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GroupBy.cs
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GroupBy.cs
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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
namespace Microsoft.Data.Analysis
{
/// <summary>
/// A GroupBy class that is typically the result of a DataFrame.GroupBy call.
/// It holds information to perform typical aggregation ops on it.
/// </summary>
public abstract class GroupBy
{
/// <summary>
/// Compute the number of non-null values in each group
/// </summary>
/// <returns></returns>
public abstract DataFrame Count(params string[] columnNames);
/// <summary>
/// Return the first value in each group
/// </summary>
/// <returns></returns>
public abstract DataFrame First(params string[] columnNames);
/// <summary>
/// Returns the first <paramref name="numberOfRows"/> rows of each group
/// </summary>
/// <param name="numberOfRows"></param>
/// <returns></returns>
public abstract DataFrame Head(int numberOfRows);
/// <summary>
/// Returns the last <paramref name="numberOfRows"/> rows of each group
/// </summary>
/// <param name="numberOfRows"></param>
/// <returns></returns>
public abstract DataFrame Tail(int numberOfRows);
/// <summary>
/// Compute the max of group values
/// </summary>
/// <param name="columnNames">The columns to find the max of. A default value finds the max of all columns</param>
public abstract DataFrame Max(params string[] columnNames);
/// <summary>
/// Compute the min of group values
/// </summary>
/// <param name="columnNames">The columns to find the min of. A default value finds the min of all columns</param>
public abstract DataFrame Min(params string[] columnNames);
/// <summary>
/// Compute the product of group values
/// </summary>
/// <param name="columnNames">The columns to find the product of. A default value finds the product of all columns</param>
public abstract DataFrame Product(params string[] columnNames);
/// <summary>
/// Compute the sum of group values
/// </summary>
/// <param name="columnNames">The columns to sum. A Default value sums up all columns</param>
public abstract DataFrame Sum(params string[] columnNames);
/// <summary>
/// Compute the mean of group values
/// </summary>
/// <param name="columnNames">The columns to find the mean of. A Default value finds the mean of all columns</param>
public abstract DataFrame Mean(params string[] columnNames);
}
public class GroupBy<TKey> : GroupBy
{
#region Internal class that implements IGrouping LINQ interface
private class Grouping : IGrouping<TKey, DataFrameRow>
{
private readonly TKey _key;
private readonly IEnumerable<DataFrameRow> _rows;
public Grouping(TKey key, IEnumerable<DataFrameRow> rows)
{
_key = key;
_rows = rows;
}
public TKey Key => _key;
public IEnumerator<DataFrameRow> GetEnumerator()
{
return _rows.GetEnumerator();
}
IEnumerator IEnumerable.GetEnumerator()
{
return _rows.GetEnumerator();
}
}
#endregion
private readonly int _groupByColumnIndex;
private readonly IDictionary<TKey, ICollection<long>> _keyToRowIndicesMap;
private readonly DataFrame _dataFrame;
public GroupBy(DataFrame dataFrame, int groupByColumnIndex, IDictionary<TKey, ICollection<long>> keyToRowIndices)
{
if (dataFrame.Columns.Count < groupByColumnIndex || groupByColumnIndex < 0)
throw new ArgumentException(nameof(groupByColumnIndex));
_groupByColumnIndex = groupByColumnIndex;
_keyToRowIndicesMap = keyToRowIndices ?? throw new ArgumentException(nameof(keyToRowIndices));
_dataFrame = dataFrame;
}
private delegate void ColumnDelegate(int columnIndex, long rowIndex, ICollection<long> rows, TKey key, bool firstGroup);
private delegate void GroupByColumnDelegate(long rowNumber, TKey key);
private void EnumerateColumnsWithRows(GroupByColumnDelegate groupByColumnDelegate, ColumnDelegate columnDelegate, params string[] columnNames)
{
long rowNumber = 0;
bool firstGroup = true;
foreach (KeyValuePair<TKey, ICollection<long>> pairs in _keyToRowIndicesMap)
