def standard(X):
    """
    standard : This function makes data ragbe between 0 and 1.
    
    Arguments:
        X (numoy array) : input data.
    
    --------
    Returns:
        standard data.
    """
    xmin = X.min()
    X = X-xmin
    xmax = X.max()
    X = X/xmax
    return X