public InputRow(IHostEnvironment env, InternalSchemaDefinition schemaDef)
: base(env, SchemaExtensions.MakeSchema(GetSchemaColumns(schemaDef)), schemaDef, MakePeeks(schemaDef), c => true)
{
_position = -1;
}
/// <summary>
/// Create a new instance of <see cref="ColumnBindings"/>.
/// </summary>
/// <param name="input">The input schema that we're adding columns to.</param>
/// <param name="addedColumns">The columns being added.</param>
public ColumnBindings(DataViewSchema input, DataViewSchema.DetachedColumn[] addedColumns)
{
Contracts.CheckValue(input, nameof(input));
Contracts.CheckValue(addedColumns, nameof(addedColumns));
InputSchema = input;
// Construct the indices.
var indices = new List <int>();
var namesUsed = new HashSet <string>();
for (int i = 0; i < input.Count; i++)
{
namesUsed.Add(input[i].Name);
indices.Add(i);
}
for (int i = 0; i < addedColumns.Length; i++)
{
string name = addedColumns[i].Name;
if (namesUsed.Add(name))
{
// New name. Append to the end.
indices.Add(~i);
}
else
{
// Old name. Find last instance and add after it.
for (int j = indices.Count - 1; j >= 0; j--)
{
var colName = indices[j] >= 0 ? input[indices[j]].Name : addedColumns[~indices[j]].Name;
if (colName == name)
{
indices.Insert(j + 1, ~i);
break;
}
}
}
}
Contracts.Assert(indices.Count == addedColumns.Length + input.Count);
// Create the output schema.
var schemaColumns = indices.Select(idx => idx >= 0 ? new DataViewSchema.DetachedColumn(input[idx]) : addedColumns[~idx]);
Schema = SchemaExtensions.MakeSchema(schemaColumns);
// Memorize column maps.
_colMap = indices.ToArray();
var addedIndices = new int[addedColumns.Length];
for (int i = 0; i < _colMap.Length; i++)
{
int colIndex = _colMap[i];
if (colIndex < 0)
{
Contracts.Assert(addedIndices[~colIndex] == 0);
addedIndices[~colIndex] = i;
}
}
AddedColumnIndices = addedIndices.AsReadOnly();
}
