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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 ?, \- Z9 Y6 q8 A
netlogo自带的social science--traffic grid这一例子当中,
/ d4 q$ V# T( v* o5 u$ Q4 v/ zglobals
- E, j3 z  H# u9 a  D[: W! m6 x! |( E6 G: h
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
$ M( ~* W9 x1 N. M% F0 E) o  grid-y-inc               ;; the amount of patches in between two roads in the y direction
$ O$ ~8 K# a# a5 x' M" p  acceleration             ;; the constant that controls how much a car speeds up or slows down by if. _; L% P1 M& o- |7 v& N, K+ J
                           ;; it is to accelerate or decelerate
+ j/ T) h- _: b0 H1 M$ M  phase                    ;; keeps track of the phase5 j1 B6 H( ?- B$ I; u2 g
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure( ?0 v7 {/ y9 n$ l% n* M
  current-light            ;; the currently selected light' i+ c, P- J. K0 n5 t3 {  C

/ T3 I, l4 S( M  ;; patch agentsets! U; m, r9 a1 G" h8 P
  intersections ;; agentset containing the patches that are intersections
$ t) Z) _/ o  c8 d% M2 R3 M  roads         ;; agentset containing the patches that are roads& _- _8 m; V0 ]+ j, e
]( L6 q# o/ l2 [" z' d% e7 B

9 B% t8 N1 C8 ~turtles-own
  C) `  Q* D" ]7 G8 V7 g# }[
* S: r" C0 S" Y5 {; q% Y  speed     ;; the speed of the turtle8 b7 [4 b+ [" a% w5 _
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right! `: @" O& F6 x
  wait-time ;; the amount of time since the last time a turtle has moved
. T* J8 B% ~( b  S' r4 |2 B; K1 l]% S/ J5 _$ Y0 n  E) j
, y, ]7 K9 k) W: ?% ]1 k
patches-own6 v* h. I5 s, d: z1 m0 Y5 m
[
- ?. o  w8 p" d& N3 j9 r  intersection?   ;; true if the patch is at the intersection of two roads
: x) S  J9 r8 J; k+ m  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
+ D) s6 q6 j, V# I8 X: S, z                  ;; false for a non-intersection patches.
( @/ K( ]2 E8 H6 t  my-row          ;; the row of the intersection counting from the upper left corner of the: r0 y7 A5 l4 E3 a8 _
                  ;; world.  -1 for non-intersection patches.
' F# [$ @6 o; o- i: f$ n/ g. ^  my-column       ;; the column of the intersection counting from the upper left corner of the. {( ^2 h% A6 A  S
                  ;; world.  -1 for non-intersection patches.
2 g6 R2 @+ |( D3 u8 q3 b  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
* p: u7 I8 a# W# P: U. p  auto?           ;; whether or not this intersection will switch automatically.
+ K: L# o" @( ]1 L! S1 a* `6 s                  ;; false for non-intersection patches.
+ x4 D# Z6 W2 {# t9 H; Y  ?]" W/ P2 n4 x. C* S% ]0 U0 Q
9 N4 v0 P* A: V6 Q" C7 D
& x. ]2 F$ u* a$ J% [  V( I
;;;;;;;;;;;;;;;;;;;;;;  S/ C% Q: `1 F4 M
;; Setup Procedures ;;+ Y" \# F5 F7 z$ ?' b$ C
;;;;;;;;;;;;;;;;;;;;;;
/ e% E5 a" \: c* c4 f; m+ Y; ~$ u3 C7 ]/ {5 m
;; Initialize the display by giving the global and patch variables initial values.. _* J" y9 K$ @( N0 }
;; Create num-cars of turtles if there are enough road patches for one turtle to8 a: e6 K4 q; C; Z
;; be created per road patch. Set up the plots.
. j  t4 j8 a; {3 nto setup* v& C9 n: \4 o. Q) k0 J
  ca, M+ h* K9 Z! w& D/ [. M
  setup-globals
/ N2 W4 j0 R: ]9 a) H  i
0 t  a$ y: X- b+ B  L  ;; First we ask the patches to draw themselves and set up a few variables8 U- q8 M* y0 l4 Q0 V9 ^
  setup-patches9 }1 t% e! {+ V4 m( o* ^
  make-current one-of intersections, V4 J* N) h7 p
  label-current# n( r8 O3 h4 b& f: p! ^

