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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。7 s' G$ z) ]3 @- D. N
netlogo自带的social science--traffic grid这一例子当中,1 Z' P" L% R1 ^7 C4 C
globals
" P5 X" G# [9 f! M1 [( d' }[
; M9 X& q* {2 h# V* x% I4 h  grid-x-inc               ;; the amount of patches in between two roads in the x direction
& q  r2 S4 C" g+ d: I2 D! v  grid-y-inc               ;; the amount of patches in between two roads in the y direction) b' k/ ]2 H# \/ p2 l9 _6 E* ^/ y6 T
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
! X) N! W. O* o* Y7 H                           ;; it is to accelerate or decelerate2 Z! w7 X7 o  z3 \- F9 a. t" I
  phase                    ;; keeps track of the phase2 [. e% m! q( c* V, o% Z
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ _+ k5 O. q! w6 n  m. V  ^  current-light            ;; the currently selected light' B9 r" g  J( ^! f4 }! T+ P

- {! y+ @, b% s7 J/ U& v, Y0 i! G6 a  ;; patch agentsets2 q) v# D1 B# u& q
  intersections ;; agentset containing the patches that are intersections+ Z9 }4 I/ Q' o5 b$ O
  roads         ;; agentset containing the patches that are roads
9 h: L  q9 Q- v]
: V" z+ e) o6 c0 C: F' J6 z
# S1 o! a! l9 i/ G4 L$ D/ T) j$ ?turtles-own+ T$ Q8 q' g$ c" F
[
3 H5 r" o9 r: \' k  speed     ;; the speed of the turtle
! x! {! @1 I, U/ a( ?  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 I! y" d- H, ~& G: K4 G8 z" T
  wait-time ;; the amount of time since the last time a turtle has moved3 e/ b' l" ^9 }
]# P/ {. ~/ N9 W, S; e
% v) E0 P  L; c8 T
patches-own
0 m) b% h% a$ b5 }[  r& p' t# u# u
  intersection?   ;; true if the patch is at the intersection of two roads
3 R+ T9 S5 t2 u9 u  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( m3 R+ F' d# D0 ]8 W  f: @% L                  ;; false for a non-intersection patches.
& }  v: t- P3 g* {& r  my-row          ;; the row of the intersection counting from the upper left corner of the* Y/ B; v: O- j4 w( z4 p6 W( s
                  ;; world.  -1 for non-intersection patches.
+ w6 C$ ~  L" B  my-column       ;; the column of the intersection counting from the upper left corner of the% N, \3 \$ ~' {; ]0 I/ y1 H8 P. g
                  ;; world.  -1 for non-intersection patches.  d2 s; s! `; G* ]$ R8 B
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
3 O7 o2 B3 z: H, O  auto?           ;; whether or not this intersection will switch automatically.: ~1 p8 i# w0 X
                  ;; false for non-intersection patches." }. j: M  ?! j4 i& B
]
2 h0 N' s( a4 [/ u0 I/ p
- M5 F" A# I( f+ J9 C8 l8 M7 U  ~. \) }8 u  e2 a1 W
;;;;;;;;;;;;;;;;;;;;;;6 l' d# `& T- h3 P! @) E5 s# |
;; Setup Procedures ;;6 j! Z4 H; i! L- n' {
;;;;;;;;;;;;;;;;;;;;;;
) Y+ I' @' Z2 v/ U1 O4 W0 g' n+ G$ a* I6 r- v7 ~
;; Initialize the display by giving the global and patch variables initial values.
2 t! m$ Y# n1 s" u# @9 F8 j8 L;; Create num-cars of turtles if there are enough road patches for one turtle to
) B8 [8 c3 A  J3 J) h;; be created per road patch. Set up the plots.
- P* W. d8 ?9 P% D. }# Qto setup
/ A# {1 }. k  |. ~/ v6 z8 |  ca3 _5 r" x/ U% |" a2 g7 N5 q- U7 f
  setup-globals& n1 f# @( `4 R% _0 o; `+ s0 u

