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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。
; j* m/ G1 i5 L8 }netlogo自带的social science--traffic grid这一例子当中,
2 {; g9 e/ D6 n2 oglobals
' V3 T; W" ^1 g& a3 h[
) Y! @" A+ x4 X+ I3 D  grid-x-inc               ;; the amount of patches in between two roads in the x direction
9 j6 W, h3 n& Q9 k  grid-y-inc               ;; the amount of patches in between two roads in the y direction
9 R) \9 i/ M* L+ u2 q4 x8 q9 I  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
9 \7 e2 f6 L  U; r. m                           ;; it is to accelerate or decelerate
! j" W3 [& z# o; a  phase                    ;; keeps track of the phase
+ t1 u" h; k, |7 |4 n! U/ t. L  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure) G4 r/ ~! C3 j
  current-light            ;; the currently selected light
# G! L9 |' z  ~% A
& L3 {# Q8 I# Y6 ~( d. A3 \  ;; patch agentsets
4 |8 u* p! \$ d; m; x- k  intersections ;; agentset containing the patches that are intersections
' P, O( u" k# q0 I  X& s, |6 v  roads         ;; agentset containing the patches that are roads
( p1 t* ]$ b6 |& F% _( r]9 V  Z. q/ ?0 j0 K6 L

" a- f- p5 t5 l8 ^: R1 q$ ?2 Iturtles-own9 E- h: ]: H8 g
[
6 d$ b; Q+ P3 @8 i  speed     ;; the speed of the turtle
7 k9 G! y- E. a! p2 o& a) H  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& j# u$ @6 }' V; L, h
  wait-time ;; the amount of time since the last time a turtle has moved6 s) r: y! N8 D* l7 u
]
% g* x* n) s1 ?' x  f: J% A( C7 S$ i" @
patches-own
; f7 x( `- U$ B( F- J5 G$ M5 ~[
+ s* ?- n9 Y! q. C  intersection?   ;; true if the patch is at the intersection of two roads
5 v& x0 f/ E8 d+ T3 s. e5 y, W0 O  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% i  _4 j- M# _$ Y                  ;; false for a non-intersection patches.
# S4 I" i. Q# I& _' }. @; M' y5 O  my-row          ;; the row of the intersection counting from the upper left corner of the
* |8 Q0 j3 v5 S! Q6 r6 S- S4 E2 E7 m                  ;; world.  -1 for non-intersection patches.
% w7 f7 x3 F0 h" s( a6 @  my-column       ;; the column of the intersection counting from the upper left corner of the
& t8 T/ Z/ z% y( O7 m$ `                  ;; world.  -1 for non-intersection patches.
- {1 D7 ~6 Q3 U& V  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
6 H  o3 P: z  e: N$ O, x7 Z  auto?           ;; whether or not this intersection will switch automatically.
. Y( s, b- S! k& F7 `! y  ?  J                  ;; false for non-intersection patches.* L4 N- }7 L* B( }0 n* _& K5 l
]
: D; d. {: t3 b# v9 r( v3 s2 |2 K% Z( T
. C4 ^* j" c( Z2 t1 u" m/ k
;;;;;;;;;;;;;;;;;;;;;;) k9 W3 L. H! O  M! b* G+ Y
;; Setup Procedures ;;0 z3 J8 m; l3 ?$ A
;;;;;;;;;;;;;;;;;;;;;;4 o$ ?4 X& z* O6 i5 h/ G
/ N6 T: G; V$ E8 M. E5 \
;; Initialize the display by giving the global and patch variables initial values.
% x7 {2 i! k- h1 `8 d2 Y;; Create num-cars of turtles if there are enough road patches for one turtle to
$ u; R7 @) n' F% q;; be created per road patch. Set up the plots.
+ q7 n- B/ F2 T+ a/ |to setup. q$ q' o, `7 k4 q: h. S+ @
  ca  o1 L. _% D2 S$ O* L7 H9 R
  setup-globals
# C1 ]$ `! \/ U& @7 Y, Z4 G& k7 s) N( N- V7 g
  ;; First we ask the patches to draw themselves and set up a few variables
: Z# G7 Y5 Y1 g  setup-patches
" Y  n: q4 c0 f  make-current one-of intersections3 ?/ u4 i( w/ m& P& }) C8 c- B
  label-current6 c. s" w" O- c. c" S

& o. }  d  I& c" f5 w  set-default-shape turtles "car"
" ?! @9 |0 f4 a
4 |# T. I( ]7 D% o5 ?  if (num-cars > count roads): A% t, w0 O" P+ b, }
  [
, g7 t; C- ]# l8 {    user-message (word "There are too many cars for the amount of "
7 E" R! [4 Z: ?4 \, o0 U) J( M                       "road.  Either increase the amount of roads "
7 k( `) f' s) U                       "by increasing the GRID-SIZE-X or "
8 }: @! K9 n" b8 N                       "GRID-SIZE-Y sliders, or decrease the "
' h4 K; J$ O+ F* u1 x5 ^                       "number of cars by lowering the NUMBER slider.\n"  ]4 E4 d* k3 ^
                       "The setup has stopped.")
