Use pandas as backend

[engFelipeMonteiro]

I sugest that makes possible to make the metrics labeled based on a pandas dataframe, follows the code segment for this logic, for 1 metric.

 >>> s = pd.DataFrame({'a': [1.1,2.2,3.3,4.4], 'b':[5.1,6.2,7.3,8.4]})
 >>> make_str = lambda x: "metric01(a={}, b={})".format(x['a'],x['b'])
 >>> a = s.apply(make_str , axis=1)
 >>> a
0    metric01(a=1.1, b=5.1)
1    metric01(a=2.2, b=6.2)
2    metric01(a=3.3, b=7.3)
3    metric01(a=4.4, b=8.4)
# convert to string
>>> a.to_string()
'0    metric01(a=1.1, b=5.1)\n1    metric01(a=2.2, b=6.2)\n2    metric01(a=3.3, b=7.3)\n3    metric01(a=4.4, b=8.4)'

the columns becomes label of metric