask turtles [ set-car-speed ]
* \- b8 B1 T- |6 F
/ N/ x/ t" h" s3 S/ F* Q7 L  reset-ticks
  F% a+ ^% {- U, f9 P" gend$ C2 X2 ]4 q2 l! C4 }' X0 Y

3 z* ^, T% U6 f+ g6 _( x;; Initialize the global variables to appropriate values
6 ~2 M) A+ N+ q1 L# B! r* P. Lto setup-globals
$ x! _2 ^) e6 k; e+ {7 u  set current-light nobody ;; just for now, since there are no lights yet6 ~5 K" g& c! {- i$ f' y9 g
  set phase 0
* n/ i% K6 k: i) d0 |  set num-cars-stopped 0) f0 P2 c/ ?3 F
  set grid-x-inc world-width / grid-size-x
2 k$ u) C$ x$ F3 m% H  set grid-y-inc world-height / grid-size-y# Z7 `7 h: m9 ~

) ^" D0 d! L$ L& d# a  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary1 N2 u+ @3 W+ C2 t% n& W
  set acceleration 0.0997 A4 H+ q. j: q0 ?4 ]& L
end+ R6 L  h& a) w
5 s9 ~7 T: a5 A1 A; c
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 H: k9 m* R6 O4 ]# V* C0 K, W;; and initialize the traffic lights to one setting% e6 b( r& S& y2 v1 N0 i4 s9 J
to setup-patches) L& x+ B# ]; l2 k2 G% T2 [
  ;; initialize the patch-owned variables and color the patches to a base-color2 E/ w+ O$ X5 l. D- q& L5 W$ [
  ask patches) m% f- ^5 E5 |
  [
) m* O* ?0 c, o0 a# B% p    set intersection? false
# K6 }) p( p2 h/ R0 I    set auto? false
; a6 X- g( K) z    set green-light-up? true
( M' G0 V6 W! @% r7 ^8 i    set my-row -17 m: C0 M3 b5 y) T) X' S0 v0 A* ^
    set my-column -1
- a7 [3 C! Q) J8 @    set my-phase -1
4 ?, v# B8 X0 \' G% }, J: V# [    set pcolor brown + 3
* H+ }+ O( o- S% Z  ]
  R  p+ r1 A5 F( _7 r
7 |: y1 u: ~( X8 @  V9 S/ H) @  ;; initialize the global variables that hold patch agentsets
# d  Y  L3 ?# ?. b. K7 U  set roads patches with
9 Y  s, z9 n6 ^* Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% o; ^$ M# L: B) C8 _3 K6 g5 J5 S
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( k( h# e* |, _2 j
  set intersections roads with" t7 d  X4 {/ O1 {( B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and3 ]$ M5 [. m9 R7 j2 k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! ~! o5 F  k8 }( U' E) X! L1 W7 z$ m

( l! E2 r- Q, u" p: c5 @  ask roads [ set pcolor white ]1 ?* e2 x" ^+ e+ j  k
    setup-intersections
* G% v1 `$ [: [  B/ Nend
) f% a2 [" ~6 p7 o) ~" t4 b其中定义道路的句子,如下所示,是什么意思啊?
  z. B7 T& `# `( x set roads patches with
+ a' A, `( p" w$ G, g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ A, w, \" v- F# W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ J4 Z3 Q' R( P8 B+ S; a- A: _
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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