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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。( P. C9 i6 L, E7 ~1 u
netlogo自带的social science--traffic grid这一例子当中,
/ v  D! B6 [( I1 Qglobals: m# V, W0 R, y' ^0 z0 ^9 v0 ^6 P
[
/ m5 H' L: @5 b9 X- {& D  grid-x-inc               ;; the amount of patches in between two roads in the x direction
" e1 E; [' K1 P$ N  grid-y-inc               ;; the amount of patches in between two roads in the y direction5 E8 i/ n3 s8 l2 w; v# d
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if, s" t- D& z- d& D8 _
                           ;; it is to accelerate or decelerate* f! s, a# H9 u: Q- f' p
  phase                    ;; keeps track of the phase* ?* J7 V( P+ ]# o" w9 l2 X
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
7 f3 D2 r8 Q* _1 I. S+ q+ c+ C5 e! V6 p  current-light            ;; the currently selected light
" m! y$ J: p& U, J' p6 i/ i4 w6 `! j7 U& ^
  ;; patch agentsets$ J2 S  h% m& M( [* K$ s
  intersections ;; agentset containing the patches that are intersections# f2 @, t6 k# l/ m3 y( s  k
  roads         ;; agentset containing the patches that are roads. O! {( ~4 B5 G% a( I) g
]
  j4 d9 |9 n3 J; I% ]8 A; B+ U+ y8 m7 p
turtles-own1 e/ m$ w1 r5 |* x
[
6 k; M, M% z# P9 B  speed     ;; the speed of the turtle9 B% c" H+ e8 A9 v) b1 ^8 h( E0 V5 G
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right4 _/ p9 u* }4 ?- e( H! t$ C
  wait-time ;; the amount of time since the last time a turtle has moved
7 ^! N  q" Q  [4 v0 D: K5 [' B' @4 g]7 \8 }- }$ i" s/ L5 E; d

! X+ d4 S# o: W) h& a$ T0 Z4 Kpatches-own. h6 ]6 T, }) G/ w5 q% o2 L& y
[
9 f9 G  C6 n% B* I6 J: L  intersection?   ;; true if the patch is at the intersection of two roads- T! m+ g+ p7 m- W6 N
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.* K3 w& j- [; p+ t5 c9 M8 c' S9 H
                  ;; false for a non-intersection patches.
6 S& @% v, I/ C4 b8 G8 F  my-row          ;; the row of the intersection counting from the upper left corner of the; L  w( d  R# |
                  ;; world.  -1 for non-intersection patches.6 d7 v7 w% i4 \  v+ z; C
  my-column       ;; the column of the intersection counting from the upper left corner of the
" f+ D( S* N6 b  r                  ;; world.  -1 for non-intersection patches.: [, f5 f2 q% ?$ \! E; _% L
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ P7 d& K9 `8 X: d9 L& }
  auto?           ;; whether or not this intersection will switch automatically.
' F5 O9 u; m& ?% T5 Y                  ;; false for non-intersection patches.
4 |+ l  ^' P1 _! @+ B: |, M]/ A/ p' P5 s  X
( I: m! ]0 @: n( x( M6 V5 y( A. \4 S

- ^: V& E' u) n1 X5 q, D0 z;;;;;;;;;;;;;;;;;;;;;;
, N: G- P! L& Q7 j% V8 A;; Setup Procedures ;;
: ^* G& u$ v  |. w) o2 @) g  z;;;;;;;;;;;;;;;;;;;;;;
" r* h) ~' ^: _- K4 e' R
7 ]0 s! a, Y1 i! |7 O- j;; Initialize the display by giving the global and patch variables initial values.
( E& h1 H* J; b7 z: ?;; Create num-cars of turtles if there are enough road patches for one turtle to
( w: z. v  n. g: \! l;; be created per road patch. Set up the plots., h3 C7 _4 u1 L! f! |6 Q. M. p
to setup, K) C  \5 d1 _7 s
  ca
" n- i% |0 f0 A# c2 L  setup-globals& E: }6 J' n' ?3 G8 e, x

( v6 ~; m# E) ^8 m  ;; First we ask the patches to draw themselves and set up a few variables
* t# X( Q6 M/ q- Y& i% o! h- `% F% \  setup-patches
: P! ?6 N% d- F  x; b2 D  make-current one-of intersections0 x; Y$ G* _2 Q8 [- S! ]6 y
  label-current
8 t0 r! C( r; J8 a1 }% d
2 N8 e: F0 {* ~: m  j( S  b  set-default-shape turtles "car"* T7 D( Y3 c( U( L- F- r: F