# `/ J9 S  h8 u& N  F  R. c+ G7 D% _1 t  set-default-shape turtles "car"# [7 x" A/ Q. \" d) z

0 @7 M$ K/ P$ s" K2 A- m& h+ S  if (num-cars > count roads)
) G6 j9 f* {3 F$ |7 D8 K  [
# t: \7 ~9 u. h8 u2 M2 J! u    user-message (word "There are too many cars for the amount of "
8 R: ?* M( C3 S) e9 A, U" o9 p                       "road.  Either increase the amount of roads "# e& U% s& K* O* m& T* n
                       "by increasing the GRID-SIZE-X or "
3 P9 `) I' Y2 k( p                       "GRID-SIZE-Y sliders, or decrease the "" ?# l7 `, z* T3 P! S; k" E
                       "number of cars by lowering the NUMBER slider.\n"/ i( R1 o& i4 n( `5 m) G, `
                       "The setup has stopped.")% `) i5 x* h1 P2 M. f9 V
    stop
5 [; G( ?# G, z% _: h; G  ]% \- \/ W* Q* c3 x3 q7 ?

, m0 ?) ]* j  Y2 w3 C" b  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color, O0 ]: X$ ?, u8 E
  crt num-cars1 p9 Q7 \2 r8 A# j
  [
( t: l+ a* F, h    setup-cars
$ H' i& a. M* X: k. t    set-car-color/ g; K. t6 z+ d" b
    record-data
# M% n( D6 @  k- }  ]
8 O. W0 Z/ V; b8 k" \
2 R+ m; C* k5 Z! o% u  ;; give the turtles an initial speed
9 W+ c) ^) G. ?  ask turtles [ set-car-speed ]
! _7 H4 q$ u$ e- g! ^  j+ G* h! c5 R+ A
  reset-ticks
. A" G4 S( ]' bend
  C: I. ^5 @0 T0 N
6 V( h' n5 y" O6 R- c  ~;; Initialize the global variables to appropriate values1 c2 z" ~3 {6 R7 a" i% ^3 Z
to setup-globals
3 z0 {& R4 D" e& b1 x  set current-light nobody ;; just for now, since there are no lights yet
1 }; Q: s$ @: c9 \  set phase 0: Q8 \4 ?4 e2 m
  set num-cars-stopped 07 E1 f9 J9 {; |8 y  R& W) w
  set grid-x-inc world-width / grid-size-x
+ W0 }+ \* [$ }7 o$ N1 E7 ]  set grid-y-inc world-height / grid-size-y, S1 b3 Q9 B* R' Q3 g
6 i* s8 ?9 E6 m! M0 |
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
: v' N' W+ y$ a- b0 s  set acceleration 0.0999 p% E- y4 u, h/ ?- O
end9 o; ]" n: o7 y; ?) i7 Y# M! p( T

  }5 v' n7 F4 V: b, @( V6 C  b8 Z;; Make the patches have appropriate colors, set up the roads and intersections agentsets,* {& \3 g  H; ]- Z
;; and initialize the traffic lights to one setting4 D! ?+ v, j+ O& @5 J
to setup-patches9 q, c$ D9 d$ R# R% N' ]
  ;; initialize the patch-owned variables and color the patches to a base-color
% G8 y0 d% M5 |8 q+ U/ |  ask patches
/ N8 U' ~# f/ i5 y" ~3 e  [9 q+ G, G: p* a- ^9 m4 M
    set intersection? false
& D, e. ]4 k: \1 E( i6 k4 @, y    set auto? false
4 b3 J+ e% S- {2 _# U3 W    set green-light-up? true" @# a3 x4 W4 ?* P1 @# f  ]0 M# P  ^4 C
    set my-row -1% M7 f; p3 n. P( c
    set my-column -1
( H& L2 h8 U8 W, \6 @- I6 ?    set my-phase -1
/ d) d$ H' j. w' ?* `7 ]    set pcolor brown + 34 Y4 _3 R0 T  M( o/ K% D/ ^
  ]( a+ r! M+ M/ k3 O  ^4 |4 O5 T# |, |

1 y) M( M+ K( @+ b5 m/ e  ;; initialize the global variables that hold patch agentsets' z$ _9 u: g/ B) d
  set roads patches with  k! H$ ?. |8 W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ A/ k8 @- p  ]0 ~% V" @* Q; W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& X  J+ E2 G* a* B; S  set intersections roads with
7 Q: U4 p# a& ~, Y# Y7 P, K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
, y, d) Y1 u9 W1 O, m2 b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 I) v0 v" n# J" W0 @
; c9 P% W1 a' y( v* }' O/ R4 j
  ask roads [ set pcolor white ]/ }5 @8 m2 n' K
    setup-intersections
7 f! B7 y( B/ b$ e+ R- `8 q( kend
% S$ |% `. O5 F其中定义道路的句子,如下所示,是什么意思啊?
+ p2 C0 g5 H  |+ a, f set roads patches with3 @5 T# R, v5 T* _. F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 z/ f: \1 Y! u$ B
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ |, E9 m: r! o+ P) D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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