/// <summary>
/// Get a row cursor. The <paramref name="columnNeeded"/> is the active column.
/// The schema of the returned cursor will be the same as the schema of the IDataView, but getting
/// a getter for the other, inactive columns will throw.
/// </summary>
/// <param name="columnNeeded">The column requested by this <see cref="RowCursor"/>, or as otherwise called, the active column.</param>
/// <param name="dv">The <see cref="IDataView"/> containing the <paramref name="columnNeeded"/>.</param>
public static RowCursor GetRowCursor(this IDataView dv, Schema.Column columnNeeded)
{
Contracts.Assert(dv.Schema[columnNeeded.Index].Equals(columnNeeded), $"The requested column named: {columnNeeded.Name}, with index: {columnNeeded.Index} and type: {columnNeeded.Type}" +
$" is not present in the {nameof(IDataView)} where the {nameof(RowCursor)} is being requested.");
return(dv.GetRowCursor(Enumerable.Repeat(columnNeeded, 1)));
}
/// <summary>
/// Returns true iff <paramref name="column"/> has IsNormalized metadata set to true.
/// </summary>
public static bool IsNormalized(this Schema.Column column)
{
var metaColumn = column.Metadata.Schema.GetColumnOrNull((Kinds.IsNormalized));
if (metaColumn == null || !metaColumn.Value.Type.IsBool)
{
return(false);
}
bool value = default;
column.Metadata.GetValue(Kinds.IsNormalized, ref value);
return(value);
}
internal static bool HasKeyValues(this Schema.Column column, int keyCount)
{
if (keyCount == 0)
{
return(false);
}
var metaColumn = column.Metadata.Schema.GetColumnOrNull(Kinds.KeyValues);
return
(metaColumn != null &&
metaColumn.Value.Type.IsVector &&
metaColumn.Value.Type.VectorSize == keyCount &&
metaColumn.Value.Type.ItemType.IsText);
}
internal static bool HasSlotNames(this Schema.Column column, int vectorSize)
{
if (vectorSize == 0)
{
return(false);
}
var metaColumn = column.Metadata.Schema.GetColumnOrNull(Kinds.SlotNames);
return
(metaColumn != null &&
metaColumn.Value.Type.IsVector &&
metaColumn.Value.Type.VectorSize == vectorSize &&
metaColumn.Value.Type.ItemType.IsText);
}
internal ColumnInfo(Schema.Column column, object[] values)
{
Column = column;
Values = values;
}
public static void GetSlotNames(this Schema.Column column, ref VBuffer <ReadOnlyMemory <char> > slotNames) => column.Metadata.GetValue(Kinds.SlotNames, ref slotNames);
/// <summary> /// Returns <c>true</c> if the specified column: /// * is a vector of length N /// * has a SlotNames metadata /// * metadata type is VBuffer<ReadOnlyMemory<char>> of length N /// </summary> public static bool HasSlotNames(this Schema.Column column) => column.Type.IsKnownSizeVector && column.HasSlotNames(column.Type.VectorSize);
/// <summary> /// Returns <c>true</c> if the specified column: /// * is a vector of length N /// * has a SlotNames metadata /// * metadata type is VBuffer<ReadOnlyMemory<char>> of length N /// </summary> public static bool HasSlotNames(this Schema.Column column) => column.Type is VectorType vectorType &&
private static void Add(Dictionary <string, List <Schema.Column> > map, ColumnRole role, Schema.Column column)
{
Contracts.AssertValue(map);
Contracts.AssertNonEmpty(role.Value);
if (!map.TryGetValue(role.Value, out var list))
{
list = new List <Schema.Column>();
map.Add(role.Value, list);
}
list.Add(column);
}
