.TH r.rescale.inf
.SH NAME
\fIr.rescale.inf\fR \- Generate a raster map layer in which the categories represent values
in a database column which have been divided into equal interval units.
.br
.I "(GRASS-RDBMS Raster Interface Program)"
.SH SYNOPSIS
\fBr.rescale.inf\fR
.br
\fBr.rescale.inf help\fR
.br
\fBr.rescale.inf\fR \fBtab=\fIname\fR \fBkey=\fIname\fR \fBcol=\fIname\fR \fBcats=\fIname\fR \fBinput=\fIname\fR \fBoutput=\fIname\fR \fB[join=\fItab,tabkey,pkey]\fR
.SH DESCRIPTION
r.rescale.inf creates a reclassed raster map layer by dividing the values in a numeric column in the currently
selected database into equal interval units. The number of resulting categories is determined by the user
via the command line parameter [cats=]. r.rescale.inf evaluates the range of values for the database
column and subsets these values into equal interval groups of records returned by the query. For example,
if the database column contains values which range from 1-1000 and the [cats] value is equal to 10 the
resulting raster map layer will contain the 10 categories:1=1-100, 2=101-200 etc. In other words, each
category in the new raster map layer will represent a range of 100 values from the database column used
in the rescale operation. The database column being evaluated must be numeric in type. To identify the 
data types of columns in a database table use the g.column.inf command with the [-v] flag. r.rescale.inf 
does not take outlying data values into account. Therefore, if the range of values for a database column 
contains a limited number of extreme values the resulting rescale operation will be skewed in the direction 
of these values.


.SH "COMMAND LINE OPTIONS"
.LP
Parameters
.IP \fItab=database_table_name\fR
Table containing a column linked to category values in an existing raster map.
.IP \fIkey=database_column_name\fR
Column corresponding to category values in an existing raster map.
.IP \fIcol=database_column_name\fR
Column to base rescale operation on which is numeric in type.
.IP \fIcats=value\fR
Number of categories to define in the resulting reclass map.
.IP \fIinput=map\fR
Name of an existing raster file with category values linked to a column in the currently selected databae.
.IP \fIoutput=map\fR
Name of new raster map.
.IP \fIjoin=tab,tabkey,pkey\fR

Tab is the table used to develop the current SQL query. Tabkey is the database column used to relate information in this table with data in the table linked to the GRASS category file. Pkey is the associated column in the table linked to the GRASS category file which is related to tabkey in the current table.

For instance, assume that seco_soil_cats is a table containing column values associated with category values 
in a the GRASS raster file soils. In addition, assume that rsprod is a table containing 
attribute data on the crop production capacity in the same area (prodfav). In this example seco_soil_cats is the table 
associated with the GRASS raster map and grass_cats is the column linking seco_soil_cats to the GRASS category 
file, the table compyld contains the attribute information to base the query/rescale on and it is linked to 
seco_soil_cats via the common column muid. To specify a rescale based on attribute values in the table rsprod: 

	r.rescale.inf tab=rsprod key=grass_cat col=prodfav
.br
	cats=5 nput=seco.soils output=prodfav.rescale 
.br
	join=seco_soil_cats,seco_soil_cats.muid,rsprod.muid


Specifying these conditions would insure that all rows from table rsprod which satisfy the query criteria would be matched with the corresponding rows in table seco_soil_cats, which are then related to the spatial features in the GRASS data layer via the GRASS category values.

This syntax is adequate to accomplish 2 table joins. However, if the query demands joins between more than 2 tables it is advisable to use the -s option [see Alternate Command Line Usage] to read a user prepared query, complete with join requirements, from a file.

.SH BUGS
None known.

.SH "NOTE"
This program requires the Informix database software.

.SH "SEE ALSO"
g.column.inf, g.select.inf, g.stats.inf, g.table.inf, d.rast.inf, d.site.inf, d.vect.inf, d.what.r.inf, d.what.s.inf, d.what.v.inf, r.reclass.inf, v.reclass.inf

.SH AUTHOR
James A. Farley, Wang Song and W. Fredrick Limp
University of Arkansas, CAST