/// <summary>
/// Selects rows in which the value of the given column matches the given criteria.
/// </summary>
/// <typeparam name="T">The type of the row data.</typeparam>
/// <param name="columnName">The name of the column.</param>
/// <param name="selector">A function which accepts or rejects values.</param>
/// <returns>A new view, containing only those rows in which the <paramref name="columnName"/> value was accepted by
/// the <paramref name="selector"/>.</returns>
public DataView Where <T> (string columnName, Func <T, bool> selector)
{
if (columnName == null)
{
throw new ArgumentNullException(nameof(columnName));
}
if (selector == null)
{
throw new ArgumentNullException(nameof(selector));
}
int columnIndex = GetColumnIndex(columnName);
IReadOnlyDataList <T> column = (IReadOnlyDataList <T>)columns[columnIndex];
List <int> newMap = new List <int>();
for (int i = 0; i < map.Count; i++)
{
T value = column[map[i]];
bool include = selector(value);
if (include)
{
newMap.Add(map[i]);
}
}
return(new DataView(this.columns, newMap));
}
/// <summary>
/// Sorts all rows by the given function of the given column.
/// </summary>
/// <typeparam name="T">The type of values being compared.</typeparam>
/// <param name="columnName">The column to sort on.</param>
/// <param name="comparer">A comparison function of <paramref name="columnName"/> values.</param>
/// <returns>A view of the data sorted by the function of the given column.</returns>
public DataView OrderBy <T>(string columnName, Comparison <T> comparer)
{
if (columnName == null)
{
throw new ArgumentNullException(nameof(columnName));
}
if (comparer == null)
{
throw new ArgumentNullException(nameof(comparer));
}
int columnIndex = GetColumnIndex(columnName);
IReadOnlyDataList <T> column = (IReadOnlyDataList <T>)columns[columnIndex];
List <int> newMap = new List <int>(map);
newMap.Sort((i, j) => comparer(column[i], column[j]));
return(new DataView(this.columns, newMap));
}