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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 w$ q' G# J" Znetlogo自带的social science--traffic grid这一例子当中,
$ n' q8 J. i# Y) ]- x( I5 ]  Yglobals
8 y  f, m4 [% J3 g' @[
0 k2 ^* ?( D$ |1 ~, Y: @  grid-x-inc               ;; the amount of patches in between two roads in the x direction
- @% v- l% Q, N* @9 K8 L  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 Y2 n4 g# y4 r* _5 Q  g- g  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
7 n) g" I" Z' C3 V/ Y, Q$ C% k                           ;; it is to accelerate or decelerate
  F3 `. c! c" B8 m# V  phase                    ;; keeps track of the phase
3 A, |! \& s/ }9 f: O  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
" I3 d) Y! v* u1 w4 P& Y0 A  current-light            ;; the currently selected light
% ?3 n6 m' [( E5 f7 S2 p
- C; S1 U3 v" a6 O, @- }& {, [$ T  ;; patch agentsets1 c' e" m$ r9 _+ k  d& b
  intersections ;; agentset containing the patches that are intersections
. C/ p# y6 o5 p) c  roads         ;; agentset containing the patches that are roads4 \. Q* S6 T' V" F5 ?8 |: |9 C1 j
]
6 Y( z2 p' U3 H/ k! ?% ^/ i
1 t% n  Z) R& aturtles-own1 e7 q" v/ [# x) j. V
[1 v6 P+ @( Y  l& q" G% M
  speed     ;; the speed of the turtle/ u7 s% @$ w& J. b; u( K, i
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: y4 F0 j! _6 m* g) x9 R+ G3 O; C  wait-time ;; the amount of time since the last time a turtle has moved* ~4 {, v* P% C4 e
]% {( T7 G9 q, y7 u) g

& \; p! [/ w* V8 Gpatches-own
6 e3 ?5 v) M" z& Y& W9 ^[
4 ]# D* R; N  L+ D5 Q5 r/ l' u  intersection?   ;; true if the patch is at the intersection of two roads
3 d8 |+ l) j+ w6 V) t  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
1 G2 E) k1 o! ?$ f' _8 X( n! L9 ^9 x                  ;; false for a non-intersection patches.. E' I/ ~% c  Z8 i
  my-row          ;; the row of the intersection counting from the upper left corner of the& J0 K! h3 C/ @/ D
                  ;; world.  -1 for non-intersection patches.8 i0 b% z% I5 ]/ w! L: w% p/ r
  my-column       ;; the column of the intersection counting from the upper left corner of the
! ]7 q9 g1 Z9 D9 y% B& d% q                  ;; world.  -1 for non-intersection patches.
* o7 {7 N3 W' \, N2 E1 \4 n  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.% I, r9 V: K) L& n5 @  ?- S
  auto?           ;; whether or not this intersection will switch automatically.
; U0 P! ]: `; F  a                  ;; false for non-intersection patches.2 G7 K" M: D; i3 r
]" m0 W! l- v/ \
6 H2 s1 }; F; q) {% h. X# N6 c

$ Z; U$ O3 ~& j9 E( K+ |) V;;;;;;;;;;;;;;;;;;;;;;/ @* ]( z( F+ |: T1 h$ B
;; Setup Procedures ;;
3 c  F- c& F. J;;;;;;;;;;;;;;;;;;;;;;& o( c1 }" b  I) ?! h+ s7 V3 e7 l
" b5 D! V/ k( F1 T
;; Initialize the display by giving the global and patch variables initial values.
- D3 p& w; b& R2 b  \" N& _- R;; Create num-cars of turtles if there are enough road patches for one turtle to
( M, ~$ q0 x* C;; be created per road patch. Set up the plots.
$ L; w7 H. i$ q. A* eto setup
3 A( o8 v# T/ @. E0 Y! d9 U5 G: s  ca
3 ]" {- p7 G9 B) ]  setup-globals
! e0 [7 e1 ^. s/ a- \
8 h( r" P) y, s$ M* I7 o5 V; ^7 z6 v  ;; First we ask the patches to draw themselves and set up a few variables3 {, }+ U3 S' q; W0 H. V
  setup-patches6 V4 `& S4 b* x# ?
  make-current one-of intersections
1 ^% r4 c; c% C! w' g  b  [* ?9 D5 P4 `  label-current
( x5 c& }# ]9 ~. ]/ |. A6 R3 g: d
  ^0 ?1 R8 E& G2 g& P( H  set-default-shape turtles "car"3 r" `' a' u* S% P2 B3 B" a

