/// <summary>
/// 通过<see cref="DataFrancis.IDataView"/>来加载机器学习数据
/// </summary>
/// <param name="datas">待加载的数据</param>
/// <returns></returns>
public static IDataViewML ToIDataView(this IDataViewF datas)
{
var dataView = datas.ToArray().ToIDirectView();
var file = ToolPerfo.CreateTemporaryFile(@"txt").Path;
CreateDataObj.PipeFromFile(file, "\t", "null").DataAdd(dataView, default);
var op = new TextLoader.Options()
{
HasHeader = true,
Separators = new[] { '\t' },
Columns = GetColumn(dataView).ToArray()
};
return(ToolML.Context.Data.LoadFromTextFile(file, op));
}
/// <summary>
/// 读取<see cref="IDataReader"/>中的全部内容
/// </summary>
/// <param name="Reader">待读取的<see cref="IDataReader"/></param>
/// <returns>枚举流中内容的枚举器</returns>
public static IEnumerable <IData> ToDatas(this IDataReader Reader)
{
var Schema = Reader.GetSchemaTable().Rows.OfType <DataRow>().ToArray();
var Titles = Schema.Select(x => x["ColumnName"].ToString()).ToArray();
var Length = Titles.Length;
while (Reader.Read())
{
var Values = new object?[Length];
Reader.GetValues(Values);
yield return(CreateDataObj.Data(Titles.Zip(Values.Select(x => x is DBNull ? null : x)).ToArray()));
}
if (Reader.NextResult())
{
throw new NotSupportedException("为保证数据架构的一致性，同一个读取器不能返回两个表");
}
}
/*对IDirect的反序列化遵循以下原则：
#对于数字类型，反序列化为System.Num
#对于布尔类型，反序列化为Boolean
#对于字符串，如果它可以被解释为DateTime，TimeOffset或Guid，
* 则将其反序列化为对应类型，否则反序列化为String
#对于集合，一律反序列化为数组
#对于除此以外的复杂对象，一律反序列化为IDirect，
* 它的键值对对应对象的属性和值*/
#endregion
#region 辅助方法
#region 反序列化为IDirect
/// <summary>
/// 读取<see cref="Utf8JsonReader"/>的对象部分，
/// 并将其反序列化为<see cref="IDirect"/>
/// </summary>
/// <param name="reader">待读取的<see cref="Utf8JsonReader"/></param>
/// <returns></returns>
private IDirect ReadDirect(ref Utf8JsonReader reader)
{
var link = new LinkedList <(string, object?)>();
while (reader.Read())
{
switch (reader.TokenType)
{
case JsonTokenType.None or JsonTokenType.Comment or JsonTokenType.StartObject:
break;
case JsonTokenType.EndObject:
return(CreateDataObj.Data(link.ToArray()));
case JsonTokenType.PropertyName:
link.AddLast((reader.GetString() !, ReadObject(ref reader))); break;
case var type:
throw new JsonException($"未识别{type}类型的令牌");
}
}
throw new JsonException($"读取器已到达末尾，但是没有找到{JsonTokenType.EndObject}令牌");
}
/// <summary> /// 将<see cref="Microsoft.ML.IDataView"/>转换为<see cref="DataFrancis.IDataView"/> /// </summary> /// <param name="data">待转换的<see cref="IDataView"/></param> /// <param name="maxRows">读取的最大列数，如果这个值过大，可能会对性能产生影响，默认为全部读取</param> /// <returns></returns> public static IDataViewF ToIData(this IDataViewML data, int maxRows = int.MaxValue) => CreateDataObj.DataView(data.Preview(maxRows).RowView.Select(x => CreateDataObj.Data(x.Values, true)).ToArray());