{
groupByColumnDelegate(rowNumber, pairs.Key);
ICollection<long> rows = pairs.Value;
IEnumerable<string> columns = columnNames;
if (columnNames == null || columnNames.Length == 0)
columns = _dataFrame.GetColumnNames();
// Assuming that the dataframe has not been modified after the groupby call
foreach (string columnName in columns)
{
int columnIndex = _dataFrame.Columns.IndexOf(columnName);
columnDelegate(columnIndex, rowNumber, rows, pairs.Key, firstGroup);
}
firstGroup = false;
rowNumber++;
}
}
public override DataFrame Count(params string[] columnNames)
{
DataFrame ret = new DataFrame();
PrimitiveDataFrameColumn<long> empty = new PrimitiveDataFrameColumn<long>("Empty");
DataFrameColumn firstColumn = _dataFrame.Columns[_groupByColumnIndex].Clone(empty);
ret.Columns.Insert(ret.Columns.Count, firstColumn);
GroupByColumnDelegate groupByColumnDelegate = new GroupByColumnDelegate((long rowIndex, TKey key) =>
{
firstColumn.Resize(rowIndex + 1);
firstColumn[rowIndex] = key;
});
ColumnDelegate columnDelegate = new ColumnDelegate((int columnIndex, long rowIndex, ICollection<long> rowEnumerable, TKey key, bool firstGroup) =>
{
if (columnIndex == _groupByColumnIndex)
return;
DataFrameColumn column = _dataFrame.Columns[columnIndex];
long count = 0;
foreach (long row in rowEnumerable)
{
if (column[row] != null)
count++;
}
DataFrameColumn retColumn;
if (firstGroup)
{
retColumn = new PrimitiveDataFrameColumn<long>(column.Name);
ret.Columns.Insert(ret.Columns.Count, retColumn);
}
else
{
// Assuming non duplicate column names
retColumn = ret.Columns[column.Name];
}
retColumn.Resize(rowIndex + 1);
retColumn[rowIndex] = count;
});
EnumerateColumnsWithRows(groupByColumnDelegate, columnDelegate, columnNames);
ret.SetTableRowCount(firstColumn.Length);
return ret;
}
public override DataFrame First(params string[] columnNames)
{
DataFrame ret = new DataFrame();
PrimitiveDataFrameColumn<long> empty = new PrimitiveDataFrameColumn<long>("Empty");
DataFrameColumn firstColumn = _dataFrame.Columns[_groupByColumnIndex].Clone(empty);
ret.Columns.Insert(ret.Columns.Count, firstColumn);
GroupByColumnDelegate groupByColumnDelegate = new GroupByColumnDelegate((long rowIndex, TKey key) =>
{
firstColumn.Resize(rowIndex + 1);
firstColumn[rowIndex] = key;
});
ColumnDelegate columnDelegate = new ColumnDelegate((int columnIndex, long rowIndex, ICollection<long> rowEnumerable, TKey key, bool firstGroup) =>
{
if (columnIndex == _groupByColumnIndex)
return;
DataFrameColumn column = _dataFrame.Columns[columnIndex];
foreach (long row in rowEnumerable)
{
DataFrameColumn retColumn;
if (firstGroup)
{
retColumn = column.Clone(empty);
ret.Columns.Insert(ret.Columns.Count, retColumn);
}
else
{
// Assuming non duplicate column names
retColumn = ret.Columns[column.Name];
}
retColumn.Resize(rowIndex + 1);
retColumn[rowIndex] = column[row];
break;
}
});
EnumerateColumnsWithRows(groupByColumnDelegate, columnDelegate, columnNames);
ret.SetTableRowCount(firstColumn.Length);
return ret;
}
public override DataFrame Head(int numberOfRows)
{
DataFrame ret = new DataFrame();
PrimitiveDataFrameColumn<long> empty = new PrimitiveDataFrameColumn<long>("Empty");
DataFrameColumn firstColumn = _dataFrame.Columns[_groupByColumnIndex].Clone(empty);
ret.Columns.Insert(ret.Columns.Count, firstColumn);
GroupByColumnDelegate groupByColumnDelegate = new GroupByColumnDelegate((long rowIndex, TKey key) =>
{
});
ColumnDelegate columnDelegate = new ColumnDelegate((int columnIndex, long rowIndex, ICollection<long> rowEnumerable, TKey key, bool firstGroup) =>
{
if (columnIndex == _groupByColumnIndex)
return;
DataFrameColumn column = _dataFrame.Columns[columnIndex];
long count = 0;
bool firstRow = true;
foreach (long row in rowEnumerable)
{
if (count < numberOfRows)
{
DataFrameColumn retColumn;
if (firstGroup && firstRow)
{
firstRow = false;
retColumn = column.Clone(empty);
ret.Columns.Insert(ret.Columns.Count, retColumn);
}
else
{
// Assuming non duplicate column names
