def normalize(df, nrm_list):
    """ Normalize samples in the phospho dataset by normalized intensities computed
    from the reference (the largest) dataset.

    Parameters
    ----------
    df : pandas dataframe
        pST or pY (single or composite) dataset.
    nrm_list : list of floats
        normalized intensities computed from the reference
        (the largest) dataset.

    Returns
    -------
    df2 : pandas dataframe
        Normalized pST or pY (single or composite) dataset.
    """
    samples = [c for c in df.columns.tolist() if '_sn_sum' in c]
    df2 = df.copy()
    df2[samples] = df2[samples].multiply(nrm_list)
    return df2