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



NNAAMMEE
       rr..rreeccllaassss   -  Creates  a new map layer whose category values are based
       upon the user's reclassification of categories in  an  existing	raster
       map layer.
       _(_G_R_A_S_S _R_a_s_t_e_r _P_r_o_g_r_a_m_)

SSYYNNOOPPSSIISS
       rr..rreeccllaassss
       rr..rreeccllaassss hheellpp
       rr..rreeccllaassss iinnppuutt==_n_a_m_e oouuttppuutt==_n_a_m_e [TTIITTLLEE==_n_a_m_e]

DDEESSCCRRIIPPTTIIOONN
       _r_._r_e_c_l_a_s_s  creates  an  _o_u_t_p_u_t  map  layer based on an _i_n_p_u_t raster map
       layer.  The output map layer will be a reclassification	of  the  input
       map layer based on reclass rules input to _r_._r_e_c_l_a_s_s, and can be treated
       in much the same way that raster files are treated.  A  _T_I_T_L_E  for  the
       output map layer may be (optionally) specified by the user.


       The  reclass  rules  are  read from standard input (i.e., from the key-
       board, redirected from a file, or piped through another program).


       The program will be run non-interactively if  the  user	specifies  the
       _n_a_m_e  of the raster map layer to be reclassified, the _n_a_m_e of an output
       layer to hold reclass rules, and (optionally) the _n_a_m_e of a  TITLE  for
       the output map:


       rr..rreeccllaassss iinnppuutt==_n_a_m_e oouuttppuutt==_n_a_m_e [TTIITTLLEE==_n_a_m_e]



       After  the user types in the above information on the command line, the
       program will (silently) prompt the user for reclass rules to be applied
       to  the	input  map  layer  categories.	 The  form  of	these rules is
       described in further detail in the sections on non-interactive  program
       use reclass rules and examples, below.


       Alternately,  the  user	can simply type rr..rreeccllaassss on the command line,
       without program arguments.  In this case, the user will be prompted for
       all needed inputs.


       Before using _r_._r_e_c_l_a_s_s one must know the following:

	      The  new categories desired;  and, which old categories fit into
	      which new categories.

	      The names of the new categories.


IINNTTEERRAACCTTIIVVEE PPRROOGGRRAAMM UUSSEE:: EEXXAAMMPPLLEE
       Suppose we want to reclassify the raster map layer _r_o_a_d_s, consisting of
       five  categories,  into the three new categories:  paved roads, unpaved
       roads, and railroad tracks.  The user is asked whether the reclass  ta-
       ble  is	to be established with each category value initially set to 0,
       or with each category value initially set to its own value.   A	screen
       like that shown below then appears, listing the categories of the _r_o_a_d_s
       raster map layer to be reclassified and prompting the user for the  new
       category values to be assigned them.



	    ENTER NEW CATEGORY NUMBERS FOR THESE CATEGORIES

	    OLD CATEGORY NAME	    OLD     NEW
				    NUM     NUM
	    no data		    0	   0___
	    Hard Surface, 2 lanes    1	    0___
	    Loose Surface, 1 lane    2	    0___
	    Improved Dirt	     3	    0___
	    Unimproved Dirt Trail    4	    0___
	    Railroad, single track   5	    0___

	    AFTER COMPLETING ALL ANSWERS, HIT <ESC> TO CONTINUE
			 (OR <Ctrl-C> TO CANCEL)

       In  the	following  screen  the	new  category values have been entered
       beside the appropriate old category  names.   Cells  assigned  category
       values 2, 3, and 4 in the old raster map layer are now assigned the new
       category value 2 in the reclassed map; cell data formerly  assigned  to
       category  value	5  in  the old raster map map are now assigned the new
       category value 3 in the reclassed map.

