DataOperationsCatalog.FilterRowsByColumn Método
Definición
Importante
Parte de la información hace referencia a la versión preliminar del producto, que puede haberse modificado sustancialmente antes de lanzar la versión definitiva. Microsoft no otorga ninguna garantía, explícita o implícita, con respecto a la información proporcionada aquí.
Filtre el conjunto de datos por los valores de una columna numérica.
public Microsoft.ML.IDataView FilterRowsByColumn (Microsoft.ML.IDataView input, string columnName, double lowerBound = -∞, double upperBound = ∞);
member this.FilterRowsByColumn : Microsoft.ML.IDataView * string * double * double -> Microsoft.ML.IDataView
Public Function FilterRowsByColumn (input As IDataView, columnName As String, Optional lowerBound As Double = -∞, Optional upperBound As Double = ∞) As IDataView
Parámetros
- input
- IDataView
Los datos de entrada.
- columnName
- String
Nombre de una columna que se va a usar para el filtrado.
- lowerBound
- Double
Límite inferior inclusivo.
- upperBound
- Double
Límite superior exclusivo.
Devoluciones
Ejemplos
using System;
using System.Collections.Generic;
using Microsoft.ML;
namespace Samples.Dynamic
{
public static class FilterRowsByColumn
{
// // Sample class showing how to filter out some rows in
// IDataView.
public static void Example()
{
// Create a new context for ML.NET operations. It can be used for
// exception tracking and logging, as a catalog of available
// operations and as the source of randomness.
var mlContext = new MLContext();
// Get a small dataset as an IEnumerable.
var enumerableOfData = GetSampleTemperatureData(10);
var data = mlContext.Data.LoadFromEnumerable(enumerableOfData);
// Before we apply a filter, examine all the records in the dataset.
Console.WriteLine($"Date\tTemperature");
foreach (var row in enumerableOfData)
{
Console.WriteLine(
$"{row.Date.ToString("d")}\t{row.Temperature}");
}
Console.WriteLine();
// Expected output:
// Date Temperature
// 1/2/2012 36
// 1/3/2012 36
// 1/4/2012 34
// 1/5/2012 35
// 1/6/2012 35
// 1/7/2012 39
// 1/8/2012 40
// 1/9/2012 35
// 1/10/2012 30
// 1/11/2012 29
// Filter the data by the values of the temperature. The lower bound is
// inclusive, the upper exclusive.
var filteredData = mlContext.Data
.FilterRowsByColumn(data, columnName: "Temperature",
lowerBound: 34, upperBound: 37);
// Look at the filtered data and observe that values outside [34,37)
// have been dropped.
var enumerable = mlContext.Data
.CreateEnumerable<SampleTemperatureData>(filteredData,
reuseRowObject: true);
Console.WriteLine($"Date\tTemperature");
foreach (var row in enumerable)
{
Console.WriteLine(
$"{row.Date.ToString("d")}\t{row.Temperature}");
}
// Expected output:
// Date Temperature
// 1/2/2012 36
// 1/3/2012 36
// 1/4/2012 34
// 1/5/2012 35
// 1/6/2012 35
// 1/9/2012 35
}
private class SampleTemperatureData
{
public DateTime Date { get; set; }
public float Temperature { get; set; }
}
/// <summary>
/// Get a fake temperature dataset.
/// </summary>
/// <param name="exampleCount">The number of examples to return.</param>
/// <returns>An enumerable of <see cref="SampleTemperatureData"/>.</returns>
private static IEnumerable<SampleTemperatureData> GetSampleTemperatureData(
int exampleCount)
{
var rng = new Random(1234321);
var date = new DateTime(2012, 1, 1);
float temperature = 39.0f;
for (int i = 0; i < exampleCount; i++)
{
date = date.AddDays(1);
temperature += rng.Next(-5, 5);
yield return new SampleTemperatureData
{
Date = date,
Temperature =
temperature
};
}
}
}
}
Comentarios
Mantenga solo las filas que cumplan la condición de intervalo: el valor de la columna columnName
debe estar entre lowerBound
(inclusivo) y upperBound
(exclusivo).