python - How to test for nan's in an apply function in pandas? -

i have simple apply function execute on of columns. but, keeps getting tripped nan values in pandas.

input_data = np.array( [ [random.randint(0,9) x in range(2)]+['']+['g'], [random.randint(0,9) x in range(3)]+['g'], [random.randint(0,9) x in range(3)]+['a'], [random.randint(0,9) x in range(3)]+['b'], [random.randint(0,9) x in range(3)]+['b'] ] )  input_df = pd.dataframe(data=input_data, columns=['b', 'c', 'd', 'label']) 

i have simple lambda this:

input_df['d'].apply(lambda acode: re.sub('\.', '', acode) if not np.isnan(acode) else acode) 

and gets tripped nan values:

file "<pyshell#460>", line 1, in <lambda>     input_df['d'].apply(lambda acode: re.sub('\.', '', acode) if not np.isnan(acode) else acode) typeerror: not implemented type 

so, tried testing nan values pandas adds:

np.isnan(input_df['d'].values[0]) np.isnan(input_df['d'].iloc[0]) 

both same error.

i not know how test nan values other np.isnan. there easier way this? thanks.

your code fails because first entry empty string , np.isnan doesn't understand empty strings:

in [55]: input_df['d'].iloc[0]  out[55]: ''  in [56]: np.isnan('')  --------------------------------------------------------------------------- typeerror                                 traceback (most recent call last) <ipython-input-56-a9f139a0c5b8> in <module>() ----> 1 np.isnan('')  typeerror: not implemented type 

ps.notnull work:

in [57]: import re input_df['d'].apply(lambda acode: re.sub('\.', '', acode) if pd.notnull(acode) else acode)  out[57]: 0      1    3 2    3 3    0 4    3 name: d, dtype: object 

however, if want replace use .str.replace:

in [58]: input_df['d'].str.replace('\.','')  out[58]: 0      1    3 2    3 3    0 4    3 name: d, dtype: object