You can try this line of code:
pdDataFrame = pd.DataFrame([np.nan] * 7)
This will create a pandas dataframe of size 7 with NaN of type float:
if you print pdDataFrame
the output will be:
0
0 NaN
1 NaN
2 NaN
3 NaN
4 NaN
5 NaN
6 NaN
Also the output for pdDataFrame.dtypes
is:
0 float64
dtype: object