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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。) A0 Z6 G3 y, n* \7 s6 b. o" j1 Z
netlogo自带的social science--traffic grid这一例子当中,4 w1 D, y" U4 q9 T4 b/ [5 R
globals% F+ E) f; N% {3 `% S" h  a
[; P5 l2 G- K1 w, h# h7 \
  grid-x-inc               ;; the amount of patches in between two roads in the x direction8 i  v5 i" W8 X" i4 Z+ R
  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ s/ Q8 I8 G7 H8 m* s7 A2 i: f) a
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
. ]. S4 }8 H# K; V                           ;; it is to accelerate or decelerate) g: J# n" v' v
  phase                    ;; keeps track of the phase/ }7 \; [  k; M: M% o! X9 W
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
% s+ g1 D/ N/ w, @. |" H  current-light            ;; the currently selected light& N: w4 z& N7 [- _" c: y/ A

0 m$ U. I  f6 A  ;; patch agentsets& x2 F. ^$ K1 U
  intersections ;; agentset containing the patches that are intersections
3 a  {& g% c4 h$ M  roads         ;; agentset containing the patches that are roads/ w1 Y. \1 N# \' y: p' [
]/ [# p' w3 e* n( q8 I

! Z! Y3 C2 t; `# F7 b! C! F1 ]: lturtles-own
! D% W( S) |9 G2 Q[
8 e2 ^) N. U; k, V- ^  speed     ;; the speed of the turtle
9 ~2 w9 d" V5 u* v  W' c* [  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
2 `; B; ^' g$ P. O  F  wait-time ;; the amount of time since the last time a turtle has moved- J* x  ]4 {2 G$ D8 [$ ?. N
]* G( V8 u/ R  W, \# x* o

/ k* X- n# m  v1 G1 d' z/ Dpatches-own
! p6 h/ M, k  d( i& H6 q4 C[
! a6 w, J" b  ~( x' `- Z" X  intersection?   ;; true if the patch is at the intersection of two roads: k3 @: {) `: a! ~7 h" |
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.  C, X2 h9 L" E  C# A7 t, x
                  ;; false for a non-intersection patches.8 ]. R! q+ F2 y9 X
  my-row          ;; the row of the intersection counting from the upper left corner of the% h2 Z3 ?3 e. y2 d5 [
                  ;; world.  -1 for non-intersection patches.* I( _) ^0 Z. N9 n( ?1 t( ]8 z
  my-column       ;; the column of the intersection counting from the upper left corner of the, R# y% N3 e9 f/ @0 d
                  ;; world.  -1 for non-intersection patches.
) p8 [+ N6 [, m1 t  v  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.9 V6 f& q' a* N2 [* x' _& x
  auto?           ;; whether or not this intersection will switch automatically.
4 N0 I) \6 \4 x( @8 W' D' t% R                  ;; false for non-intersection patches.! I! K( d9 E9 R; q* ^# o+ V
]
+ l# e- j6 @& j! ]
6 f8 k! }5 i. n: ~1 r2 ?/ e+ p
2 K5 `" N  y- a( k" z;;;;;;;;;;;;;;;;;;;;;;- O2 l" I/ n8 |8 R
;; Setup Procedures ;;4 a+ ?! {$ i4 e; q1 \: k% c
;;;;;;;;;;;;;;;;;;;;;;4 n2 Z1 L4 w: R2 O6 @" R
2 Y# ^8 ^: D# u0 D% X. P
;; Initialize the display by giving the global and patch variables initial values.6 n0 w1 M7 I( ~
;; Create num-cars of turtles if there are enough road patches for one turtle to1 A6 b+ v9 C) @9 P  i+ {- I5 N7 a
;; be created per road patch. Set up the plots.5 c8 n& z' x. F9 ^1 ~
to setup2 I$ h: @. @7 R3 v1 B
  ca
* s" v: Y- E( ]* ~! t  setup-globals
5 p6 W! ~; W7 `5 U  a6 h! z% G8 f( K5 @) l2 V" `
  ;; First we ask the patches to draw themselves and set up a few variables: x# z* L* O2 G! G8 b* u, W7 O
  setup-patches
6 a  p% c; z" M6 H) e5 Q  make-current one-of intersections
+ }/ Z3 ?" R* p/ J8 Y0 g) [- I  label-current
( D, @9 K+ h2 y8 P( I
0 N( D$ H& o- G3 a  set-default-shape turtles "car") c# F, L6 s! l% w1 H

