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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 l! `) z" Z) \  R1 q8 u3 znetlogo自带的social science--traffic grid这一例子当中,
- R5 s, f5 G. kglobals
7 A* r& _) E, y% S0 v  y' w[3 k/ ^7 V5 ~$ h' U& G: h2 Q
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
4 g+ l4 C* s# u. r( I  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, }; G& \+ T; Q: B( x' C( `  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, M* `2 z, q; X& k                           ;; it is to accelerate or decelerate( }" k& q% `: L7 m% @
  phase                    ;; keeps track of the phase
' ]5 A6 v5 M( r& J  I+ \  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure+ _( z# c( r0 _/ I+ D* S% z, e# o
  current-light            ;; the currently selected light0 S$ Q  S" D0 d  }

1 l+ c, o* n9 T0 w+ s# |  ;; patch agentsets# Z: o" o* W9 D/ R1 S1 ^# r% A# x
  intersections ;; agentset containing the patches that are intersections' D6 q1 m- a5 n6 n3 X- h
  roads         ;; agentset containing the patches that are roads
5 d1 E8 u$ y5 q1 l) A]
8 {- Q* F, m9 `1 i/ T
0 k2 I! D* a* v8 F* w9 |turtles-own" V- e. x% }& B8 w: G2 G; Q
[$ n5 e* A) p* j
  speed     ;; the speed of the turtle
5 \3 f; T; Y, x3 J8 c" @  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 S/ @) P: U5 M5 m
  wait-time ;; the amount of time since the last time a turtle has moved2 ^8 ]. ?2 w' {- ?
]
. L( H" E" k$ ~2 b- T# O
( p2 \& Y1 v! [1 Vpatches-own3 k5 }* {$ V4 Y7 V6 {2 H- o" ]1 x
[3 w3 U# u6 ^- J# n! V! ?% ^
  intersection?   ;; true if the patch is at the intersection of two roads" ^+ F$ t5 Y: n9 _3 L& p
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.. U% P# W3 E# |- w6 I& t
                  ;; false for a non-intersection patches.
2 Z( T3 g* t0 E% W; E( w  my-row          ;; the row of the intersection counting from the upper left corner of the* H! f0 c" A9 C/ ?% `5 W6 b
                  ;; world.  -1 for non-intersection patches.1 O7 G, c( D, u' W
  my-column       ;; the column of the intersection counting from the upper left corner of the3 d- B4 v; c0 ^: W0 }9 r' L
                  ;; world.  -1 for non-intersection patches.
3 o) f& M# N' @; h& j4 @' D  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
: l& e+ C/ h! t' T" D  auto?           ;; whether or not this intersection will switch automatically.
9 D( s% ^& A' X, j% Q2 E7 d                  ;; false for non-intersection patches.! p1 y) z3 i( W: r
]
5 |5 S' U2 j, [; F: y
3 Q( }! f- z5 c: T" d6 R/ j! |6 A( H1 }
;;;;;;;;;;;;;;;;;;;;;;
3 l4 R3 R2 u: y+ k/ o. A;; Setup Procedures ;;5 V& h2 R! O. s: j2 D- f. g
;;;;;;;;;;;;;;;;;;;;;;
) N' ]9 p+ l) n) l
* @" N4 u; g7 h0 V& l6 j! h2 ~/ C;; Initialize the display by giving the global and patch variables initial values.