	    ENTER NEW CATEGORY NUMBERS FOR THESE CATEGORIES


	    OLD CATEGORY NAME	      OLD     NEW
				     NUM     NUM
	    no data		      0      0___
	    Hard Surface, 2 lanes     1      1___
	    Loose Surface, 1 lane     2      2___
	    Improved Dirt	  3	 2___
	    Unimproved Dirt Trail     4      2___
	    Railroad, single track    5      3___

	    AFTER COMPLETING ALL ANSWERS, HIT <ESC> TO CONTINUE
			 (OR <Ctrl-C> TO CANCEL)

       Hitting the escape key  will  bring  up	the  following	screen,  which
       prompts	the user to enter a new TITLE and category label for the newly
       rreeccllaasssseedd categories.

	    ENTER NEW CATEGORY NAMES FOR THESE CATEGORIES

	    TITLE:  Roads Reclassified
		   CAT	       NEW CATEGORY NAME
		   NUM
		    0	       no data
		    1	       Paved Roads
		    2	       Unpaved Roads
		    3	       Railroad, single track

	      AFTER COMPLETING ALL ANSWERS, HIT <ESC> TO CONTINUE
			    (OR <Ctrl-C> TO CANCEL)

       Based upon the information supplied by the user	in  the  above	sample
       screens,  the  new output map, supporting category, color, history, and
       header files are created.

NNOONN--IINNTTEERRAACCTTIIVVEE PPRROOGGRRAAMM UUSSEE:: RREECCLLAASSSS RRUULLEESS
       In non-interactive program use, the names of an input map, output  map,
       and  output  map  TITLE	are  given  on the command line.  However, the
       reclass rules are still read from standard input (i.e., from  the  key-
       board, redirected from a file, or piped through another program).


       Once the user has specified an input raster map layer, output map layer
       name, and (optionally) output  map  layer  TITLE  by  typing  rr..rreeccllaassss
       iinnppuutt==_n_a_m_e oouuttppuutt==_n_a_m_e [TTIITTLLEE==_n_a_m_e]

       Each  line  of  input  must  have  the  following  format:  iinnppuutt__ccaattee--
       ggoorriieess==_o_u_t_p_u_t___c_a_t_e_g_o_r_y  [_l_a_b_e_l]



       where the input lines specify the category values in the  input	raster
       map layer to be reclassified to the new _o_u_t_p_u_t___c_a_t_e_g_o_r_y category value.
       Specification of a _l_a_b_e_l to be associated with the new output map layer
       category  is  optional.	 If  specified, it is recorded as the category
       label for the new category value.  The equal sign = is  required.   The
       _i_n_p_u_t___c_a_t_e_g_o_r_y_(_i_e_s_) may consist of single category values or a range of
       such values in the format "_l_o_w thru _h_i_g_h."  The	word  "thru"  must  be
       present.


       To  include  all  (remaining)  values the asterix "*" can be used. This
       rule has to be set as last rule. No further rules  are  accepted  after
       setting this rule.


       No data have to be spcified with NULL.


       A line containing only the word eenndd terminates the input.

NNOONN--IINNTTEERRAACCTTIIVVEE PPRROOGGRRAAMM UUSSEE:: EEXXAAMMPPLLEESS
       The following examples may help clarify the reclass rules.



	1. This example reclassifies categories 1, 2 and 3 in the input raster
	      map  layer "roads" to category 1 with category label "good qual-
	      ity" in the output map layer, and reclassifies input raster  map
	      layer  categories  4  and  5  to category 2 with the label "poor
	      quality" in the output map layer.

		  1 2 3   = 1	 good quality
		  4 5	  = 2	 poor quality



       2. This example reclassifies input raster map layer categories  1  thru
       10  to  output map layer category 1, input map layer categories 11 thru
       20 to output map layer category 2, and input map  layer	categories  21
       thru  30  to output map layer category 3, all without labels. The range
       from 30 to 40 is reclassified as NULL.

	    1 thru 10 = 1
	   11 thru 20 = 2
	   21 thru 30 = 3
	   30 thru 40  = NULL

       3. Subsequent rules override  previous  rules.	Therefore,  the  below
       example reclassifies input raster map layer categories 1 thru 19 and 51
       thru 100 to category 1 in the output map layer, input raster map  layer
       categories  20  thru 24 and 26 thru 50 to the output map layer category
       2, and input raster map layer category 25 to the output category 3.

