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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。  v) k4 A0 _1 o5 _# j% I, C! H& O
netlogo自带的social science--traffic grid这一例子当中,! g4 ~, p4 k( x$ G, U) e; [" x$ J; x
globals8 N5 p) H' H1 n% M# Z
[
" }. V; h& i& h; N6 j1 R2 I  grid-x-inc               ;; the amount of patches in between two roads in the x direction# U0 O2 c6 @, n
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 ?/ A$ O" e  U1 W  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
3 Y$ y3 l3 `8 z- `4 o; m# {                           ;; it is to accelerate or decelerate
, e8 e  t8 _1 L7 P# G' x  phase                    ;; keeps track of the phase
7 [% A% {  H+ U8 X( `2 |1 i& y  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure$ c9 Y" ?4 A  B# f$ U/ C: i
  current-light            ;; the currently selected light8 I. l" r# Y/ R
# |- e# ^5 P! R, o1 R: M' n: M1 y
  ;; patch agentsets
7 x: D; y& r! C  intersections ;; agentset containing the patches that are intersections9 V) D  G  A7 b8 E
  roads         ;; agentset containing the patches that are roads7 o& b' l( s5 J) [
]
8 `- D8 |, p( m. \7 y% O" S) o9 G) E. }& W- ]1 b+ Z
turtles-own
& }6 s# ~( P  o6 F. j[7 o) a+ \. X9 q6 n
  speed     ;; the speed of the turtle
7 V! l# [' B0 T7 H/ a  z6 x  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
+ g) _. u2 x. T. N% S1 Q  wait-time ;; the amount of time since the last time a turtle has moved4 q1 w+ F8 B& }0 x" @9 [% t
]
( t! z! ]$ x) o" Z6 B6 O
& h, i* N- D- F7 T3 l$ }patches-own
# i# _: i' @: Y4 p: u( H[
+ Y: X, }5 l: B  ]$ E: q9 n  intersection?   ;; true if the patch is at the intersection of two roads# F! j) N- _8 Y' a  W
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.# D+ |7 m' S2 B8 ?
                  ;; false for a non-intersection patches.3 [: X6 Z: x( r6 @; y! k" }/ Z5 b: }
  my-row          ;; the row of the intersection counting from the upper left corner of the
! h' G/ a6 l& N$ n' U                  ;; world.  -1 for non-intersection patches.- i9 r/ {# j& y3 |! a7 q" `
  my-column       ;; the column of the intersection counting from the upper left corner of the- I4 I( F& f! l4 a  G) W  ?
                  ;; world.  -1 for non-intersection patches.
/ h( }* T; x5 i, b+ T3 M7 L7 J' P  W  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
& ^0 _/ I1 g; l+ m; n; T* |1 C* |  auto?           ;; whether or not this intersection will switch automatically." F3 g/ K* K# S% S
                  ;; false for non-intersection patches.' G. N0 w9 j  ~* I
]
& G2 s* M; R7 v# D! a( w$ a( L; W) ~

$ A8 E7 }8 z- T; e) D2 I4 L. M;;;;;;;;;;;;;;;;;;;;;;9 l3 o4 p, a0 J# u
;; Setup Procedures ;;
. l, {/ N9 D4 ^, U5 @2 I;;;;;;;;;;;;;;;;;;;;;;
8 _" a: b' ]5 A  G. C, p; M) r/ i. d/ `0 j9 q# T7 \
;; Initialize the display by giving the global and patch variables initial values.! M0 ?7 H' P4 r- n8 D
;; Create num-cars of turtles if there are enough road patches for one turtle to1 p& I) @2 H( M3 e8 k
;; be created per road patch. Set up the plots.8 t1 \+ p( w6 j' D3 O/ Q6 o
to setup
8 h/ I# l; d2 V6 _! \  ca
/ W2 s# k7 M# ]( E  setup-globals
4 E  u2 G+ W% A! K
/ x' r0 h# D- U5 [9 w3 u  ;; First we ask the patches to draw themselves and set up a few variables( k% \& Y5 \. J* M, ?( Z' ]& ~7 {
  setup-patches* Y+ H1 {) F! ]9 c. m( g
  make-current one-of intersections! r% S4 _! F2 R9 e: l' u5 |
  label-current5 @, D, I6 K& l# f) B: l- f$ F! \

