Load the datafiles and return cov, mag, phase and fpi phase values.

def read_datafiles(files, dtype, column):
    '''Load the datafiles and return cov, mag, phase and fpi phase values.
    '''
    pha = []
    pha_fpi = []
    for filename, filetype in zip(files, dtype):
        if filetype == 'cov':
            cov = load_cov(filename)
        elif filetype == 'mag':
            mag = load_rho(filename, column)
        elif filetype == 'pha':
            pha = load_rho(filename, 2)
        elif filetype == 'pha_fpi':
            pha_fpi = load_rho(filename, 2)

    return cov, mag, pha, pha_fpi