r.lags(1)		      Grass User's Manual		     r.lags(1)



NNAAMMEE
       rr..llaaggss  - GRASS module to calculate various spatial dependence measures
       for all possible lags within a given image. Each  measure  is  made  by
       comparing  two  cells only for each lag azimuth and distance. The whole
       image is read once for each cell in the image, therefore is very compu-
       tationally  expensive.  A Sparc 2 would typically take 1 hour to calcu-
       late a 150x150 image.



UUssaaggee::
       r.lags [-sc] _i_n_=name _o_u_t_=name [_m_e_a_s_u_r_e_=name]



FFllaaggss::
       -n   Calculate non-zero values only

       -v   Calculate semi-variogram instead

PPaarraammeetteerrss::
       in=name	 Raster surface layer to measure


       out=name   Output raster containing lag map


       measure=name   Spatial dependence measure (Moran's I or texture)

       options: moran,texture

       default: moran


HHIISSTTOORRYY

       V1.0 written 17.6.92 to calculate Moran autocorrelation statistic.

       V2.0 written 18.7.92 to also calulate Haralick's grey-tone spatial
       dependence textural measures.

       V2.1 modified 18.9.95 to conform to standard GRASS program structure.


       Future improvements could include (i) Option of faster,	memory	inten-
       sive
       option;	(ii)  Further  lag  dependent  measures; (iii) Cumulative lags
       under
       some distance weighting function.  (iv)	Option	of  ignoring/including
       zero
       values in the calculation.

       Jo Wood, November, 1995
	jwo@le.ac.uk

       ASSIST's home

       _L_a_s_t _c_h_a_n_g_e_d_: _$_D_a_t_e_: _2_0_0_2_/_0_1_/_2_5 _0_5_:_4_5_:_3_4 _$



GRASS 5.0							     r.lags(1)
