/// <summary>
/// Trains and returns a <see cref="ITransformer"/>.
/// </summary>
public ITransformer Fit(IDataView input)
{
_host.CheckValue(input, nameof(input));
int[] colSizes;
var scores = CountFeatureSelectionUtils.Train(_host, input, _columns.Select(column => column.InputColumnName).ToArray(), out colSizes);
var size = _columns.Length;
using (var ch = _host.Start("Dropping Slots"))
{
// If no slots should be dropped from a column, use copy column to generate the corresponding output column.
SlotsDroppingTransformer.ColumnOptions[] dropSlotsColumns;
(string outputColumnName, string inputColumnName)[] copyColumnsPairs;
/// <summary>
/// Create method corresponding to SignatureDataTransform.
/// </summary>
public static IDataTransform Create(IHostEnvironment env, Arguments args, IDataView input)
{
Contracts.CheckValue(env, nameof(env));
var host = env.Register(RegistrationName);
host.CheckValue(args, nameof(args));
host.CheckValue(input, nameof(input));
host.CheckUserArg(Utils.Size(args.Column) > 0, nameof(args.Column));
host.CheckUserArg(args.Count > 0, nameof(args.Count));
int[] colSizes;
var scores = CountFeatureSelectionUtils.Train(host, input, args.Column, out colSizes);
var size = args.Column.Length;
using (var ch = host.Start("Dropping Slots"))
{
int[] selectedCount;
var columns = CreateDropSlotsColumns(args, size, scores, out selectedCount);
if (columns.Count <= 0)
{
ch.Info("No features are being dropped.");
return(NopTransform.CreateIfNeeded(host, input));
}
for (int i = 0; i < selectedCount.Length; i++)
{
ch.Info(MessageSensitivity.Schema, "Selected {0} slots out of {1} in column '{2}'", selectedCount[i], colSizes[i], args.Column[i]);
}
ch.Info("Total number of slots selected: {0}", selectedCount.Sum());
var dsArgs = new DropSlotsTransform.Arguments();
dsArgs.Column = columns.ToArray();
return(new DropSlotsTransform(host, dsArgs, input));
}
}