how to name the output dataframe generated by python-ply
<p>How can I name the data frame generated by the following code?</p>

<pre><code>import re
import os
import csv
import codecs
import numpy as np
import matplotlib as p
import pdb
import pandas as pd
from pandas_ply import install_ply, X, sym_call

install_ply(pd)



(data_merged
    .groupby('index')
    .ply_select(
        count = X.index.count(),
        p_avg = X.item_price.mean()
        ))
</code></pre>