private static IDataView AppendFloatMapper <TInput>(IHostEnvironment env, IChannel ch, IDataView input,
string col, KeyType type, int seed)
{
// Any key is convertible to ulong, so rather than add special case handling for all possible
// key-types we just upfront convert it to the most general type (ulong) and work from there.
KeyType dstType = new KeyType(DataKind.U8, type.Min, type.Count, type.Contiguous);
bool identity;
var converter = Conversions.Instance.GetStandardConversion <TInput, ulong>(type, dstType, out identity);
var isNa = Conversions.Instance.GetIsNAPredicate <TInput>(type);
ulong temp = 0;
ValueMapper <TInput, Single> mapper;
if (seed == 0)
{
mapper =
(ref TInput src, ref Single dst) =>
{
if (isNa(ref src))
{
dst = Single.NaN;
return;
}
converter(ref src, ref temp);
dst = (Single)(temp - 1);
};
}
else
{
ch.Check(type.Count > 0, "Label must be of known cardinality.");
int[] permutation = Utils.GetRandomPermutation(RandomUtils.Create(seed), type.Count);
mapper =
(ref TInput src, ref Single dst) =>
{
if (isNa(ref src))
{
dst = Single.NaN;
return;
}
converter(ref src, ref temp);
dst = (Single)permutation[(int)(temp - 1)];
};
}
return(LambdaColumnMapper.Create(env, "Key to Float Mapper", input, col, col, type, NumberType.Float, mapper));
}
private IDataView ExtractRelevantIndex(IDataView data)
{
IDataView output = data;
for (int i = 0; i < data.Schema.ColumnCount; i++)
{
var type = data.Schema.GetColumnType(i);
if (type.IsKnownSizeVector && type.ItemType == NumberType.R8)
{
var name = data.Schema.GetColumnName(i);
var index = _index ?? type.VectorSize / 2;
output = LambdaColumnMapper.Create(Host, "Quantile Regression", output, name, name, type, NumberType.R8,
(ref VBuffer <Double> src, ref Double dst) => dst = src.GetItemOrDefault(index));
}
}
return(output);
}
private static IDataView AddVarLengthColumn <TSrc>(IHostEnvironment env, IDataView idv, string variableSizeVectorColumnName, ColumnType typeSrc)
{
return(LambdaColumnMapper.Create(env, "ChangeToVarLength", idv, variableSizeVectorColumnName,
variableSizeVectorColumnName + "_VarLength", typeSrc, new VectorType(typeSrc.ItemType.AsPrimitive),
(ref VBuffer <TSrc> src, ref VBuffer <TSrc> dst) => src.CopyTo(ref dst)));
}
