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GetFeaturesByColumnValue

#1

Hi,


I am trying to add multiple features with different values to a collection.  I am succeeding in this, buy by making multiple passes through the dbf/shp file.  This is extremely inefficient and I am looking for a way to scan the dbf/shp file only once and pull out the features i want based on one of multiple possible values instead of having to scan through once for every unique value.


Code below, and thank you,


Eric


 


 


 



public LayerOverlay defineSSA(ShapeFileFeatureLayer shapefilelayer)
        {
            Collection<Feature> SSAZipCodes = new Collection<Feature>();

            shapefilelayer.Open();
            SSAZipCodes.Add(shapefilelayer.QueryTools.GetFeaturesByColumnValue("ZCTA5CE10", "95814")[0]);
            SSAZipCodes.Add(shapefilelayer.QueryTools.GetFeaturesByColumnValue("ZCTA5CE10", "95816")[0]);
            SSAZipCodes.Add(shapefilelayer.QueryTools.GetFeaturesByColumnValue("ZCTA5CE10", "95811")[0]);
            SSAZipCodes.Add(shapefilelayer.QueryTools.GetFeaturesByColumnValue("ZCTA5CE10", "95815")[0]);
            SSAZipCodes.Add(shapefilelayer.QueryTools.GetFeaturesByColumnValue("ZCTA5CE10", "95817")[0]);
            SSAZipCodes.Add(shapefilelayer.QueryTools.GetFeaturesByColumnValue("ZCTA5CE10", "95818")[0]);
            SSAZipCodes.Add(shapefilelayer.QueryTools.GetFeaturesByColumnValue("ZCTA5CE10", "95819")[0]);
            SSAZipCodes.Add(shapefilelayer.QueryTools.GetFeaturesByColumnValue("ZCTA5CE10", "95834")[0]);
            SSAZipCodes.Add(shapefilelayer.QueryTools.GetFeaturesByColumnValue("ZCTA5CE10", "95822")[0]);
            SSAZipCodes.Add(shapefilelayer.QueryTools.GetFeaturesByColumnValue("ZCTA5CE10", "95820")[0]);
            SSAZipCodes.Add(shapefilelayer.QueryTools.GetFeaturesByColumnValue("ZCTA5CE10", "95826")[0]);
            SSAZipCodes.Add(shapefilelayer.QueryTools.GetFeaturesByColumnValue("ZCTA5CE10", "95691")[0]);
            SSAZipCodes.Add(shapefilelayer.QueryTools.GetFeaturesByColumnValue("ZCTA5CE10", "95838")[0]);
            SSAZipCodes.Add(shapefilelayer.QueryTools.GetFeaturesByColumnValue("ZCTA5CE10", "95825")[0]);
            SSAZipCodes.Add(shapefilelayer.QueryTools.GetFeaturesByColumnValue("ZCTA5CE10", "95821")[0]);
            SSAZipCodes.Add(shapefilelayer.QueryTools.GetFeaturesByColumnValue("ZCTA5CE10", "95833")[0]);
            SSAZipCodes.Add(shapefilelayer.QueryTools.GetFeaturesByColumnValue("ZCTA5CE10", "95605")[0]);
            shapefilelayer.Close();

            AreaStyle SSAStyle = new AreaStyle();
            SSAStyle.OutlinePen.Color = GeoColor.StandardColors.Blue;

            InMemoryFeatureLayer ServiceAreaLayer = new InMemoryFeatureLayer();
            ServiceAreaLayer.ZoomLevelSet.ZoomLevel01.DefaultAreaStyle = SSAStyle;
            ServiceAreaLayer.ZoomLevelSet.ZoomLevel01.ApplyUntilZoomLevel = ApplyUntilZoomLevel.Level20;

            MultipolygonShape PSAPolygon = PolygonShape.Union(SSAZipCodes);
            Feature SSA = new Feature(PSAPolygon);

            ServiceAreaLayer.InternalFeatures.Add(SSA);

            LayerOverlay SSAOverlay = new LayerOverlay();
            SSAOverlay.IsBaseOverlay = false;
            SSAOverlay.Layers.Add(ServiceAreaLayer);

            return SSAOverlay;
        }


#2

Eric, 
  
 Thanks for your questions! 
  
 I reviewed your code and think it was correct, you mentioned you just want to scan the dbf once to get all of the unique value,  
 currently we don’t have the API to support it, for example , the GetFeaturesByColumnValue API would return all of the possible results, the logic is that it would loop though all of the dbf recrods and filter the results to the list. If you have the unique value for a column, you have to do the operation for each unique value. 
  
 Thanks, 
  
 Scott,