Join Vector Layers using GIS C# Library

Join Vector Layers

Aspose.GIS API lets you to join the vector layers as shown in the code snippet below.

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
//one-to-one left join two layers by 'city' attribute
var options = new JoinOptions
{
    JoinAttributeName = "city",
    TargetAttributeName = "city"
};

using (var main = Drivers.Kml.OpenLayer(Path.Combine(workFolder, "main.kml")))
using (var second = Drivers.Kml.OpenLayer(Path.Combine(workFolder, "second.kml")))
using (var joined = main.Join(second, options))
{
    // read and print joined
    var featuresCount = joined.Count;
    var attributesCount = joined.Attributes.Count;
    var spatialRefSys = joined.SpatialReferenceSystem;
    var code = spatialRefSys == null ? "'no srs'" : spatialRefSys.EpsgCode.ToString();
    var joinedTempValue = joined[0].GetValue("joined_temp");

    Console.WriteLine($"featuresCount: {featuresCount}");
    Console.WriteLine($"attributesCount: {attributesCount}");
    Console.WriteLine($"spatialRefSys: {code}");
    Console.WriteLine($"joinedTempValue: {joinedTempValue}");
}

Join Layer using Few Attributes

Aspose.GIS API lets you to join a few attributes as shown in the code snippet below.

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
//one-to-one left join two layers by 'city' attribute
var options = new JoinOptions
{
    JoinAttributeName = "city",
    TargetAttributeName = "city",

    //define attributes to join
    JoinAttributeNames = new List<string> { "temp", "date" }
};

using (var main = Drivers.Kml.OpenLayer(Path.Combine(workFolder, "main.kml")))
using (var second = Drivers.Kml.OpenLayer(Path.Combine(workFolder, "second.kml")))
using (var joined = main.Join(second, options))
{
    // read and print joined
    var featuresCount = joined.Count;
    var attributesCount = joined.Attributes.Count;
    var spatialRefSys = joined.SpatialReferenceSystem;
    var code = spatialRefSys == null ? "'no srs'" : spatialRefSys.EpsgCode.ToString();

    Console.WriteLine($"featuresCount: {featuresCount}");
    Console.WriteLine($"attributesCount: {attributesCount}");
    Console.WriteLine($"spatialRefSys: {code}");
}

Join Layer using own Comparer

Aspose.GIS API lets you to join a layer using own Comparer as shown in the code snippet below. This approach is good when you need to join data using insensitive strings.

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
//one-to-one left join two layers by 'city' attribute
var options = new JoinOptions
{
    JoinAttributeName = "city",
    TargetAttributeName = "city",

    //use custom comparer
    ConditionComparer = new InsensitiveComparer()
};

using (var main = Drivers.Kml.OpenLayer(Path.Combine(workFolder, "main.kml")))
using (var second = Drivers.Kml.OpenLayer(Path.Combine(workFolder, "second.kml")))
using (var joined = main.Join(second, options))
{
    // read and print joined
    var featuresCount = joined.Count;
    var attributesCount = joined.Attributes.Count;
    var spatialRefSys = joined.SpatialReferenceSystem;
    var code = spatialRefSys == null ? "'no srs'" : spatialRefSys.EpsgCode.ToString();
    var cityValue = joined[4].GetValue("city");
    var joinedCityValue = joined[4].GetValue("joined_city");

    Console.WriteLine($"featuresCount: {featuresCount}");
    Console.WriteLine($"attributesCount: {attributesCount}");
    Console.WriteLine($"spatialRefSys: {code}");
    Console.WriteLine($"cityValue: {cityValue}");
    Console.WriteLine($"joinedCityValue: {joinedCityValue}");
}

Comparer implementation.

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET

        private class InsensitiveComparer : IEqualityComparer<object>
        {
            bool IEqualityComparer<object>.Equals(object x, object y)
            {
                if (x == null || y == null)
                {
                    return x == y;
                }

                var xString = x.ToString();
                var yString = y.ToString();
                return xString.Equals(yString, StringComparison.InvariantCultureIgnoreCase);

            }

            public int GetHashCode(object obj)
            {
                return obj.ToString().ToLower().GetHashCode();
            }
        }