pandas (original) (raw)

related #4805

It would be nice to allow automatic conversion to a MultiIndex when a dict with tuple keys is passed into the DataFrame constructor. Here's what currently happens:

from pandas import Index, DataFrame from numpy.random import rand import itertools as itools d = {(i, j): rand(10) for i, j in itools.product(xrange(3), repeat=2)} df = DataFrame(d) assert type(df.columns) == Index

The same issue shows up in pd.concat when you pass in a dict of sequences (lists and ndarrays and friends) and axis=1, however if you have a dict of DataFrames the columns keys are converted to a MultiIndex. E.g.,

from pandas import MultiIndex d = {(i, j): DataFrame(rand(10, 2), columns=['a', 'b']) for i, j in itools.product(xrange(3), repeat=2)} df = pd.concat(d, axis=1) assert type(df.columns) == MultiIndex