4 c7 s4 F9 W; x1 J: b- g;; Create num-cars of turtles if there are enough road patches for one turtle to9 {3 m6 H2 P/ o) Z$ `
;; be created per road patch. Set up the plots.4 v. G7 H0 F8 N  C
to setup3 [; j$ c$ i4 c8 _/ E
  ca
: a9 v6 I  C1 f& N  setup-globals; n  e/ L# f. S) x* n

& F% }/ p& S- v9 v2 ^6 B+ }0 S  ;; First we ask the patches to draw themselves and set up a few variables
7 I. L1 {% Y; p  setup-patches4 @$ h, y6 R4 R% B; ?3 R
  make-current one-of intersections
( Y( `5 f& [5 {3 `9 b- s& V# u  label-current/ W: {) Y" m6 v# W' ~
- F, v# e$ Z( K  N* y/ r6 V4 m* c) t
  set-default-shape turtles "car"- Y  ~: o1 I% Y# S: U5 x9 o: b; e
, J1 k% o3 z: H# g9 k
  if (num-cars > count roads)' T# D. `" g- |+ f
  [; @( J7 E9 Z/ d# X( V
    user-message (word "There are too many cars for the amount of "5 h' q. E4 w0 Y8 A
                       "road.  Either increase the amount of roads "* b) j! w0 ]3 Z2 f
                       "by increasing the GRID-SIZE-X or "4 z: c9 L: L8 M
                       "GRID-SIZE-Y sliders, or decrease the "! u# P2 M7 ?4 U: _8 m
                       "number of cars by lowering the NUMBER slider.\n"2 o% J7 _! }& j
                       "The setup has stopped.")8 z. I1 Y/ l4 `" y1 k: v8 W7 l# \
    stop, j" L5 W- L8 Y9 {( y- A
  ]
& n$ @- G9 h9 M( F- G7 j# b/ z+ |; o* Z
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color& B, S$ n( |% [+ }8 f1 j
  crt num-cars
7 X, T% b; W" [8 ]: j0 v$ W  [
6 N. Y+ G% `7 q    setup-cars( E6 M2 C( }4 o. L" y
    set-car-color" T. r% S  Q) n" O1 i3 C( d
    record-data
% v+ C; k4 K& i- U  ]% h! C; A  B1 e
6 R" w% q2 r+ Z  F" G+ C, S
  ;; give the turtles an initial speed3 R* E2 G7 f' _/ O4 G
  ask turtles [ set-car-speed ]
( U) u/ J  c4 E9 t1 g
# a# N+ T' y, r2 K/ [: Z  reset-ticks. V# z1 M/ J3 R6 w. U1 [
end  L) X- N* S; j- p% b9 c2 `
# O; ^2 n  j" a4 U
;; Initialize the global variables to appropriate values
& Q8 V0 w" M9 W. T4 M" {. r, dto setup-globals/ `9 a( [  ?# q9 X; s, D$ h0 i/ x5 u
  set current-light nobody ;; just for now, since there are no lights yet5 t! ?  V# m. l2 g$ h
  set phase 0
  v/ T$ X3 J" w7 t6 g7 ~( j  set num-cars-stopped 0
$ N) ?. B/ u, d& O8 c2 i  set grid-x-inc world-width / grid-size-x  F- A9 h( M( |
  set grid-y-inc world-height / grid-size-y! O+ Q- S( @  [2 p9 y, `% ?
5 d1 x- z) p# y# Y/ S+ H
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% ~; o' ^+ a9 E' x0 Y  set acceleration 0.099
4 L7 _: h1 |. i2 Z5 `- wend
% _. q" x+ ]/ W% g6 _0 V. `8 @& L/ z: A$ ?
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,. b/ D0 X1 E' i/ U" {5 G+ Q
;; and initialize the traffic lights to one setting" {0 P- [( r# n, Y) S
to setup-patches- V4 |6 V# c1 Q
  ;; initialize the patch-owned variables and color the patches to a base-color" {' p; q' \" m( H& `
  ask patches
; ?! s6 o/ _0 q  `: @4 {  [
8 ~+ z0 d! ~7 M: E* k, K6 l    set intersection? false
3 N  `+ N' f2 H+ Z" c2 s, V! ?    set auto? false$ j! r2 a2 C$ }" x% i
    set green-light-up? true+ J3 H4 s! M( Z% U+ g7 t+ A% E
    set my-row -16 w! }( l9 N; c& P0 e4 m: O9 m
    set my-column -1$ c9 Y8 p6 o3 ^% X! C
    set my-phase -1
9 R8 i" O3 C. C+ \6 g    set pcolor brown + 3
/ @, U, j  K0 i8 m  ]
) D; V( o6 C" f; \) G8 e( Z* P) q1 {+ V/ M/ Q
  ;; initialize the global variables that hold patch agentsets& l2 B8 @* }6 G; n8 A+ j2 n
  set roads patches with+ r7 l- S& |$ }! @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' `& I: ~3 ?0 r$ S% t4 p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- D4 i1 w5 P& B, t
  set intersections roads with
2 O0 [; e, o% M4 f1 S7 v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" E6 M  L2 c* Y& a8 T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 ]2 m5 _0 B7 v8 P5 ?* n* R4 A0 Z$ S3 p$ s& O8 |
  ask roads [ set pcolor white ]9 O7 `9 V* M$ n* W0 T
    setup-intersections
5 M' B* s, E! L6 g0 Nend
+ c" o' M/ c1 f. H: C) J& L其中定义道路的句子,如下所示,是什么意思啊?
# R* l3 F* s2 L2 ?; G set roads patches with
0 g; k) W" \$ C0 ~9 R# u, e    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 w4 L2 Q1 h- O$ |" H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; S, s8 i/ k) n  r  r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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