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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。/ _. P$ i2 B5 W3 z( w
netlogo自带的social science--traffic grid这一例子当中,! I+ V4 U$ t( l
globals% p9 o! Y* X/ _8 F8 `
[
6 X' l- @. c. i8 \- C& S  grid-x-inc               ;; the amount of patches in between two roads in the x direction
' Q, q# b- X1 c6 v" z/ }  grid-y-inc               ;; the amount of patches in between two roads in the y direction8 m3 m; F. j- p/ W* V
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if( t# @6 S* W# u) q. P6 R( S
                           ;; it is to accelerate or decelerate
, V( b9 Y' @* z" s6 ~  phase                    ;; keeps track of the phase( I; G: V# F- p! t; D3 s: W
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
# ]4 T- B$ i, k2 g0 m7 {  current-light            ;; the currently selected light' [; f; }% i. `" a
0 D* c- z' c- q8 N% }5 }5 C
  ;; patch agentsets
7 D3 C$ }! p6 c/ l/ K  intersections ;; agentset containing the patches that are intersections/ t4 V8 s6 a) n6 v' u" q
  roads         ;; agentset containing the patches that are roads& m1 k! |# G5 S! Q0 h& I; |
]5 B9 v) V1 v4 z1 a! E; O* p

: R) r& i5 C3 J5 wturtles-own6 J5 T: I, c) Z. M  K
[, M: `- \1 N, f0 V- h
  speed     ;; the speed of the turtle
# @4 Z! u' ~  x( h2 f  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
% c; }; V# k2 o  r3 h  wait-time ;; the amount of time since the last time a turtle has moved6 Z3 N( u# _9 v
]
0 ?2 Z( U* S8 X
/ ]: ?5 h& @1 `! G; @% _! xpatches-own
- ^" M0 y$ X, s  B[
& u% L1 U: Z$ n( }( l  intersection?   ;; true if the patch is at the intersection of two roads+ Y6 S4 B, G! C/ }3 P' v, V+ D
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
0 I* C( _4 ]# ~0 p8 ~& T! ?$ p% N                  ;; false for a non-intersection patches.
; g* d3 G) {2 }9 H4 B# W  my-row          ;; the row of the intersection counting from the upper left corner of the
6 J2 `$ ?  }( T4 s6 t                  ;; world.  -1 for non-intersection patches.
7 Q) T( ?* S6 d/ ^& |+ |( W7 B" L  my-column       ;; the column of the intersection counting from the upper left corner of the5 @' B% h0 i& @0 @' v- d
                  ;; world.  -1 for non-intersection patches.6 K# z, h; F# \! v; Y5 K
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
, i- ^$ O$ g" E  q9 N( u4 P  auto?           ;; whether or not this intersection will switch automatically.* L( Z" C7 ~' a' N) D: c
                  ;; false for non-intersection patches.+ H0 E* W0 u2 R4 C
]
5 K8 H. S; B* i$ S( K5 m/ v7 r* z. j* m2 {0 g6 P

: J* s5 F9 Y/ S7 A0 s;;;;;;;;;;;;;;;;;;;;;;/ G8 m& m8 L" G0 M9 e
;; Setup Procedures ;;
9 a+ m5 S' b" a$ d;;;;;;;;;;;;;;;;;;;;;;
, w5 ~) C. q9 ]2 c
! P5 y  p. P( W2 F- V1 ];; Initialize the display by giving the global and patch variables initial values.
. `! [  G+ t4 u9 n;; Create num-cars of turtles if there are enough road patches for one turtle to8 N1 U0 ?1 F( J; y2 x* C1 a
;; be created per road patch. Set up the plots.
3 R; s: }, i, L! `to setup
3 J5 E4 v! }7 L, h/ [% Z2 A  ca
' P4 S& M2 o6 r* J! f6 u  setup-globals: |. x6 M+ G  R; y# g+ l. E+ @

5 J# C6 s$ M1 M3 g  ;; First we ask the patches to draw themselves and set up a few variables" C# [3 T7 g; w7 ]) a
  setup-patches
& ~# m" h1 h( {6 S* o: R  make-current one-of intersections6 e# e6 i8 j. ^3 \6 {
  label-current- R0 L5 {0 Y/ I, x! X/ S; W
5 \: K1 e- B; R
  set-default-shape turtles "car"
8 B* d/ q* w0 C% g  X% b# y# s! b' |; b3 z$ w
  if (num-cars > count roads)! z: P( C: }$ Y! I$ v
  [! s+ U* {# I2 z: s- [
    user-message (word "There are too many cars for the amount of "
* `+ \/ Y8 \8 V% b$ V) N* @                       "road.  Either increase the amount of roads "
# S, i# P) S0 I9 _( R2 h& _3 r                       "by increasing the GRID-SIZE-X or "
& ?0 i) _* G! h+ N2 D3 A% L                       "GRID-SIZE-Y sliders, or decrease the ". n# ~6 A! ~! I
                       "number of cars by lowering the NUMBER slider.\n"+ p9 p' ?, ^2 h6 K* y
                       "The setup has stopped.")
- C( D: O5 D& Q$ v$ i; O5 e    stop
1 @" \. L. M  `  ]9 D1 R' R4 [" I; p* ?% q