3 g" Y3 A8 |$ K# L" W    stop' H5 n/ _. ?7 I- c2 ~4 ~. Q
  ]" i+ s  T+ ?$ e& ?
: S7 [3 R2 s8 T: N$ z# n7 h3 _; c+ O
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
5 N$ A7 C! d2 S) O  crt num-cars
* p* \' R9 W  F, A( S  [2 o) D& l- ^* Q: W5 Z
    setup-cars: r( x- G6 C2 w5 j* j9 S, r
    set-car-color( l9 K4 N1 Q4 Z! L
    record-data
3 m' J8 h. {) J  c! \3 H/ Z3 m. u; m  ]
- }5 V0 J7 S) B  ]9 {& h4 U7 f/ _, p9 n. |- T1 h
  ;; give the turtles an initial speed3 e+ M" x' f" c/ h3 F
  ask turtles [ set-car-speed ]' |( c8 U" ~9 P8 }
. r, I; h, d- ?; z
  reset-ticks* d2 m7 W8 x$ H2 a
end8 `! F$ x6 q: I# y$ b
: M2 h1 P* Q' O# @$ D( o8 ?
;; Initialize the global variables to appropriate values- R/ R, U7 j4 [# {! O& X0 k& t  `
to setup-globals
; e6 _- k, T& q5 {  set current-light nobody ;; just for now, since there are no lights yet) R; {1 f/ V! d$ O; F
  set phase 0
# M' I8 O  U# ]) p  set num-cars-stopped 0
! A" E: K9 j, {' U" f7 x  set grid-x-inc world-width / grid-size-x7 P/ U4 g, v' Q3 S4 g9 V
  set grid-y-inc world-height / grid-size-y
0 Z/ M$ F) E4 A. _  x0 v: C, V. D- `1 O2 Y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary  p: A3 E* ^0 O
  set acceleration 0.0992 m9 P" z* \( N/ r) t
end
, h3 h  d( O2 `8 Q9 f# f5 ~! N$ A1 V
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
3 c( c7 L9 V5 D; ^7 W# R;; and initialize the traffic lights to one setting
& n& ?- l. E. ?' [  yto setup-patches
: K4 e) M+ Q4 k" t2 f7 k+ v3 t  ;; initialize the patch-owned variables and color the patches to a base-color
' M* p8 ?3 H) u: @  ask patches
& R6 c) i' l) z  [
6 W- B, \/ D& M" \- O5 Z    set intersection? false2 y/ n9 v7 t2 D, N, I
    set auto? false
. L' ?0 f8 K( l! m    set green-light-up? true
( M* n$ z% v. R" A    set my-row -1( a; S8 o3 a% M1 y' s7 z4 T' [
    set my-column -1, A* |8 i1 ]) Z) }% [+ {% y' j/ m
    set my-phase -1) o3 W* X8 l$ `; Y' B/ m
    set pcolor brown + 3: Q4 s& n: o3 D
  ]
" H! d& O" Y. Y7 E+ w0 h: T4 k2 o3 b4 |9 N3 J2 k" d( z# G
  ;; initialize the global variables that hold patch agentsets
$ I5 L2 k  C' C# Q' H8 V  set roads patches with
7 l4 ]" Z; K1 j( J/ U& J5 A0 N% C% L: T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 \' e0 k/ D, p) t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ a# e/ m/ {/ J0 y: [' n- k' P
  set intersections roads with
! A& b% ]2 g. K! U! l# n8 ^  o# c" U    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and; ~: k/ a, J3 L% h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; J7 H8 b( r: A3 ^* O9 q
6 g" N$ _. Z2 F9 ^# T( U- H. p: Z  ask roads [ set pcolor white ]
2 K2 z4 f: ^; G4 U2 q5 {    setup-intersections% t* p7 W0 I0 u. k
end
7 F: J- k+ Z& Z6 j. b, V$ u其中定义道路的句子,如下所示,是什么意思啊?
( f) I" V% b1 k1 r set roads patches with& ?$ x9 ~( S4 E
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  a6 ^/ S. p( Y$ ^
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 R# n0 W3 W1 J( H" G
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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