def convert_to_float(lst, purpose):
    """
    Returns list of all float-convertable values of `lst`,
    along with length of new list
    """
    float_times = []
    len_times = 0
    for t in lst:
        if (str(t)[:3] != 'DNF') and (t != '') and (str(t)[-1] != '+'):
            float_times.append(float(t))
            len_times += 1
        elif str(t)[-1] == '+':
            if purpose == 'average':
                float_times.append(float(t[:-1]))
                len_times += 1
            elif purpose == 'single':
                float_times.append(t)
                len_times += 1
    return float_times, len_times