public static void SaveDataView(IChannel ch, IDataSaver saver, IDataView view, Stream stream, bool keepHidden = false)
{
Contracts.CheckValue(ch, nameof(ch));
ch.CheckValue(saver, nameof(saver));
ch.CheckValue(view, nameof(view));
ch.CheckValue(stream, nameof(stream));
var cols = new List <int>();
for (int i = 0; i < view.Schema.ColumnCount; i++)
{
if (!keepHidden && view.Schema.IsHidden(i))
{
continue;
}
var type = view.Schema.GetColumnType(i);
if (saver.IsColumnSavable(type))
{
cols.Add(i);
}
else
{
ch.Info(MessageSensitivity.Schema, "The column '{0}' will not be written as it has unsavable column type.", view.Schema.GetColumnName(i));
}
}
ch.Check(cols.Count > 0, "No valid columns to save");
saver.SaveData(stream, view, cols.ToArray());
}
public bool IsColumnSavable(ColumnType type)
{
_host.CheckValue(type, nameof(type));
// We can't transpose variable length columns at all, so nor can we save them.
if (type.IsVector && !type.IsKnownSizeVector)
{
return(false);
}
// Since we'll be presumably saving vectors of these, attempt to construct
// an artificial vector type out of this. Obviously if you can't make a vector
// out of the items, then you could not save each slot's values.
var itemType = type.ItemType;
var primitiveType = itemType as PrimitiveType;
if (primitiveType == null)
{
return(false);
}
var vectorType = new VectorType(primitiveType, size: 2);
return(_internalSaver.IsColumnSavable(vectorType));
}
