Takes the proportion data from relative_abundance() and applies the
    variance stabilizing arcsine square root transformation:

    X = sin^{-1} \sqrt p

def arcsine_sqrt_transform(rel_abd):
    """
    Takes the proportion data from relative_abundance() and applies the
    variance stabilizing arcsine square root transformation:

    X = sin^{-1} \sqrt p
    """
    arcsint = lambda p: math.asin(math.sqrt(p))
    return {col_id: {row_id: arcsint(rel_abd[col_id][row_id])
                     for row_id in rel_abd[col_id]} for col_id in rel_abd}