Read in file and return pandas data_frame.

    Parameters
    ----------
    filename : Filename including path.

    Returns
    -------
    df : pandas data frame

def file_to_df(file_name):
    """Read in file and return pandas data_frame.

    Parameters
    ----------
    filename : Filename including path.

    Returns
    -------
    df : pandas data frame
    """
    filename, file_extension = os.path.splitext(file_name)
    if file_extension=='.csv':
        df = pd.read_csv(file_name, sep=',', header=0).iloc[:,1:]
    elif file_extension=='.tsv':
        df = pd.read_csv(file_name, sep='\t', header=0).iloc[:,1:]
    else:
        print('Please provide valid csv or tsv file format with header names.')
    return(df)