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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。# T7 U9 }& w' D1 b! D# {
netlogo自带的social science--traffic grid这一例子当中,0 F: Y% S3 z) [% R" `3 E' g$ s
globals
& H7 k. t, N# Y2 {' P  I& z7 b[2 Z8 \/ s' C# G6 ^( u0 x
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
8 J, u9 z) A( {  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! ?/ `+ @" @  E5 H9 ]/ D  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
) }8 h/ b& v2 b4 ~2 b                           ;; it is to accelerate or decelerate! M$ S3 O9 `0 m1 e2 s8 J& l" U
  phase                    ;; keeps track of the phase9 z% u0 D, @: Y! U1 T
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
8 Z. C! d7 Q& Q% }3 B2 ?  current-light            ;; the currently selected light
: L& B: |% s, a% e$ c- m% Y& m0 m; l" C0 }% \
  ;; patch agentsets) M* s9 o2 F! U5 t6 j
  intersections ;; agentset containing the patches that are intersections
4 F6 ]! S: v- I8 g  roads         ;; agentset containing the patches that are roads' F, J2 S) u. S$ G
]
) c% \8 j7 m# p8 V* ~) Q! F
/ r7 \0 a- s' T$ ]# ^. L- Nturtles-own
9 \) N. _7 l2 [[
8 ~$ \0 a4 V+ T  speed     ;; the speed of the turtle) W  p1 o1 Y& v% \
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 b) Q- R  ~4 f" c+ f  wait-time ;; the amount of time since the last time a turtle has moved
0 U. R) A0 {( B: k]
1 m- c$ N: _5 a
% c* x9 _/ K$ v* l' ?2 Cpatches-own
4 R& d: Z/ `7 e[
' W% k" ^+ D4 j, n( i  intersection?   ;; true if the patch is at the intersection of two roads
4 ~2 |1 Q4 ]9 E  green-light-up? ;; true if the green light is above the intersection.  otherwise, false., D% I. s7 `1 O
                  ;; false for a non-intersection patches.
8 O3 g1 o$ m- t  p6 x- U& Y  my-row          ;; the row of the intersection counting from the upper left corner of the
* z* b+ S4 E+ w/ a1 o" D3 g$ a                  ;; world.  -1 for non-intersection patches., T, W2 T+ m- Z; h+ U9 Y
  my-column       ;; the column of the intersection counting from the upper left corner of the# M3 y/ ~4 N4 P& k( |
                  ;; world.  -1 for non-intersection patches.
& Z2 n) @7 h) R8 T6 F7 s( H  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ m# v0 M- R0 t5 z" {9 U% `! S
  auto?           ;; whether or not this intersection will switch automatically." P7 e8 X/ y' F4 R4 m2 {
                  ;; false for non-intersection patches.! N2 V! P. v4 ?0 [, J3 r( M
]
; `& ], \  U0 j$ }" a; Y  z2 c* H; w$ C0 a5 B

/ F$ U/ O* a! a;;;;;;;;;;;;;;;;;;;;;;
9 h  u2 }  s( E3 v! F% A* H;; Setup Procedures ;;
+ ~5 [$ e4 g5 n- H;;;;;;;;;;;;;;;;;;;;;;
0 @# ^5 q0 y+ W# q) e" S
' T8 j4 x6 x9 s2 d8 V$ W;; Initialize the display by giving the global and patch variables initial values.
3 m4 F, R$ P4 Y5 ]( p;; Create num-cars of turtles if there are enough road patches for one turtle to
) v8 [7 l6 [" P: G& ?;; be created per road patch. Set up the plots.
$ A- }2 \1 R0 H4 l! l1 kto setup
" o6 N) [$ c% d0 t- v) ^2 R3 I" X8 j  ca7 u: g+ E# m4 T; N2 ~% r% X
  setup-globals2 H( P7 M. M0 @% c2 l' T' H9 M' g

3 {6 Z' e. R% p6 A/ a  ;; First we ask the patches to draw themselves and set up a few variables
" P+ N1 h* S% {8 G  ^( y9 q, k  setup-patches
4 H  P. x- W( ^8 S  make-current one-of intersections
; u! `; t' B4 p" y7 f3 _3 F  n  label-current3 p  w2 v5 M$ @+ V: J+ ?' n8 N/ {

