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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。/ W8 u1 x& ]$ y. ~  {7 V! o
netlogo自带的social science--traffic grid这一例子当中,
; i/ }; L: m9 B+ c% fglobals9 T, a  y# c( V, |; T/ N4 t
[. d. k, z0 f8 B/ |! A9 f
  grid-x-inc               ;; the amount of patches in between two roads in the x direction/ M6 U3 J. {+ a/ e; x
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
. p& h: x5 p' _' _9 O) O5 s  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, n0 q' U. j" A; ~' O7 Y                           ;; it is to accelerate or decelerate2 ?2 G$ {% b1 X# @% c
  phase                    ;; keeps track of the phase
* B! Z1 Y" ~" m  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ y; G6 p4 m/ y/ `6 N- M5 ~$ n2 s
  current-light            ;; the currently selected light
$ T% i8 e( g+ e0 u8 l; I' [6 Q' \: G. T
  ;; patch agentsets
  v  y1 {: [, j$ }9 w  intersections ;; agentset containing the patches that are intersections
. C, h1 w3 R/ ^- `4 s  roads         ;; agentset containing the patches that are roads
9 ?/ M' b; n* t1 e! ^1 M9 @]
6 l! V6 x; {  z/ ^3 ]1 p4 r6 u3 z. z  |# n. u0 G4 _
turtles-own/ ]/ p+ v1 \: ?& `; k% G, I
[
# |1 t  ~. r3 K1 M$ h  speed     ;; the speed of the turtle
% d; Z% }. L, ~  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
5 }& `+ @' u% p5 x( y$ V( Q  wait-time ;; the amount of time since the last time a turtle has moved
1 T4 I0 o0 p; A6 @]. L  n" [3 D. G6 D  Q: Q9 `1 N7 {

: K# V/ R! p3 ?5 opatches-own
9 n/ W( A& A( v[
7 e1 I; T4 i9 T$ y  intersection?   ;; true if the patch is at the intersection of two roads
( ], B) Q8 C  f3 v& i  i' j  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.0 V# w  l" x# m+ Y
                  ;; false for a non-intersection patches.! x, \9 c# z8 R  K- E0 k
  my-row          ;; the row of the intersection counting from the upper left corner of the
7 c% n( {) e4 Z/ L                  ;; world.  -1 for non-intersection patches.  I( C( @* _6 l9 C1 e
  my-column       ;; the column of the intersection counting from the upper left corner of the
% R. R8 m- m3 n$ i5 s                  ;; world.  -1 for non-intersection patches.) ^9 o& R5 `) c' a
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
# }! ~, D( y) X& }& T$ Z" r  auto?           ;; whether or not this intersection will switch automatically.. b, K# r. _  E% f# A- p, B
                  ;; false for non-intersection patches.$ D+ j$ ^2 y3 {) x# ^
]
4 p4 e; z8 Z9 K' P+ R. e) f$ e8 x( x( z8 n5 N
- H8 u8 Y! M( X
;;;;;;;;;;;;;;;;;;;;;;( M% o: Y0 G+ V: H: ~  V
;; Setup Procedures ;;
& f- x( O, _+ j% p9 w! Q;;;;;;;;;;;;;;;;;;;;;;
8 X4 u/ J( w3 B$ ^7 e0 d
( X& j6 a( ~5 `/ M. f: E/ T;; Initialize the display by giving the global and patch variables initial values.
' {% E' W: h  i  s7 z;; Create num-cars of turtles if there are enough road patches for one turtle to
7 K+ d- b8 c' g$ a5 x( Z;; be created per road patch. Set up the plots.
6 a) z" ?, g4 ?# `) xto setup% |7 U( C" a8 q. r( g
  ca
6 v! g9 f, l+ b  d  setup-globals/ O/ k1 W! q; ?* T/ P
! X& N% n2 x/ @+ U! ]
  ;; First we ask the patches to draw themselves and set up a few variables5 M* R$ `! r4 J  d* O* r
  setup-patches  C' s$ J! z8 ^6 O6 x0 W/ L
  make-current one-of intersections, S( V7 w$ F! ?: ~
  label-current
1 J& b+ }: n8 `2 l/ Y4 j. V. c4 f
  set-default-shape turtles "car"
: Q5 A) s0 `' R# `4 a7 `
, \4 v; Y; j6 ~# |. ]# b* z  [) v  if (num-cars > count roads)
+ S2 i5 ~( Y" X; e# _$ C0 B  [; ?! a; k3 ^# T5 D
    user-message (word "There are too many cars for the amount of "! V- E  H! |( ~2 Q
                       "road.  Either increase the amount of roads "$ ?8 Y! z6 T  k
                       "by increasing the GRID-SIZE-X or "9 v9 f0 t5 y" G3 D5 U" B& K6 ?
                       "GRID-SIZE-Y sliders, or decrease the "
' T4 g; |) F7 Q8 H- r5 A( x8 l9 c6 r                       "number of cars by lowering the NUMBER slider.\n"$ i$ B1 j, {& J7 _& \$ I5 V" h( @, M
                       "The setup has stopped.")+ }, U, k5 J$ b8 y( J5 X* E
    stop! Y6 I9 N$ o4 t# s; c
  ]$ r& g6 G5 a. }0 x2 b3 k
, p+ V& \  o' o3 g
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color8 E6 O1 l4 |. N, L1 b# b
  crt num-cars5 y& \3 I/ R' u) b4 n7 y/ D
  [  p% C7 [) h4 [; V! a  _
    setup-cars2 e+ l: n4 \3 t) s" R* H" W
    set-car-color) l0 q( q' A% C% ]9 c) A, D4 Z: N
    record-data0 g- n+ I; R! d- n# a2 {* |! ~
  ]6 q0 t. n; p( m9 `& G1 q

