def getColData(data, colnums = None, colnames = None, copy=False):
    """
    Get data from a DataFrame column(s)
    
    Inputs:
      > data: The DataFrame
      > colnums: The number(s) of the column(s)
      > colnames: The name(s) of the column(s)
      > copy (False by default): should we copy the data?
      
    Output:
      > DataFrame of the specified column data
    """
    if colnums is not None:
        if copy is True:
            subdata = data.iloc[:,colnums].copy()
        else:
            subdata = data.iloc[:,colnums]
    elif colnames is not None:
        if copy is True:
            subdata = data[colnames].copy()
        else:
            subdata = data[colnames]         
    else:
        print("Not doing anything with the data in getColData")
        return data
    return subdata