internal CountTableTransformer(IHostEnvironment env, CountTargetEncodingFeaturizer featurizer, string[] labelClassNames,
int[] seeds, (string outputColumnName, string inputColumnName)[] columns)
public CountTableTransformer Fit(IDataView input)
{
var labelCol = input.Schema.GetColumnOrNull(_labelColumnName);
if (labelCol == null)
{
throw _host.ExceptUserArg(nameof(_labelColumnName), "Label column '{0}' not found", _labelColumnName);
}
CheckLabelType(new RoleMappedData(input, roles: RoleMappedSchema.CreatePair(RoleMappedSchema.ColumnRole.Label, _labelColumnName)), out var labelCardinality);
var labelColumnType = labelCol.GetValueOrDefault().Type;
var labelClassNames = InitLabelClassNames(_host, labelCol.GetValueOrDefault(), labelCardinality);
var n = _columns.Length;
var inputColumns = new DataViewSchema.Column[_columns.Length];
for (int i = 0; i < inputColumns.Length; i++)
{
var col = input.Schema.GetColumnOrNull(_columns[i].InputColumnName);
if (col == null)
{
throw _host.Except($"Could not find column {_columns[i].InputColumnName} in input schema");
}
inputColumns[i] = col.GetValueOrDefault();
}
_host.Assert(_initialCounts != null || _sharedBuilder != null || _builders != null);
MultiCountTableBuilderBase multiBuilder;
if (_initialCounts != null)
{
multiBuilder = _initialCounts.Featurizer.MultiCountTable.ToBuilder(_host, inputColumns, labelCardinality);
}
else if (_builders != null)
{
multiBuilder = new ParallelMultiCountTableBuilder(_host, inputColumns, _builders, labelCardinality);
}
else
{
multiBuilder = new BagMultiCountTableBuilder(_host, inputColumns, _sharedBuilder, labelCardinality);
}
var cols = new List <DataViewSchema.Column>();
foreach (var c in _columns)
{
var col = input.Schema.GetColumnOrNull(c.InputColumnName);
_host.Assert(col.HasValue);
cols.Add(col.Value);
}
TrainTables(input, cols, multiBuilder, labelCol.GetValueOrDefault());
var multiCountTable = multiBuilder.CreateMultiCountTable();
var featurizer = new CountTargetEncodingFeaturizer(_host, _columns.Select(col => col.PriorCoefficient).ToArray(), _columns.Select(col => col.LaplaceScale).ToArray(), labelCardinality, multiCountTable);
return(new CountTableTransformer(_host, featurizer, labelClassNames,
_columns.Select(col => col.Seed).ToArray(), _columns.Select(col => (col.Name, col.InputColumnName)).ToArray()));
}