6 A* r1 `/ C/ z, e0 q& \' u% V. M  if (num-cars > count roads)
; P; G( A# k5 F# W3 F  [
' [/ y7 x2 h- q    user-message (word "There are too many cars for the amount of "
8 t3 j9 F4 ~. b* [                       "road.  Either increase the amount of roads "
, e4 G3 _  N3 p, f. y                       "by increasing the GRID-SIZE-X or "& ]  T! `3 {' g9 ^
                       "GRID-SIZE-Y sliders, or decrease the "( h  ~  d9 A" I) m" u" ?* ]' R
                       "number of cars by lowering the NUMBER slider.\n"! A9 u1 ~# Z5 H; b& C+ W
                       "The setup has stopped.")
5 I6 i) a! |$ q    stop2 V& k$ Y" |9 Y) }6 m
  ]. @8 p; k0 H0 b+ Z$ m7 `

0 U: p9 f( Y7 U) B  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
9 G- q: ?/ l* z" i- H' N+ Q) u  crt num-cars
) M3 ?. ?1 m- Z3 b  J" {" {- ]  [# J# C0 u; D5 R' a0 @
    setup-cars. H8 N' n* s/ {4 D8 @( X0 f
    set-car-color
9 a' R" A# p) J5 F/ L3 y    record-data9 W# H! S$ I9 L- p; d
  ]: m6 ^1 H* Y. N" R: |/ e
! a( [8 U# r7 V; U$ f+ Y( r
  ;; give the turtles an initial speed
% X  s, o/ `0 O- G3 L2 l5 g5 V  ask turtles [ set-car-speed ]
& N1 H4 f' E$ U& A* ]
/ K4 _9 q4 q: o2 z/ V  reset-ticks
$ ]+ G' ]& |1 R2 p5 Dend
- N8 ~  F! r1 r. @  Q5 b' v( s
- K2 k# m- j" l, g3 e;; Initialize the global variables to appropriate values
! W6 l; z5 q. G$ Mto setup-globals( B% g* g: u( G4 g. z
  set current-light nobody ;; just for now, since there are no lights yet
! F! D2 o* Y1 m8 J  set phase 0& f2 N" Y9 f4 S) _! P: ?; X  {
  set num-cars-stopped 0
" C3 j4 m! Z; V( a  set grid-x-inc world-width / grid-size-x
" i2 z) \- r) q$ F  set grid-y-inc world-height / grid-size-y
9 F/ ?8 D( C! m7 s
6 s. g' `9 V) |  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
8 @' V8 g- F6 V3 c  f: K9 P# {  set acceleration 0.099% }' Q- i% C. a; ^) h5 C0 e$ R
end
2 Q$ b5 Z: g2 k0 P9 w6 G6 _, N: B  j8 W% a# j
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
. }, I) B/ `: w! R1 ?;; and initialize the traffic lights to one setting
& L* a5 r" w5 uto setup-patches
+ g& ]" z: b  M8 I5 U& ~  l  ;; initialize the patch-owned variables and color the patches to a base-color& R2 s' {. J. M$ t1 p& E
  ask patches
2 f, F! o( l7 Z* e" ?. ?( W  [8 ]9 a$ A4 \  r  J* y$ O
    set intersection? false7 X. u8 |, ?' c- Y7 J3 i
    set auto? false+ l# C2 u1 ~1 D) p$ q. t
    set green-light-up? true
; M" ~0 j6 G  G2 I5 a* ~5 ]# d& ]    set my-row -1
! F# Z8 W; k$ N, z( ^1 |# Z9 }    set my-column -1# q, ^; B; T1 V# M1 F
    set my-phase -1. F& w% s3 v" u+ B
    set pcolor brown + 3* L( ~0 d: z) B# ~
  ]
* P1 ^! E4 ~/ C( V) C$ M
3 {5 W. b. T& S6 \/ _  ;; initialize the global variables that hold patch agentsets+ U# I3 s& }' q
  set roads patches with7 m: U& g8 c1 Y  K5 `1 e
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( J) S+ c0 `4 E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. d1 j, ^% x* C/ g$ B) o
  set intersections roads with
" H1 p& M% w; I4 N0 B    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and: T+ |9 K: F4 e9 A! g0 j: I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% I8 v1 d% ^* \
5 Q$ [, i+ m" O  g( E) O' l
  ask roads [ set pcolor white ]
: U; f- _' J( U& D1 b5 q    setup-intersections
& ^2 z/ e) n. |; C1 pend* a) d8 {% P6 L. b  Y
其中定义道路的句子,如下所示,是什么意思啊?6 B4 e) R# d  E; _( \, T1 s( C# R
set roads patches with, Q' {. e8 t- S6 Z( U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: T6 c1 g7 v0 k2 @* R- G7 f1 g  |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( B$ r% _1 \% ?% L* H6 [" f- P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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