Content Comparison

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The remaining processes are completed in ArcGIS, regardless of whether ArcGIS or ET GeoWizards was used for the creation of the line shapefile.

• Add
the following
• fields to the output boundary polyline shapefile
:
• LEFT_A2, LEFT_A1, LEFT_A0, RIGHT_A0, RIGHT_A1, RIGHT_A2 (if the input polygon shapefile is administrative level 3), with the field type (typically TEXT) and length being compatible with the input polygon shapefile administrative level 3 P-code field.  Note that the necessary fields correspond to the administrative levels above the input polygon shapefile.  
• AdminLevel or similar, type integer
• as follows:

• Right-click the output polyline shapefile > "Joins & Relates" > "Join..." (or properties > Joins & Relates) and provide the Join Data as follows:
• "What do you want to join to this layer?" = Join attributes from a table
• "Choose the field in this layer that the join will be based on:" = LEFT_FID
• "Choose the table to join to this layer, or load the table from disk:"  = (the input polygon shapefile)
• "Choose the field in the table to base the join on:" = OBJECTID (or FID)
• (Optionally) Click the ‘Validate Join’ button.  Do not expect all records to match - because the ‘left’ side of all exterior lines will have no neighboring polygon.  Do not worry if you receive a “Field names that match reserved words should not be used in database schema and can cause the join to fail. The following fields match reserved words….” message
• 
• Click ‘OK’
• Set a definition query to exclude the ‘NULL’ values of the input polygon shapefile.  (This might refer to a .FID or a .OBJECTID)

• This should reveal the internal boundary lines.  (External boundary lines are deselected because they border the outside of the country and received a 'NULL' left polygon identifyier.  THIS WORDING CAN BE IMPROVED.)
• Open the output polyline shapefile attribute table
• Use the Field Calculator to calculate all the LEFT_Ax values (for the LEFT_Ax fileds recently added to the polyline shapefile ) equal to the coresponding administrative levels of the polygon shapefile.

• the LEFT_A2 = adm2code, that is, each LEFT_A2 value will be made equal to the adm2code of the joined input polygon shapefile feature.

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