def is_normalized(exprsn):
    """ Check whether the expression profile has been normalized or not

    Parameters
    ----------
    exprsn : pd.DataFrame
        Gene expression profile, index by gene id and columns by sample id

    Returns
    -------
    Boolean
        Information about whether the expression profile has been normalized
    """
    posNegRatio = (exprsn > 0).unstack().value_counts() / float(exprsn.
        shape[0] * exprsn.shape[1])
    sign = posNegRatio.max()
    if sign > 0.8:
        print(
            '[WARN] The majority(>80%) of genes with {} expression in your inputted data. Please Normalize your data'
            .format({(True): 'positive', (False): 'negative'}[posNegRatio.
            idxmax()]))
        return False
    else:
        return True