	    1 thru 100	   = 1	  poor quality
	   20 thru 50 = 2    medium quality
	   25		 = 3	good quality

       4. This example reclassifies categories 1, 3 and 5 in the input	raster
       map  layer to category 1 with category label "poor quality" in the out-
       put map layer, and reclassifies input raster map layer categories 2, 4,
       and  6  to  category  2 with the label "good quality" in the output map
       layer.  All other values are reclassified to NULL.

	   1 3 5   = 1	  poor quality
	   2 4 6   = 2	  good quality
	   *	   = NULL



       5. The previous example could also have been entered as:

	    1 thru 19  51 thru 100   = 1    poor quality
	   20 thru 24  26 thru 50    = 2    medium quality
	   25			= 3    good quality

       or as:

	    1 thru 19  = 1    poor quality
	   51 thru 100	    = 1
	   20 thru 24  = 2
	   26 thru 50  = 2    medium quality
	   25	       = 3    good quality



       The final example was given to show how the labels are handled.	 If  a
       new  category  value appears in more than one rule (as is the case with
       new category values 1 and  2),  the  last  label  which	was  specified
       becomes	the  label  for  that  category.   In this case the labels are
       assigned exactly as in the two previous examples.

NNOOTTEESS
       In fact, the _r_._r_e_c_l_a_s_s program does _n_o_t generate  any  new  raster  map
       layers  (in  the  interests  of	disk  space conservation).  Instead, a
       rreeccllaassss ttaabbllee is stored which will be used to reclassify  the  original
       raster  map  layer each time the new (reclassed) map name is requested.
       As far as the user (and programmer) is concerned, that raster  map  has
       been  created.	Also  note  that  although  the  user  can  generate a
       _r_._r_e_c_l_a_s_s map  which  is  based	on  another  _r_._r_e_c_l_a_s_s	map,  the  new
       _r_._r_e_c_l_a_s_s  map map will be stored in GRASS as a reclass of the _o_r_i_g_i_n_a_l
       raster map on which the first  reclassed  map  was  based.   Therefore,
       while  GRASS allows the user to provide _r_._r_e_c_l_a_s_s map layer information
       which is based on an already reclassified map (for  the	user's	conve-
       nience),  no  _r_._r_e_c_l_a_s_s	map  layer  (i.e., _r_e_c_l_a_s_s _t_a_b_l_e) will ever be
       _s_t_o_r_e_d as a _r_._r_e_c_l_a_s_s of a _r_._r_e_c_l_a_s_s.


       To convert a reclass map to a regular raster map layer, set  your  geo-
       graphic	region	settings  to  match the settings in the header for the
       reclass map (an ASCII file found under the _c_e_l_l_h_d directory,  or  view-
       able by running _r_._r_e_s_a_m_p_l_e.


       _r_._m_a_p_c_a_l_c can also be used to convert a reclass map to a regular raster
       map layer:


       rr..mmaappccaallcc rraasstteerr__mmaapp==reclass_map



       where _r_a_s_t_e_r___m_a_p is the name to be given to the	new  raster  map,  and
       _r_e_c_l_a_s_s___m_a_p is an existing reclass map.

BBEEWWAARREE
       Because	_r_._r_e_c_l_a_s_s  generates  a table referencing some original raster
       map layer  rather  than	creating  a  reclassed	raster	map  layer,  a
       _r_._r_e_c_l_a_s_s map layer will no longer be accessible if the original raster
       map layer upon which it was based is later removed.


       A _r_._r_e_c_l_a_s_s map is not a true raster map layer.	Rather, it is a  table
       of  reclassification values which reference the input raster map layer.
       Therefore, users who wish to retain reclassified map layers  must  also
       save  the  original input raster map layers from which they were gener-
       ated. Alternatively r.recode can be used.


       Category values which are not explicitly reclassified to a new value by
       the user will be reclassified to NULL.

SSEEEE AALLSSOO
       _r_._r_e_s_a_m_p_l_e

       _r_._r_e_s_c_a_l_e, _r_._r_e_c_o_d_e

AAUUTTHHOORRSS
       James Westervelt,
       Michael Shapiro,
       U.S.Army Construction Engineering Research Laboratory

       _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.reclass(1)