7 ]( T+ c* Y6 [- Q. Q* q  ;; give the turtles an initial speed; W+ i4 T- K- P- z' s( M
  ask turtles [ set-car-speed ]& m; d1 U2 q( A- }

( p$ a1 m3 s8 ~7 B* X  reset-ticks
, V  y3 N5 W1 |6 @5 F9 Bend; x, P6 c' j4 C. I" l7 v. B
  |- K* k9 n: g# e, S
;; Initialize the global variables to appropriate values
( O0 @$ l5 W$ A/ }9 ]1 a9 dto setup-globals
) P9 \* h2 [$ n7 w  set current-light nobody ;; just for now, since there are no lights yet' J% ?6 f/ m1 C# p4 X
  set phase 0
  o( ^2 b. t- P- M  set num-cars-stopped 07 Q: \/ D- v1 w5 V% M5 @) p& f; O! B
  set grid-x-inc world-width / grid-size-x
2 d4 W8 d& Z) O' f, g; q  set grid-y-inc world-height / grid-size-y
, N' D( _2 w# ~) s# d; {. [0 e3 Z) d
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary. G) \9 [) ?+ m& H; R
  set acceleration 0.0995 h9 h/ c  X- ~4 \
end
, e8 j" d8 h) @4 U, W; [% w
/ j* R: [8 U; ~8 g;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
, t' l& K& o/ L! S0 ?0 ?# [9 L! ~;; and initialize the traffic lights to one setting, P  w# F, o% W- q4 Q3 B4 W
to setup-patches
- _0 f2 ^5 N3 `9 g2 s2 z  ;; initialize the patch-owned variables and color the patches to a base-color: }8 q2 {9 F( u: |8 j8 R: T8 Y
  ask patches6 b5 B) y6 R# ~8 f
  [
5 _' X2 j. _/ }0 H7 a1 k$ c0 R    set intersection? false
0 I% u7 P( {. d    set auto? false2 a; t2 a1 ^, m! p* ~2 M
    set green-light-up? true
/ m- w# X; {4 C    set my-row -1
% F) q- t5 A( |- L  E    set my-column -17 v) x3 Y! ^- _5 G
    set my-phase -1, |; L7 k  m# Y* j1 X  r! L6 ?
    set pcolor brown + 3
& T3 M- h5 r2 p2 V( R4 Z  ]
8 e( z* w& }1 x! J  a  w1 E/ h1 \6 s( F9 {6 G5 l( c
  ;; initialize the global variables that hold patch agentsets
: I% K. j1 L6 \' ?/ _. u! I% f4 E; {* n  set roads patches with0 Y9 _1 t& T( t" a: E* {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ u* H- _% n2 d7 V3 e3 Q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 C! e# G: S3 m! M8 S! A/ L  set intersections roads with5 x. w& y. x6 J# ]5 \2 p* |4 G  {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and9 f& S4 Z0 ]! T  z& @" m
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 _% j8 h- K3 r' D, _# x
* y; c4 T/ _1 G# x  ask roads [ set pcolor white ]6 T/ `1 j9 W4 d
    setup-intersections
6 d( n+ [7 P: ^) F+ H& qend$ I8 V; j* a. P7 s
其中定义道路的句子,如下所示,是什么意思啊?
" z  O# F6 F/ ~- B' k# y set roads patches with
1 Y9 M; N8 O: [# p8 \    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) w' S  M) m% d0 d) H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], V0 {4 I- R6 u/ k
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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