protected ColumnBase DoColumn <T> (ColumnBase oldcol, Dictionary <long, int> map, Timeline axis)
{
RCArray <int> index;
RCArray <T> data;
ApplyArrayRank((RCArray <T>)oldcol.Array, oldcol.Index, map, axis.Count, out data, out index);
ColumnBase result = ColumnBase.FromArray(axis, index, data);
return(result);
}