/ P; S% k) {, q( S( u+ l8 Z1 {  ;; First we ask the patches to draw themselves and set up a few variables5 f. Y) }  w( i3 \; U, ]! f# }
  setup-patches- y2 s, N3 L; }2 n5 l
  make-current one-of intersections; y  A6 f" Z& W1 ]) E1 h
  label-current
6 H6 u! l; L7 D1 U+ f- o% t3 l5 d5 W* a9 p7 T& i5 j& n$ k+ l/ p
  set-default-shape turtles "car"
& f  J% j+ [- q* R
$ u' O; E+ l# a. S6 e+ W+ Z* `  if (num-cars > count roads)% H1 k- I4 h, b" {
  [/ Z# W  T1 p; k7 `
    user-message (word "There are too many cars for the amount of "
  j7 T- ^0 {, W" S5 E$ }" R# [* U                       "road.  Either increase the amount of roads "
* _2 z7 N( I! L5 u3 r                       "by increasing the GRID-SIZE-X or "
. V( d( b3 c6 f9 q                       "GRID-SIZE-Y sliders, or decrease the "$ ?9 o. P) ?1 _0 x
                       "number of cars by lowering the NUMBER slider.\n"% r5 {4 y2 T3 x- M2 |8 |+ ~
                       "The setup has stopped.")8 @1 C4 K1 t& w
    stop
9 `, q# U2 u! Q1 M  t$ \# P  ]
: Y  g$ ]" S" E7 I% c3 _2 R" z
3 L0 O6 r8 z  {  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color9 X1 Z+ M. @  h$ @2 n$ ?
  crt num-cars
9 u8 U* X" k: J; g% w; z) q# }  [
4 p' j9 r) v3 R7 v) J/ B/ k    setup-cars: y. j( U$ Q. _: v( j" H6 `
    set-car-color
+ \  u  Y6 O, v1 }7 i% B    record-data
% t0 {/ ~% B' t$ i  ]1 ^6 m; l+ m' C% U) X) q4 t( ~

- P- K/ N( U) q2 v2 m  ;; give the turtles an initial speed
  d; C( [# r1 P; n3 z/ u8 \. G7 V  ask turtles [ set-car-speed ]
) h6 U2 x  {: d, M" I: {5 ^$ K5 B; ^8 {+ M8 w/ r0 n
  reset-ticks
& F" I+ |/ ~; z* r4 [end4 [: R$ i6 N% i
; h& M% W; x3 b& }+ C5 P5 ~, l/ w
;; Initialize the global variables to appropriate values
0 o" ]# Q9 a* G3 Qto setup-globals
* C5 ^5 M2 w$ q+ v3 H$ ~  set current-light nobody ;; just for now, since there are no lights yet
8 f: L+ Z, q4 c0 Z& W" G2 w  set phase 0! l6 d6 O! ~& D, R9 ]8 ?
  set num-cars-stopped 0
% \# t5 ], S! i  set grid-x-inc world-width / grid-size-x9 u% r% a+ z' X. A' M, k# s
  set grid-y-inc world-height / grid-size-y4 t1 i# g  F% |/ L0 Y& _
# V& O, u; V. g. ^% h2 ]1 T7 B! ]
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
  z( @2 @' }* K+ h  set acceleration 0.099: h+ J% `) O; d# Y' F+ b- x
end
. g0 @# V! z9 Z1 V4 v
& f8 u4 t6 N# `! u2 c;; Make the patches have appropriate colors, set up the roads and intersections agentsets,# y" [; v. {8 a. W  h0 H
;; and initialize the traffic lights to one setting
3 @" v; h; {$ p) s& n5 b4 tto setup-patches4 q2 b; j2 H# v7 w: d9 x
  ;; initialize the patch-owned variables and color the patches to a base-color
" V7 U+ B/ a3 p; H" W4 u' ]5 {  ask patches8 e# x1 }! m& m5 }- h2 z0 W
  [
. w9 P9 B; n. Z% B: P( i2 ^4 _    set intersection? false
2 y) R/ B% W% u/ b    set auto? false  X# [$ G( m* \8 d
    set green-light-up? true( K- U# y5 u) E# ~4 b/ Z- W
    set my-row -10 {3 V# O8 H& G+ `$ c4 a
    set my-column -14 D* v* m  b% J/ v7 f* e& N' U
    set my-phase -1
- w4 `/ f/ Z0 l+ A, q6 q( r    set pcolor brown + 3
% e0 h7 ^: C. J; ~% }5 O  ]" u4 q6 q# Y2 s7 A  P$ U) O

; K6 H- W, \) v# p. Q  ;; initialize the global variables that hold patch agentsets7 P0 L! Y  O% U2 S) w+ n
  set roads patches with1 F% O  Y! t+ C8 M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  P$ o3 S, _0 Y: q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 P" K( `6 E4 m) J& ^  set intersections roads with- Q) N; {- [3 U5 ~) c" Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and4 X3 @. Q* {* f$ r0 D0 B
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  p( M8 N7 a1 @9 \
) T2 c& w$ R, {6 E
  ask roads [ set pcolor white ], Q9 c! C& U8 X5 X& X7 B
    setup-intersections6 X8 r9 t* u- C
end2 C/ L6 O8 z. @# r0 \
其中定义道路的句子,如下所示,是什么意思啊?
" j# _+ i( b* J( G5 g' _& [9 W+ F" r set roads patches with
9 x3 u5 g3 ~) d  M' W: c2 N4 y' n2 R. F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" q- d& `3 g, g3 I0 ~* O5 @/ v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! ^5 V' a, b8 O# ^0 Z9 X! a& n5 K' N
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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