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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。
1 O* I6 L. p" p: c3 s. u$ w& u; ^netlogo自带的social science--traffic grid这一例子当中,
/ W/ a3 {0 ]) S( i) T$ J) l5 k2 B" U  cglobals1 u7 Y, U0 |* I) [
[8 O1 E/ }5 {& d' f7 F
  grid-x-inc               ;; the amount of patches in between two roads in the x direction/ w9 p) V% o1 b0 N" P
  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ B  ~0 O; I2 U4 X  J: A( K
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
/ s; Q$ E' z# w                           ;; it is to accelerate or decelerate
/ _, J4 ~/ T, R  phase                    ;; keeps track of the phase( ?9 d* \; a- @' P, d5 I
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ }) k1 E( O- K) h) @! g8 [3 @+ V  current-light            ;; the currently selected light
5 W' l) D- k, h5 w, _  U
/ y" h" ^  n' a0 h2 `! a  ;; patch agentsets
) B( }' T# q- p0 l  intersections ;; agentset containing the patches that are intersections
% Z2 B, u* Z( `: ?/ Z/ w$ \  roads         ;; agentset containing the patches that are roads& T+ u% _% U6 H0 Q
]! k$ c. L" r& _* T: d2 c

! r; r$ m2 Z9 E* I! e1 Y/ zturtles-own5 \9 Y9 N4 w9 i% @: C3 |& a
[/ O! J, G4 b/ o( T" D( B# M
  speed     ;; the speed of the turtle4 V) {- b$ N6 ?& Z
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
# r6 p, l; U4 V+ y  wait-time ;; the amount of time since the last time a turtle has moved
. n7 F0 |% J! L# {; D]
2 X* g, y& |, o1 G8 A3 Z  K/ @4 x; ]8 Z7 I% S
patches-own
/ k5 F' n3 O# R. e( g' T[6 o' X5 \' @8 S: J& {6 b! Z
  intersection?   ;; true if the patch is at the intersection of two roads
3 u' C: P7 q2 p. T0 ?  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
0 N; O/ T, O& E5 P; L2 [                  ;; false for a non-intersection patches.* h; R9 V- @9 f1 V5 }+ g- ]
  my-row          ;; the row of the intersection counting from the upper left corner of the
# t9 u3 R# w7 d( G                  ;; world.  -1 for non-intersection patches." ]* L: O- R& S6 x7 W# i
  my-column       ;; the column of the intersection counting from the upper left corner of the" s: I4 P' p( x- i/ k; D" [
                  ;; world.  -1 for non-intersection patches.
+ u2 l- D( e( N3 [  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.0 h$ Q! i( |: r  ?' ?
  auto?           ;; whether or not this intersection will switch automatically.$ f) x" L3 O/ w5 h. t% K" o
                  ;; false for non-intersection patches.
- }5 r( z& O7 H$ j5 r]* X# E( v4 z* h) w- O' x
% K" `1 X6 J: J
! e% x! q& x) f- V5 d6 F
;;;;;;;;;;;;;;;;;;;;;;! U- F/ [5 L2 ^7 O. f8 r
;; Setup Procedures ;;
- U' y  }- U, S' {" |) }; u( c, N9 _;;;;;;;;;;;;;;;;;;;;;;. _4 p8 T) N2 k* \( s

2 J( F" }- u7 ^" _;; Initialize the display by giving the global and patch variables initial values.' W5 W" L* ]2 g4 s8 L
;; Create num-cars of turtles if there are enough road patches for one turtle to
/ B. m3 Y! {) w4 @7 P6 g1 v. c# G, I;; be created per road patch. Set up the plots.
% s0 k& I' U5 A! M" o( gto setup5 g, h& [% @5 h1 V: \, @
  ca
6 q) j" _( T( t- |# c- s& o  setup-globals7 z( ?( P3 |+ a6 r  {: o  g
; B$ c- q& ~# }
  ;; First we ask the patches to draw themselves and set up a few variables
" e5 w" g% D/ [/ b  setup-patches! R7 w% C) N4 M+ J- {; q# C
  make-current one-of intersections
6 ^) Q9 r' D# X% U" Y) \  label-current4 i0 E8 b  _1 T# P* P/ d
  X6 g: k' w" {" k9 R9 x: @6 K
  set-default-shape turtles "car"
' X/ o) o* p) @" B" @$ a
0 b) H8 x  s' _/ u0 e1 m+ N  if (num-cars > count roads)9 m% I4 J: ~( y% i
  [
. U" Y. S2 \, X8 S9 x    user-message (word "There are too many cars for the amount of "4 r" Z" H; O6 B5 R
                       "road.  Either increase the amount of roads "
- d5 u. y1 O1 _  [( v' ^! Y1 V2 J8 G                       "by increasing the GRID-SIZE-X or ") k2 r8 ^! M9 o: Z% e& q* ^
                       "GRID-SIZE-Y sliders, or decrease the "# v+ |9 v+ a) E6 J' U3 `: A- s' E
                       "number of cars by lowering the NUMBER slider.\n"! A) n2 T; X2 \+ M/ P& C  y/ u% [
                       "The setup has stopped.")0 s+ @4 j; D% U7 Z
    stop, @( P+ v# L" y' e* i; p1 b
  ]) ~; k8 {" }: f  R+ J5 |# Y) u