+ X- a4 x9 ]' ?0 o8 ]( |4 l& H  if (num-cars > count roads). a2 f7 [% d0 B+ V4 P5 r8 I
  [1 f* j9 ~( O% B; V8 ^" W6 F4 q: e
    user-message (word "There are too many cars for the amount of "9 u- l* T: @; Y6 @
                       "road.  Either increase the amount of roads "
" c) W: S, [# U/ U. ?  D                       "by increasing the GRID-SIZE-X or "
; P4 S, P/ j1 _5 I8 u: |                       "GRID-SIZE-Y sliders, or decrease the "
& n7 H" u; ~6 t* V  y2 h2 A                       "number of cars by lowering the NUMBER slider.\n"# M% F. S, _% p+ A9 U6 r# h
                       "The setup has stopped.")
. k# Z3 E) d4 r) @    stop
2 d2 g" B/ `4 i4 q1 _& _  ]
; J( S* s. y: P4 L  T3 e- g
9 g) {9 g7 Q1 \0 b; }  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color1 x9 N' I! C3 F5 Z# H! M
  crt num-cars* B: H) f( \' ^% V
  [
9 q) d; M" ?+ J1 M3 W7 E    setup-cars
8 L; [# L6 v1 x    set-car-color
6 ~( r( {) U1 r; `    record-data. `- q, k8 x+ h, [. E
  ]
; O( a) `( i6 [" N- L! A# P5 x3 ]+ }3 d) w4 V
  ;; give the turtles an initial speed
: ]4 f6 d2 F- l3 t# f# d! J  ask turtles [ set-car-speed ]! ]# F- ^! c. z7 G; ]- N
9 ?/ T* H, q; P" f, V
  reset-ticks% _! Y4 {8 M: S- h( x) M
end, {- R: b0 W1 W$ @; g, V
# O) k. K/ y1 }; X4 t& F- u
;; Initialize the global variables to appropriate values8 ?2 J1 k8 F  [  K( u* o9 w! X
to setup-globals, u5 e2 X- Q, }
  set current-light nobody ;; just for now, since there are no lights yet
( q: }2 H/ `3 ~# F; ]  set phase 06 A% K. w, G8 K1 Q+ Y  N( `5 ]; ?
  set num-cars-stopped 05 M& f1 @5 C! l7 G
  set grid-x-inc world-width / grid-size-x8 [0 c1 Q* [8 n$ _+ Z8 R- Z
  set grid-y-inc world-height / grid-size-y
$ o8 K. P' n* p! @" J0 E2 ?: n9 ]1 x7 p3 _9 J$ ~( C6 T8 M
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary' Y! U# T2 p; @+ L* s' v' b
  set acceleration 0.0990 x0 Y- S4 O, {& {6 o
end
0 P4 N( u, P4 y  t# ~$ _/ ?+ r: h3 W8 f
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,. \: _' W3 p9 a& d3 \/ t6 _  u
;; and initialize the traffic lights to one setting3 g) C1 X; ]- z. Q% o' \
to setup-patches
, \& Z- [& ^( k) s) W9 v7 n$ L  ;; initialize the patch-owned variables and color the patches to a base-color
2 v% o2 {7 m' N* u% k9 R/ y, x/ T  ask patches
$ c5 }, H, ?5 b! j! f# O& V  [' D' D3 P/ \: t, ^; b
    set intersection? false) b" T8 Q$ Y  s% Q: z
    set auto? false9 m' ~" v7 z2 x( _$ i& }2 C' m$ }
    set green-light-up? true% b, ^$ J* o9 y; @9 S9 }
    set my-row -1
4 G" O; R5 m) o$ d    set my-column -1' W- Y& D- f% s, j/ f
    set my-phase -1. Z' T5 K- ~/ s, k9 ~  D, l
    set pcolor brown + 3
! c) k8 T4 Y9 Y$ U# H/ x$ c  ]6 V3 _. x+ R$ p6 L
+ S! n) }: y) O! m! h) V
  ;; initialize the global variables that hold patch agentsets& i. U% v. n9 `- g' D  \
  set roads patches with2 U/ f6 t$ h7 O0 A. X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 V( b- m: S% ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 E( n0 G: u- a+ A/ ^5 v4 A9 F
  set intersections roads with
4 B* x# E( A2 V2 L, w$ x: c/ e    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
+ G% ]) y- i4 g3 d    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; K; G  T  l% v1 l

: t+ U1 q6 B6 k6 a$ {+ t: k  ask roads [ set pcolor white ]$ b1 r9 p# @. v! W3 X
    setup-intersections
& O, I: o7 X/ r0 W7 ~' qend: H) s7 o8 E- M0 R1 y2 Z- z( l( L
其中定义道路的句子,如下所示,是什么意思啊?8 y. z) @# o! e1 @
set roads patches with
. O9 t/ v" C9 s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) u& i3 p4 |  m4 f% d* d. [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 x. i8 T3 \# r$ J" @9 M7 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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