( o& _7 p4 A9 i' b8 F! e  set-default-shape turtles "car"
5 ]- z5 |5 |: {  T2 g. ?
% ^/ R; `/ S! ~1 v1 g  if (num-cars > count roads); r* ], ~) `* T" z
  [1 N- ~0 k, \* Z* A' X$ T
    user-message (word "There are too many cars for the amount of "
$ _. \( [& h. A                       "road.  Either increase the amount of roads "
! p5 X. d; u, o0 {                       "by increasing the GRID-SIZE-X or "
9 T; q- j1 O6 o. N                       "GRID-SIZE-Y sliders, or decrease the "
3 L5 Q% z; \3 K; k# P3 o5 Z; v6 P- N                       "number of cars by lowering the NUMBER slider.\n"
* Z' s# a9 U4 r- F" D# I                       "The setup has stopped.")
9 y4 {6 d9 h5 P    stop
, U6 r/ m# e% v. J; @+ f2 j9 A. Z  ]
/ a5 C; f5 y" x" \
8 d  [+ m6 c8 E, ?  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
/ o5 }2 P) m  n) s, e* N! n  crt num-cars# i/ |+ N& l1 [/ O3 S) L
  [7 r3 W) e( d- A( _
    setup-cars
5 t  R* `% B) F. `& n9 q# ?2 Q    set-car-color% M3 d6 n7 o. G# M1 k! P$ B' E
    record-data
; n, x& X6 _; k) A  ]' Z, U: [- W1 y! H
: Z2 d8 k& a- S$ D) A) W& M
  ;; give the turtles an initial speed
. P7 R: e, S8 g% h  ask turtles [ set-car-speed ], I& V1 ~& Z: u7 i; f6 I4 C
" @- N: C9 K( ]) V" D; _. p7 w
  reset-ticks6 ^& L% t/ G$ a& S. \
end2 o! a+ W  H) s2 _% \) z
! p* n6 {6 \8 _5 ^( j8 F' o; i
;; Initialize the global variables to appropriate values+ L. O2 k" _# b' f+ o
to setup-globals
. y) H7 ^! t  ^" R; E  set current-light nobody ;; just for now, since there are no lights yet, k7 d* Q: g+ a- W( b
  set phase 0+ w( f  N% r" p1 b
  set num-cars-stopped 0
3 l9 s8 S$ J* ~0 H, P, o. W6 N  set grid-x-inc world-width / grid-size-x
. f# c% s4 p; p7 R  set grid-y-inc world-height / grid-size-y
: Y* w0 i8 i$ q0 A* I8 M$ h8 _
, i) C$ w- k* Z' y  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary: `) ^0 ^7 e9 Y5 D2 m
  set acceleration 0.0997 Y$ J. ?9 L1 |( N8 Y
end' r2 \: M. d" |2 `! a2 }9 [. \
1 ]4 y" m% u6 Q) E; b% c1 B
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,# A' M! Y4 {" N# v3 J5 V4 F/ l
;; and initialize the traffic lights to one setting. x$ x# m, a1 Z( l0 h/ T
to setup-patches
3 V* v# E; x6 k, Z, X  ;; initialize the patch-owned variables and color the patches to a base-color
/ i6 g; c0 X! d6 _1 H0 U" [4 X  f  ask patches
# {; V1 [. A5 |* b# i, j( E  [  V! m6 a* S% [! X" |) B
    set intersection? false
( Y/ i4 H* l$ j0 J    set auto? false
2 b& A+ ]4 b4 s: A+ _, i    set green-light-up? true
8 V/ {$ d% t6 K& \; u2 j& }% E' k    set my-row -12 l& _& I. |8 Y( k; Z
    set my-column -1+ R/ i' |: n' L4 U$ c  e4 n
    set my-phase -1
: F! k, ]9 ]5 f7 s: `* Q    set pcolor brown + 3
( a4 I  \  K" O9 Q- C, ^# N  ]
% e6 b% N' ~0 {7 p
1 h7 e0 U3 Y4 v  ;; initialize the global variables that hold patch agentsets& f. i9 F% b! G1 i+ V
  set roads patches with
8 f0 G: x( s2 |7 R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 N" ^# e2 m3 G" w! t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* K2 M! Z" \, n7 ]  set intersections roads with- E0 F8 v9 |4 v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and8 J6 y/ ~- g3 f- @( M8 X$ s
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 k, r1 P4 J( V

6 G! c2 L, f9 U: V: [( S  ask roads [ set pcolor white ]. i+ r8 c* o7 X  `+ |  s6 M
    setup-intersections  y$ j8 ?' p, \( [$ g: z8 _  @. n6 v
end/ d$ r; k+ N) |( n
其中定义道路的句子,如下所示,是什么意思啊?1 X9 ?; k9 g: O1 F
set roads patches with6 h' n/ \8 ]) Z6 D( z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- o8 D, R5 a( Q) F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) \5 k4 k1 N, }2 a& t, k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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