& O. B8 a9 F( f1 [$ \5 \  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
0 C6 z( d8 E1 `! p& N2 w  crt num-cars. e% [0 V) Q4 e0 H# W! ~0 U- w
  [
+ o4 c0 I4 W. X- \& u    setup-cars7 K6 G2 D0 d2 Z5 B3 v
    set-car-color
6 I' z4 t; L0 Y5 f; U$ j6 m; d" X    record-data
. a- u0 T; f4 o1 X  ]* d4 m4 B" z) r# p2 [

" G/ K5 U' N. {- B3 J  ;; give the turtles an initial speed9 Z* [: ~1 d/ x( Y
  ask turtles [ set-car-speed ]2 L& B  ]" S/ o& v! T
" ?7 k8 e4 E# S: \5 E
  reset-ticks
* L. f# o% ~" z/ n" t# p! Xend
0 T; K" M- `: G) p/ U" ^  e& q; U+ y/ E; S* b; F, r; R: [" r
;; Initialize the global variables to appropriate values' p; f4 \8 ~  E3 x+ _$ v
to setup-globals8 z& s! J. }& k; i+ [* C/ w" \
  set current-light nobody ;; just for now, since there are no lights yet
  l( i. w/ g$ I: G  set phase 0
  c0 a4 W7 n5 }  set num-cars-stopped 0
7 ^* `4 Y- U  Z$ k& ?3 t  set grid-x-inc world-width / grid-size-x+ d! S* Z) t. f# N6 l
  set grid-y-inc world-height / grid-size-y
) v# X* }: {$ Q- i8 N7 S; E2 j
1 w6 Y  M4 ?! |  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
# a; X' [+ P, h* w+ g& H  set acceleration 0.099( r9 d' j% ?! g: n3 x
end7 I- i3 J) B4 [) ^/ n" i; x3 k

% L( e/ d5 {: A; b) z# c;; Make the patches have appropriate colors, set up the roads and intersections agentsets,& b1 K% x' \8 N5 M2 g5 B
;; and initialize the traffic lights to one setting) _# ?$ Q: Q) Q/ I
to setup-patches
# x/ w4 c, J7 P% r! U  t& Y  ;; initialize the patch-owned variables and color the patches to a base-color
" u$ Y$ {7 \+ s5 ^  ask patches8 _( r" y- f; K! {. E/ |+ V
  [
7 [% D: G2 {% \7 o    set intersection? false
. v; h% u6 G, D, \( p# A    set auto? false
* J/ Y+ c. C" |4 C5 r    set green-light-up? true7 s1 E# w9 M) U" d7 Q; y2 o7 }1 r
    set my-row -1
# t# u4 t7 p) e( F& r0 w+ F    set my-column -1
( D: l; w1 [: m5 \1 H' t    set my-phase -10 J3 @& f* d2 J/ w* ^
    set pcolor brown + 3( `7 q5 o  u/ B* [; D
  ]
: @. T7 [3 N& b) p/ ?, v
2 }( x  U% r- i+ Y  ;; initialize the global variables that hold patch agentsets
! U) g# u  [6 Y" U7 R5 X9 U  set roads patches with
1 M6 u% n) k( R( `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; w$ q( j8 r. s3 c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" m% v2 i  Y( `8 ~9 G6 V  set intersections roads with
' S6 k6 m3 U0 C4 m( t. l. Z& k9 N    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and  Y$ U8 Z0 P7 T3 n- s- l9 O+ `; s+ {# X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 k; B) n) U, O- h& ^) }) ]" S
# i4 R( a6 Y1 F' k$ V: T  ask roads [ set pcolor white ]: w7 I7 n8 `5 s
    setup-intersections/ R) U- _! G7 c$ Z9 }) Y
end( B3 z5 c: S! G
其中定义道路的句子,如下所示,是什么意思啊?
9 H& V' i' `, S( i1 p+ U; C set roads patches with: Z+ U* G3 ?. h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 X. Z" ]. l& `/ r5 g3 `6 }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- x2 M+ O0 h$ b# w
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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