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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。
9 B9 M# ?$ g1 d2 y$ ^. lnetlogo自带的social science--traffic grid这一例子当中,
& Y: b- h- d* E, d6 n% B4 iglobals
# o7 |1 Y, ~3 @: a: C! O" x  O[% R, j) ]# w/ J, Z0 F
  grid-x-inc               ;; the amount of patches in between two roads in the x direction8 N! [9 y7 ~2 ~& Q. H' |  X$ V
  grid-y-inc               ;; the amount of patches in between two roads in the y direction4 N4 M& c" [3 _; [: Q0 A
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, {3 m1 V# L! u3 Y$ p- C                           ;; it is to accelerate or decelerate
( I$ N! V# I2 R& E  phase                    ;; keeps track of the phase) b6 @4 k1 {9 @, b. _; l8 g
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
6 ^% h  h+ X$ k+ g; ^& A  current-light            ;; the currently selected light
/ ~1 Q  `+ d3 Z' Z8 S5 d* j! h- O; t4 t4 P4 L2 A. l
  ;; patch agentsets
4 D- E1 |: D( r7 |! J. v  intersections ;; agentset containing the patches that are intersections
" ?0 t$ S& w/ e  roads         ;; agentset containing the patches that are roads
; C. b" }2 ^5 l4 }& M]! y+ C5 f3 |' g( o. M' |

$ u9 ~- y" ^  E0 }turtles-own# M+ i) A& @4 }" N& g+ z
[
; D4 d: ]. o/ J1 g2 B1 L4 R, N3 R  speed     ;; the speed of the turtle
6 q  F- ^1 C2 U" S2 Q. N1 q  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& d) p' \9 H$ T$ D8 d7 p
  wait-time ;; the amount of time since the last time a turtle has moved$ k% h  x+ x5 r3 n4 |  p6 Y
]
# C) Q2 T9 K1 }7 I0 ^
3 y, ^! Q9 P0 T  Ppatches-own* X7 }9 h- L0 N2 m
[# x. u% B  c0 {6 N0 s) z
  intersection?   ;; true if the patch is at the intersection of two roads, z% s' Y% s8 G3 J: _1 q) N8 S1 A
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.9 _& @; P/ p( p& Y- h' R
                  ;; false for a non-intersection patches.4 D( _% S! D! ^$ J( M2 B
  my-row          ;; the row of the intersection counting from the upper left corner of the1 f( f# V+ \; e4 U# w* `4 H
                  ;; world.  -1 for non-intersection patches." ^, F/ `' w/ X" J( b/ T
  my-column       ;; the column of the intersection counting from the upper left corner of the/ k9 A( Q% W+ i( x3 T
                  ;; world.  -1 for non-intersection patches.
% ~+ T2 e# b- X* n' @+ C  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
# z/ X; _  Y8 E7 n  auto?           ;; whether or not this intersection will switch automatically.
" U0 i" h$ j# h" q$ q* l                  ;; false for non-intersection patches.
* |( v/ C* ?/ E- j/ s) I7 _7 r1 u* ^]
1 O9 p% D$ l; c+ j, H$ D; w) S0 j) ~1 `, J, S
% c1 H$ ]) c* p# w
;;;;;;;;;;;;;;;;;;;;;;8 A) f1 {+ R3 }. U/ q$ o+ R
;; Setup Procedures ;;
5 k' h+ z1 U4 |% S# @* ~( U;;;;;;;;;;;;;;;;;;;;;;+ @+ G+ |0 ~) p
) c- r( a' _$ F9 w, C
;; Initialize the display by giving the global and patch variables initial values.
3 O3 C& m% ?& Q  x# v. k) P% e;; Create num-cars of turtles if there are enough road patches for one turtle to6 B; D7 B1 Y+ ^) o) O) A
;; be created per road patch. Set up the plots.
. N. r0 k& n! e% G9 F, ]to setup: T0 U1 R. d5 B5 W' O% z% G
  ca
' g/ D- b: s2 _. I2 l0 d  setup-globals
7 p8 M" [8 F# |- g7 d3 m; v% E' k1 i) q  _! Z
  ;; First we ask the patches to draw themselves and set up a few variables* ~" Z% q/ Y" M- ]
  setup-patches
" j( B3 L3 \! F( z# c2 U  make-current one-of intersections
4 C4 d& h! A+ Z0 _9 ^! x  e! n  label-current8 v0 S1 h+ j$ N' _, V

* I5 V+ f1 F7 ?  set-default-shape turtles "car"1 W3 d; T1 g! \( _) a/ Z# e1 d/ g

