/// <summary>
/// Selects a set of columns. This is a variant of `select` that can only select
/// existing columns using column names (i.e. cannot construct expressions).
///
/// df.Select("colA", "colB")
///
/// </summary>
/// <param name="firstColumnName">first column name - required</param>
/// <param name="otherColumnNames">other column names - optional</param>
/// <returns></returns>
public DataFrame Select(string firstColumnName, params string[] otherColumnNames)
{
return(new DataFrame(dataFrameProxy.Select(firstColumnName, otherColumnNames), sparkContext));
}