  F+ o' s! I' i- M+ W" ^  set-default-shape turtles "car"
: Z6 ]" Y3 x1 z! f4 B. H4 K
  e% u0 q  K- I  if (num-cars > count roads)
$ ~. j1 f) B7 b. j4 Z4 @5 y& G  [& y1 D+ K0 ~, c  {8 Y: A# G( y
    user-message (word "There are too many cars for the amount of "
/ z( s# ]" Y% V                       "road.  Either increase the amount of roads "
6 {' Q/ H; t3 J8 u3 p4 K' o                       "by increasing the GRID-SIZE-X or "9 t7 U' Y3 [- D7 s# L
                       "GRID-SIZE-Y sliders, or decrease the "
; Z2 }8 A0 U& e, j" f$ [                       "number of cars by lowering the NUMBER slider.\n"6 R/ E) s& }  o& X/ |
                       "The setup has stopped.")
: p0 ]6 u9 M, W$ y! S- [, Z& j8 l    stop; j3 H* k( B5 s* \) J3 [: y
  ]# f; e% m7 z) L) ?
9 f9 O# E+ Z. S) i8 Q. I
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color9 [4 a) L' [& R( i8 q# s- k4 P
  crt num-cars" b  [& I# d- I3 j2 ]
  [' u3 b: O. _( u2 Q" t0 R
    setup-cars
$ e, w7 ~: G4 o    set-car-color# J4 F+ E5 E9 J
    record-data( Q& K# S5 R5 H1 h
  ]
: O( a5 O# K) K" |% }% E" D+ f* \9 E, {; M) `9 U
  ;; give the turtles an initial speed9 Q" B2 j6 q! L$ p" ?( I
  ask turtles [ set-car-speed ]4 B+ r  |+ {' E3 ^0 }3 ~

- {; [! [3 v" f& x8 I9 X7 w  reset-ticks; H0 c0 W% V* q& x: f$ z2 Q& H
end$ C3 n' e3 I- m' A9 M  \# Q! w: m1 N
' m0 @/ f7 Q& [" [6 Q$ E" s. r
;; Initialize the global variables to appropriate values0 r* ?4 m0 @4 m7 p, A' b
to setup-globals8 Y, l9 o2 q$ ^9 G7 i; e0 o, G$ t8 i
  set current-light nobody ;; just for now, since there are no lights yet
; d, w' |: O3 I; x9 H8 \/ L9 {8 j  set phase 0
' R8 z' y( w/ e" S6 ]' u  set num-cars-stopped 0$ {+ ^7 L. _9 c
  set grid-x-inc world-width / grid-size-x
1 s+ p0 C4 v" c0 T* k/ V( V0 _  set grid-y-inc world-height / grid-size-y
7 z  S3 K0 S0 Q1 ^" n
! c) B5 Y3 p& b5 y! g, b4 R  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary9 q! h% o' h: H! Z- k
  set acceleration 0.099& N2 l( f6 L! q9 _/ y
end( H% F7 p0 l9 v0 H- I
# ]$ L+ X* }! D4 y7 i
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,) g! {: ~* M( A* W; @, \) H0 c
;; and initialize the traffic lights to one setting
) U* r- i/ @. P, a: j8 S% Bto setup-patches* K, t  c' N+ K$ t) i& I" |- w
  ;; initialize the patch-owned variables and color the patches to a base-color
' ?4 t( P, h0 V0 w: H' e  ask patches; |. I* h  N) T' L4 `
  [( |* Z1 G9 Z2 [3 g( ]
    set intersection? false% D* r  z$ y* M. C! P; V6 W
    set auto? false
4 h, N% J3 |/ x% j! K    set green-light-up? true
  D% d7 y; m0 T2 y  }7 }    set my-row -1
' g/ T) j( P+ Q& c/ E$ W    set my-column -18 Y% [% r# @; O
    set my-phase -1& @4 q6 a0 q* i: ^4 d% K: e7 [6 h
    set pcolor brown + 39 W9 p8 F  d8 Z* U
  ]
* f9 X3 r+ m# b+ l8 d4 |9 |
7 `' ~4 a2 ?! V6 c  ;; initialize the global variables that hold patch agentsets/ _) X4 f8 y7 D' E9 k0 ~
  set roads patches with
. |! ?! Q4 K0 H) v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% F1 [/ U) F; Q1 d% c' m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 ]4 R5 W2 y  a9 c2 o9 I  set intersections roads with
  p, O3 U0 ]7 |$ P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and1 R3 _; ^* D* g4 i7 b
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 r5 l7 p3 e- `( ]

+ J2 _" S% _1 N- ~- J* w  ask roads [ set pcolor white ]0 E  a& u- x+ w, i3 h
    setup-intersections
6 D. w: b% D& x3 t. s- A! v6 dend' L( I, m5 c( y4 t8 ]( ]: L) B/ q8 G
其中定义道路的句子,如下所示,是什么意思啊?3 }, L4 z2 P3 x; k
set roads patches with
' @5 s% L4 |" {: r6 A    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) ^* j$ u- i) g* l3 U  E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; E# W; N, {' e) n# ~6 l5 \
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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