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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 q4 E2 N7 c7 x4 ]: \
netlogo自带的social science--traffic grid这一例子当中,
  y/ y( f3 e, Y9 T: M( g" Tglobals
; f- Y% Y  o' {$ o6 n8 k- L' r: f8 ][
' t* X& u, S$ i! Z1 R; E8 a  grid-x-inc               ;; the amount of patches in between two roads in the x direction
7 I& }- l- `# {7 j  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 |, Z+ J- \7 N6 c0 c* i- y  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
" h+ Y# d3 ^/ q                           ;; it is to accelerate or decelerate
) g1 b3 G9 k3 @2 t1 q  phase                    ;; keeps track of the phase
) x9 K9 @" e1 ^5 u/ A  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
2 Q8 K3 k' u" d, r3 |8 y  current-light            ;; the currently selected light. o7 O& V+ Q1 h  e. W
( D1 ^+ ]0 \# c% b
  ;; patch agentsets- o; A6 A9 q+ P7 l7 F
  intersections ;; agentset containing the patches that are intersections
9 k0 g- `4 C( B  roads         ;; agentset containing the patches that are roads; F9 i8 m1 o" a% _
]3 X+ A" A. L/ a6 K2 \! S" f8 A; c

- o0 r' s+ u/ k0 O- dturtles-own' y+ m9 O# H1 d1 N' \7 ?- @
[
5 D7 Q4 F3 e( i) ^* x  speed     ;; the speed of the turtle1 u) x( e' V1 e/ J) s9 n/ Y
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right% T/ k  L" K& k! V7 k8 M5 W* Q
  wait-time ;; the amount of time since the last time a turtle has moved- l# K; l: c+ r5 I9 A
]4 Z" Z2 [9 j5 A! h6 T8 z0 K% w( P
! d7 E1 b5 \2 \7 b' c( x0 V! E
patches-own4 Y: c2 ~% G# |8 w8 x* T5 [5 B
[
+ u2 |  B% M( x0 I+ w  intersection?   ;; true if the patch is at the intersection of two roads5 C1 U, G  t7 L$ p  L2 k; }/ y7 j
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.1 @; d" y% c' t! h4 Y1 I
                  ;; false for a non-intersection patches.; n0 k1 F1 y( V( t+ u: t8 o
  my-row          ;; the row of the intersection counting from the upper left corner of the+ L6 Q* M2 }; U  J' Q: V# s
                  ;; world.  -1 for non-intersection patches.
+ z" S7 ^" f! o: L  my-column       ;; the column of the intersection counting from the upper left corner of the
3 d& F4 n  K- M. U                  ;; world.  -1 for non-intersection patches.
/ p& {: ~! q% U  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
: N& ^( Q& I8 S: ?/ [  auto?           ;; whether or not this intersection will switch automatically.' l$ g) v5 e5 G  I' q
                  ;; false for non-intersection patches.
3 r/ U; f/ v) d5 T" Z1 ^9 B]
6 J( p# @; m& A
. h0 D% O1 h) `3 U$ ?9 V! s" Q' q5 K. h1 |
;;;;;;;;;;;;;;;;;;;;;;
/ i: q3 B% i" i. J) w" e7 U;; Setup Procedures ;;4 ]7 t, v. g6 n1 {, ]
;;;;;;;;;;;;;;;;;;;;;;
; E# H( H" Q3 Y8 Z" v- e0 m" r: l! s8 T6 P0 {# f! L( Y( ~9 L) k
;; Initialize the display by giving the global and patch variables initial values.' y3 W1 R" g9 T
;; Create num-cars of turtles if there are enough road patches for one turtle to
7 [5 ?& L- {& d* h;; be created per road patch. Set up the plots.
4 T6 G- b/ j8 Z) b% Hto setup/ }6 g8 K8 m7 j. A" r
  ca2 k+ Z# j7 ^" q# m5 Q
  setup-globals. G  a# D$ N5 `7 m8 r! @- s