retColumn = ret.Columns[column.Name];
}
long retColumnLength = retColumn.Length;
retColumn.Resize(retColumnLength + 1);
retColumn[retColumnLength] = column[row];
if (firstColumn.Length <= retColumnLength)
{
firstColumn.Resize(retColumnLength + 1);
}
firstColumn[retColumnLength] = key;
count++;
}
if (count == numberOfRows)
break;
}
});
EnumerateColumnsWithRows(groupByColumnDelegate, columnDelegate);
ret.SetTableRowCount(firstColumn.Length);
return ret;
}
public override DataFrame Tail(int numberOfRows)
{
DataFrame ret = new DataFrame();
PrimitiveDataFrameColumn<long> empty = new PrimitiveDataFrameColumn<long>("Empty");
DataFrameColumn firstColumn = _dataFrame.Columns[_groupByColumnIndex].Clone(empty);
ret.Columns.Insert(ret.Columns.Count, firstColumn);
GroupByColumnDelegate groupByColumnDelegate = new GroupByColumnDelegate((long rowIndex, TKey key) =>
{
});
ColumnDelegate columnDelegate = new ColumnDelegate((int columnIndex, long rowIndex, ICollection<long> rowEnumerable, TKey key, bool firstGroup) =>
{
if (columnIndex == _groupByColumnIndex)
return;
DataFrameColumn column = _dataFrame.Columns[columnIndex];
long count = 0;
bool firstRow = true;
ICollection<long> values = _keyToRowIndicesMap[key];
int numberOfValues = values.Count;
foreach (long row in rowEnumerable)
{
if (count >= numberOfValues - numberOfRows)
{
DataFrameColumn retColumn;
if (firstGroup && firstRow)
{
firstRow = false;
retColumn = column.Clone(empty);
ret.Columns.Insert(ret.Columns.Count, retColumn);
}
else
{
// Assuming non duplicate column names
retColumn = ret.Columns[column.Name];
}
long retColumnLength = retColumn.Length;
if (firstColumn.Length <= retColumnLength)
{
firstColumn.Resize(retColumnLength + 1);
firstColumn[retColumnLength] = key;
}
retColumn.Resize(retColumnLength + 1);
retColumn[retColumnLength] = column[row];
}
count++;
}
});
EnumerateColumnsWithRows(groupByColumnDelegate, columnDelegate);
ret.SetTableRowCount(firstColumn.Length);
return ret;
}
private DataFrameColumn ResizeAndInsertColumn(int columnIndex, long rowIndex, bool firstGroup, DataFrame ret, PrimitiveDataFrameColumn<long> empty, Func<string, DataFrameColumn> getColumn = null)
{
if (columnIndex == _groupByColumnIndex)
return null;
DataFrameColumn column = _dataFrame.Columns[columnIndex];
DataFrameColumn retColumn;
if (firstGroup)
{
retColumn = getColumn == null ? column.Clone(empty) : getColumn(column.Name);
ret.Columns.Insert(ret.Columns.Count, retColumn);
}
else
{
// Assuming unique column names
retColumn = ret.Columns[column.Name];
}
retColumn.Resize(rowIndex + 1);
return retColumn;
}
public override DataFrame Max(params string[] columnNames)
{
DataFrame ret = new DataFrame();
PrimitiveDataFrameColumn<long> empty = new PrimitiveDataFrameColumn<long>("Empty");
DataFrameColumn firstColumn = _dataFrame.Columns[_groupByColumnIndex].Clone(empty);
ret.Columns.Insert(ret.Columns.Count, firstColumn);
GroupByColumnDelegate groupByColumnDelegate = new GroupByColumnDelegate((long rowIndex, TKey key) =>
{
firstColumn.Resize(rowIndex + 1);
firstColumn[rowIndex] = key;
});
ColumnDelegate columnDelegate = new ColumnDelegate((int columnIndex, long rowIndex, ICollection<long> rowEnumerable, TKey key, bool firstGroup) =>
{
DataFrameColumn retColumn = ResizeAndInsertColumn(columnIndex, rowIndex, firstGroup, ret, empty);
if (!(retColumn is null))
{
retColumn[rowIndex] = _dataFrame.Columns[columnIndex].Max(rowEnumerable);
}
});
EnumerateColumnsWithRows(groupByColumnDelegate, columnDelegate, columnNames);
ret.SetTableRowCount(firstColumn.Length);
return ret;
}
public override DataFrame Min(params string[] columnNames)
{
DataFrame ret = new DataFrame();
PrimitiveDataFrameColumn<long> empty = new PrimitiveDataFrameColumn<long>("Empty");
DataFrameColumn firstColumn = _dataFrame.Columns[_groupByColumnIndex].Clone(empty);
ret.Columns.Insert(ret.Columns.Count, firstColumn);
GroupByColumnDelegate groupByColumnDelegate = new GroupByColumnDelegate((long rowIndex, TKey key) =>
