I have a big dataset, where in one of the columns I want to replace all the NaN values by "ZZZ". I have already done this:
df['code_diag_secund_icd10'].fillna("ZZZ", inplace = True)
However, when I do
df['code_diag_secund_icd10'].isnull().sum()
It gives me the same amount of nan values as before.
Anyone can help me, please?