Perform Z-Normalization on each numeric column of the given table.

    Parameters
    ----------
    table : pandas.DataFrame or numpy.ndarray
        Data to standardize.

    with_std : bool, optional, default: True
        If ``False`` data is only centered and not converted to unit variance.

    Returns
    -------
    normalized : pandas.DataFrame
        Table with numeric columns normalized.
        Categorical columns in the input table remain unchanged.

def standardize(table, with_std=True):
    """
    Perform Z-Normalization on each numeric column of the given table.

    Parameters
    ----------
    table : pandas.DataFrame or numpy.ndarray
        Data to standardize.

    with_std : bool, optional, default: True
        If ``False`` data is only centered and not converted to unit variance.

    Returns
    -------
    normalized : pandas.DataFrame
        Table with numeric columns normalized.
        Categorical columns in the input table remain unchanged.
    """
    if isinstance(table, pandas.DataFrame):
        cat_columns = table.select_dtypes(include=['category']).columns
    else:
        cat_columns = []

    new_frame = _apply_along_column(table, standardize_column, with_std=with_std)

    # work around for apply converting category dtype to object
    # https://github.com/pydata/pandas/issues/9573
    for col in cat_columns:
        new_frame[col] = table[col].copy()

    return new_frame