Pandas - find first non-null value in column

Question

If I have a series that has either NULL or some non-null value. How can I find the 1st row where the value is not NULL so I can report back the datatype to the user. If the value is non-null all values are the same datatype in that series.

Thanks

Answer 1

You can use first_valid_index with select by loc:

s = pd.Series([np.nan,2,np.nan]) print (s) 0    NaN 1    2.0 2    NaN dtype: float64  print (s.first_valid_index()) 1  print (s.loc[s.first_valid_index()]) 2.0  # If your Series contains ALL NaNs, you'll need to check as follows:  s = pd.Series([np.nan, np.nan, np.nan]) idx = s.first_valid_index()  # Will return None first_valid_value = s.loc[idx] if idx is not None else None print(first_valid_value) None