% @(#)classiimag.hlq	17.1.1.1 (ESO-IPG) 01/25/02 17:50:00
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%.COPYRIGHT  (c)  1993 European Southern Observatory
%.IDENT      apply_rule.hlq
%.AUTHOR     05-MAY-93, IPG/ESO
%.KEYWORDS   MIDAS, help files, 
%.PURPOSE    On-line help file for the command: CLASSIFY/IMAGE
%.VERSION    1.0  MP : Creation, 05-MAY-93
%----------------------------------------------------------------
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SECTION./IMAG
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CLASSIFY/IMAGE   				   MP  05-MAY-93
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CLASSIFY/IMAGE  table descr outcol outchar 
     classify images according to one or several rules. 	
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Purpose:    
           classify images according to one or several classification rules.
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Syntax:     
            CLASSIFY/IMAGE table descr outcol outchar (a)
            CLASSIFY/IMAGE table classtable (b)
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            table       =  name of the Observation Summary Table
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\ap\pa
            descr       =  name of the descriptor containing the classification
                           rule
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\ap\pa
            classtable  =  name of the table containing the classification
                           parameters followed by the extension of the file
                           (.tbl)
 \\
\ap\pa
            outcol      =  reference of the output column in the OST. Will
                           be created with type C*8 if it doesn't exist.
                           This column  will contain the character string 
                           'outchar'
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\ap\pa
            outchar     =  character string for flagging the rows that satisfy 
                           the classification rule
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\ap\sa
See also: 
            CREATE/CRULE
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Note:       
            1) A classification rule is a selection criterion for the 
               SELECT/TABLE command. The classification process selects the
               rows satisfying the criteria and flags them with a given 
               character string that is stored in the output column of the OST. 
               The different rules are applied sequentially. Descriptors 
               containing suitable classification rules may be created with
               the command CREATE/CRULE   

            2) The string outchar may contain the special character \&
               which will
               be interpreted as a wild card replacement character, i.e 
               if  outchar is substring\&no, the final character string will
               be built by finding the no-th occurence of the "*" character in 
               the classification rule, reading the contents of the
               corresponding column and appending the result to substring.
               For instance, one has created the  classification rule
               WFIB for flagging all exposures obtained in the blue arm of EMMI
               using the Wide-field imaging  mode. One wants to flag these 
               exposures with a character string containing the filter number
               that has been used.
               The WFIB descriptor may in natural language be:
               "Find all frames exposed in the blue arm using a filter and 
                no grating" 
               The translated selected criterion looks as follows:
               :FILTB_ID.EQ."*".AND.:FILTB_TYP.EQ."FILTER*".AND.:GRATB_ID.EQ.""
               The command
               CLASSIFY/IMAGE ntt WFIB :OPATH FB\&1  
               will flag all files from the table ntt which satisfy this 
               selection criterion and will store in the column OPATH the
               character string obtained by appending to the string FB
               the contents of  column :FILTB_ID

     
           3)  When  option b is chosen,  a table classtable containing
               three character columns :DESCR, :OUTCOL and :OUTCHAR must be 
               provided. Each row of this table should contain respectively
               the name of one classification rule descriptor, the label
               to the output column in the OST and the character string for
               flagging the rows satisfying the corresponding rule. 

 \\
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Examples:
\ex
            CLASSIFY/IMAGE  ost SCI :EXPTYPE SCI
            will flag all files from the table ost classified as scientific
            exposure with the character string SCI. The classification rule
            to be applied is taken from descriptor SCI of table ost.
\xe \sxe