! u8 G* A# ^$ f2 i  P  if (num-cars > count roads)+ w! d: Z4 W/ A# P% p
  [' Y, f0 o0 F$ q2 g) D/ O! }
    user-message (word "There are too many cars for the amount of "
- r  n: I$ Z3 l5 N' H. \% F                       "road.  Either increase the amount of roads "
. G; j& l; y9 e                       "by increasing the GRID-SIZE-X or "
3 A7 r4 I: L: w                       "GRID-SIZE-Y sliders, or decrease the "
7 L. C& w* W% w/ X                       "number of cars by lowering the NUMBER slider.\n"9 Y5 g8 e! A; W7 k
                       "The setup has stopped.")
3 X) ~. W( g) `, |, M& C4 x    stop
5 q# }' E' i, J  ]# t  K  q  z. f

" |8 L/ r! R" h* @/ t  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
4 Z; g; R4 V* O' D+ a+ L5 B+ @) }  crt num-cars
! F9 {4 U2 ]5 u; A0 o  [8 b9 l$ M0 m' A$ M* M$ ?- e
    setup-cars
5 _2 k$ [, V2 z8 n    set-car-color4 F+ e1 W) ?0 H9 b' S
    record-data- P# _. E$ B. B( [4 [( }* d2 l7 u
  ]
9 r- _/ U4 g+ k& l8 I& B( H
  Z: m8 \' ], u/ L+ ]+ D- r3 e  ;; give the turtles an initial speed2 w/ Z3 ~% x, g$ U0 p1 m/ D, _
  ask turtles [ set-car-speed ]' R; M' e( e, H" N) I. ]6 M% W% b
# g, G0 G' i3 e' @7 M' j
  reset-ticks
" k$ w, l3 L: u$ I) V/ pend
: Q( ?4 d" d2 `0 i3 E8 ^( P3 c+ S" p3 `* M
;; Initialize the global variables to appropriate values( a) _7 Z3 ?  E) [
to setup-globals
4 ~# f- R$ A+ r  set current-light nobody ;; just for now, since there are no lights yet2 v: k! }  W. X" ]' F, T
  set phase 0) z) S/ r' i4 n9 J( w. M; P- @/ Y
  set num-cars-stopped 0
& c8 Z0 X# e; y  set grid-x-inc world-width / grid-size-x
+ e3 q9 j1 }- @) ^* t0 Z- U  set grid-y-inc world-height / grid-size-y
" U  G& G& t& `8 `8 Y
& q5 J! g' ~, X0 Z2 Y0 ]2 U  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary8 o# G( A0 w: D# T
  set acceleration 0.099
  l/ {' ^- U1 s" rend
; q- ?. Q, }7 ]* W2 `5 g
1 c& I) E" Q8 d;; Make the patches have appropriate colors, set up the roads and intersections agentsets,- Z3 R4 w! g7 D' j7 y9 P
;; and initialize the traffic lights to one setting
" W3 w# j) T8 g  Q# W& R. bto setup-patches
/ j2 Z" \# p- v  ;; initialize the patch-owned variables and color the patches to a base-color
+ Z/ p: Z8 Y$ ]0 l' Z  a  ask patches9 @* X( Z' C& i! \0 j6 h) ^/ }
  [$ p- x$ [: G; M$ K
    set intersection? false
( A& ^7 A& |7 i    set auto? false
( K" B' `) H  B' @5 D8 C# `    set green-light-up? true
, \% }5 F  l8 _8 W    set my-row -1' i) o: T, K& j* U
    set my-column -1: A; o( d  v- Q, s
    set my-phase -1
7 a# O! S" D1 e3 @: h' x5 X    set pcolor brown + 3* e/ A7 k1 A7 ]8 w2 x" V) g5 P
  ]
9 b* X1 |6 \( R+ o6 J' |3 b6 D* t8 E7 J! y) G
  ;; initialize the global variables that hold patch agentsets
4 J8 s! w( O3 k4 @5 M' D* S  set roads patches with
; V# E: x2 c, [    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) Q* y5 Y8 X( u. R# |. d
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& _5 t6 X6 B: \; D+ \
  set intersections roads with
4 ~  m: {% T: J, z" q' y1 \" y- Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 I' W; t9 r4 K6 t2 ]1 `3 X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& k9 F9 s3 J1 X2 V

4 @8 P1 t8 v! Y- ^) Y" f  ask roads [ set pcolor white ]) k, T0 F6 p/ T" x
    setup-intersections, b8 I, e; Y) P/ J1 {6 Z. {2 T4 Y( p
end% @$ I& a& w5 g: E" e' [3 y3 b; m
其中定义道路的句子,如下所示,是什么意思啊?% u2 t" h2 t& }8 F0 U, l
set roads patches with
$ `# J; S! x; v4 L- e2 V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' D* r' Z2 e* k  z  s. F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' `  o9 g- r( A6 m) ^
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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