def to_str(s, integer=True):
    """Convert a column to strings
    usage: new_var = data.apply(lambda f : to_str(f['COLNAME']) , axis = 1)
    integer: boolean for whether to convert to int first
    """

    try:
        if integer:
            s1 = str(int(s))

        else:
            s1 = str(s)

        return s1

    except ValueError:
        return s