{
firstColumn.Resize(rowIndex + 1);
firstColumn[rowIndex] = key;
});
ColumnDelegate columnDelegate = new ColumnDelegate((int columnIndex, long rowIndex, ICollection<long> rowEnumerable, TKey key, bool firstGroup) =>
{
DataFrameColumn retColumn = ResizeAndInsertColumn(columnIndex, rowIndex, firstGroup, ret, empty);
if (!(retColumn is null))
{
retColumn[rowIndex] = _dataFrame.Columns[columnIndex].Min(rowEnumerable);
}
});
EnumerateColumnsWithRows(groupByColumnDelegate, columnDelegate, columnNames);
ret.SetTableRowCount(firstColumn.Length);
return ret;
}
public override DataFrame Product(params string[] columnNames)
{
DataFrame ret = new DataFrame();
PrimitiveDataFrameColumn<long> empty = new PrimitiveDataFrameColumn<long>("Empty");
DataFrameColumn firstColumn = _dataFrame.Columns[_groupByColumnIndex].Clone(empty);
ret.Columns.Insert(ret.Columns.Count, firstColumn);
GroupByColumnDelegate groupByColumnDelegate = new GroupByColumnDelegate((long rowIndex, TKey key) =>
{
firstColumn.Resize(rowIndex + 1);
firstColumn[rowIndex] = key;
});
ColumnDelegate columnDelegate = new ColumnDelegate((int columnIndex, long rowIndex, ICollection<long> rowEnumerable, TKey key, bool firstGroup) =>
{
DataFrameColumn retColumn = ResizeAndInsertColumn(columnIndex, rowIndex, firstGroup, ret, empty);
if (!(retColumn is null))
{
retColumn[rowIndex] = _dataFrame.Columns[columnIndex].Product(rowEnumerable);
}
});
EnumerateColumnsWithRows(groupByColumnDelegate, columnDelegate, columnNames);
ret.SetTableRowCount(firstColumn.Length);
return ret;
}
public override DataFrame Sum(params string[] columnNames)
{
DataFrame ret = new DataFrame();
PrimitiveDataFrameColumn<long> empty = new PrimitiveDataFrameColumn<long>("Empty");
DataFrameColumn firstColumn = _dataFrame.Columns[_groupByColumnIndex].Clone(empty);
ret.Columns.Insert(ret.Columns.Count, firstColumn);
GroupByColumnDelegate groupByColumnDelegate = new GroupByColumnDelegate((long rowIndex, TKey key) =>
{
firstColumn.Resize(rowIndex + 1);
firstColumn[rowIndex] = key;
});
ColumnDelegate columnDelegate = new ColumnDelegate((int columnIndex, long rowIndex, ICollection<long> rowEnumerable, TKey key, bool firstGroup) =>
{
DataFrameColumn retColumn = ResizeAndInsertColumn(columnIndex, rowIndex, firstGroup, ret, empty);
if (!(retColumn is null))
{
retColumn[rowIndex] = _dataFrame.Columns[columnIndex].Sum(rowEnumerable);
}
});
EnumerateColumnsWithRows(groupByColumnDelegate, columnDelegate, columnNames);
ret.SetTableRowCount(firstColumn.Length);
return ret;
}
public override DataFrame Mean(params string[] columnNames)
{
DataFrame ret = new DataFrame();
PrimitiveDataFrameColumn<long> empty = new PrimitiveDataFrameColumn<long>("Empty");
DataFrameColumn firstColumn = _dataFrame.Columns[_groupByColumnIndex].Clone(empty);
ret.Columns.Insert(ret.Columns.Count, firstColumn);
GroupByColumnDelegate groupByColumnDelegate = new GroupByColumnDelegate((long rowIndex, TKey key) =>
{
firstColumn.Resize(rowIndex + 1);
firstColumn[rowIndex] = key;
});
ColumnDelegate columnDelegate = new ColumnDelegate((int columnIndex, long rowIndex, ICollection<long> rowEnumerable, TKey key, bool firstGroup) =>
{
DataFrameColumn retColumn = ResizeAndInsertColumn(columnIndex, rowIndex, firstGroup, ret, empty, (name) => new PrimitiveDataFrameColumn<double>(name));
if (!(retColumn is null))
{
retColumn[rowIndex] = (double)Convert.ChangeType(_dataFrame.Columns[columnIndex].Sum(rowEnumerable), typeof(double)) / rowEnumerable.Count;
}
});
EnumerateColumnsWithRows(groupByColumnDelegate, columnDelegate, columnNames);
ret.SetTableRowCount(firstColumn.Length);
return ret;
}
/// <summary>
/// Returns a collection of Grouping objects, where each object represent a set of DataFrameRows having the same Key
/// </summary>
public IEnumerable<IGrouping<TKey, DataFrameRow>> Groupings
{
get
{
return _keyToRowIndicesMap.Select(kvp => new Grouping(kvp.Key, kvp.Value.Select(index => _dataFrame.Rows[index])));
}
}
}
}