mjd mjd - 2 months ago 14
Python Question

Elegant way to create empty pandas DataFrame with NaN of type float

I want to create a Pandas DataFrame filled with NaNs. During my research I found an answer:

import pandas as pd

df = pd.DataFrame(index=range(0,4),columns=['A'])


This code results in a DataFrame filled with NaNs of type "object". So they cannot be used later on for example with the interpolate() method. Therefore, I created the DataFrame with this complicated code (inspired by this answer):

import pandas as pd
import numpy as np

dummyarray = np.empty((4,1))
dummyarray[:] = np.nan

df = pd.DataFrame(dummyarray)


This results in a DataFrame filled with NaN of type "float", so it can be used later on with interpolate(). Is there a more elegant way to create the same result?

Answer

This one-liner seems to work as well:

 >>> df = pd.DataFrame(np.nan, index=[0,1,2,3], columns=['A'])
 >>> df.dtypes
 A    float64
 dtype: object
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