ufunc 'isnan' not supported for the input types-CodePudding

I have a df where a particular col has several null values. I want to extract the first non null value.

print(df.kst_erloes_stpfl.to_list())
[nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, 'WH042700', 90510000, 90510000]

import numpy as np

def not_na(array):
    return ~np.isnan(array)

def first_not_na_value(array):
    return list(filter(not_na, array))[0]

first = first_not_na_value(df.kst_erloes_stpfl)
print(first)

However, I get this error:

TypeError: ufunc 'isnan' not supported for the input types, and the inputs could not be safely coerced to any supported types according to the casting rule ''safe''

What else can I try to extract the first non null value?

CodePudding user response：

The easiest way is to use pandas built-in function dropna:

import numpy as np
import pandas as pd

values = [np.nan, np.nan, np.nan, np.nan, np.nan, np.nan, np.nan, np.nan,
          np.nan, np.nan, np.nan, np.nan, np.nan, 'WH042700', 90510000, 90510000]

df = pd.DataFrame(values)

first_non_na = df.dropna().iloc[0,0]

print(first_non_na)