3 j" O" O% o9 D0 N9 Z  if (num-cars > count roads)
  v5 d$ ~: O: r( o) f. p6 J* i: ~- ]  [& _+ n: F6 [* b0 O" |! d
    user-message (word "There are too many cars for the amount of ": c; B4 A2 s0 {& d& a/ v$ P  i
                       "road.  Either increase the amount of roads "
, d. C) s7 k8 d* ~" F. B7 L                       "by increasing the GRID-SIZE-X or "" S& d2 O6 a: z# \2 H
                       "GRID-SIZE-Y sliders, or decrease the "
' |/ z8 n$ y. ~, s1 A- R- E                       "number of cars by lowering the NUMBER slider.\n"
# Z* O0 C+ X' s( ?" k/ ?                       "The setup has stopped.")
2 S$ Z  c' w# Z) Z8 y    stop
, A' x- A8 Z; x! b  ]$ h/ r/ P2 [6 w
. d" `3 o  b9 _/ I: q0 O' ?  _3 u
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
% }. ?0 u  l- x+ M  crt num-cars
( }. }8 ]* z" k# v* J# k  [& y! ]% ^) Q* H
    setup-cars
- N) f  k0 ?0 N4 K9 H    set-car-color
4 g: [% q& o0 k1 d9 g    record-data
5 j3 e5 C) [7 c% C' v  ]- Z* S7 t: Z! f7 @2 k" f! C

- e6 `( H7 v2 D8 ?7 E  ;; give the turtles an initial speed$ e6 q, l& g5 [& a
  ask turtles [ set-car-speed ]; c# F4 ^" C8 `' Y. ~/ B

8 o2 t* j- k2 _* O8 k) ?- u$ \+ @  reset-ticks
% f7 t( X+ L" _1 y! Qend
, v% A$ B5 C  y$ @' V  w! j1 v
;; Initialize the global variables to appropriate values( \' c! P7 Q: [, G( R
to setup-globals3 s" w! j# t  `) V
  set current-light nobody ;; just for now, since there are no lights yet9 z- @5 C% R3 j3 o
  set phase 0( T! M5 f5 x! t  O, E" k. {
  set num-cars-stopped 0
" P8 `% w/ W$ Y" S1 W# w  set grid-x-inc world-width / grid-size-x
! L' u! V1 C7 p5 c& F( J4 b0 m  set grid-y-inc world-height / grid-size-y: h  L/ U/ _! w& r% N/ Q

+ k+ S# U. }% b. }# E/ B' }  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary: _0 _5 z7 Y" m* s4 {: X5 |
  set acceleration 0.099
+ q! ~: n6 P% s$ q% d  dend
, p! s6 ?" J+ K2 g$ P; s; [
  ?3 O) L) E9 C2 {, q2 o( C. w;; Make the patches have appropriate colors, set up the roads and intersections agentsets,0 l2 z- s0 w, i0 O2 f7 E3 n8 l2 K) C
;; and initialize the traffic lights to one setting5 s" ?) h; z/ w& U% N
to setup-patches
$ g1 Z) @' h$ f9 ]# @6 ]$ [  ;; initialize the patch-owned variables and color the patches to a base-color5 z( E) n+ a: d$ V
  ask patches
" k- I& f* D( N, ^  [- l- u1 w" c" b. a
    set intersection? false( O! L* W- o2 b8 |: ?& R! t" L; N
    set auto? false
. q3 e, D. [) P    set green-light-up? true  L2 z4 k* k- P+ z5 s: G
    set my-row -1
9 v! s2 z* Y3 h9 B9 {    set my-column -16 t: h7 z$ J! X1 S: G' m5 B1 z
    set my-phase -17 r9 K' H3 V+ M
    set pcolor brown + 3
$ p% |/ L- I3 ]5 n. @6 s  ]
3 j9 u' q; w9 L2 d, C
& y+ N! |6 v7 l# @8 d  ;; initialize the global variables that hold patch agentsets8 G8 N* H5 ^/ a6 D
  set roads patches with4 J0 c- o& V& |8 Y- s
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ U7 U. a- K/ X; H; ?3 A* B% T
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 f! S# O. k+ R( n
  set intersections roads with* B1 j4 e6 S! g% i0 p0 p7 U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
( w8 R; }5 P" h) N0 q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# R9 e* R9 ^6 r0 s' c3 X, g8 k; f+ P, x0 v! B* j# ]9 p
  ask roads [ set pcolor white ]; E* ^+ q5 N* N- p% o8 e7 E3 _
    setup-intersections2 H8 A; f: ^! Y# X$ x
end
$ f* q: s+ z% V: i. p# N; h其中定义道路的句子,如下所示,是什么意思啊?" |3 a# ?+ s1 {
set roads patches with6 a; ^6 m4 e# H  J* y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- f7 {# M" k$ k& a) j' |+ q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 L' d; c$ `% A4 m( Y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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