User's Guide

AGGRG2

Collapses columns of numbers in an IBIS tabular file into smaller columns using a designated column as the control.

Function:

Collapses columns of numbers in an image based information system (IBIS) tabular file into smaller columns using a designated column as the control. Within the control column each number which is repeated defines one row. There are three methods of collapsing columns:


1.  The first option, which is the default one, deter-
    mines the output value for a column by selecting 
    the maximum value from the column based on the 
    limits defined by the control values.  Column num-
    bers not entered in the AREACOL or SUMCOL parame-
    ters are collapsed by this method.

2.  The second option determines the output value for
    a column by aggregating all the values in a column
    based on the limits defined by the control values.  
    Column numbers specified in the SUMCOL parameter 
    are collapsed by this method.

3.  The third option determines the output value for 
    a column by selecting a value from a column based 
    on the row position of the maximum value from the 
    area key column.  One value is selected for each 
    group of control values.  Column numbers speci-
    fied in the AREACOL parameter are collapsed by 
    this method.

To illustrate the options, a sample case is shown:

                Sample Input  

      Control      Area Key   Sample column to      
       column       column      be collapsed	     
         1            10              2                
         1	      20	      4	      	      
         1	      15	      6	   	      
         2 	      24	      8	  	      
         2	      31	     10		      
         3	      16	     12
         3	      31	     14
         3	      53	     16
         4	      10	     18
         5	      20	     20

 	        Sample Output

      Option 	    Option         Option
        One	     Two	   Three
         6            12              4
        10	      18	     10
        16	      42	     16
        18	      18	     18
        20	      20	     20

Parameters:

INFILE
Input file. Input IBIS tabular file. This file must be sorted on the column specified in CONKEY.

OUTFILE
Output file. Output IBIS tabular file.

CONKEY(1)
Control key column number. This column number is used as a control for the columns to be compressed. Each number repeated in this column will form one row in the output file.

AREAKEY(1)
Area key column number. This column number is used as an area maximum key. The maximum value is found in each index group and stored by row position. This row position is a pointer to the same positions in other columns specified by AREACOL.

AREACOL(0)
Columns collapsed by area method. These are the columns which are collapsed by the method described in option three in the Function description. They are collapsed by selecting one row position for each index group by the maximum key area.

SUMCOL(0)
Columns collapsed by sum method. These are the columns which are collapsed by the method described in option two in the Function description. They are collapsed by aggregating all values for an index group.

Examples:

  1. LAS> aggrg2 infile=input outfile=output conkey=2

    This example collapses the input file by replacing multiple rows with the same value in column 2 by a single row. The value for each column in this output row is determined by choosing the largest value from the multiple input rows.

  2. LAS> aggrg2 infile=input outfile=output conkey=5 sumcol=(3,4)

    The input file is collapsed by replacing multiple rows with the same value in column 5 by a single row. The values for columns 3 and 4 in this output row are determined by adding the values from columns 3 and 4 of the multiple input rows. All the other columns in the output row are determined by the default method which is selecting the largest value from the multiple input rows.

  3. LAS> aggrg2 infile=input outfile=output conkey=3 areakey=4 areacol=(1,2) sumcol=(5,6)

    The input file is collapsed by replacing multiple rows with the same value in column 3 by a single row. The values for columns 1 and 2 in this output row are determined by the row position of the maximum value from the area key column 4. The values for columns 5 and 6 are determined by aggregating the values from the multiple input rows, while the remaining columns are collapsed by the default method.

Description/Algorithm:

After initialization and retrieval of the user-specified parameters, the input IBIS tabular file is opened. The control key and area key columns are retrieved, and the control ranges and maximum areas are determined. The output IBIS file is opened. Each column is then collapsed as specified and the results written to the output file.

Nonfatal Error Message:

  1. [aggrg2-close] Error closing <XXXXX> file

    An error was encountered while closing the <XXXXX> file. The data may still be valid.

Fatal Error Messages:

  1. [aggrg2-fatal] Fatal error encountered

    A fatal error was encountered during processing. The output IBIS tabular file may or may not be valid. The message that is displayed immediately preceding this message is the specific error that was encountered.

  2. [aggrg2-open] Error opening <XXX> file

    An error was encountered while trying to open the specified file.

  3. [aggrg2-read] Error reading input file

    An error was encountered while trying to read from the specified IBIS tabular file.

  4. [aggrg2-write] Error writing output file

    An error was encountered while trying to write to the specified IBIS tabular file.

User Note:

  1. The input IBIS tabular file must be sorted on the column used as the control column. If the file is not already sorted in this way, the routine MTBSORT can be used to do this.