9 o; a7 j; g% T% b& _  ;; First we ask the patches to draw themselves and set up a few variables
9 ^( P& @1 ]' c1 w2 F, V  setup-patches
* c  F  ?7 h! i0 G- W# X/ D9 [  make-current one-of intersections
! R5 ^  ]: N" k( m7 l' D. E2 P  label-current
; M) n/ Z0 O" t/ b; }; y; |3 g
5 [5 ?: j% ]  n5 Y) ]  set-default-shape turtles "car"& k5 M9 O1 |; u0 ]
8 {. w' u# y4 K0 v
  if (num-cars > count roads)
/ u; p; i0 e4 p/ f" [  [
( \4 T/ C# e/ ~+ t! @    user-message (word "There are too many cars for the amount of "
5 ?1 _4 {0 @  k- T  a                       "road.  Either increase the amount of roads "# L' l) b  Y, u: O/ f" \
                       "by increasing the GRID-SIZE-X or "3 Y3 s& N5 y" d, G( Y: C& r' e- U4 A, n( A
                       "GRID-SIZE-Y sliders, or decrease the "( g8 [. e9 Y) W% j2 x& ?) L
                       "number of cars by lowering the NUMBER slider.\n"
( {6 V' H& H$ a: j) s                       "The setup has stopped.")
8 E1 u. _7 k- v. d9 U3 l    stop
, Y+ ?* g% i$ ?2 N" v  ]
$ u. l- X1 g& `6 s$ H9 g; I' O4 p2 K' G- Q3 E# s
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: ]6 Y. R; E$ r0 ?* Q6 I( V. U  q
  crt num-cars
- m) H0 q# ^' w: s9 b  [  H2 v; z/ q) D8 R
    setup-cars" V" p9 g  Q/ P6 {
    set-car-color
, a1 f( s, v8 h* U6 q% t    record-data
/ p* R, y9 j# c8 U9 \% l  s  ]
$ {2 K" `: {8 L& Y$ a4 k( L$ m: m4 \, H! }
  ;; give the turtles an initial speed% H, s, ~. G9 G$ k
  ask turtles [ set-car-speed ]
' D3 |4 Z- p% Z1 J
2 p. L' x$ Y( v' Z+ t8 r* c9 p  reset-ticks
3 d5 B' l* n: Jend4 v, p2 |- s1 C% D

7 h8 M# t$ |8 U: B: k; M;; Initialize the global variables to appropriate values
0 j5 w. }* ]# x( j& s4 }6 Ato setup-globals
$ ^, `, _1 U% U9 h: D7 _  set current-light nobody ;; just for now, since there are no lights yet, K) c% M- o  W$ [+ I1 \- G
  set phase 0
6 a% H, [# P9 {# Q  n: K! R& ~  set num-cars-stopped 0
! h5 i1 @. h+ l1 {8 w3 {  set grid-x-inc world-width / grid-size-x
4 }) X) _8 G+ Q2 @7 q  set grid-y-inc world-height / grid-size-y7 R$ M5 ?/ l9 y# N" p
* d5 H( ~6 i- n& f3 D7 x
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) M( a5 N" u% A: g
  set acceleration 0.0997 d, \8 ]4 x+ S* C, b0 [
end: a; H. M6 y% k7 F

, J  ~; [! ^' v: Z+ m8 n1 o" B/ V, };; Make the patches have appropriate colors, set up the roads and intersections agentsets,/ C" H+ `2 h7 Q6 v
;; and initialize the traffic lights to one setting0 R5 h; g7 U& u3 a6 w  p0 m
to setup-patches
6 H/ R  P' F5 Z+ b8 }/ l  ;; initialize the patch-owned variables and color the patches to a base-color$ J! s! F2 A5 B% f# o; u& Y: a- @
  ask patches
; e- u2 ^- ]- Q5 Y  o) w  G4 E  [' |* q# X& w  N
    set intersection? false
2 ^" `" e8 ]/ }$ C# c    set auto? false
- O+ \6 \$ r& W9 T" i% N' M5 Z    set green-light-up? true8 Y- O2 W0 V" W, {+ [: R) e
    set my-row -1  `' _% }' {, ~, T0 Y# I
    set my-column -1% x6 d1 O4 Z' w/ i7 c0 u
    set my-phase -1) f$ z5 N8 u$ l: L
    set pcolor brown + 3
7 R. Y, ]3 b+ A; P9 `) O2 ]  ]
& M2 R9 F* g9 F' x, G. N! d# D9 R5 ^# u6 p: Y) i
  ;; initialize the global variables that hold patch agentsets; O6 p' V( L3 P+ ~' s! N( E
  set roads patches with# p  b1 f  k% R. S6 P/ _
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ Z0 }( k+ @4 ]
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 P9 g( C% e7 a/ i9 |% D0 Y
  set intersections roads with
+ N5 ~, M" {8 d( E& \    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
( l' Q- |/ S+ j+ L/ _0 f1 Z3 N. ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) x$ R, ~0 o- B2 t7 b
1 g- n2 A+ }' z  m
  ask roads [ set pcolor white ]
$ D# o" W& x5 N4 W2 H( {    setup-intersections
* P) ?, `8 Z- M+ ^/ a7 Aend; f1 q' ~# i& H1 {- e3 o8 b
其中定义道路的句子,如下所示,是什么意思啊?9 Y, b! G4 \7 ]/ ~; \$ N$ a8 P- ?
set roads patches with
8 R& |, y% U; _3 Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 m! C. j/ a5 f' R
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 E, R; N* w/ o( ^1 P" r: \) m9 c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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