def txt_category_to_dict(category_str):
    """
    Parameters
    ----------
    category_str: str of nominal values from dataset meta information

    Returns
    -------
    dict of the nominal values and their one letter encoding

    Example
    -------
    "bell=b, convex=x" -> {"bell": "b", "convex": "x"}
    """

    string_as_words = category_str.split()
    result_dict = {}
    for word in string_as_words:
        seperator_pos = word.find("=")
        key = word[: seperator_pos]
        val = word[seperator_pos + 1 :][0]
        result_dict[key] = val
    return result_dict