7 W: H5 f" n9 Q- C  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color, n" E3 P; A5 w% k  G; F
  crt num-cars
# Y5 g$ j* L. P& H  _0 m  [9 o  p6 u; U: o2 k; [
    setup-cars
+ r4 J2 J. j9 [# F, q# [    set-car-color+ j' _" B& \' ]( d0 S$ h
    record-data
3 B  b6 U6 p( }2 ]  ]( x+ K* {: ?7 {+ \

: j! S4 D' T( R" P  ;; give the turtles an initial speed# h2 D( V9 |* p( J+ p# }0 O2 r
  ask turtles [ set-car-speed ]
/ K4 `$ i3 H( v  L8 {' `# D: e7 u" \! {5 Z$ K" h( @6 _
  reset-ticks- u' m( d1 H' Z* B, ]3 X$ O
end4 ?. n2 m9 w; N/ g. d
) a; }: h2 u1 q
;; Initialize the global variables to appropriate values* E( Q7 F; @* g* T7 q# F
to setup-globals
# e8 j8 {; S( @( o; f3 S  set current-light nobody ;; just for now, since there are no lights yet
8 h2 F# X: T# `2 t3 ?1 G- W  set phase 0- V9 s2 G, }$ h( X
  set num-cars-stopped 0
2 W/ B, I- L, B! s  set grid-x-inc world-width / grid-size-x
' d; k! Y1 n% o* m& ^  set grid-y-inc world-height / grid-size-y
$ V8 j$ l) |" ?- A. L- C& d1 N8 O. F8 V
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary4 |; F0 V: n" h1 ^0 r
  set acceleration 0.099. o. A7 R9 ~! J  v
end
2 F# }, c2 ], f4 ~
2 i) `2 O6 m  P4 \;; Make the patches have appropriate colors, set up the roads and intersections agentsets,- Y' s. M7 w: d+ l7 O' X0 u9 ^
;; and initialize the traffic lights to one setting+ V8 l7 B2 T3 S  r  c# r
to setup-patches- e2 ~" d3 k  G
  ;; initialize the patch-owned variables and color the patches to a base-color1 \, @, O2 R' a4 \# _" H
  ask patches8 D+ M& D/ Y& y  p3 z, s1 E
  [
9 E; x/ J5 K+ h1 Q3 j! r3 y    set intersection? false
, U% \# C- Z& f2 h* {    set auto? false
5 n6 k5 q( L% U) N" p. n    set green-light-up? true' i8 S- h( L! }' H8 V& L
    set my-row -1
3 w$ b; U: R1 @; y: K" O  E/ Q    set my-column -1
+ V- y$ Y4 E/ I0 Y* P2 k" y" V    set my-phase -1% e9 f1 j" O9 J6 B$ d8 W' A* V
    set pcolor brown + 3$ G) Y7 N3 a. ^
  ]/ F/ J8 A, x# p4 h; h4 S$ d8 Z
- u+ q; w' B1 P$ n3 N  ^2 D9 f( y  D8 k, |
  ;; initialize the global variables that hold patch agentsets& o0 t" h4 x7 U0 @) H. Y+ q
  set roads patches with
7 L  Y$ }: k7 u7 j$ d; [    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# T% g1 w& }" d$ d
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% j( T, L0 `, h
  set intersections roads with9 E1 {1 _9 @! D* P" N; W/ T7 _$ D
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
8 ?6 V1 p7 d5 I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 C+ H$ I, a: \- N) \
2 L8 v. P+ N/ y  ask roads [ set pcolor white ]
* H! J2 @" K/ q" ]    setup-intersections/ x% C6 f  g# o# B% U* ^
end
  E' Q' u! p/ _其中定义道路的句子,如下所示,是什么意思啊?
' v; D, l# ~0 U5 | set roads patches with
1 p2 ^4 |( z( p8 i9 J* F4 }# a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 @$ ]6 l- r; u& q1 v/ m' f- O+ f) g
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  z' ~3 b& D9 j% i8 y
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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